Added working first stuff.

src/main/java/nl/andrewl/coyotecredit/config/WebMvcConfig.java

@@ -0,0 +1,19 @@
+package nl.andrewl.coyotecredit.config;
+
+import org.springframework.context.annotation.Configuration;
+import org.springframework.http.CacheControl;
+import org.springframework.web.servlet.config.annotation.ResourceHandlerRegistry;
+import org.springframework.web.servlet.config.annotation.WebMvcConfigurer;
+
+import java.time.Duration;
+
+@Configuration
+public class WebMvcConfig implements WebMvcConfigurer {
+	@Override
+	public void addResourceHandlers(ResourceHandlerRegistry registry) {
+		registry.addResourceHandler("/static/**")
+				.addResourceLocations("classpath:/static/")
+				.setOptimizeLocations(true)
+				.setCacheControl(CacheControl.maxAge(Duration.ofHours(1)));
+	}
+}

src/main/java/nl/andrewl/coyotecredit/config/WebSecurityConfig.java

@@ -26,7 +26,7 @@ public class WebSecurityConfig extends WebSecurityConfigurerAdapter {
 		http
 			.authorizeRequests()
 				.antMatchers(
-						"/login", "/login/processing"
+						"/login", "/login/processing", "/static/**"
 				).permitAll()
 				.and()
 			.authorizeRequests().anyRequest().authenticated()

src/main/java/nl/andrewl/coyotecredit/ctl/AccountPage.java

@@ -1,14 +1,18 @@
 package nl.andrewl.coyotecredit.ctl;
 
+import com.fasterxml.jackson.databind.node.ObjectNode;
 import lombok.RequiredArgsConstructor;
 import nl.andrewl.coyotecredit.model.User;
 import nl.andrewl.coyotecredit.service.AccountService;
+import org.springframework.http.HttpStatus;
 import org.springframework.security.core.annotation.AuthenticationPrincipal;
 import org.springframework.stereotype.Controller;
 import org.springframework.ui.Model;
-import org.springframework.web.bind.annotation.GetMapping;
+import org.springframework.util.MultiValueMap;
-import org.springframework.web.bind.annotation.PathVariable;
+import org.springframework.web.bind.annotation.*;
-import org.springframework.web.bind.annotation.RequestMapping;
+import org.springframework.web.server.ResponseStatusException;
+
+import java.util.Map;
 
 @Controller
 @RequestMapping(path = "/accounts/{accountId}")
@@ -26,4 +30,18 @@ public class AccountPage {
 		model.addAttribute("account", data);
 		return "account";
 	}
+
+	@GetMapping(path = "/editBalances")
+	public String getEditBalancesPage(Model model, @PathVariable long accountId, @AuthenticationPrincipal User user) {
+		var data = accountService.getAccountData(user, accountId);
+		if (!data.userAdmin()) throw new ResponseStatusException(HttpStatus.NOT_FOUND);
+		model.addAttribute("account", data);
+		return "account/edit_balances";
+	}
+
+	@PostMapping(path = "/editBalances")
+	public String postEditBalances(@PathVariable long accountId, @AuthenticationPrincipal User user, @RequestParam MultiValueMap<String, String> paramMap) {
+		accountService.editBalances(accountId, user, paramMap);
+		return "redirect:/accounts/" + accountId;
+	}
 }

src/main/java/nl/andrewl/coyotecredit/ctl/ExchangePage.java

@@ -0,0 +1,53 @@
+package nl.andrewl.coyotecredit.ctl;
+
+import lombok.RequiredArgsConstructor;
+import nl.andrewl.coyotecredit.ctl.dto.AddAccountPayload;
+import nl.andrewl.coyotecredit.model.User;
+import nl.andrewl.coyotecredit.service.ExchangeService;
+import org.springframework.security.core.annotation.AuthenticationPrincipal;
+import org.springframework.stereotype.Controller;
+import org.springframework.ui.Model;
+import org.springframework.web.bind.annotation.*;
+
+@Controller
+@RequestMapping(path = "/exchanges/{exchangeId}")
+@RequiredArgsConstructor
+public class ExchangePage {
+	private final ExchangeService exchangeService;
+
+	@GetMapping
+	public String get(Model model, @PathVariable long exchangeId, @AuthenticationPrincipal User user) {
+		model.addAttribute("exchange", exchangeService.getData(exchangeId, user));
+		return "exchange";
+	}
+
+	@GetMapping(path = "/accounts")
+	public String getAccountsPage(Model model, @PathVariable long exchangeId, @AuthenticationPrincipal User user) {
+		model.addAttribute("accounts", exchangeService.getAccounts(exchangeId, user));
+		return "exchange/accounts";
+	}
+
+	@GetMapping(path = "/addAccount")
+	public String getAddAccountPage(@PathVariable long exchangeId, @AuthenticationPrincipal User user) {
+		exchangeService.ensureAdminAccount(exchangeId, user);
+		return "exchange/addAccount";
+	}
+
+	@PostMapping(path = "/addAccount")
+	public String postAddAcount(@PathVariable long exchangeId, @AuthenticationPrincipal User user, @ModelAttribute AddAccountPayload payload) {
+		long accountId = exchangeService.addAccount(exchangeId, user, payload);
+		return "redirect:/accounts/" + accountId;
+	}
+
+	@GetMapping(path = "/removeAccount/{accountId}")
+	public String getRemoveAccountPage(@PathVariable long exchangeId, @PathVariable long accountId, @AuthenticationPrincipal User user) {
+		exchangeService.ensureAdminAccount(exchangeId, user);
+		return "exchange/removeAccount";
+	}
+
+	@PostMapping(path = "/removeAccount/{accountId}")
+	public String postRemoveAccount(@PathVariable long exchangeId, @PathVariable long accountId, @AuthenticationPrincipal User user) {
+		exchangeService.removeAccount(exchangeId, accountId, user);
+		return "redirect:/exchanges/" + exchangeId + "/accounts";
+	}
+}

src/main/java/nl/andrewl/coyotecredit/ctl/TradePage.java

@@ -0,0 +1,41 @@
+package nl.andrewl.coyotecredit.ctl;
+
+import lombok.RequiredArgsConstructor;
+import nl.andrewl.coyotecredit.ctl.dto.TradePayload;
+import nl.andrewl.coyotecredit.model.User;
+import nl.andrewl.coyotecredit.service.ExchangeService;
+import nl.andrewl.coyotecredit.service.TradeService;
+import org.springframework.security.core.annotation.AuthenticationPrincipal;
+import org.springframework.stereotype.Controller;
+import org.springframework.ui.Model;
+import org.springframework.web.bind.annotation.*;
+
+import javax.validation.Valid;
+
+@Controller
+@RequestMapping(path = "/trade/{accountId}")
+@RequiredArgsConstructor
+public class TradePage {
+	private final TradeService tradeService;
+	private final ExchangeService exchangeService;
+
+	@GetMapping
+	public String get(
+			Model model,
+			@PathVariable long accountId,
+			@AuthenticationPrincipal User user
+	) {
+		model.addAttribute("data", tradeService.getTradeData(accountId, user));
+		return "trade";
+	}
+
+	@PostMapping
+	public String doTrade(
+			@PathVariable long accountId,
+			@AuthenticationPrincipal User user,
+			@ModelAttribute @Valid TradePayload payload
+	) {
+		exchangeService.doTrade(accountId, payload, user);
+		return "redirect:/accounts/" + accountId;
+	}
+}

src/main/java/nl/andrewl/coyotecredit/ctl/UserPage.java

@@ -0,0 +1,24 @@
+package nl.andrewl.coyotecredit.ctl;
+
+import lombok.RequiredArgsConstructor;
+import nl.andrewl.coyotecredit.model.User;
+import nl.andrewl.coyotecredit.service.UserService;
+import org.springframework.security.core.annotation.AuthenticationPrincipal;
+import org.springframework.stereotype.Controller;
+import org.springframework.ui.Model;
+import org.springframework.web.bind.annotation.GetMapping;
+import org.springframework.web.bind.annotation.PathVariable;
+import org.springframework.web.bind.annotation.RequestMapping;
+
+@Controller
+@RequestMapping(path = "/users/{userId}")
+@RequiredArgsConstructor
+public class UserPage {
+	private final UserService userService;
+
+	@GetMapping
+	public String get(Model model, @PathVariable long userId, @AuthenticationPrincipal User user) {
+		model.addAttribute("user", userService.getUser(userId, user));
+		return "user";
+	}
+}

src/main/java/nl/andrewl/coyotecredit/ctl/api/ExchangeApiController.java

@@ -0,0 +1,22 @@
+package nl.andrewl.coyotecredit.ctl.api;
+
+import lombok.RequiredArgsConstructor;
+import nl.andrewl.coyotecredit.service.ExchangeService;
+import org.springframework.web.bind.annotation.GetMapping;
+import org.springframework.web.bind.annotation.PathVariable;
+import org.springframework.web.bind.annotation.RequestMapping;
+import org.springframework.web.bind.annotation.RestController;
+
+import java.util.Map;
+
+@RestController
+@RequestMapping("/api/exchanges/{exchangeId}")
+@RequiredArgsConstructor
+public class ExchangeApiController {
+	private final ExchangeService exchangeService;
+
+	@GetMapping(path = "/tradeables")
+	public Map<Long, String> getCurrentTradeables(@PathVariable long exchangeId) {
+		return exchangeService.getCurrentTradeables(exchangeId);
+	}
+}

