Removed add account functionality in favor of invite user.

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

@@ -2,6 +2,8 @@ package nl.andrewl.coyotecredit.ctl;
 
 import lombok.RequiredArgsConstructor;
 import nl.andrewl.coyotecredit.ctl.dto.AddAccountPayload;
+import nl.andrewl.coyotecredit.ctl.dto.EditExchangePayload;
+import nl.andrewl.coyotecredit.ctl.dto.InviteUserPayload;
 import nl.andrewl.coyotecredit.model.User;
 import nl.andrewl.coyotecredit.service.ExchangeService;
 import org.springframework.security.core.annotation.AuthenticationPrincipal;
@@ -9,6 +11,8 @@ import org.springframework.stereotype.Controller;
 import org.springframework.ui.Model;
 import org.springframework.web.bind.annotation.*;
 
+import javax.validation.Valid;
+
 @Controller
 @RequestMapping(path = "/exchanges")
 @RequiredArgsConstructor
@@ -33,16 +37,28 @@ public class ExchangeController {
 		return "exchange/accounts";
 	}
 
-	@GetMapping(path = "/{exchangeId}/addAccount")
-	public String getAddAccountPage(@PathVariable long exchangeId, @AuthenticationPrincipal User user) {
+	@GetMapping(path = "/{exchangeId}/inviteUser")
+	public String getInviteUserPage(@PathVariable long exchangeId, @AuthenticationPrincipal User user) {
 		exchangeService.ensureAdminAccount(exchangeId, user);
-		return "exchange/addAccount";
+		return "exchange/invite_user";
 	}
 
-	@PostMapping(path = "/{exchangeId}/addAccount")
-	public String postAddAcount(@PathVariable long exchangeId, @AuthenticationPrincipal User user, @ModelAttribute AddAccountPayload payload) {
-		long accountId = exchangeService.addAccount(exchangeId, user, payload);
-		return "redirect:/accounts/" + accountId;
+	@PostMapping(path = "/{exchangeId}/inviteUser")
+	public String postInviteUser(@PathVariable long exchangeId, @AuthenticationPrincipal User user, @ModelAttribute InviteUserPayload payload) {
+		exchangeService.inviteUser(exchangeId, user, payload);
+		return "redirect:/exchanges/" + exchangeId;
+	}
+
+	@PostMapping(path = "/{exchangeId}/acceptInvite/{inviteId}")
+	public String postAcceptInvite(@PathVariable long exchangeId, @PathVariable long inviteId, @AuthenticationPrincipal User user) {
+		exchangeService.acceptInvite(exchangeId, inviteId, user);
+		return "redirect:/exchanges/" + exchangeId;
+	}
+
+	@PostMapping(path = "/{exchangeId}/rejectInvite/{inviteId}")
+	public String postRejectInvite(@PathVariable long exchangeId, @PathVariable long inviteId, @AuthenticationPrincipal User user) {
+		exchangeService.rejectInvite(exchangeId, inviteId, user);
+		return "redirect:/users/" + user.getId();
 	}
 
 	@GetMapping(path = "/{exchangeId}/removeAccount/{accountId}")
@@ -56,4 +72,16 @@ public class ExchangeController {
 		exchangeService.removeAccount(exchangeId, accountId, user);
 		return "redirect:/exchanges/" + exchangeId + "/accounts";
 	}
+
+	@GetMapping(path = "/{exchangeId}/edit")
+	public String getEditPage(Model model, @PathVariable long exchangeId, @AuthenticationPrincipal User user) {
+		model.addAttribute("exchange", exchangeService.getData(exchangeId, user));
+		return "exchange/edit";
+	}
+
+	@PostMapping(path = "/{exchangeId}/edit")
+	public String postEdit(@PathVariable long exchangeId, @AuthenticationPrincipal User user, @Valid @ModelAttribute EditExchangePayload payload) {
+		exchangeService.edit(exchangeId, payload, user);
+		return "redirect:/exchanges/" + exchangeId;
+	}
 }

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

@@ -2,8 +2,11 @@ package nl.andrewl.coyotecredit.ctl;
 
 import lombok.RequiredArgsConstructor;
 import nl.andrewl.coyotecredit.ctl.dto.RegisterPayload;
+import nl.andrewl.coyotecredit.dao.ExchangeInvitationRepository;
 import nl.andrewl.coyotecredit.service.UserService;
 import org.springframework.stereotype.Controller;
+import org.springframework.transaction.annotation.Transactional;
+import org.springframework.ui.Model;
 import org.springframework.web.bind.annotation.GetMapping;
 import org.springframework.web.bind.annotation.ModelAttribute;
 import org.springframework.web.bind.annotation.PostMapping;
@@ -13,14 +16,26 @@ import org.springframework.web.bind.annotation.RequestParam;
 @RequiredArgsConstructor
 public class PublicPageController {
 	private final UserService userService;
+	private final ExchangeInvitationRepository invitationRepository;
 
 	@GetMapping(path = "/login")
 	public String getLoginPage() {
 		return "public/login";
 	}
 
