<?php

require_once __DIR__ . '/db.php';
require_once __DIR__ . '/account_service.php';
require_once __DIR__ . '/installment_service.php';
require_once __DIR__ . '/helpers.php';
require_once __DIR__ . '/card_billing_service.php';

function build_transaction_fingerprint(
    int $userId,
    int $accountId,
    ?int $relatedAccountId,
    int $categoryId,
    string $transactionType,
    float $amount,
    string $transactionDate,
    ?string $merchantName,
    ?string $description
): string {
    $raw = implode('|', [
        $userId,
        $accountId,
        $relatedAccountId ?? 0,
        $categoryId,
        $transactionType,
        number_format($amount, 2, '.', ''),
        $transactionDate,
        trim((string)$merchantName),
        trim((string)$description),
    ]);

    return hash('sha256', $raw);
}

function get_account_for_transaction(int $userId, int $accountId): ?array
{
    $pdo = db();

    $stmt = $pdo->prepare("
        SELECT *
        FROM accounts
        WHERE id = ?
          AND user_id = ?
        LIMIT 1
    ");
    $stmt->execute([$accountId, $userId]);

    $row = $stmt->fetch();
    return $row ?: null;
}

function create_transaction(array $data, bool $skipIfDuplicate = false): bool
{
    $pdo = db();
    $pdo->beginTransaction();

    try {
        $fingerprint = build_transaction_fingerprint(
            (int)$data['user_id'],
            (int)$data['account_id'],
            !empty($data['related_account_id']) ? (int)$data['related_account_id'] : null,
            (int)$data['category_id'],
            (string)$data['transaction_type'],
            (float)$data['amount'],
            (string)$data['transaction_date'],
            $data['merchant_name'] ?? null,
            $data['description'] ?? null
        );

        if ($skipIfDuplicate) {
            $stmt = $pdo->prepare("
                SELECT id
                FROM transactions
                WHERE user_id = ?
                  AND fingerprint = ?
                LIMIT 1
            ");
            $stmt->execute([$data['user_id'], $fingerprint]);

            if ($stmt->fetch()) {
                $pdo->commit();
                return false;
            }
        }

        $account = get_account_for_transaction(
            (int)$data['user_id'],
            (int)$data['account_id']
        );

        $billingYearMonth = null;
        if ($account) {
            $billingYearMonth = get_card_billing_year_month(
                $account,
                (string)$data['transaction_date']
            );
        }

        $isInstallment = !empty($data['is_installment']) ? 1 : 0;
        $installmentMonths = !empty($data['installment_months']) ? (int)$data['installment_months'] : null;
        $installmentInterestRate = !empty($data['installment_interest_rate']) ? (float)$data['installment_interest_rate'] : 0.0;

        $installmentInterestTotal =
            isset($data['installment_interest_total']) &&
            $data['installment_interest_total'] !== null &&
            $data['installment_interest_total'] !== ''
            ? (float)$data['installment_interest_total']
            : null;

        $installmentTotalBilled =
            isset($data['installment_total_billed']) &&
            $data['installment_total_billed'] !== null &&
            $data['installment_total_billed'] !== ''
            ? (float)$data['installment_total_billed']
            : null;

        if ($isInstallment && ($installmentMonths === null || $installmentMonths <= 1)) {
            throw new RuntimeException('할부 개월 수가 올바르지 않습니다.');
        }

        if ($isInstallment) {
            if ($installmentInterestTotal === null) {
                $installmentInterestTotal = calculate_installment_interest_total(
                    (float)$data['amount'],
                    $installmentMonths,
                    $installmentInterestRate
                );
            }

            $expectedTotal = round(
                (float)$data['amount'] + (float)$installmentInterestTotal,
                2
            );

            if ($installmentTotalBilled === null) {
                $installmentTotalBilled = $expectedTotal;
            }

            if (round($installmentTotalBilled, 2) !== $expectedTotal) {
                throw new RuntimeException('총 청구금액은 원금 + 할부이자와 같아야 합니다.');
            }
        } else {
            $installmentMonths = null;
            $installmentInterestRate = 0.0;
            $installmentInterestTotal = 0.0;
            $installmentTotalBilled = null;
        }

