<?php

require_once __DIR__ . '/db.php';
require_once __DIR__ . '/account_service.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,
    ?int $sourceLoanId = null
): string {
    $parts = [
        $userId,
        $accountId,
        $relatedAccountId ?? 0,
        $categoryId,
        $transactionType,
        number_format($amount, 2, '.', ''),
        $transactionDate,
        trim((string)$merchantName),
        trim((string)$description),
    ];

    if ($sourceLoanId !== null) {
        $parts[] = $sourceLoanId;
    }

    return hash('sha256', implode('|', $parts));
}

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 get_transaction_billing_year_month(int $userId, int $accountId, string $transactionDate): ?string
{
    $account = get_account_for_transaction($userId, $accountId);
    return $account ? get_card_billing_year_month($account, $transactionDate) : null;
}

function transaction_category_type(string $transactionType): string
{
    if ($transactionType === 'income') {
        return 'income';
    }

    if ($transactionType === 'expense') {
        return 'expense';
    }

    return 'transfer';
}

function parse_money_input($value): float
{
    return (float)str_replace(',', '', trim((string)$value));
}

function build_transaction_payload_from_input(array $input, int $userId): array
{
    $pdo = db();

    $transactionType = (string)($input['transaction_type'] ?? 'expense');
    $accountId = (int)($input['account_id'] ?? 0);
    $categoryId = (int)($input['category_id'] ?? 0);
    $amount = parse_money_input($input['amount'] ?? 0);
    $transactionDate = (string)($input['transaction_date'] ?? date('Y-m-d'));
    $merchantName = trim((string)($input['merchant_name'] ?? ''));
    $description = trim((string)($input['description'] ?? ''));
    $relatedAccountId = !empty($input['related_account_id']) ? (int)$input['related_account_id'] : null;
    $isInstallment = (int)($input['is_installment'] ?? 0);
    $installmentMonths = trim((string)($input['installment_months'] ?? '')) !== ''
        ? (int)$input['installment_months']
        : null;
    $installmentInterestRate = trim((string)($input['installment_interest_rate'] ?? '0')) !== ''
        ? (float)$input['installment_interest_rate']
        : 0.0;
    $installmentInterestTotal = trim((string)($input['installment_interest_total'] ?? '')) !== ''
        ? parse_money_input($input['installment_interest_total'])
        : null;
    $installmentTotalBilled = trim((string)($input['installment_total_billed'] ?? '')) !== ''
        ? parse_money_input($input['installment_total_billed'])
        : null;

    if ($amount <= 0) {
        throw new RuntimeException('금액은 0보다 커야 합니다.');
    }

    if (!in_array($transactionType, ['income', 'expense', 'transfer', 'card_payment'], true)) {
        throw new RuntimeException('거래 유형이 올바르지 않습니다.');
    }

    if ($accountId <= 0) {
        throw new RuntimeException('주 계좌/카드를 선택하세요.');
    }

    $stmt = $pdo->prepare("SELECT id FROM accounts WHERE id = ? AND user_id = ? AND is_active = 1 LIMIT 1");
    $stmt->execute([$accountId, $userId]);
    if (!$stmt->fetch()) {
        throw new RuntimeException('선택한 주 계좌/카드를 사용할 수 없습니다.');
    }

    if ($categoryId <= 0) {
        throw new RuntimeException('카테고리를 선택하세요.');
    }

    $stmt = $pdo->prepare("
        SELECT category_type
        FROM categories
        WHERE id = ?
          AND user_id = ?
          AND is_active = 1
        LIMIT 1
    ");
    $stmt->execute([$categoryId, $userId]);
    $category = $stmt->fetch();
    if (!$category) {
        throw new RuntimeException('선택한 카테고리를 사용할 수 없습니다.');
    }

    if ((string)$category['category_type'] !== transaction_category_type($transactionType)) {
        throw new RuntimeException('거래 유형과 카테고리 유형이 일치하지 않습니다.');
    }

    if (in_array($transactionType, ['transfer', 'card_payment'], true) && !$relatedAccountId) {
        throw new RuntimeException('관련 계좌를 선택해야 합니다.');
    }

    if ($relatedAccountId) {
        if ($relatedAccountId === $accountId) {
            throw new RuntimeException('주 계좌와 관련 계좌는 같을 수 없습니다.');
        }

        $stmt = $pdo->prepare("SELECT id FROM accounts WHERE id = ? AND user_id = ? AND is_active = 1 LIMIT 1");
        $stmt->execute([$relatedAccountId, $userId]);
        if (!$stmt->fetch()) {
            throw new RuntimeException('선택한 관련 계좌를 사용할 수 없습니다.');
        }
    }

    if ($transactionType !== 'expense') {
        $isInstallment = 0;
        $installmentMonths = null;
        $installmentInterestRate = 0.0;
        $installmentInterestTotal = null;
        $installmentTotalBilled = null;
    }

    return [
        'user_id' => $userId,
        'account_id' => $accountId,
        'category_id' => $categoryId,
        'transaction_type' => $transactionType,
        'amount' => $amount,
        'transaction_date' => $transactionDate,
        'merchant_name' => $merchantName !== '' ? $merchantName : null,
        'description' => $description !== '' ? $description : null,
        'related_account_id' => $relatedAccountId,
        'is_installment' => $isInstallment,
        'installment_months' => $installmentMonths,
        'installment_interest_rate' => $installmentInterestRate,
        'installment_interest_total' => $installmentInterestTotal,
        'installment_total_billed' => $installmentTotalBilled,
    ];
}

function insert_transaction_record(array $data, bool $skipIfDuplicate = true): int
{
    $pdo = db();

    $sourceLoanId = !empty($data['source_loan_id']) ? (int)$data['source_loan_id'] : null;
    $fingerprint = build_transaction_fingerprint(
        (int)$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,
        $sourceLoanId
    );

    if ($skipIfDuplicate) {
        $stmt = $pdo->prepare("
            SELECT id
            FROM transactions
            WHERE user_id = ?
              AND fingerprint = ?
            LIMIT 1
        ");
        $stmt->execute([$data['user_id'], $fingerprint]);
        $exists = $stmt->fetch();

        if ($exists) {
            return (int)$exists['id'];
        }
    }

    $billingYearMonth = get_transaction_billing_year_month(
        (int)$data['user_id'],
        (int)$data['account_id'],
        (string)$data['transaction_date']
    );

    $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,
            source_loan_id,
            fingerprint
        )
        VALUES (?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?)
    ");

    $stmt->execute([
        $data['user_id'],
        $data['account_id'],
        $data['category_id'],
        $data['transaction_type'],
        $data['amount'],
        !empty($data['is_installment']) ? 1 : 0,
        $data['installment_months'] ?? null,
        $data['installment_interest_rate'] ?? 0,
        $data['installment_interest_total'] ?? 0,
        $data['installment_total_billed'] ?? null,
        $data['installment_prepay_amount'] ?? 0,
        $data['transaction_date'],
        $billingYearMonth,
        $data['merchant_name'] ?? null,
        $data['description'] ?? null,
        $data['related_account_id'] ?? null,
        $sourceLoanId,
        $fingerprint,
    ]);

    return (int)$pdo->lastInsertId();
}