-	@GetMapping(path = "/register")
-	public String getRegisterPage() {
+	@GetMapping(path = "/register") @Transactional(readOnly = true)
+	public String getRegisterPage(
+			Model model,
+			@RequestParam(name = "inviteCode", required = false) String inviteCode
+	) {
+		if (inviteCode != null && !inviteCode.isBlank()) {
+			invitationRepository.findByCode(inviteCode).ifPresent(invite -> {
+				model.addAttribute("inviteCode", inviteCode);
+				model.addAttribute("inviteUserEmail", invite.getUserEmail());
+				model.addAttribute("inviteSenderName", invite.getSender().getName());
+				model.addAttribute("inviteExchangeName", invite.getExchange().getName());
+			});
+		}
 		return "public/register";
 	}
 

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

@@ -1,8 +0,0 @@
-package nl.andrewl.coyotecredit.ctl.dto;
-
-public record AddAccountPayload(
-		String name,
-		String email,
-		String username,
-		String password
-) {}

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

@@ -0,0 +1,20 @@
+package nl.andrewl.coyotecredit.ctl.dto;
+
+import javax.validation.constraints.NotBlank;
+import javax.validation.constraints.NotNull;
+import javax.validation.constraints.PositiveOrZero;
+
+public record EditExchangePayload(
+		@NotNull @NotBlank
+		String name,
+		String description,
+		boolean publiclyAccessible,
+		@PositiveOrZero
+		long primaryTradeableId,
+
+		// Colors
+		String primaryBackgroundColor,
+		String secondaryBackgroundColor,
+		String primaryForegroundColor,
+		String secondaryForegroundColor
+) {}

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

@@ -8,7 +8,13 @@ import java.util.List;
 public record FullExchangeData (
 		long id,
 		String name,
+		String description,
+		boolean publiclyAccessible,
 		TradeableData primaryTradeable,
+		String primaryBackgroundColor,
+		String secondaryBackgroundColor,
+		String primaryForegroundColor,
+		String secondaryForegroundColor,
 		List<TradeableData> supportedTradeables,
 		String totalMarketValue,
 		int accountCount,

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

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

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

@@ -0,0 +1,10 @@
+package nl.andrewl.coyotecredit.ctl.dto;
+
+import javax.validation.constraints.NotBlank;
+import javax.validation.constraints.NotNull;
+
+public record InviteUserPayload(
+		@NotBlank @NotNull
+		String email
+) {
+}

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

@@ -3,5 +3,8 @@ package nl.andrewl.coyotecredit.ctl.dto;
 public record RegisterPayload (
 		String username,
 		String email,
-		String password
+		String password,
+		// Invite data, this may be null.
+		String inviteCode,
+		String accountName
 ) {}

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

@@ -2,6 +2,7 @@ package nl.andrewl.coyotecredit.ctl.dto;
 
 public record SimpleAccountData (
 		long id,
+		long userId,
 		String number,
 		String name,
 		boolean admin,

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

@@ -1,7 +1,10 @@
 package nl.andrewl.coyotecredit.ctl.dto;
 
+import java.util.List;
+
 public record UserData (
 		long id,
 		String username,
-		String email
+		String email,
+		List<InvitationData> exchangeInvitations
 ) {}

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

@@ -0,0 +1,15 @@
+package nl.andrewl.coyotecredit.dao;
+
+import nl.andrewl.coyotecredit.model.ExchangeInvitation;
+import org.springframework.data.jpa.repository.JpaRepository;
+import org.springframework.stereotype.Repository;
+
+import java.util.List;
+import java.util.Optional;
+
+@Repository
+public interface ExchangeInvitationRepository extends JpaRepository<ExchangeInvitation, Long> {
+	Optional<ExchangeInvitation> findByCode(String code);
+
+	List<ExchangeInvitation> findAllByUserEmail(String email);
+}

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

@@ -10,4 +10,6 @@ import java.util.Optional;
 public interface UserRepository extends JpaRepository<User, Long> {
 	Optional<User> findByUsername(String username);
 	boolean existsByUsername(String username);
+
+	Optional<User> findByEmail(String email);
 }

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

@@ -3,6 +3,7 @@ package nl.andrewl.coyotecredit.model;
 import lombok.AccessLevel;
 import lombok.Getter;
 import lombok.NoArgsConstructor;
+import lombok.Setter;
 
 import javax.persistence.*;
 import java.util.HashSet;
@@ -23,15 +24,34 @@ public class Exchange {
 	/**
 	 * The name for this exchange.
 	 */
-	@Column(nullable = false)
+	@Column(nullable = false) @Setter
 	private String name;
 
 	/**
 	 * The primary tradeable that's used by this exchange.
 	 */
-	@ManyToOne(optional = false, fetch = FetchType.LAZY)
+	@ManyToOne(optional = false, fetch = FetchType.LAZY) @Setter
 	private Tradeable primaryTradeable;
 