src/main/java/nl/andrewl/coyotecredit/ctl/dto/AddAccountPayload.java

@@ -0,0 +1,7 @@
+package nl.andrewl.coyotecredit.ctl.dto;
+
+public record AddAccountPayload(
+		String name,
+		String username,
+		String password
+) {}

src/main/java/nl/andrewl/coyotecredit/ctl/dto/BalanceData.java

@@ -0,0 +1,7 @@
+package nl.andrewl.coyotecredit.ctl.dto;
+
+public record BalanceData(
+	long id,
+	String symbol,
+	String amount
+) {}

src/main/java/nl/andrewl/coyotecredit/ctl/dto/ExchangeData.java

@@ -0,0 +1,8 @@
+package nl.andrewl.coyotecredit.ctl.dto;
+
+public record ExchangeData(
+		long id,
+		String name,
+		String primaryTradeable
+) {
+}

src/main/java/nl/andrewl/coyotecredit/ctl/dto/FullAccountData.java

@@ -0,0 +1,19 @@
+package nl.andrewl.coyotecredit.ctl.dto;
+
+import java.util.List;
+
+/**
+ * The data that's needed for displaying a user's account page.
+ */
+public record FullAccountData (
+		long id,
+		String number,
+		String name,
+		boolean admin,
+		boolean userAdmin,
+		ExchangeData exchange,
+		List<BalanceData> balances,
+		String totalBalance,
+		List<TransactionData> recentTransactions
+) {
+}

src/main/java/nl/andrewl/coyotecredit/ctl/dto/FullExchangeData.java

@@ -0,0 +1,16 @@
+package nl.andrewl.coyotecredit.ctl.dto;
+
+import java.util.List;
+
+/**
+ * The data that's used on the exchange page.
+ */
+public record FullExchangeData (
+		long id,
+		String name,
+		TradeableData primaryTradeable,
+		List<TradeableData> supportedTradeables,
+		// Account info
+		boolean accountAdmin
+) {
+}

src/main/java/nl/andrewl/coyotecredit/ctl/dto/SimpleAccountData.java

@@ -0,0 +1,10 @@
+package nl.andrewl.coyotecredit.ctl.dto;
+
+public record SimpleAccountData (
+		long id,
+		String number,
+		String name,
+		boolean admin,
+		String totalBalance
+) {
+}

src/main/java/nl/andrewl/coyotecredit/ctl/dto/TradeData.java

@@ -0,0 +1,14 @@
+package nl.andrewl.coyotecredit.ctl.dto;
+
+import java.math.BigDecimal;
+import java.util.List;
+import java.util.Map;
+
+public record TradeData(
+		long accountId,
+		String accountNumber,
+		long exchangeId,
+		List<TradeableData> tradeablesToSell,
+		Map<String, BigDecimal> accountBalances,
+		List<TradeableData> tradeablesToBuy
+) {}

src/main/java/nl/andrewl/coyotecredit/ctl/dto/TradePayload.java

@@ -0,0 +1,23 @@
+package nl.andrewl.coyotecredit.ctl.dto;
+
+/**
+ * The payload that's sent when a user performs a trade with the market. This
+ * can be either a SELL or a BUY trade.
+ *
+ * <p>
+ *     In a SELL trade, the user indicates an amount of their selling tradeable
+ *     to sell in exchange for the market-equivalent value of the buying
+ *     tradeable.
+ * </p>
+ * <p>
+ *     In a BUY trade, the opposite happens, where the user indicates how much
+ *     of the buying tradeable they want to acquire, and will have a market-
+ *     equivalent value deducted from their selling tradeable.
+ * </p>
+ */
+public record TradePayload(
+		String type, // SELL or BUY
+		long sellTradeableId,
+		long buyTradeableId,
+		String value
+) {}

src/main/java/nl/andrewl/coyotecredit/ctl/dto/TradeableData.java

@@ -0,0 +1,23 @@
+package nl.andrewl.coyotecredit.ctl.dto;
+
+import nl.andrewl.coyotecredit.model.Tradeable;
+
+public record TradeableData(
+		long id,
+		String symbol,
+		String type,
+		String marketPriceUsd,
+		String name,
+		String description
+) {
+	public TradeableData(Tradeable t) {
+		this(
+				t.getId(),
+				t.getSymbol(),
+				t.getType().name(),
+				t.getMarketPriceUsd().toPlainString(),
+				t.getName(),
+				t.getDescription()
+		);
+	}
+}

src/main/java/nl/andrewl/coyotecredit/ctl/dto/TransactionData.java

@@ -0,0 +1,25 @@
+package nl.andrewl.coyotecredit.ctl.dto;
+
+import nl.andrewl.coyotecredit.model.Transaction;
+
+import java.time.format.DateTimeFormatter;
+
+public record TransactionData(
+		long id,
+		TradeableData from,
+		String fromAmount,
+		TradeableData to,
+		String toAmount,
+		String timestamp
+) {
+	public TransactionData(Transaction t) {
+		this(
+				t.getId(),
+				new TradeableData(t.getFrom()),
+				t.getFromAmount().toPlainString(),
+				new TradeableData(t.getTo()),
+				t.getToAmount().toPlainString(),
+				t.getTimestamp().format(DateTimeFormatter.ISO_LOCAL_DATE_TIME)
+		);
+	}
+}

src/main/java/nl/andrewl/coyotecredit/ctl/dto/UserData.java

@@ -0,0 +1,6 @@
+package nl.andrewl.coyotecredit.ctl.dto;
+
+public record UserData (
+		long id,
+		String username
+) {}

src/main/java/nl/andrewl/coyotecredit/dao/AccountRepository.java

@@ -1,13 +1,17 @@
 package nl.andrewl.coyotecredit.dao;
 
 import nl.andrewl.coyotecredit.model.Account;
+import nl.andrewl.coyotecredit.model.Exchange;
 import nl.andrewl.coyotecredit.model.User;
 import org.springframework.data.jpa.repository.JpaRepository;
 import org.springframework.stereotype.Repository;
 
 import java.util.List;
+import java.util.Optional;
 
 @Repository
 public interface AccountRepository extends JpaRepository<Account, Long> {
 	List<Account> findAllByUser(User user);
+	Optional<Account> findByNumber(String number);
+	Optional<Account> findByUserAndExchange(User user, Exchange exchange);
 }

src/main/java/nl/andrewl/coyotecredit/dao/ExchangeRepository.java

@@ -0,0 +1,9 @@
+package nl.andrewl.coyotecredit.dao;
+
+import nl.andrewl.coyotecredit.model.Exchange;
+import org.springframework.data.jpa.repository.JpaRepository;
+import org.springframework.stereotype.Repository;
+
+@Repository
+public interface ExchangeRepository extends JpaRepository<Exchange, Long> {
+}

src/main/java/nl/andrewl/coyotecredit/dao/TradeableRepository.java

@@ -0,0 +1,9 @@
+package nl.andrewl.coyotecredit.dao;
+
+import nl.andrewl.coyotecredit.model.Tradeable;
+import org.springframework.data.jpa.repository.JpaRepository;
+import org.springframework.stereotype.Repository;
+
+@Repository
+public interface TradeableRepository extends JpaRepository<Tradeable, Long> {
+}

src/main/java/nl/andrewl/coyotecredit/dao/TransactionRepository.java

@@ -0,0 +1,12 @@
+package nl.andrewl.coyotecredit.dao;
+
+import nl.andrewl.coyotecredit.model.Transaction;
+import org.springframework.data.domain.Page;
+import org.springframework.data.domain.Pageable;
+import org.springframework.data.jpa.repository.JpaRepository;
+import org.springframework.stereotype.Repository;
+
+@Repository
+public interface TransactionRepository extends JpaRepository<Transaction, Long> {
+	Page<Transaction> findAllByAccountNumberOrderByTimestampDesc(String accountNumber, Pageable pageable);
+}

src/main/java/nl/andrewl/coyotecredit/model/Account.java

@@ -6,7 +6,9 @@ import lombok.NoArgsConstructor;
 
 import javax.persistence.*;
 import java.math.BigDecimal;
+import java.math.RoundingMode;
 import java.util.HashMap;
+import java.util.HashSet;
 import java.util.Map;
 import java.util.Set;
 
@@ -22,23 +24,72 @@ public class Account {
 	@GeneratedValue(strategy = GenerationType.IDENTITY)
 	private Long id;
 
+	/**
+	 * The unique account number.
+	 */
 	@Column(nullable = false, unique = true)
 	private String number;
 
+	/**
+	 * The user that this account belongs to.
+	 */
 	@ManyToOne(fetch = FetchType.LAZY, optional = false)
 	private User user;
 
+	/**
+	 * The name on this account.
+	 */
+	@Column
+	private String name;
+
+	/**
+	 * The exchange that this account belongs to.
+	 */
 	@ManyToOne(fetch = FetchType.LAZY, optional = false)
 	private Exchange exchange;
 
+	/**
+	 * Whether this account is an administrator in the exchange it's linked to.
+	 * Administrators have special permissions to add and remove other accounts,
+	 * custom tradeables, exchange rates, and more.
+	 */
+	@Column(nullable = false)
+	private boolean admin;
+
+	/**
+	 * The set of tradeable balances that this account has.
+	 */
 	@OneToMany(mappedBy = "account", fetch = FetchType.LAZY, cascade = CascadeType.ALL, orphanRemoval = true)
 	private Set<Balance> balances;
 