        $stmt = $pdo->prepare("
            INSERT INTO transactions
            (
                user_id,
                account_id,
                category_id,
                transaction_type,
                amount,
                is_installment,
                installment_months,
                installment_interest_rate,
                installment_interest_total,
                installment_total_billed,
                installment_prepay_amount,
                transaction_date,
                billing_year_month,
                merchant_name,
                description,
                related_account_id,
                fingerprint
            )
            VALUES (?, ?, ?, ?, ?, ?, ?, ?, ?, ?, 0, ?, ?, ?, ?, ?, ?)
        ");

        $stmt->execute([
            $data['user_id'],
            $data['account_id'],
            $data['category_id'],
            $data['transaction_type'],
            $data['amount'],
            $isInstallment,
            $installmentMonths,
            $installmentInterestRate,
            $installmentInterestTotal,
            $installmentTotalBilled,
            $data['transaction_date'],
            $billingYearMonth,
            $data['merchant_name'],
            $data['description'],
            $data['related_account_id'],
            $fingerprint,
        ]);

        $transactionId = (int)$pdo->lastInsertId();
        $pdo->commit();

        if (
            $data['transaction_type'] === 'expense' &&
            $isInstallment === 1 &&
            $installmentMonths !== null &&
            $installmentMonths > 1
        ) {
            create_installment_schedule(
                (int)$data['user_id'],
                $transactionId,
                (int)$data['account_id'],
                (float)$data['amount'],
                $installmentMonths,
                (string)$data['transaction_date'],
                $installmentInterestRate,
                $installmentInterestTotal,
                $installmentTotalBilled,
                $installmentInterestRate > 0 ? 'fixed_total' : 'none'
            );
        }

        if (
            $data['transaction_type'] === 'card_payment' &&
            !empty($data['related_account_id'])
        ) {
            $yearMonth = date('Y-m', strtotime((string)$data['transaction_date']));

            $processedCount = mark_installment_month_billed_for_card_payment(
                (int)$data['user_id'],
                (int)$data['related_account_id'],
                $yearMonth
            );

            if ($processedCount > 0) {
                set_flash_message(
                    'success',
                    $yearMonth . ' 할부 청구 회차 ' . intvalf($processedCount) . '건 자동 처리'
                );
            }
        }

        recalculate_account_balance((int)$data['account_id']);

        if (!empty($data['related_account_id'])) {
            recalculate_account_balance((int)$data['related_account_id']);
        }

        return true;

    } catch (Throwable $e) {
        if ($pdo->inTransaction()) {
            $pdo->rollBack();
        }
        throw $e;
    }
}

function update_transaction(int $transactionId, int $userId, array $data): void
{
    $pdo = db();
    $pdo->beginTransaction();

    try {
        $stmt = $pdo->prepare("
            SELECT account_id, related_account_id
            FROM transactions
            WHERE id = ?
              AND user_id = ?
            LIMIT 1
        ");
        $stmt->execute([$transactionId, $userId]);

        $old = $stmt->fetch();

        if (!$old) {
            throw new RuntimeException('거래를 찾을 수 없습니다.');
        }

        $fingerprint = build_transaction_fingerprint(
            $userId,
            (int)$data['account_id'],
            !empty($data['related_account_id']) ? (int)$data['related_account_id'] : null,
            (int)$data['category_id'],
            (string)$data['transaction_type'],
            (float)$data['amount'],
            (string)$data['transaction_date'],
            $data['merchant_name'] ?? null,
            $data['description'] ?? null
        );

        $account = get_account_for_transaction(
            $userId,
            (int)$data['account_id']
        );