+	/**
+	 * A user-provided description for the exchange.
+	 */
+	@Column(length = 1024) @Setter
+	private String description;
+
+	@Column(nullable = false) @Setter
+	private boolean publiclyAccessible;
+
+	// Colors:
+	@Column @Setter
+	private String primaryBackgroundColor;
+	@Column @Setter
+	private String secondaryBackgroundColor;
+	@Column @Setter
+	private String primaryForegroundColor;
+	@Column @Setter
+	private String secondaryForegroundColor;
+
 	/**
 	 * The set of tradeables that this exchange allows users to interact with.
 	 */

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

@@ -0,0 +1,52 @@
+package nl.andrewl.coyotecredit.model;
+
+import lombok.AccessLevel;
+import lombok.Getter;
+import lombok.NoArgsConstructor;
+
+import javax.persistence.*;
+import java.time.LocalDateTime;
+import java.time.ZoneOffset;
+
+/**
+ * Represents an invitation which an admin can send to users (or any email
+ * address) to invite them to participate in an exchange. If no user with the
+ * given email address exists, then a registration code will be sent to the
+ * email address, which when present at the /register page, will give context
+ * to allow the user to be automatically added to the exchange.
+ */
+@Entity
+@NoArgsConstructor(access = AccessLevel.PROTECTED)
+@Getter
+public class ExchangeInvitation {
+	@Id
+	@GeneratedValue(strategy = GenerationType.IDENTITY)
+	private Long id;
+
+	@ManyToOne(optional = false, fetch = FetchType.LAZY)
+	private Exchange exchange;
+
+	@ManyToOne(optional = false, fetch = FetchType.LAZY)
+	private Account sender;
+
+	@Column(nullable = false)
+	private String userEmail;
+
+	@Column(nullable = false, unique = true)
+	private String code;
+
+	@Column(nullable = false)
+	private LocalDateTime expiresAt;
+
+	public ExchangeInvitation(Exchange exchange, Account sender, String userEmail, String code, LocalDateTime expiresAt) {
+		this.exchange = exchange;
+		this.sender = sender;
+		this.userEmail = userEmail;
+		this.code = code;
+		this.expiresAt = expiresAt;
+	}
+
+	public boolean isExpired() {
+		return getExpiresAt().isBefore(LocalDateTime.now(ZoneOffset.UTC));
+	}
+}

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

@@ -5,21 +5,24 @@ import nl.andrewl.coyotecredit.ctl.dto.*;
 import nl.andrewl.coyotecredit.dao.*;
 import nl.andrewl.coyotecredit.model.*;
 import nl.andrewl.coyotecredit.util.AccountNumberUtils;
+import nl.andrewl.coyotecredit.util.StringUtils;
+import org.springframework.beans.factory.annotation.Value;
 import org.springframework.http.HttpStatus;
+import org.springframework.mail.javamail.JavaMailSender;
+import org.springframework.mail.javamail.MimeMessageHelper;
 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 javax.mail.MessagingException;
+import javax.mail.internet.MimeMessage;
 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;
+import java.util.*;
 
 @Service
 @RequiredArgsConstructor
@@ -29,8 +32,13 @@ public class ExchangeService {
 	private final TransactionRepository transactionRepository;
 	private final TradeableRepository tradeableRepository;
 	private final UserRepository userRepository;
+	private final ExchangeInvitationRepository invitationRepository;
+	private final JavaMailSender mailSender;
 	private final PasswordEncoder passwordEncoder;
 