-	public Map<Currency, BigDecimal> getMappedBalances() {
+	public Account(String number, User user, String name, Exchange exchange) {
-		Map<Currency, BigDecimal> b = new HashMap<>();
+		this.number = number;
+		this.user = user;
+		this.name = name;
+		this.exchange = exchange;
+		this.balances = new HashSet<>();
+	}
+
+	public Map<Tradeable, BigDecimal> getMappedBalances() {
+		Map<Tradeable, BigDecimal> b = new HashMap<>();
 		for (var bal : getBalances()) {
-			b.put(bal.getCurrency(), bal.getAmount());
+			b.put(bal.getTradeable(), bal.getAmount());
 		}
 		return b;
 	}
+
+	public Balance getBalanceForTradeable(Tradeable t) {
+		for (var bal : getBalances()) {
+			if (bal.getTradeable().equals(t)) return bal;
+		}
+		return null;
+	}
+
+	public BigDecimal getTotalBalance() {
+		BigDecimal totalUsd = new BigDecimal(0);
+		for (var bal : getBalances()) {
+			totalUsd = totalUsd.add(bal.getTradeable().getMarketPriceUsd().multiply(bal.getAmount()));
+		}
+		return totalUsd.divide(getExchange().getPrimaryTradeable().getMarketPriceUsd(), RoundingMode.HALF_UP);
+	}
 }

src/main/java/nl/andrewl/coyotecredit/model/Balance.java

@@ -1,24 +1,43 @@
 package nl.andrewl.coyotecredit.model;
 
+import lombok.AccessLevel;
 import lombok.Getter;
+import lombok.NoArgsConstructor;
+import lombok.Setter;
 
 import javax.persistence.*;
 import java.math.BigDecimal;
 
+/**
+ * Represents an account's balance for a certain amount of tradeables in their
+ * exchange.
+ */
 @Entity
+@NoArgsConstructor(access = AccessLevel.PROTECTED)
 @Table(name = "account_balance")
 @Getter
 public class Balance {
-	@Id
+	@EmbeddedId
-	@GeneratedValue(strategy = GenerationType.IDENTITY)
+	private BalanceId balanceId;
-	private Long id;
 
+	@MapsId("accountId")
 	@ManyToOne(optional = false, fetch = FetchType.LAZY)
+	@JoinColumn(name = "account_id")
 	private Account account;
 
+	@MapsId("tradeableId")
 	@ManyToOne(optional = false, fetch = FetchType.EAGER)
-	private Currency currency;
+	@JoinColumn(name = "tradeable_id")
+	private Tradeable tradeable;
 
 	@Column(nullable = false, precision = 24, scale = 10)
+	@Setter
 	private BigDecimal amount;
+
+	public Balance(Account account, Tradeable tradeable, BigDecimal amount) {
+		this.balanceId = new BalanceId(tradeable.getId(), account.getId());
+		this.account = account;
+		this.tradeable = tradeable;
+		this.amount = amount;
+	}
 }

src/main/java/nl/andrewl/coyotecredit/model/BalanceId.java

@@ -0,0 +1,17 @@
+package nl.andrewl.coyotecredit.model;
+
+import lombok.AllArgsConstructor;
+import lombok.EqualsAndHashCode;
+import lombok.NoArgsConstructor;
+
+import javax.persistence.Embeddable;
+import java.io.Serializable;
+
+@Embeddable
+@EqualsAndHashCode
+@AllArgsConstructor
+@NoArgsConstructor
+public class BalanceId implements Serializable {
+	private Long tradeableId;
+	private Long accountId;
+}

src/main/java/nl/andrewl/coyotecredit/model/Currency.java

@@ -1,48 +0,0 @@
-package nl.andrewl.coyotecredit.model;
-
-import lombok.Getter;
-
-import javax.persistence.*;
-import java.util.Objects;
-
-/**
- * Represents a type of currency. This can be an actual fiat currency, or
- * perhaps a cryptocurrency, or stocks, or really anything tradeable on the
- * exchange.
- */
-@Entity
-@Table(uniqueConstraints = @UniqueConstraint(columnNames = {"identifier", "type"}))
-@Getter
-public class Currency {
-	@Id
-	@GeneratedValue(strategy = GenerationType.IDENTITY)
-	private Long id;
-
-	@Column(nullable = false)
-	private String identifier;
-
-	@Enumerated(EnumType.STRING)
-	private CurrencyType type;
-
-	@Column(nullable = false)
-	private String name;
-
-	@Column
-	private String description;
-
-	@Column(nullable = false)
-	private float minDenomination = 0.01f;
-
-	@Override
-	public boolean equals(Object other) {
-		if (!(other instanceof Currency c)) return false;
-		if (c.getId() != null && this.getId() != null) return this.getId().equals(c.getId());
-		return this.identifier.equals(c.getIdentifier()) &&
-				this.type.equals(c.getType());
-	}
-
-	@Override
-	public int hashCode() {
-		return Objects.hash(this.identifier, this.type);
-	}
-}

src/main/java/nl/andrewl/coyotecredit/model/CustomTradeable.java

@@ -0,0 +1,20 @@
+package nl.andrewl.coyotecredit.model;
+
+import lombok.AccessLevel;
+import lombok.Getter;
+import lombok.NoArgsConstructor;
+
+import javax.persistence.Entity;
+import javax.persistence.FetchType;
+import javax.persistence.ManyToOne;
+
+@Entity
+@NoArgsConstructor(access = AccessLevel.PROTECTED)
+@Getter
+public class CustomTradeable extends Tradeable {
+	/**
+	 * The exchange that the tradeable belongs to.
+	 */
+	@ManyToOne(optional = false, fetch = FetchType.LAZY)
+	private Exchange exchange;
+}

src/main/java/nl/andrewl/coyotecredit/model/Exchange.java

@@ -1,15 +1,19 @@
 package nl.andrewl.coyotecredit.model;
 
+import lombok.AccessLevel;
 import lombok.Getter;
+import lombok.NoArgsConstructor;
 
 import javax.persistence.*;
 import java.util.HashSet;
+import java.util.Objects;
 import java.util.Set;
 
 /**
  * Represents a large collection of users that interact with each other.
  */
 @Entity
+@NoArgsConstructor(access = AccessLevel.PROTECTED)
 @Getter
 public class Exchange {
 	@Id
@@ -22,15 +26,50 @@ public class Exchange {
 	@Column(nullable = false)
 	private String name;
 
-	@OneToMany(mappedBy = "exchange")
+	/**
-	private Set<ExchangePair> currencyPairs;
+	 * The primary tradeable that's used by this exchange.
+	 */
+	@ManyToOne(optional = false, fetch = FetchType.LAZY)
+	private Tradeable primaryTradeable;
 
-	public Set<Currency> getSupportedCurrencies() {
+	/**
-		Set<Currency> currencies = new HashSet<>();
+	 * The set of tradeables that this exchange allows users to interact with.
-		for (var pair : getCurrencyPairs()) {
+	 */
-			currencies.add(pair.getFromCurrency());
+	@ManyToMany(fetch = FetchType.LAZY)
-			currencies.add(pair.getToCurrency());
+	@JoinTable(
+			name = "exchange_supported_tradeable",
+			joinColumns = @JoinColumn(name = "exchange_id"),
+			inverseJoinColumns = @JoinColumn(name = "tradeable_id")
+	)
+	private Set<Tradeable> supportedTradeables;
+
+	/**
+	 * The set of custom tradeables created specifically for use in this exchange.
+	 */
+	@OneToMany(mappedBy = "exchange", fetch = FetchType.LAZY, cascade = CascadeType.ALL, orphanRemoval = true)
+	private Set<CustomTradeable> customTradeables;
+
+	/**
+	 * The set of accounts that are registered with this exchange.
+	 */
+	@OneToMany(mappedBy = "exchange", fetch = FetchType.LAZY)
+	private Set<Account> accounts;
+
+	public Set<Tradeable> getAllTradeables() {
+		Set<Tradeable> s = new HashSet<>();
+		s.addAll(getSupportedTradeables());
+		s.addAll(getCustomTradeables());
+		return s;
 	}
-		return currencies;
+
+	@Override
+	public boolean equals(Object other) {
+		if (!(other instanceof Exchange e)) return false;
+		return this.getId() != null && e.getId() != null && this.getId().equals(e.getId());
+	}
+
+	@Override
+	public int hashCode() {
+		return Objects.hash(this.getId());
 	}
 }

src/main/java/nl/andrewl/coyotecredit/model/ExchangePair.java

@@ -1,30 +0,0 @@
-package nl.andrewl.coyotecredit.model;
-
-import lombok.Getter;
-
-import javax.persistence.*;
-import java.math.BigDecimal;
-
-/**
- * Represents a pair of currencies that can be exchanged at a set exchange rate.
- */
-@Entity
-@Table(uniqueConstraints = @UniqueConstraint(columnNames = {"from_currency_id", "to_currency_id", "exchange_id"}))
-@Getter
-public class ExchangePair {
-	@Id
-	@GeneratedValue(strategy = GenerationType.IDENTITY)
-	private Long id;
-
-	@ManyToOne(optional = false)
-	private Exchange exchange;
-
-	@ManyToOne(optional = false)
-	private Currency fromCurrency;
-
-	@ManyToOne(optional = false)
-	private Currency toCurrency;
-
-	@Column(nullable = false, precision = 24, scale = 10)
-	private BigDecimal exchangeRate = new BigDecimal("1.0");
-}

