module transaction.service;

import handy_http_primitives;
import std.datetime;

import transaction.api;
import transaction.model;
import transaction.data;
import transaction.dto;
import profile.data;
import account.model;
import account.data;
import util.money;
import util.pagination;

// Transactions Services

Page!TransactionsListItem getTransactions(ProfileDataSource ds, in PageRequest pageRequest) {
    Page!TransactionsListItem page = ds.getTransactionRepository()
        .findAll(pageRequest);
    return page;
}

TransactionDetail getTransaction(ProfileDataSource ds, ulong transactionId) {
    return ds.getTransactionRepository().findById(transactionId)
        .orElseThrow(() => new HttpStatusException(HttpStatus.NOT_FOUND));
}

TransactionDetail addTransaction(ProfileDataSource ds, in AddTransactionPayload payload) {
    TransactionVendorRepository vendorRepo = ds.getTransactionVendorRepository();
    TransactionCategoryRepository categoryRepo = ds.getTransactionCategoryRepository();
    AccountRepository accountRepo = ds.getAccountRepository();

    // Validate transaction details:
    if (payload.creditedAccountId.isNull && payload.debitedAccountId.isNull) {
        throw new HttpStatusException(HttpStatus.BAD_REQUEST, "At least one account must be linked.");
    }
    if (
        !payload.creditedAccountId.isNull &&
        !payload.debitedAccountId.isNull &&
        payload.creditedAccountId.get == payload.debitedAccountId.get
    ) {
        throw new HttpStatusException(HttpStatus.BAD_REQUEST, "Cannot link the same account as both credit and debit.");
    }
    if (payload.amount == 0) {
        throw new HttpStatusException(HttpStatus.BAD_REQUEST, "Amount should be greater than 0.");
    }
    SysTime now = Clock.currTime(UTC());
    SysTime timestamp = SysTime.fromISOExtString(payload.timestamp, UTC());
    if (timestamp > now) {
        throw new HttpStatusException(HttpStatus.BAD_REQUEST, "Cannot create transaction in the future.");
    }
    if (!payload.vendorId.isNull && !vendorRepo.existsById(payload.vendorId.get)) {
        throw new HttpStatusException(HttpStatus.BAD_REQUEST, "Vendor doesn't exist.");
    }
    if (!payload.categoryId.isNull && !categoryRepo.existsById(payload.categoryId.get)) {
        throw new HttpStatusException(HttpStatus.BAD_REQUEST, "Category doesn't exist.");
    }
    if (!payload.creditedAccountId.isNull && !accountRepo.existsById(payload.creditedAccountId.get)) {
        throw new HttpStatusException(HttpStatus.BAD_REQUEST, "Credited account doesn't exist.");
    }
    if (!payload.debitedAccountId.isNull && !accountRepo.existsById(payload.debitedAccountId.get)) {
        throw new HttpStatusException(HttpStatus.BAD_REQUEST, "Debited account doesn't exist.");
    }
    foreach (tag; payload.tags) {
        import std.regex;
        auto r = ctRegex!(`^[a-z0-9-_]{3,32}$`);
        if (!matchFirst(tag, r)) {
            throw new HttpStatusException(HttpStatus.BAD_REQUEST, "Invalid tag: \"" ~ tag ~ "\".");
        }
    }
    if (payload.lineItems.length > 0) {
        long lineItemsTotal = 0;
        foreach (lineItem; payload.lineItems) {
            if (!lineItem.categoryId.isNull && !categoryRepo.existsById(lineItem.categoryId.get)) {
                throw new HttpStatusException(HttpStatus.BAD_REQUEST, "Line item's category doesn't exist.");
            }
            if (lineItem.quantity == 0) {
                throw new HttpStatusException(HttpStatus.BAD_REQUEST, "Line item's quantity should greater than zero.");
            }
            for (ulong i = 0; i < lineItem.quantity; i++) {
                lineItemsTotal += lineItem.valuePerItem;
            }
        }
        if (lineItemsTotal != payload.amount) {
            throw new HttpStatusException(
                HttpStatus.BAD_REQUEST,
                "Total of all line items doesn't equal the transaction's total."
            );
        }
    }

    // Add the transaction:
    ulong txnId;
    ds.doTransaction(() {
        TransactionRepository txRepo = ds.getTransactionRepository();
        TransactionDetail txn = txRepo.insert(payload);
        AccountJournalEntryRepository jeRepo = ds.getAccountJournalEntryRepository();
        if (!payload.creditedAccountId.isNull) {
            jeRepo.insert(
                timestamp,
                payload.creditedAccountId.get,
                txn.id,
                txn.amount,
                AccountJournalEntryType.CREDIT,
                txn.currency
            );
        }
        if (!payload.debitedAccountId.isNull) {
            jeRepo.insert(
                timestamp,
                payload.debitedAccountId.get,
                txn.id,
                txn.amount,
                AccountJournalEntryType.DEBIT,
                txn.currency
            );
        }
        TransactionTagRepository tagRepo = ds.getTransactionTagRepository();
        tagRepo.updateTags(txn.id, payload.tags);
        txnId = txn.id;
    });
    return ds.getTransactionRepository().findById(txnId).orElseThrow();
}

// Vendors Services

TransactionVendor[] getAllVendors(ProfileDataSource ds) {
    return ds.getTransactionVendorRepository().findAll();
}

TransactionVendor getVendor(ProfileDataSource ds, ulong vendorId) {
    return ds.getTransactionVendorRepository().findById(vendorId)
        .orElseThrow(() => new HttpStatusException(HttpStatus.NOT_FOUND));
}

TransactionVendor createVendor(ProfileDataSource ds, in VendorPayload payload) {
    auto vendorRepo = ds.getTransactionVendorRepository();
    if (vendorRepo.existsByName(payload.name)) {
        throw new HttpStatusException(HttpStatus.BAD_REQUEST, "Vendor name is already in use.");
    }
    return vendorRepo.insert(payload.name, payload.description);
}

TransactionVendor updateVendor(ProfileDataSource ds, ulong vendorId, in VendorPayload payload) {
    TransactionVendorRepository repo = ds.getTransactionVendorRepository();
    TransactionVendor existingVendor = repo.findById(vendorId)
        .orElseThrow(() => new HttpStatusException(HttpStatus.NOT_FOUND));
    if (payload.name != existingVendor.name && repo.existsByName(payload.name)) {
        throw new HttpStatusException(
            HttpStatus.BAD_REQUEST,
            "Vendor name is already in use."
        );
    }
    return repo.updateById(vendorId, payload.name, payload.description);
}

void deleteVendor(ProfileDataSource ds, ulong vendorId) {
    ds.getTransactionVendorRepository().deleteById(vendorId);
}