+	@Value("${coyote-credit.base-url}")
+	private String baseUrl;
+
 	@Transactional(readOnly = true)
 	public FullExchangeData getData(long exchangeId, User user) {
 		Exchange e = exchangeRepository.findById(exchangeId)
@@ -46,7 +54,13 @@ public class ExchangeService {
 		return new FullExchangeData(
 				e.getId(),
 				e.getName(),
+				e.getDescription(),
+				e.isPubliclyAccessible(),
 				new TradeableData(e.getPrimaryTradeable()),
+				e.getPrimaryBackgroundColor(),
+				e.getSecondaryBackgroundColor(),
+				e.getPrimaryForegroundColor(),
+				e.getSecondaryForegroundColor(),
 				e.getAllTradeables().stream()
 						.map(TradeableData::new)
 						.sorted(Comparator.comparing(TradeableData::symbol))
@@ -72,6 +86,7 @@ public class ExchangeService {
 				.sorted(Comparator.comparing(Account::getName))
 				.map(a -> new SimpleAccountData(
 						a.getId(),
+						a.getUser().getId(),
 						a.getNumber(),
 						a.getName(),
 						a.isAdmin(),
@@ -203,9 +218,125 @@ public class ExchangeService {
 		return accountRepository.findAllByUser(user).stream()
 				.map(a -> new ExchangeAccountData(
 						new ExchangeData(a.getExchange().getId(), a.getExchange().getName(), a.getExchange().getPrimaryTradeable().getSymbol()),
-						new SimpleAccountData(a.getId(), a.getNumber(), a.getName(), a.isAdmin(), TradeableData.DECIMAL_FORMAT.format(a.getTotalBalance()))
+						new SimpleAccountData(
+								a.getId(),
+								user.getId(),
+								a.getNumber(),
+								a.getName(),
+								a.isAdmin(),
+								TradeableData.DECIMAL_FORMAT.format(a.getTotalBalance())
+						)
 				))
 				.sorted(Comparator.comparing(d -> d.exchange().name()))
 				.toList();
 	}
+
+	@Transactional
+	public void edit(long exchangeId, EditExchangePayload payload, 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));
+		if (!account.isAdmin()) throw new ResponseStatusException(HttpStatus.NOT_FOUND);
+		e.setName(payload.name());
+		e.setDescription(payload.description());
+		Tradeable primaryTradeable = tradeableRepository.findById(payload.primaryTradeableId())
+						.orElseThrow(() -> new ResponseStatusException(HttpStatus.BAD_REQUEST, "Unknown primary tradeable currency."));
+		if (!e.getAllTradeables().contains(primaryTradeable)) {
+			throw new ResponseStatusException(HttpStatus.BAD_REQUEST, "This exchange doesn't support " + primaryTradeable.getSymbol() + ".");
+		}
+		if (primaryTradeable.getType().equals(TradeableType.STOCK)) {
+			throw new ResponseStatusException(HttpStatus.BAD_REQUEST, "Invalid primary tradeable currency. Stocks are not permitted.");
+		}
+		e.setPrimaryTradeable(primaryTradeable);
+		e.setPubliclyAccessible(payload.publiclyAccessible());
+
+		e.setPrimaryBackgroundColor(payload.primaryBackgroundColor());
+		e.setSecondaryBackgroundColor(payload.secondaryBackgroundColor());
+		e.setPrimaryForegroundColor(payload.primaryForegroundColor());
+		e.setSecondaryForegroundColor(payload.secondaryForegroundColor());
+		exchangeRepository.save(e);
+	}
+
+	@Transactional
+	public void inviteUser(long exchangeId, User user, InviteUserPayload 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);
+		LocalDateTime expiresAt = LocalDateTime.now(ZoneOffset.UTC).plusDays(7);
+		ExchangeInvitation invitation = invitationRepository.save(
+				new ExchangeInvitation(exchange, account, payload.email(), StringUtils.random(64), expiresAt));
+		Optional<User> invitedUser = userRepository.findByEmail(payload.email());
+		if (invitedUser.isEmpty()) {
+			try {
+				sendInvitationEmail(invitation);
+			} catch (MessagingException e) {
+				e.printStackTrace();
+				throw new ResponseStatusException(HttpStatus.INTERNAL_SERVER_ERROR, "Could not send invitation email.");
+			}
+		}
+	}
+
+	@Transactional
+	public void acceptInvite(long exchangeId, long inviteId, User user) {
+		Exchange exchange = exchangeRepository.findById(exchangeId)
+				.orElseThrow(() -> new ResponseStatusException(HttpStatus.NOT_FOUND));
+		ExchangeInvitation invite = invitationRepository.findById(inviteId)
+				.orElseThrow(() -> new ResponseStatusException(HttpStatus.NOT_FOUND));
+		if (!invite.getUserEmail().equalsIgnoreCase(user.getEmail())) {
+			throw new ResponseStatusException(HttpStatus.BAD_REQUEST, "This invite is for someone else.");
+		}
+		if (!invite.getExchange().getId().equals(exchangeId)) {
+			throw new ResponseStatusException(HttpStatus.BAD_REQUEST, "This invite is for a different exchange.");
+		}
+		// If the user already has an account, silently delete the invite.
+		if (accountRepository.existsByUserAndExchange(user, exchange)) {
+			invitationRepository.delete(invite);
+		}
+		if (invite.isExpired()) {
+			throw new ResponseStatusException(HttpStatus.BAD_REQUEST, "This invite is expired.");
+		}
+		// Create the account.
+		Account account = accountRepository.save(new Account(AccountNumberUtils.generate(), user, user.getUsername(), exchange));
+		invitationRepository.delete(invite);
+		for (var t : exchange.getAllTradeables()) {
+			account.getBalances().add(new Balance(account, t, BigDecimal.ZERO));
+		}
+		accountRepository.save(account);
+	}
+
+	@Transactional
+	public void rejectInvite(long exchangeId, long inviteId, User user) {
+		ExchangeInvitation invite = invitationRepository.findById(inviteId)
+				.orElseThrow(() -> new ResponseStatusException(HttpStatus.NOT_FOUND));
+		if (!invite.getUserEmail().equalsIgnoreCase(user.getEmail())) {
+			throw new ResponseStatusException(HttpStatus.BAD_REQUEST, "This invite is for someone else.");
+		}
+		if (!invite.getExchange().getId().equals(exchangeId)) {
+			throw new ResponseStatusException(HttpStatus.BAD_REQUEST, "This invite is for a different exchange.");
+		}
+		invitationRepository.delete(invite);
+	}
+
+	private void sendInvitationEmail(ExchangeInvitation invitation) throws MessagingException {
+		MimeMessage msg = mailSender.createMimeMessage();
+		MimeMessageHelper helper = new MimeMessageHelper(msg);
+		helper.setFrom("Coyote Credit <noreply@coyote-credit.com>");
+		helper.setTo(invitation.getUserEmail());
+		helper.setSubject("Exchange Invitation");
+		String url = baseUrl + "/register?inviteCode=" + invitation.getCode();
+		helper.setText(String.format(
+				"""
+				<p>You have been invited by %s to join %s on Coyote Credit.
+				Click the link below to register an account.</p>
+				<a href="%s">%s</a>
+				""",
+				invitation.getSender().getName(),
+				invitation.getExchange().getName(),
+				url, url
+		), true);
+		mailSender.send(msg);
+	}
 }