src/main/java/nl/andrewl/coyotecredit/model/Tradeable.java

@@ -0,0 +1,59 @@
+package nl.andrewl.coyotecredit.model;
+
+import lombok.AccessLevel;
+import lombok.Getter;
+import lombok.NoArgsConstructor;
+
+import javax.persistence.*;
+import java.math.BigDecimal;
+import java.util.Objects;
+
+/**
+ * Represents a type of currency. This can be an actual fiat currency, or
+ * perhaps a cryptocurrency, or stocks, or really anything tradeable on the
+ * exchange.
+ */
+@Entity
+@Inheritance(strategy = InheritanceType.JOINED)
+@NoArgsConstructor(access = AccessLevel.PROTECTED)
+@Getter
+public class Tradeable {
+	@Id
+	@GeneratedValue(strategy = GenerationType.IDENTITY)
+	private Long id;
+
+	@Column(nullable = false)
+	private String symbol;
+
+	@Enumerated(EnumType.STRING)
+	private TradeableType type;
+
+	@Column(nullable = false, precision = 24, scale = 10)
+	private BigDecimal marketPriceUsd = new BigDecimal(1);
+
+	@Column(nullable = false)
+	private String name;
+
+	@Column
+	private String description;
+
+	public Tradeable(String symbol, TradeableType type, String name, String description, BigDecimal marketPriceUsd) {
+		this.symbol = symbol;
+		this.type = type;
+		this.name = name;
+		this.description = description;
+		this.marketPriceUsd = marketPriceUsd;
+	}
+
+	@Override
+	public boolean equals(Object other) {
+		if (!(other instanceof Tradeable c)) return false;
+		if (this.getId() != null && c.getId() != null) return this.getId().equals(c.getId());
+		return this.getSymbol().equals(c.getSymbol()) && this.getType().equals(c.getType());
+	}
+
+	@Override
+	public int hashCode() {
+		return Objects.hash(this.id, this.symbol);
+	}
+}

src/main/java/nl/andrewl/coyotecredit/model/TradeableType.java

@@ -1,6 +1,6 @@
 package nl.andrewl.coyotecredit.model;
 
-public enum CurrencyType {
+public enum TradeableType {
 	FIAT,
 	CRYPTO,
 	STOCK

src/main/java/nl/andrewl/coyotecredit/model/Transaction.java

@@ -0,0 +1,53 @@
+package nl.andrewl.coyotecredit.model;
+
+import lombok.AccessLevel;
+import lombok.Getter;
+import lombok.NoArgsConstructor;
+import org.hibernate.annotations.CreationTimestamp;
+
+import javax.persistence.*;
+import java.math.BigDecimal;
+import java.time.LocalDateTime;
+
+/**
+ * Represents a permanent record of a trade transaction.
+ */
+@Entity
+@NoArgsConstructor(access = AccessLevel.PROTECTED)
+@Getter
+public class Transaction {
+	@Id
+	@GeneratedValue(strategy = GenerationType.IDENTITY)
+	private Long id;
+
+	@Column(nullable = false)
+	private String accountNumber;
+
+	@ManyToOne(optional = false, fetch = FetchType.LAZY)
+	private Exchange exchange;
+
+	@ManyToOne(optional = false, fetch = FetchType.LAZY)
+	private Tradeable from;
+
+	@Column(nullable = false, precision = 24, scale = 10)
+	private BigDecimal fromAmount;
+
+	@ManyToOne(optional = false, fetch = FetchType.LAZY)
+	private Tradeable to;
+
+	@Column(nullable = false, precision = 24, scale = 10)
+	private BigDecimal toAmount;
+
+	@Column(nullable = false, updatable = false)
+	private LocalDateTime timestamp;
+
+	public Transaction(String accountNumber, Exchange exchange, Tradeable from, BigDecimal fromAmount, Tradeable to, BigDecimal toAmount, LocalDateTime timestamp) {
+		this.accountNumber = accountNumber;
+		this.exchange = exchange;
+		this.from = from;
+		this.fromAmount = fromAmount;
+		this.to = to;
+		this.toAmount = toAmount;
+		this.timestamp = timestamp;
+	}
+}

src/main/java/nl/andrewl/coyotecredit/model/User.java

@@ -1,18 +1,22 @@
 package nl.andrewl.coyotecredit.model;
 
+import lombok.AccessLevel;
 import lombok.Getter;
+import lombok.NoArgsConstructor;
 import org.springframework.security.core.GrantedAuthority;
 import org.springframework.security.core.userdetails.UserDetails;
 
 import javax.persistence.*;
 import java.util.Collection;
 import java.util.Collections;
+import java.util.HashSet;
 import java.util.Set;
 
 /**
  * Represents a basic user in the system.
  */
 @Entity
+@NoArgsConstructor(access = AccessLevel.PROTECTED)
 @Getter
 public class User implements UserDetails {
 	@Id
@@ -31,6 +35,11 @@ public class User implements UserDetails {
 	@OneToMany(fetch = FetchType.LAZY, mappedBy = "user", cascade = CascadeType.ALL, orphanRemoval = true)
 	private Set<Account> accounts;
 
+	public User(String username, String passwordHash) {
+		this.username = username;
+		this.passwordHash = passwordHash;
+		this.accounts = new HashSet<>();
+	}
 
 	// USER DETAILS IMPLEMENTATION
 

src/main/java/nl/andrewl/coyotecredit/service/AccountService.java

@@ -1,22 +1,34 @@
 package nl.andrewl.coyotecredit.service;
 
-import lombok.AllArgsConstructor;
 import lombok.RequiredArgsConstructor;
+import nl.andrewl.coyotecredit.ctl.dto.BalanceData;
+import nl.andrewl.coyotecredit.ctl.dto.ExchangeData;
+import nl.andrewl.coyotecredit.ctl.dto.FullAccountData;
+import nl.andrewl.coyotecredit.ctl.dto.TransactionData;
 import nl.andrewl.coyotecredit.dao.AccountRepository;
+import nl.andrewl.coyotecredit.dao.TradeableRepository;
+import nl.andrewl.coyotecredit.dao.TransactionRepository;
 import nl.andrewl.coyotecredit.model.Account;
+import nl.andrewl.coyotecredit.model.Balance;
+import nl.andrewl.coyotecredit.model.Tradeable;
 import nl.andrewl.coyotecredit.model.User;
+import org.springframework.data.domain.PageRequest;
 import org.springframework.http.HttpStatus;
 import org.springframework.stereotype.Service;
 import org.springframework.transaction.annotation.Transactional;
+import org.springframework.util.MultiValueMap;
 import org.springframework.web.server.ResponseStatusException;
 
-import java.util.ArrayList;
+import java.math.BigDecimal;
+import java.util.Comparator;
 import java.util.List;
 
 @Service
 @RequiredArgsConstructor
 public class AccountService {
 	private final AccountRepository accountRepository;
+	private final TransactionRepository transactionRepository;
+	private final TradeableRepository tradeableRepository;
 
 	public static record AccountData (
 			long id,
@@ -27,40 +39,68 @@ public class AccountService {
 	@Transactional(readOnly = true)
 	public List<AccountData> getAccountsOverview(User user) {
 		return accountRepository.findAllByUser(user).stream()
-				.map(a -> new AccountData(a.getId(), a.getNumber(), a.getExchange().getName()))
+				.map(a -> new AccountData(
+						a.getId(),
+						a.getNumber(),
+						a.getExchange().getName()
+				))
 				.toList();
 	}
 