        $billingYearMonth = null;
        if ($account) {
            $billingYearMonth = get_card_billing_year_month(
                $account,
                (string)$data['transaction_date']
            );
        }

        $isInstallment = !empty($data['is_installment']) ? 1 : 0;
        $installmentMonths = !empty($data['installment_months']) ? (int)$data['installment_months'] : null;
        $installmentInterestRate = !empty($data['installment_interest_rate']) ? (float)$data['installment_interest_rate'] : 0.0;

        $stmt = $pdo->prepare("
            UPDATE transactions
            SET
                account_id = ?,
                category_id = ?,
                transaction_type = ?,
                amount = ?,
                is_installment = ?,
                installment_months = ?,
                installment_interest_rate = ?,
                installment_interest_total = ?,
                installment_total_billed = ?,
                transaction_date = ?,
                billing_year_month = ?,
                merchant_name = ?,
                description = ?,
                related_account_id = ?,
                fingerprint = ?
            WHERE id = ?
              AND user_id = ?
        ");

        $stmt->execute([
            $data['account_id'],
            $data['category_id'],
            $data['transaction_type'],
            $data['amount'],
            $isInstallment,
            $installmentMonths,
            $installmentInterestRate,
            $data['installment_interest_total'] ?? 0,
            $data['installment_total_billed'] ?? null,
            $data['transaction_date'],
            $billingYearMonth,
            $data['merchant_name'],
            $data['description'],
            $data['related_account_id'],
            $fingerprint,
            $transactionId,
            $userId
        ]);

        delete_installment_by_transaction_id($transactionId);

        if (
            $data['transaction_type'] === 'expense' &&
            $isInstallment === 1 &&
            $installmentMonths !== null &&
            $installmentMonths > 1
        ) {
            $interestTotal = calculate_installment_interest_total(
                (float)$data['amount'],
                $installmentMonths,
                $installmentInterestRate
            );

            $totalBilled = round(
                (float)$data['amount'] + (float)$interestTotal,
                2
            );

            create_installment_schedule(
                $userId,
                $transactionId,
                (int)$data['account_id'],
                (float)$data['amount'],
                $installmentMonths,
                (string)$data['transaction_date'],
                $installmentInterestRate,
                $interestTotal,
                $totalBilled,
                $installmentInterestRate > 0 ? 'fixed_total' : 'none'
            );
        }

        $pdo->commit();

        $recalcIds = array_unique(array_filter([
            (int)$old['account_id'],
            !empty($old['related_account_id']) ? (int)$old['related_account_id'] : null,
            (int)$data['account_id'],
            !empty($data['related_account_id']) ? (int)$data['related_account_id'] : null,
        ]));

        foreach ($recalcIds as $id) {
            recalculate_account_balance((int)$id);
        }

    } catch (Throwable $e) {
        if ($pdo->inTransaction()) {
            $pdo->rollBack();
        }
        throw $e;
    }
}

function delete_transaction(int $transactionId, int $userId): void
{
    $pdo = db();
    $pdo->beginTransaction();

    try {
        $stmt = $pdo->prepare("
            SELECT account_id, related_account_id
            FROM transactions
            WHERE id = ?
              AND user_id = ?
            LIMIT 1
        ");
        $stmt->execute([$transactionId, $userId]);

        $row = $stmt->fetch();

        if (!$row) {
            throw new RuntimeException('거래를 찾을 수 없습니다.');
        }

        delete_installment_by_transaction_id($transactionId);

        $stmt = $pdo->prepare("
            DELETE FROM transactions
            WHERE id = ?
              AND user_id = ?
        ");
        $stmt->execute([$transactionId, $userId]);

        $pdo->commit();

        recalculate_account_balance((int)$row['account_id']);

        if (!empty($row['related_account_id'])) {
            recalculate_account_balance((int)$row['related_account_id']);
        }

    } catch (Throwable $e) {
        if ($pdo->inTransaction()) {
            $pdo->rollBack();
        }
        throw $e;
    }
}