<?php
session_start();
require_once '../db/config.php';

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

if (!isset($_SESSION['user_id'])) {
    echo json_encode(['success' => false, 'error' => 'Unauthorized']);
    exit;
}

$user_id = $_SESSION['user_id'];
$data = json_decode(file_get_contents('php://input'), true);

if (!$data) {
    echo json_encode(['success' => false, 'error' => 'Invalid data']);
    exit;
}

$symbol = $data['symbol'];
$type = $data['type']; // spot or futures
$side = $data['side']; // buy or sell
$order_type = $data['order_type']; // limit or market
$price = $data['price'];
$amount = $data['amount'];
$total = $data['total'];
$leverage = $data['leverage'] ?? 1;
$tp_price = $data['tp_price'] ?? null;
$sl_price = $data['sl_price'] ?? null;

try {
    $db = db();
    $db->beginTransaction();

    // Check balance if buying spot or opening long/short futures (simplified)
    $stmt = $db->prepare("SELECT balance FROM users WHERE id = ? FOR UPDATE");
    $stmt->execute([$user_id]);
    $user = $stmt->fetch();

    if ($side === 'buy' || $type === 'futures') {
        $cost = $type === 'futures' ? $total / $leverage : $total;
        if ($user['balance'] < $cost) {
            $db->rollBack();
            echo json_encode(['success' => false, 'error' => 'Insufficient balance']);
            exit;
        }

        // Deduct balance
        $stmt = $db->prepare("UPDATE users SET balance = balance - ? WHERE id = ?");
        $stmt->execute([$cost, $user_id]);
    }

    // Insert order
    $stmt = $db->prepare("INSERT INTO trading_orders (user_id, symbol, type, side, order_type, price, amount, total, leverage, tp_price, sl_price) VALUES (?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?)");
    $stmt->execute([$user_id, $symbol, $type, $side, $order_type, $price, $amount, $total, $leverage, $tp_price, $sl_price]);

    $db->commit();
    echo json_encode(['success' => true]);

} catch (Exception $e) {
    if (isset($db)) $db->rollBack();
    echo json_encode(['success' => false, 'error' => $e->getMessage()]);
}