-	public static class FullAccountData {
-		public long id;
-		public String number;
-		public String exchangeName;
-		public List<BalanceData> balances;
-	}
-
-	@AllArgsConstructor
-	public static class BalanceData {
-		public String currencyIdentifier;
-		public String amount;
-	}
-
 	@Transactional(readOnly = true)
 	public FullAccountData getAccountData(User user, long accountId) {
 		Account account = accountRepository.findById(accountId)
 				.orElseThrow(() -> new ResponseStatusException(HttpStatus.NOT_FOUND));
-
+		Account userAccount = accountRepository.findByUserAndExchange(user, account.getExchange())
-		if (!account.getUser().getId().equals(user.getId())) {
+				.orElseThrow(() -> new ResponseStatusException(HttpStatus.NOT_FOUND));
+		if (!userAccount.isAdmin() && !account.getUser().getId().equals(user.getId())) {
 			throw new ResponseStatusException(HttpStatus.NOT_FOUND);
 		}
-		FullAccountData d = new FullAccountData();
+		List<TransactionData> transactionData = transactionRepository.findAllByAccountNumberOrderByTimestampDesc(account.getNumber(), PageRequest.of(0, 5))
-		d.id = account.getId();
+				.map(TransactionData::new)
-		d.number = account.getNumber();
+				.stream().toList();
-		d.exchangeName = account.getExchange().getName();
+		return new FullAccountData(
-		List<BalanceData> balanceData = new ArrayList<>();
+				account.getId(),
-		for (var bal : account.getBalances()) {
+				account.getNumber(),
-			balanceData.add(new BalanceData(bal.getCurrency().getIdentifier(), bal.getAmount().toPlainString()));
+				account.getName(),
+				account.isAdmin(),
+				userAccount.isAdmin(),
+				new ExchangeData(
+						account.getExchange().getId(),
+						account.getExchange().getName(),
+						account.getExchange().getPrimaryTradeable().getSymbol()
+				),
+				account.getBalances().stream()
+						.map(b -> new BalanceData(b.getTradeable().getId(), b.getTradeable().getSymbol(), b.getAmount().toPlainString()))
+						.sorted(Comparator.comparing(BalanceData::symbol))
+						.toList(),
+				account.getTotalBalance().toPlainString(),
+				transactionData
+		);
 	}
-		d.balances = balanceData;
+
-		return d;
+	@Transactional
+	public void editBalances(long accountId, User user, MultiValueMap<String, String> paramMap) {
+		Account account = accountRepository.findById(accountId)
+				.orElseThrow(() -> new ResponseStatusException(HttpStatus.NOT_FOUND));
+		Account userAccount = accountRepository.findByUserAndExchange(user, account.getExchange())
+				.orElseThrow(() -> new ResponseStatusException(HttpStatus.NOT_FOUND));
+		if (!userAccount.isAdmin()) throw new ResponseStatusException(HttpStatus.NOT_FOUND);
+		for (var entry : paramMap.entrySet()) {
+			if (entry.getKey().startsWith("tradeable-")) {
+				long tradeableId = Long.parseLong(entry.getKey().substring(10));
+				Tradeable tradeable = tradeableRepository.findById(tradeableId)
+						.orElseThrow(() -> new ResponseStatusException(HttpStatus.BAD_REQUEST));
+				BigDecimal value = new BigDecimal(entry.getValue().get(0));
+				Balance bal = account.getBalanceForTradeable(tradeable);
+				if (bal == null) {
+					bal = new Balance(account, tradeable, value);
+					account.getBalances().add(bal);
+				} else {
+					bal.setAmount(value);
+				}
+			}
+		}
+		accountRepository.save(account);
 	}
 }

src/main/java/nl/andrewl/coyotecredit/service/ExchangeService.java

@@ -0,0 +1,191 @@
+package nl.andrewl.coyotecredit.service;
+
+import lombok.RequiredArgsConstructor;
+import nl.andrewl.coyotecredit.ctl.dto.*;
+import nl.andrewl.coyotecredit.dao.*;
+import nl.andrewl.coyotecredit.model.*;
+import nl.andrewl.coyotecredit.util.AccountNumberUtils;
+import org.springframework.http.HttpStatus;
+import org.springframework.security.crypto.password.PasswordEncoder;
+import org.springframework.stereotype.Service;
+import org.springframework.transaction.annotation.Transactional;
+import org.springframework.web.server.ResponseStatusException;
+
+import java.math.BigDecimal;
+import java.math.RoundingMode;
+import java.text.DecimalFormat;
+import java.time.LocalDateTime;
+import java.time.ZoneOffset;
+import java.util.Comparator;
+import java.util.HashMap;
+import java.util.List;
+import java.util.Map;
+
+@Service
+@RequiredArgsConstructor
+public class ExchangeService {
+	private final ExchangeRepository exchangeRepository;
+	private final AccountRepository accountRepository;
+	private final TransactionRepository transactionRepository;
+	private final TradeableRepository tradeableRepository;
+	private final UserRepository userRepository;
+	private final PasswordEncoder passwordEncoder;
+
+	@Transactional(readOnly = true)
+	public FullExchangeData getData(long exchangeId, User user) {
+		Exchange e = exchangeRepository.findById(exchangeId)
+				.orElseThrow(() -> new ResponseStatusException(HttpStatus.NOT_FOUND));
+		Account account = accountRepository.findByUserAndExchange(user, e)
+				.orElseThrow(() -> new ResponseStatusException(HttpStatus.NOT_FOUND));
+		return new FullExchangeData(
+				e.getId(),
+				e.getName(),
+				new TradeableData(e.getPrimaryTradeable()),
+				e.getAllTradeables().stream()
+						.map(TradeableData::new)
+						.sorted(Comparator.comparing(TradeableData::symbol))
+						.toList(),
+				account.isAdmin()
+		);
+	}
+
+	@Transactional(readOnly = true)
+	public List<SimpleAccountData> getAccounts(long exchangeId, User user) {
+		Exchange exchange = exchangeRepository.findById(exchangeId)
+				.orElseThrow(() -> new ResponseStatusException(HttpStatus.NOT_FOUND));
+		Account account = accountRepository.findByUserAndExchange(user, exchange)
+				.orElseThrow(() -> new ResponseStatusException(HttpStatus.NOT_FOUND));
+		if (!account.isAdmin()) {
+			throw new ResponseStatusException(HttpStatus.NOT_FOUND);
+		}
+		DecimalFormat df = new DecimalFormat("#,###0.00");
+		return exchange.getAccounts().stream()
+				.sorted(Comparator.comparing(Account::getName))
+				.map(a -> new SimpleAccountData(
+						a.getId(),
+						a.getNumber(),
+						a.getName(),
+						a.isAdmin(),
+						df.format(a.getTotalBalance()) + ' ' + exchange.getPrimaryTradeable().getSymbol()
+				))
+				.toList();
+	}
+
+	@Transactional(readOnly = true)
+	public void ensureAdminAccount(long exchangeId, User user) {
+		Exchange exchange = exchangeRepository.findById(exchangeId)
+				.orElseThrow(() -> new ResponseStatusException(HttpStatus.NOT_FOUND));
+		Account account = accountRepository.findByUserAndExchange(user, exchange)
+				.orElseThrow(() -> new ResponseStatusException(HttpStatus.NOT_FOUND));
+		if (!account.isAdmin()) {
+			throw new ResponseStatusException(HttpStatus.NOT_FOUND);
+		}
+	}
+
+	@Transactional
+	public long addAccount(long exchangeId, User user, AddAccountPayload payload) {
+		Exchange exchange = exchangeRepository.findById(exchangeId)
+				.orElseThrow(() -> new ResponseStatusException(HttpStatus.NOT_FOUND));
+		Account account = accountRepository.findByUserAndExchange(user, exchange)
+				.orElseThrow(() -> new ResponseStatusException(HttpStatus.NOT_FOUND));
+		if (!account.isAdmin()) {
+			throw new ResponseStatusException(HttpStatus.NOT_FOUND);
+		}
+		User u = userRepository.save(new User(payload.username(), passwordEncoder.encode(payload.password())));
+		Account a = accountRepository.save(new Account(
+				AccountNumberUtils.generate(),
+				u,
+				payload.name(),
+				exchange
+		));
+		for (var t : exchange.getAllTradeables()) {
+			a.getBalances().add(new Balance(a, t, BigDecimal.ZERO));
+		}
+		a = accountRepository.save(a);
+		return a.getId();
+	}
+
+	@Transactional
+	public void removeAccount(long exchangeId, long accountId, User user) {
+		Exchange exchange = exchangeRepository.findById(exchangeId)
+				.orElseThrow(() -> new ResponseStatusException(HttpStatus.NOT_FOUND));
+		Account account = accountRepository.findById(accountId)
+				.orElseThrow(() -> new ResponseStatusException(HttpStatus.NOT_FOUND));
+		Account userAccount = accountRepository.findByUserAndExchange(user, exchange)
+				.orElseThrow(() -> new ResponseStatusException(HttpStatus.NOT_FOUND));
+		if (!userAccount.isAdmin()) {
+			throw new ResponseStatusException(HttpStatus.NOT_FOUND);
+		}
+		accountRepository.delete(account);
+	}
+
+	@Transactional(readOnly = true)
+	public Map<Long, String> getCurrentTradeables(long exchangeId) {
+		Exchange e = exchangeRepository.findById(exchangeId)
+				.orElseThrow(() -> new ResponseStatusException(HttpStatus.NOT_FOUND));
+		Map<Long, String> tradeables = new HashMap<>();
+		for (var t : e.getAllTradeables()) {
+			tradeables.put(t.getId(), t.getMarketPriceUsd().toPlainString());
+		}
+		return tradeables;
+	}
+
+	@Transactional
+	public void doTrade(long accountId, TradePayload payload, User user) {
+		Account account = accountRepository.findById(accountId)
+				.orElseThrow(() -> new ResponseStatusException(HttpStatus.BAD_REQUEST, "Account not found."));
+		if (!account.getUser().getId().equals(user.getId())) {
+			throw new ResponseStatusException(HttpStatus.NOT_FOUND);
+		}
+		Exchange exchange = account.getExchange();
+		Tradeable from = tradeableRepository.findById(payload.sellTradeableId())
+				.orElseThrow(() -> new ResponseStatusException(HttpStatus.BAD_REQUEST, "Sell tradeable not found."));
+		Tradeable to = tradeableRepository.findById(payload.buyTradeableId())
+				.orElseThrow(() -> new ResponseStatusException(HttpStatus.BAD_REQUEST, "Buy tradeable not found."));
+		BigDecimal value = new BigDecimal(payload.value());
+		if (from.getType().equals(TradeableType.STOCK)) {
+			if (!payload.type().equalsIgnoreCase("SELL")) {
+				throw new ResponseStatusException(HttpStatus.BAD_REQUEST, "Can only perform SELL operations when selling stocks.");
+			}
+			if (to.getType().equals(TradeableType.STOCK)) {
+				throw new ResponseStatusException(HttpStatus.BAD_REQUEST, "Cannot sell stock to purchase stock.");
+			}
+		}
+		if (to.getType().equals(TradeableType.STOCK)) {
+			if (!payload.type().equalsIgnoreCase("BUY")) {
+				throw new ResponseStatusException(HttpStatus.BAD_REQUEST, "Can only perform BUY operations when buying stocks.");
+			}
+			if (from.getType().equals(TradeableType.STOCK)) {
+				throw new ResponseStatusException(HttpStatus.BAD_REQUEST, "Cannot sell stock to purchase stock.");
+			}
+		}
+		if (value.compareTo(BigDecimal.ZERO) <= 0) {
+			throw new ResponseStatusException(HttpStatus.BAD_REQUEST, "Only positive value may be specified.");
+		}
+
+		BigDecimal fromValue;
+		BigDecimal toValue;
+		if (payload.type().equalsIgnoreCase("SELL")) {
+			fromValue = value;
+			toValue = fromValue.multiply(from.getMarketPriceUsd()).divide(to.getMarketPriceUsd(), RoundingMode.HALF_UP);
+		} else {
+			toValue = value;
+			fromValue = toValue.multiply(to.getMarketPriceUsd()).divide(from.getMarketPriceUsd(), RoundingMode.HALF_UP);
+		}
+		Balance fromBalance = account.getBalanceForTradeable(from);
+		if (fromBalance == null || fromBalance.getAmount().compareTo(fromValue) < 0) {
+			throw new ResponseStatusException(HttpStatus.BAD_REQUEST, "Missing required balance of " + fromValue.toPlainString() + " from " + from.getSymbol());
+		}
+		fromBalance.setAmount(fromBalance.getAmount().subtract(fromValue));
+		Balance toBalance = account.getBalanceForTradeable(to);
+		if (toBalance == null) {
+			toBalance = new Balance(account, to, toValue);
+			account.getBalances().add(toBalance);
+		} else {
+			toBalance.setAmount(toBalance.getAmount().add(toValue));
+		}
+		accountRepository.save(account);
+		Transaction tx = new Transaction(account.getNumber(), exchange, from, fromValue, to, toValue, LocalDateTime.now(ZoneOffset.UTC));
+		transactionRepository.save(tx);
+	}
+}