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

@@ -1,12 +1,18 @@
 package nl.andrewl.coyotecredit.service;
 
 import lombok.RequiredArgsConstructor;
+import nl.andrewl.coyotecredit.ctl.dto.InvitationData;
 import nl.andrewl.coyotecredit.ctl.dto.RegisterPayload;
 import nl.andrewl.coyotecredit.ctl.dto.UserData;
+import nl.andrewl.coyotecredit.dao.AccountRepository;
+import nl.andrewl.coyotecredit.dao.ExchangeInvitationRepository;
 import nl.andrewl.coyotecredit.dao.UserActivationTokenRepository;
 import nl.andrewl.coyotecredit.dao.UserRepository;
+import nl.andrewl.coyotecredit.model.Account;
+import nl.andrewl.coyotecredit.model.Balance;
 import nl.andrewl.coyotecredit.model.User;
 import nl.andrewl.coyotecredit.model.UserActivationToken;
+import nl.andrewl.coyotecredit.util.AccountNumberUtils;
 import nl.andrewl.coyotecredit.util.StringUtils;
 import org.springframework.beans.factory.annotation.Value;
 import org.springframework.http.HttpStatus;
@@ -20,14 +26,20 @@ import org.springframework.web.server.ResponseStatusException;
 
 import javax.mail.MessagingException;
 import javax.mail.internet.MimeMessage;
+import java.math.BigDecimal;
 import java.time.LocalDateTime;
 import java.time.ZoneOffset;
+import java.util.ArrayList;
+import java.util.Comparator;
+import java.util.List;
 
 @Service
 @RequiredArgsConstructor
 public class UserService {
 	private final UserRepository userRepository;
+	private final AccountRepository accountRepository;
 	private final UserActivationTokenRepository activationTokenRepository;
+	private final ExchangeInvitationRepository exchangeInvitationRepository;
 	private final JavaMailSender mailSender;
 	private final PasswordEncoder passwordEncoder;
 
@@ -42,7 +54,13 @@ public class UserService {
 		} else {
 			user = userRepository.findById(userId).orElseThrow(() -> new ResponseStatusException(HttpStatus.NOT_FOUND));
 		}
-		return new UserData(user.getId(), user.getUsername(), user.getEmail());
+		List<InvitationData> exchangeInvitations = new ArrayList<>();
+		for (var invitation : exchangeInvitationRepository.findAllByUserEmail(user.getEmail())) {
+			if (invitation.isExpired()) continue;
+			exchangeInvitations.add(new InvitationData(invitation.getId(), invitation.getExchange().getId(), invitation.getExchange().getName()));
+		}
+		exchangeInvitations.sort(Comparator.comparing(InvitationData::id));
+		return new UserData(user.getId(), user.getUsername(), user.getEmail(), exchangeInvitations);
 	}
 
 	@Transactional
@@ -52,6 +70,26 @@ public class UserService {
 		}
 		User user = new User(payload.username(), passwordEncoder.encode(payload.password()), payload.email());
 		user = userRepository.save(user);
+		if (payload.inviteCode() != null) {
+			var invite = exchangeInvitationRepository.findByCode(payload.inviteCode())
+					.orElseThrow(() -> new ResponseStatusException(HttpStatus.BAD_REQUEST, "Invalid invitation code."));
+			if (!invite.getUserEmail().equalsIgnoreCase(user.getEmail())) {
+				throw new ResponseStatusException(HttpStatus.BAD_REQUEST, "This invitation code is for somebody else.");
+			}
+			if (invite.isExpired()) {
+				throw new ResponseStatusException(HttpStatus.BAD_REQUEST, "This invitation code is expired.");
+			}
+			exchangeInvitationRepository.delete(invite);
+			Account account = new Account(AccountNumberUtils.generate(), user, payload.accountName(), invite.getExchange());
+			account = accountRepository.save(account);
+			for (var tradeable : invite.getExchange().getAllTradeables()) {
+				account.getBalances().add(new Balance(account, tradeable, BigDecimal.ZERO));
+			}
+			account = accountRepository.save(account);
+			user.getAccounts().add(account);
+			user = userRepository.save(user);
+		}
+
 		String token = StringUtils.random(64);
 		LocalDateTime expiresAt = LocalDateTime.now(ZoneOffset.UTC).plusHours(24);
 		UserActivationToken activationToken = new UserActivationToken(token, user, expiresAt);

