<?php
require_once __DIR__ . '/../includes/uuid.php';
require_once __DIR__ . '/../db/config.php';
require_once __DIR__ . '/../includes/journal_helpers.php';
require_once __DIR__ . '/../includes/audit_helpers.php';

header('Content-Type: application/json');

if ($_SERVER['REQUEST_METHOD'] !== 'POST') {
    http_response_code(405);
    echo json_encode(['error' => 'Method not allowed']);
    exit();
}

$data = json_decode(file_get_contents('php://input'), true);

if (empty($data['vendor_id']) || empty($data['payment_date']) || empty($data['payment_account_code']) || empty($data['amount']) || empty($data['bill_ids'])) {
    http_response_code(400);
    echo json_encode(['error' => 'Missing required fields: vendor_id, payment_date, payment_account_code, amount, and bill_ids array.']);
    exit();
}

$pdo = db();

try {
    $pdo->beginTransaction();

    $total_payment_amount = (float)$data['amount'];
    $ap_account_code = '2100-AP'; // Accounts Payable

    // 1. Create Journal Entry to settle AP
    $journal_lines = [
        // Debit Accounts Payable
        [
            'account_code' => $ap_account_code,
            'type' => 'DEBIT',
            'amount' => $total_payment_amount
        ],
        // Credit the cash/bank account used for payment
        [
            'account_code' => $data['payment_account_code'],
            'type' => 'CREDIT',
            'amount' => $total_payment_amount
        ]
    ];

    $journal_payload = [
        'entry_date' => $data['payment_date'],
        'description' => 'Payment for vendor ' . $data['vendor_id'],
        'lines' => $journal_lines
    ];

    $journal_result = post_journal_entry($pdo, $journal_payload);
    if (empty($journal_result['journal_entry_id'])) {
        throw new Exception('Failed to post journal entry: ' . ($journal_result['error'] ?? 'Unknown error'));
    }
    $journal_entry_id = $journal_result['journal_entry_id'];

    // 2. Create the Payment Record
    $payment_id = uuid_v4();
    $stmt = $pdo->prepare(
        "INSERT INTO payments (id, journal_entry_id, vendor_id, payment_date, amount, payment_method, reference_type) VALUES (?, ?, ?, ?, ?, ?, 'BILL')"
    );
    $stmt->execute([
        $payment_id, 
        $journal_entry_id, 
        $data['vendor_id'], 
        $data['payment_date'], 
        $total_payment_amount, 
        $data['payment_method'] ?? 'Bank Transfer'
    ]);

    // 3. Link payment to bills in payment_lines (and update bill statuses)
    $stmt_line = $pdo->prepare("INSERT INTO payment_lines (id, payment_id, invoice_id) VALUES (?, ?, ?)"); // Reusing invoice_id for bill_id
    $stmt_update_bill = $pdo->prepare("UPDATE bills SET status = 'PAID' WHERE bill_id = ?");

    foreach($data['bill_ids'] as $bill_id) {
        $stmt_line->execute([uuid_v4(), $payment_id, $bill_id]);
        $stmt_update_bill->execute([$bill_id]);
    }

    // Log audit trail
    log_audit_trail($pdo, 'pay_bill', ['payment_id' => $payment_id, 'vendor_id' => $data['vendor_id'], 'amount' => $total_payment_amount]);

    $pdo->commit();

    http_response_code(201);
    echo json_encode([
        'status' => 'success',
        'payment_id' => $payment_id,
        'journal_entry_id' => $journal_entry_id
    ]);

} catch (Exception $e) {
    $pdo->rollBack();
    http_response_code(500);
    echo json_encode(['error' => 'Payment failed: ' . $e->getMessage()]);
}