src/main/java/nl/andrewl/coyotecredit/service/TradeService.java

@@ -0,0 +1,42 @@
+package nl.andrewl.coyotecredit.service;
+
+import lombok.RequiredArgsConstructor;
+import nl.andrewl.coyotecredit.ctl.dto.TradeData;
+import nl.andrewl.coyotecredit.ctl.dto.TradeableData;
+import nl.andrewl.coyotecredit.dao.AccountRepository;
+import nl.andrewl.coyotecredit.model.Account;
+import nl.andrewl.coyotecredit.model.User;
+import org.springframework.http.HttpStatus;
+import org.springframework.stereotype.Service;
+import org.springframework.transaction.annotation.Transactional;
+import org.springframework.web.server.ResponseStatusException;
+
+import java.math.BigDecimal;
+import java.util.*;
+
+@Service
+@RequiredArgsConstructor
+public class TradeService {
+	private final AccountRepository accountRepository;
+
+	@Transactional(readOnly = true)
+	public TradeData getTradeData(long accountId, User user) {
+		Account account = accountRepository.findById(accountId).orElseThrow(() -> new ResponseStatusException(HttpStatus.NOT_FOUND));
+		if (!account.getUser().getId().equals(user.getId())) {
+			throw new ResponseStatusException(HttpStatus.NOT_FOUND);
+		}
+		List<TradeableData> sellList = new ArrayList<>();
+		Map<String, BigDecimal> accountBalances = new HashMap<>();
+		for (var bal : account.getBalances()) {
+			sellList.add(new TradeableData(bal.getTradeable()));
+			accountBalances.put(bal.getTradeable().getSymbol(), bal.getAmount());
+		}
+		sellList.sort(Comparator.comparing(TradeableData::symbol));
+		List<TradeableData> buyList = new ArrayList<>();
+		for (var t : account.getExchange().getAllTradeables()) {
+			buyList.add(new TradeableData(t));
+		}
+
+		return new TradeData(account.getId(), account.getNumber(), account.getExchange().getId(), sellList, accountBalances, buyList);
+	}
+}

src/main/java/nl/andrewl/coyotecredit/service/UserService.java

@@ -0,0 +1,27 @@
+package nl.andrewl.coyotecredit.service;
+
+import lombok.RequiredArgsConstructor;
+import nl.andrewl.coyotecredit.ctl.dto.UserData;
+import nl.andrewl.coyotecredit.dao.UserRepository;
+import nl.andrewl.coyotecredit.model.User;
+import org.springframework.http.HttpStatus;
+import org.springframework.stereotype.Service;
+import org.springframework.transaction.annotation.Transactional;
+import org.springframework.web.server.ResponseStatusException;
+
+@Service
+@RequiredArgsConstructor
+public class UserService {
+	private final UserRepository userRepository;
+
+	@Transactional
+	public UserData getUser(long userId, User requestingUser) {
+		User user;
+		if (requestingUser.getId().equals(userId)) {
+			user = requestingUser;
+		} else {
+			user = userRepository.findById(userId).orElseThrow(() -> new ResponseStatusException(HttpStatus.NOT_FOUND));
+		}
+		return new UserData(user.getId(), user.getUsername());
+	}
+}

src/main/java/nl/andrewl/coyotecredit/util/AccountNumberUtils.java

@@ -8,7 +8,7 @@ public class AccountNumberUtils {
 		StringBuilder sb = new StringBuilder(19);
 		Random rand = new SecureRandom();
 		for (int i = 0; i < 16; i++) {
-			if (i % 4 == 0) sb.append('-');
+			if (i > 0 && i % 4 == 0) sb.append('-');
 			sb.append(rand.nextInt(0, 10));
 		}
 		return sb.toString();

src/main/resources/static/js/trade.js

@@ -0,0 +1,155 @@
+const sellValueInput = document.getElementById("sellValueInput");
+const sellTradeableSelect = document.getElementById("sellTradeableSelect");
+const sellTradeableSelectText = document.getElementById("sellTradeableSelectText");
+const buyValueInput = document.getElementById("buyValueInput");
+const buyTradeableSelect = document.getElementById("buyTradeableSelect");
+const submitButton = document.getElementById("submitButton");
+
+sellTradeableSelect.selectedIndex = null;
+buyTradeableSelect.selectedIndex = null;
+
+sellTradeableSelect.addEventListener("change", onSellSelectChanged);
+sellValueInput.addEventListener("change", onSellInputChanged);
+buyTradeableSelect.addEventListener("change", onBuySelectChanged);
+buyValueInput.addEventListener("change", onBuyInputChanged);
+submitButton.addEventListener("click", onSubmitClicked);
+
+let tradeables = {};
+const exchangeId = Number(document.getElementById("exchangeIdInput").value);
+const accountId = Number(document.getElementById("accountIdInput").value);
+refreshTradeables();
+window.setInterval(refreshTradeables, 10000);
+
+function refreshTradeables() {
+    fetch("/api/exchanges/" + exchangeId + "/tradeables")
+        .then((response) => {
+            if (response.status !== 200) {
+                console.error("Exchange API call failed.");
+            } else {
+                response.json().then((data) => {
+                    tradeables = data;
+                });
+            }
+        });
+}
+
+function getSelectedSellOption() {
+    return sellTradeableSelect.options[sellTradeableSelect.selectedIndex];
+}
+
+function getSelectedBuyOption() {
+    return buyTradeableSelect.options[buyTradeableSelect.selectedIndex];
+}
+
+function updateInputSettings(input, step, min, max) {
+    input.setAttribute("step", step);
+    input.setAttribute("min", min);
+    input.setAttribute("max", max);
+}
+
+function resetValueInputs() {
+    sellValueInput.value = null;
+    buyValueInput.value = null;
+}
+
+// Event handlers
+
+function onSellSelectChanged() {
+    resetValueInputs();
+    const sellOption = getSelectedSellOption();
+    const sellType = sellOption.dataset.type;
+    const sellBalance = Number(sellOption.dataset.balance);
+
+    // Don't allow the user to buy the same thing they're selling.
+    for (let i = 0; i < buyTradeableSelect.length; i++) {
+        const buyOption = buyTradeableSelect.options[i];
+        const buyType = buyOption.dataset.type;
+
+        let isOptionDisabled = buyOption.value === sellOption.value;
+        if (sellType === "STOCK" && buyType === "STOCK") {
+            isOptionDisabled = true;
+        }
+
+        if (isOptionDisabled) {
+            buyOption.setAttribute("disabled", true);
+        } else {
+            buyOption.removeAttribute("disabled");
+        }
+        // If the user is currently selecting an invalid choice, reset.
+        if (i === buyTradeableSelect.selectedIndex && isOptionDisabled) {
+            buyTradeableSelect.value = "";
+        }
+    }
+
+    // Update the sell value input for the current type's parameters.
+    if (sellType === "STOCK") {
+        updateInputSettings(sellValueInput, 1, 0, sellBalance);
+        buyValueInput.setAttribute("readonly", true);
+    } else if (sellType === "FIAT" || sellType === "CRYPTO") {
+        updateInputSettings(sellValueInput, 0.0000000001, 0, sellBalance);
+        buyValueInput.removeAttribute("readonly");
+    }
+
+    // Update the subtext to show the value.
+    sellTradeableSelectText.innerText = `Balance: ${sellBalance}`;
+    sellTradeableSelectText.removeAttribute("hidden");
+}
+
+function onBuySelectChanged() {
+    resetValueInputs();
+    const buyOption = getSelectedBuyOption();
+    const buyType = buyOption.dataset.type;
+
+    if (buyType === "STOCK") {
+        updateInputSettings(buyValueInput, 1, 0, 1000000);
+        sellValueInput.setAttribute("readonly", true);
+    } else if (buyType === "FIAT" || buyType === "CRYPTO") {
+        updateInputSettings(buyValueInput, 0.0000000001, 0, 1000000);
+        sellValueInput.removeAttribute("readonly");
+    }
+}
+
+function onSellInputChanged() {
+    const sellOption = getSelectedSellOption();
+    const buyOption = getSelectedBuyOption();
+    const sellId = sellOption.value;
+    const buyId = buyOption.value;
+    const sellPriceUsd = tradeables[sellId];
+    const buyPriceUsd = tradeables[buyId];
+
+    if (sellPriceUsd && buyPriceUsd) {
+        const sellVolume = Number(sellValueInput.value);
+        buyValueInput.value = (sellPriceUsd * sellVolume) / buyPriceUsd;
+    }
+}
+
+function onBuyInputChanged() {
+    const sellOption = getSelectedSellOption();
+    const buyOption = getSelectedBuyOption();
+    const sellId = sellOption.value;
+    const buyId = buyOption.value;
+    const sellPriceUsd = tradeables[sellId];
+    const buyPriceUsd = tradeables[buyId];
+
+    if (sellPriceUsd && buyPriceUsd) {
+        const buyVolume = Number(buyValueInput.value);
+        sellValueInput.value = (buyPriceUsd * buyVolume) / sellPriceUsd;
+    }
+}
+
+function onSubmitClicked() {
+    let type = "SELL";
+    let value = Number(sellValueInput.value);
+    if (sellValueInput.hasAttribute("readonly")) {
+        type = "BUY";
+        value = Number(buyValueInput.value);
+    }
+    const sellTradeableId = parseInt(getSelectedSellOption().value);
+    const buyTradeableId = parseInt(getSelectedBuyOption().value);
+    const form = document.getElementById("tradeForm");
+    form.elements["type"].value = type;
+    form.elements["sellTradeableId"].value = sellTradeableId;
+    form.elements["buyTradeableId"].value = buyTradeableId;
+    form.elements["value"].value = value;
+    form.submit();
+}