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

@@ -2,7 +2,7 @@
 <html
         lang="en"
         xmlns:th="http://www.thymeleaf.org"
-        th:replace="~{layout/basic_page :: layout (title='Add Account', content=~{::#content})}"
+        th:replace="~{layout/basic_page :: layout (title='Edit Balances', content=~{::#content})}"
 >
 <div id="content" class="container">
     <h1>Edit Balances</h1>

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

@@ -2,7 +2,7 @@
 <html
         lang="en"
         xmlns:th="http://www.thymeleaf.org"
-        th:replace="~{layout/basic_page :: layout (title='Add Account', content=~{::#content})}"
+        th:replace="~{layout/basic_page :: layout (title='Transfer', content=~{::#content})}"
 >
 <div id="content" class="container">
     <h1 class="display-4">Transfer</h1>

src/main/resources/templates/error.html

@@ -2,7 +2,7 @@
 <html
         lang="en"
         xmlns:th="http://www.thymeleaf.org"
-        th:replace="~{layout/basic_page :: layout (title='Home', content=~{::#content})}"
+        th:replace="~{layout/basic_page :: layout (title='Error', content=~{::#content})}"
 >
 <div id="content" class="container">
     <div class="row justify-content-center">

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

@@ -19,14 +19,18 @@
         </thead>
         <tbody>
             <tr th:each="account : ${accounts}">
-                <td><a th:href="@{/accounts/{id}(id=${account.id()})}" th:text="${account.number()}"></a></td>
+                <td><a class="colored-link" th:href="@{/accounts/{id}(id=${account.id()})}" th:text="${account.number()}"></a></td>
                 <td th:text="${account.name()}"></td>
                 <td th:text="${account.admin()}"></td>
                 <td class="monospace" th:text="${account.totalBalance()}"></td>
-                <td><a th:href="@{/exchanges/{eId}/removeAccount/{aId}(eId=${exchangeId}, aId=${account.id()})}">Remove</a></td>
+                <td><a
+                        class="colored-link"
+                        th:href="@{/exchanges/{eId}/removeAccount/{aId}(eId=${exchangeId}, aId=${account.id()})}"
+                        th:if="${account.userId() != #authentication.getPrincipal().getId()}"
+                >Remove</a></td>
             </tr>
         </tbody>
     </table>
 
-    <a class="btn btn-primary" th:href="@{/exchanges/{eId}/addAccount(eId=${exchangeId})}">Add Account</a>
+    <a class="btn btn-primary" th:href="@{/exchanges/{eId}/inviteUser(eId=${exchangeId})}">Invite User</a>
 </div>

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

@@ -1,33 +0,0 @@
-<!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=${exchangeId})}" th:method="post">
-        <div class="mb-3">
-            <label for="nameInput" class="form-label">Name</label>
-            <input id="nameInput" type="text" class="form-control" name="name" required/>
-        </div>
-        <div class="mb-3">
-            <label for="usernameInput" class="form-label">Username</label>
-            <input id="usernameInput" type="text" class="form-control" name="username" required/>
-        </div>
-        <div class="mb-3">
-            <label for="emailInput" class="form-label">Email</label>
-            <input id="emailInput" type="email" class="form-control" name="email" required/>
-        </div>
-        <div class="mb-3">
-            <label for="passwordInput" class="form-label">Password</label>
-            <input id="passwordInput" type="password" class="form-control" name="password" required/>
-        </div>
-        <input type="hidden" name="_csrf" th:value="${_csrf.getToken()}"/>
-        <button type="submit" class="btn btn-primary">Submit</button>
-    </form>
-</div>