src/main/resources/templates/account.html

@@ -2,18 +2,53 @@
 <html
         lang="en"
         xmlns:th="http://www.thymeleaf.org"
+        th:replace="~{layout/basic_page :: layout (title='Account', content=~{::#content})}"
 >
-<head>
-    <title>CC - Account</title>
-</head>
 
-<body>
+<div id="content" class="container">
-    <h1>Account <span th:text="${account.number}"></span></h1>
+    <h1>Account <span th:text="${account.number()}"></span></h1>
+    <p>In <a th:href="@{/exchanges/{id}(id=${account.exchange().id()})}" th:text="${account.exchange().name()}"></a></p>
+    <p>Total value of <span th:text="${account.totalBalance() + ' ' + account.exchange().primaryTradeable()}"></span></p>
 
-    <h3>Balance</h3>
+    <h3>Overview</h3>
-    <ul>
+
-        <li th:each="balance : ${account.balances}">
+    <table class="table">
-            <span th:text="${balance.currencyIdentifier}"></span> - <span th:text="${balance.amount}"></span>
+        <thead>
-        </li>
+            <tr>
-    </ul>
+                <th>Currency</th>
-</body>
+                <th>Balance</th>
+            </tr>
+        </thead>
+        <tbody>
+            <tr th:each="bal : ${account.balances()}">
+                <td th:text="${bal.symbol()}"></td>
+                <td th:text="${bal.amount()}"></td>
+            </tr>
+        </tbody>
+    </table>
+
+    <h3>Recent Transactions</h3>
+    <table class="table">
+        <thead>
+            <tr>
+                <th>From</th>
+                <th>Amount From</th>
+                <th>To</th>
+                <th>Amount To</th>
+                <th>Timestamp</th>
+            </tr>
+        </thead>
+        <tbody>
+            <tr th:each="tx : ${account.recentTransactions()}">
+                <td th:text="${tx.from().name()}"></td>
+                <td th:text="${tx.fromAmount()}"></td>
+                <td th:text="${tx.to().name()}"></td>
+                <td th:text="${tx.toAmount()}"></td>
+                <td th:text="${tx.timestamp()}"></td>
+            </tr>
+        </tbody>
+    </table>
+
+    <a class="btn btn-success" th:href="@{/trade/{account}(account=${account.id()})}">Trade</a>
+    <a class="btn btn-primary" th:if="${account.userAdmin()}" th:href="@{/accounts/{aId}/editBalances(aId=${account.id()})}">Edit Balances</a>
+</div>

src/main/resources/templates/account/edit_balances.html

@@ -0,0 +1,17 @@
+<!DOCTYPE html>
+<html
+        lang="en"
+        xmlns:th="http://www.thymeleaf.org"
+        th:replace="~{layout/basic_page :: layout (title='Add Account', content=~{::#content})}"
+>
+<div id="content" class="container">
+    <h1>Edit Balances</h1>
+
+    <form th:action="@{/accounts/{aId}/editBalances(aId=${accountId})}" th:method="post">
+        <div class="mb-3" th:each="bal, iter : ${account.balances()}">
+            <label th:for="${'tradeable-' + bal.id()}" class="form-label" th:text="${bal.symbol()}"></label>
+            <input type="number" min="0" th:value="${bal.amount()}" th:name="${'tradeable-' + bal.id()}" class="form-control"/>
+        </div>
+        <button type="submit" class="btn btn-success">Submit</button>
+    </form>
+</div>

src/main/resources/templates/exchange.html

@@ -0,0 +1,39 @@
+<!DOCTYPE html>
+<html
+        lang="en"
+        xmlns:th="http://www.thymeleaf.org"
+        th:replace="~{layout/basic_page :: layout (title='Exchange', content=~{::#content})}"
+>
+<div id="content" class="container">
+    <h1 th:text="${exchange.name()}"></h1>
+
+    <p>
+        Primary tradeable: <span th:text="${exchange.primaryTradeable().name()}"></span>
+    </p>
+
+    <h3>Supported Tradeable Currencies / Stocks</h3>
+    <table class="table">
+        <thead>
+            <tr>
+                <th>Symbol</th>
+                <th>Type</th>
+                <th>Price ($)</th>
+                <th>Name</th>
+            </tr>
+        </thead>
+        <tbody>
+            <tr th:each="tradeable : ${exchange.supportedTradeables()}">
+                <td th:text="${tradeable.symbol()}"></td>
+                <td th:text="${tradeable.type()}"></td>
+                <td th:text="${tradeable.marketPriceUsd()}"></td>
+                <td th:text="${tradeable.name()}"></td>
+            </tr>
+        </tbody>
+    </table>
+
+    <div th:if="${exchange.accountAdmin()}">
+        <div>
+            <a class="btn btn-primary" th:href="@{/exchanges/{eId}/accounts(eId=${exchange.id()})}">View Accounts</a>
+        </div>
+    </div>
+</div>

src/main/resources/templates/exchange/accounts.html

@@ -0,0 +1,31 @@
+<!DOCTYPE html>
+<html
+        lang="en"
+        xmlns:th="http://www.thymeleaf.org"
+        th:replace="~{layout/basic_page :: layout (title='Exchange Accounts', content=~{::#content})}"
+>
+<div id="content" class="container">
+    <h1>Accounts</h1>
+
+    <a class="btn btn-primary" th:href="@{/exchanges/{eId}/addAccount(eId=${exchangeId})}">Add Account</a>
+
+    <table class="table">
+        <thead>
+            <tr>
+                <th>Number</th>
+                <th>Name</th>
+                <th>Admin</th>
+                <th>Balance</th>
+            </tr>
+        </thead>
+        <tbody>
+            <tr th:each="account : ${accounts}">
+                <td><a th:href="@{/accounts/{id}(id=${account.id()})}" th:text="${account.number()}"></a></td>
+                <td th:text="${account.name()}"></td>
+                <td th:text="${account.admin()}"></td>
+                <td th:text="${account.totalBalance()}"></td>
+                <td><a th:href="@{/exchanges/{eId}/removeAccount/{aId}(eId=${exchangeId}, aId=${account.id()})}">Remove</a></td>
+            </tr>
+        </tbody>
+    </table>
+</div>

src/main/resources/templates/exchange/addAccount.html

@@ -0,0 +1,29 @@
+<!DOCTYPE html>
+<html
+        lang="en"
+        xmlns:th="http://www.thymeleaf.org"
+        th:replace="~{layout/basic_page :: layout (title='Add Account', content=~{::#content})}"
+>
+<div id="content" class="container">
+    <h1>Add Account</h1>
+    <p>
+        Use this page to add an account to the exchange.
+    </p>
+
+    <form th:href="@{/exchanges/{eId}/addAccount(eId=${exchangeId})}" th:method="post">
+        <div class="mb-3">
+            <label for="nameInput" class="form-label">Name</label>
+            <input id="nameInput" type="text" class="form-control" name="name"/>
+        </div>
+        <div class="mb-3">
+            <label for="usernameInput" class="form-label">Username</label>
+            <input id="usernameInput" type="text" class="form-control" name="username"/>
+        </div>
+        <div class="mb-3">
+            <label for="passwordInput" class="form-label">Password</label>
+            <input id="passwordInput" type="password" class="form-control" name="password"/>
+        </div>
+        <input type="hidden" name="_csrf" th:value="${_csrf.getToken()}"/>
+        <button type="submit" class="btn btn-primary">Submit</button>
+    </form>
+</div>

src/main/resources/templates/exchange/removeAccount.html

@@ -0,0 +1,16 @@
+<!DOCTYPE html>
+<html
+        lang="en"
+        xmlns:th="http://www.thymeleaf.org"
+        th:replace="~{layout/basic_page :: layout (title='Add Account', content=~{::#content})}"
+>
+<div id="content" class="container">
+    <h1>Remove Account</h1>
+    <p>
+        Are you sure you want to remove this account?
+    </p>
+    <form th:action="@{/exchanges/{eId}/removeAccount/{aId}(eId=${exchangeId}, aId=${accountId})}" th:method="post">
+        <a class="btn btn-secondary" th:href="@{/exchanges/{eId}/accounts(eId=${exchangeId})}">Cancel</a>
+        <button class="btn btn-danger" type="submit">Remove</button>
+    </form>
+</div>

src/main/resources/templates/fragment/header.html

@@ -0,0 +1,35 @@
+<!DOCTYPE html>
+<html
+        lang="en"
+        xmlns:th="http://www.thymeleaf.org"
+        xmlns:sec="http://www.thymeleaf.org/extras/spring-security"
+>
+<head>
+    <meta charset="UTF-8">
+    <title>header</title>
+</head>
+<body>
+
+<nav th:fragment="header" class="navbar navbar-expand-lg navbar-light bg-light">
+    <div class="container-fluid">
+        <a class="navbar-brand" href="/">Coyote Credit</a>
+        <button class="navbar-toggler" type="button" data-bs-toggle="collapse" data-bs-target="#navbarSupportedContent" aria-controls="navbarSupportedContent" aria-expanded="false" aria-label="Toggle navigation">
+            <span class="navbar-toggler-icon"></span>
+        </button>
+        <div class="collapse navbar-collapse" id="navbarSupportedContent">
+            <ul class="navbar-nav me-auto mb-2 mb-lg-0">
+                <li class="nav-item">
+                    <a class="nav-link" th:href="@{/}">Home</a>
+                </li>
+                <li class="nav-item">
+                    <a class="nav-link" th:href="@{/users/{id}(id=${#authentication.getPrincipal().getId()})}">My Profile</a>
+                </li>
+            </ul>
+            <form class="d-flex" th:action="@{/logout}" th:method="post">
+                <button class="btn btn-outline-success" type="submit">Logout</button>
+            </form>
+        </div>
+    </div>
+</nav>
+
+</body>

src/main/resources/templates/home.html

@@ -2,25 +2,19 @@
 <html
         lang="en"
         xmlns:th="http://www.thymeleaf.org"
+        th:replace="~{layout/basic_page :: layout (title='Home', content=~{::#content})}"
 >
-<head>
-    <title>CC - Home</title>
-</head>
 
-<body>
+<div id="content" class="container">
     <h1>Welcome!</h1>
 
     <h3>Your Accounts:</h3>
     <ul>
         <li th:each="account : ${accounts}">
             <a th:href="@{/accounts/{id}(id=${account.id()})}">
-                <span th:text="${account.accountNumber()}"></span>@
+                <span th:text="${account.accountNumber()}"></span> @
                 <span th:text="${account.exchangeName()}"></span>
             </a>
         </li>
     </ul>
-
+</div>
-    <form th:action="@{/logout}" th:method="post">
-        <input type="submit" value="Logout">
-    </form>
-</body>

src/main/resources/templates/layout/basic_page.html

@@ -0,0 +1,39 @@
+<!DOCTYPE html>
+<html
+        lang="en"
+        xmlns:th="http://www.thymeleaf.org"
+        xmlns:sec="http://www.thymeleaf.org/extras/spring-security"
+        th:fragment="layout (title, content)"
+>
+<head>
+    <meta charset="UTF-8">
+    <title th:text="${'Coyote Credit - ' + title}">Coyote Credit</title>
+
+    <link rel="stylesheet" href="/static/css/style.css"/>
+    <link
+            href="https://cdn.jsdelivr.net/npm/bootstrap@5.1.3/dist/css/bootstrap.min.css"
+            rel="stylesheet"
+            integrity="sha384-1BmE4kWBq78iYhFldvKuhfTAU6auU8tT94WrHftjDbrCEXSU1oBoqyl2QvZ6jIW3"
+            crossorigin="anonymous"
+    >
+
+</head>
+
+<body>
+    <header sec:authorize="isAuthenticated()">
+        <div th:replace="~{fragment/header :: header}"></div>
+    </header>
+
+    <div class="container-fluid">
+        <div th:replace="${content}" class="row">
+            <p>Placeholder content.</p>
+        </div>
+    </div>
+
+    <script
+            src="https://cdn.jsdelivr.net/npm/bootstrap@5.1.3/dist/js/bootstrap.bundle.min.js"
+            integrity="sha384-ka7Sk0Gln4gmtz2MlQnikT1wXgYsOg+OMhuP+IlRH9sENBO0LRn5q+8nbTov4+1p"
+            crossorigin="anonymous"
+    ></script>
+</body>
+</html>

src/main/resources/templates/trade.html

@@ -0,0 +1,64 @@
+<!DOCTYPE html>
+<html
+        lang="en"
+        xmlns:th="http://www.thymeleaf.org"
+        th:replace="~{layout/basic_page :: layout (title='Trade', content=~{::#content})}"
+>
+<div id="content" class="container">
+    <h1>Trade</h1>
+
+    <form id="tradeForm" th:action="@{/trade/{account}(account=${data.accountId()})}" method="post">
+        <input type="hidden" id="exchangeIdInput" th:value="${data.exchangeId()}"/>
+        <input type="hidden" id="accountIdInput" th:value="${data.accountId()}"/>
+        <div class="mb-3">
+            <label for="sellTradeableSelect" class="form-label">Tradeable to Sell</label>
+            <select id="sellTradeableSelect" class="form-select">
+                <option selected hidden>Choose something to sell</option>
+                <option
+                        th:each="t : ${data.tradeablesToSell()}"
+                        th:value="${t.id()}"
+                        th:text="${t.name() + ' (' + t.symbol() + ')'}"
+                        th:data-priceusd="${t.marketPriceUsd()}"
+                        th:data-type="${t.type()}"
+                        th:data-balance="${data.accountBalances().get(t.symbol()).toPlainString()}"
+                        th:disabled="${data.accountBalances().get(t.symbol()).signum() == 0 ? true : false}"
+                ></option>
+            </select>
+            <div id="sellTradeableSelectText" class="form-text" hidden></div>
+        </div>
+
+        <div class="mb-3">
+            <label for="sellValueInput" class="form-label">Value to Sell</label>
+            <input type="number" class="form-control" id="sellValueInput"/>
+        </div>
+
+        <div class="mb-3">
+            <label for="buyTradeableSelect" class="form-label">Tradeable to Buy</label>
+            <select id="buyTradeableSelect" class="form-select">
+                <option value="" selected disabled hidden>Choose something to buy</option>
+                <option
+                        th:each="t : ${data.tradeablesToBuy()}"
+                        th:value="${t.id()}"
+                        th:text="${t.name() + ' (' + t.symbol() + ')'}"
+                        th:data-priceusd="${t.marketPriceUsd()}"
+                        th:data-type="${t.type()}"
+                ></option>
+            </select>
+        </div>
+
+        <div class="mb-3">
+            <label for="buyValueInput" class="form-label">Value to Buy</label>
+            <input type="number" class="form-control" id="buyValueInput"/>
+        </div>
+
+        <input type="hidden" name="_csrf" th:value="${_csrf.getToken()}"/>
+        <input type="hidden" name="type"/>
+        <input type="hidden" name="sellTradeableId"/>
+        <input type="hidden" name="buyTradeableId"/>
+        <input type="hidden" name="value"/>
+
+        <button id="submitButton" type="button" class="btn btn-primary">Submit</button>
+    </form>
+
+    <script src="/static/js/trade.js"></script>
+</div>

src/main/resources/templates/user.html

@@ -0,0 +1,18 @@
+<!DOCTYPE html>
+<html
+        lang="en"
+        xmlns:th="http://www.thymeleaf.org"
+        th:replace="~{layout/basic_page :: layout (title='My Profile', content=~{::#content})}"
+>
+<div id="content" class="container">
+    <h1>My Profile</h1>
+
+    <table class="table">
+        <tbody>
+            <tr>
+                <th scope="row">Username</th>
+                <td th:text="${user.username()}"></td>
+            </tr>
+        </tbody>
+    </table>
+</div>