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

@@ -0,0 +1,85 @@
+<!DOCTYPE html>
+<html
+        lang="en"
+        xmlns:th="http://www.thymeleaf.org"
+        th:replace="~{layout/basic_page :: layout (title='Edit Exchange', content=~{::#content})}"
+>
+<div id="content" class="container">
+    <h1 class="display-4">Edit Exchange Settings</h1>
+
+    <form th:action="@{/exchanges/{eId}/edit(eId=${exchange.id()})}" th:method="post">
+        <div class="row">
+            <div class="col-md-4">
+                <div class="mb-3">
+                    <label for="nameInput" class="form-label">Name</label>
+                    <input type="text" name="name" id="nameInput" class="form-control" th:value="${exchange.name()}"/>
+                </div>
+                <div class="mb-3">
+                    <label for="descriptionInput" class="form-label">Description</label>
+                    <textarea id="descriptionInput" name="description" class="form-control" rows="3" maxlength="1024" th:text="${exchange.description()}"></textarea>
+                </div>
+                <div class="form-check form-switch">
+                    <input class="form-check-input" type="checkbox" name="publiclyAccessible" id="publiclyAccessibleCheck" th:checked="${exchange.publiclyAccessible()}"/>
+                    <input type="hidden" value="on" name="_publiclyAccessible"/>
+                    <label class="form-check-label" for="publiclyAccessibleCheck">Publicly Accessible</label>
+                </div>
+            </div>
+            <div class="col-md-4">
+                <label for="primaryTradeableIdSelect" class="form-label">Primary Currency</label>
+                <select name="primaryTradeableId" id="primaryTradeableIdSelect" class="form-select">
+                    <option
+                        th:each="tb : ${exchange.supportedTradeables()}"
+                        th:if="${tb.type().equals('FIAT') || tb.type().equals('CRYPTO')}"
+                        th:text="${tb.symbol() + ' ' + tb.name()}"
+                        th:value="${tb.id()}"
+                        th:selected="${tb.id() == exchange.primaryTradeable().id()}"
+                    ></option>
+                </select>
+            </div>
+            <div class="col-md-4">
+                <div class="mb-3">
+                    <label for="primaryBackgroundColorInput" class="form-label">Primary Background Color</label>
+                    <input
+                            name="primaryBackgroundColor"
+                            id="primaryBackgroundColorInput"
+                            type="color"
+                            class="form-control form-control-color"
+                            th:value="${exchange.primaryBackgroundColor()}"
+                    />
+                </div>
+                <div class="mb-3">
+                    <label for="secondaryBackgroundColorInput" class="form-label">Secondary Background Color</label>
+                    <input
+                            name="secondaryBackgroundColor"
+                            id="secondaryBackgroundColorInput"
+                            type="color"
+                            class="form-control form-control-color"
+                            th:value="${exchange.secondaryBackgroundColor()}"
+                    />
+                </div>
+                <div class="mb-3">
+                    <label for="primaryForegroundColorInput" class="form-label">Primary Foreground Color</label>
+                    <input
+                            name="primaryForegroundColor"
+                            id="primaryForegroundColorInput"
+                            type="color"
+                            class="form-control form-control-color"
+                            th:value="${exchange.primaryForegroundColor()}"
+                    />
+                </div>
+                <div class="mb-3">
+                    <label for="secondaryForegroundColorInput" class="form-label">Secondary Foreground Color</label>
+                    <input
+                            name="secondaryForegroundColor"
+                            id="secondaryForegroundColorInput"
+                            type="color"
+                            class="form-control form-control-color"
+                            th:value="${exchange.secondaryForegroundColor()}"
+                    />
+                </div>
+            </div>
+        </div>
+
+        <button type="submit" class="btn btn-primary">Save</button>
+    </form>
+</div>

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

@@ -6,6 +6,7 @@
 >
 <div id="content" class="container">
     <h1 class="display-4" th:text="${exchange.name()}"></h1>
+    <p class="lead" th:if="${exchange.description() != null && !exchange.description().isBlank()}" th:text="${exchange.description()}"></p>
 
     <div class="card text-white bg-dark mb-3">
         <div class="card-body">
@@ -22,31 +23,39 @@
                 <dt class="col-sm-6">Number of Accounts</dt>
                 <dd class="col-sm-6" th:text="${exchange.accountCount()}"></dd>
             </dl>
+            <a class="btn btn-primary" th:href="@{/accounts/{aId}(aId=${exchange.accountId()})}">My Account</a>
         </div>
     </div>
 
-    <h3>Tradeable Assets</h3>
-    <table class="table table-dark">
-        <thead>
-            <tr>
-                <th>Symbol</th>
-                <th>Type</th>
-                <th>Price (in USD)</th>
-                <th>Name</th>
-            </tr>
-        </thead>
-        <tbody>
-            <tr th:each="tradeable : ${exchange.supportedTradeables()}">
-                <td th:text="${tradeable.symbol()}"></td>
-                <td th:text="${tradeable.type()}"></td>
-                <td class="monospace" th:text="${tradeable.formattedPriceUsd()}"></td>
-                <td th:text="${tradeable.name()}"></td>
-            </tr>
-        </tbody>
-    </table>
+    <div class="card text-white bg-dark mb-3">
+        <div class="card-body">
+            <h5 class="card-title">Tradeable Assets</h5>
+            <table class="table table-dark">
+                <thead>
+                <tr>
+                    <th>Symbol</th>
+                    <th>Type</th>
+                    <th>Price (in USD)</th>
+                    <th>Name</th>
+                </tr>
+                </thead>
+                <tbody>
+                <tr th:each="tradeable : ${exchange.supportedTradeables()}">
+                    <td th:text="${tradeable.symbol()}"></td>
+                    <td th:text="${tradeable.type()}"></td>
+                    <td class="monospace" th:text="${tradeable.formattedPriceUsd()}"></td>
+                    <td th:text="${tradeable.name()}"></td>
+                </tr>
+                </tbody>
+            </table>
+        </div>
+    </div>
 
-    <div>
-        <a class="btn btn-primary" th:href="@{/accounts/{aId}(aId=${exchange.accountId()})}">My Account</a>
-        <a class="btn btn-primary" th:if="${exchange.accountAdmin()}" th:href="@{/exchanges/{eId}/accounts(eId=${exchange.id()})}">All Accounts</a>
+    <div class="card text-white bg-dark mb-3" th:if="${exchange.accountAdmin()}">
+        <div class="card-body">
+            <h5 class="card-title">Administrator Tools</h5>
+            <a class="btn btn-primary" th:href="@{/exchanges/{eId}/accounts(eId=${exchange.id()})}">View All Accounts</a>
+            <a class="btn btn-secondary" th:href="@{/exchanges/{eId}/edit(eId=${exchange.id()})}">Edit Exchange Settings</a>
+        </div>
     </div>
 </div>

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

@@ -0,0 +1,23 @@
+<!DOCTYPE html>
+<html
+        lang="en"
+        xmlns:th="http://www.thymeleaf.org"
+        th:replace="~{layout/basic_page :: layout (title='Invite User', content=~{::#content})}"
+>
+<div id="content" class="container">
+    <h1 class="display-4">Invite User</h1>
+    <p class="lead">
+        Invite someone to join your exchange. If they've already got an account,
+        their account will receive an invitation, or if not, they'll receive an
+        email so they can create an account.
+    </p>
+
+    <form th:href="@{/exchanges/{eId}/inviteUser(eId=${exchangeId})}" th:method="post">
+        <div class="mb-3">
+            <label for="emailInput" class="form-label">Email</label>
+            <input id="emailInput" name="email" type="email" class="form-control" required/>
+        </div>
+        <input type="hidden" name="_csrf" th:value="${_csrf.getToken()}"/>
+        <button type="submit" class="btn btn-primary">Invite</button>
+    </form>
+</div>

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

@@ -2,7 +2,7 @@
 <html
         lang="en"
         xmlns:th="http://www.thymeleaf.org"
-        th:replace="~{layout/basic_page :: layout (title='Add Account', content=~{::#content})}"
+        th:replace="~{layout/basic_page :: layout (title='Remove Account', content=~{::#content})}"
 >
 <div id="content" class="container">
     <h1>Remove Account</h1>

src/main/resources/templates/public/register.html

@@ -16,7 +16,15 @@
 
                 <div class="mb-3">
                     <label for="emailInput" class="form-label">Email</label>
-                    <input name="email" id="emailInput" class="form-control" type="email" required/>
+                    <input
+                            name="email"
+                            id="emailInput"
+                            class="form-control"
+                            type="email"
+                            required
+                            th:readonly="${inviteUserEmail != null}"
+                            th:value="${inviteUserEmail == null ? '' : inviteUserEmail}"
+                    />
                 </div>
 
                 <div class="mb-3">
@@ -24,7 +32,21 @@
                     <input name="password" id="passwordInput" class="form-control" type="password" required/>
                 </div>
 
-                <input type="submit" class="btn btn-primary" value="Register">
+                <div class="mb-3" th:if="${inviteCode != null}">
+                    <label for="accountNameInput" class="form-label">Account Name</label>
+                    <small class="text-muted">
+                        You have been invited by <span th:text="${inviteSenderName}"></span> to join <span th:text="${inviteExchangeName}"></span>.
+                    </small>
+                    <input name="accountName" id="accountNameInput" class="form-control" type="text" required/>
+                    <input name="inviteCode" type="hidden" th:value="${inviteCode}"/>
+                </div>
+
+                <input type="submit" class="btn btn-primary mb-3" value="Register">
+
+                <p class="alert alert-dark">
+                    After registering, you will receive an email with a verification link. Please
+                    click that link to verify your account before attempting to log in.
+                </p>
             </form>
         </div>
     </div>

src/main/resources/templates/tradeable.html

@@ -2,7 +2,7 @@
 <html
         lang="en"
         xmlns:th="http://www.thymeleaf.org"
-        th:replace="~{layout/basic_page :: layout (title='Account', content=~{::#content})}"
+        th:replace="~{layout/basic_page :: layout (title='Tradeable', content=~{::#content})}"
 >
 <div id="content" class="container">
     <h1>

src/main/resources/templates/user.html

@@ -19,4 +19,22 @@
             </tr>
         </tbody>
     </table>
+
+    <div class="card text-white bg-dark mb-3">
+        <div class="card-body">
+            <h5 class="card-title">Exchange Invitations</h5>
+        </div>
+        <ul class="list-group list-group-flush">
+            <li class="list-group-item list-group-item-dark" th:each="invite : ${user.exchangeInvitations()}">
+                <span th:text="${invite.exchangeName()}"></span>
+
+                <form th:action="@{/exchanges/{eId}/rejectInvite/{iId}(eId=${invite.exchangeId()}, iId=${invite.id()})}" method="post" class="float-end">
+                    <button type="submit" class="btn btn-danger">Reject</button>
+                </form>
+                <form th:action="@{/exchanges/{eId}/acceptInvite/{iId}(eId=${invite.exchangeId()}, iId=${invite.id()})}" method="post" class="float-end">
+                    <button type="submit" class="btn btn-success">Accept</button>
+                </form>
+            </li>
+        </ul>
+    </div>
 </div>