<?php
/**
 * process_ride_payments.php — Payment Processing Server
 * 
 * Receives S2S (Server-to-Server) requests from finish_ride_updates.php.
 * Authenticated via X-S2S-Api-Key header matching a shared secret.
 * 
 * Flow:
 *   1. Validate X-S2S-Api-Key header
 *   2. BEGIN TRANSACTION
 *   3. Insert payment record
 *   4. Deduct from passenger wallet (if walletChecked)
 *   5. Settle passenger debt (if negative balance)
 *   6. Deduct driver points (8%)
 *   7. COMMIT / ROLLBACK on failure
 */

// Adjust path as needed for your payment server structure
require_once __DIR__ . '/../../jwtconnect.php';

// === Secure S2S Configuration ===
define('S2S_SHARED_KEY', getenv('S2S_SHARED_KEY'));

// ============================================================
// 1. API Key Authentication (X-S2S-Api-Key header)
// ============================================================
$providedKey = $_SERVER['HTTP_X_S2S_API_KEY'] ?? '';

if (empty($providedKey) || $providedKey !== S2S_SHARED_KEY) {
    http_response_code(401);
    printFailure("Unauthorized: Invalid or missing X-S2S-Api-Key.");
    exit;
}

// ============================================================
// 2. Receive All Required Parameters
// ============================================================
$rideId              = filterRequest("rideId");
$driverId            = filterRequest("driverId");
$passengerId         = filterRequest("passengerId");
$paymentAmount       = filterRequest("paymentAmount");
$paymentMethod       = filterRequest("paymentMethod");
$walletChecked       = filterRequest("walletChecked");           // 'true' or 'false'
$authToken           = filterRequest("authToken");               // kept for logging/audit, not used for auth

// --- Validate required fields ---
if (empty($rideId) || empty($driverId) || empty($passengerId) || 
    !isset($paymentAmount) || empty($paymentMethod) || 
    !isset($walletChecked)) {
    printFailure("Missing required parameters for payment processing.");
    exit;
}

// ============================================================
// 3. Atomic Payment Processing
// ============================================================
try {
    // --- Begin Transaction ---
    $con->beginTransaction();

    // 3a. Insert main payment record
    $finalPaymentMethod = ($walletChecked === 'true') ? $paymentMethod . "Ride" : $paymentMethod;
    $stmtPayment = $con->prepare(
        "INSERT INTO payments (id, amount, payment_method, passengerID, rideId, driverID)
         VALUES (UUID_SHORT(), :amount, :payment_method, :passengerID, :rideId, :driverID)"
    );
    $stmtPayment->execute([
        ':amount'         => $paymentAmount,
        ':payment_method' => $finalPaymentMethod,
        ':passengerID'    => $passengerId,
        ':rideId'         => $rideId,
        ':driverID'       => $driverId,
    ]);

    if ($stmtPayment->rowCount() <= 0) {
        throw new Exception("Failed to create payment record.");
    }

    // 3b. Deduct from passenger wallet (if wallet payment)
    if ($walletChecked === 'true') {
        // Check actual balance with row lock
        $stmtBalance = $con->prepare(
            "SELECT COALESCE(SUM(balance), 0) AS current_balance
             FROM passengerWallet
             WHERE passenger_id = :passenger_id
             FOR UPDATE"
        );
        $stmtBalance->execute([':passenger_id' => $passengerId]);
        $balanceRow = $stmtBalance->fetch(PDO::FETCH_ASSOC);
        $currentBalance = floatval($balanceRow['current_balance']);

        $deductionAmount = floatval($paymentAmount);
        if ($currentBalance < $deductionAmount) {
            throw new Exception("Insufficient wallet balance. Required: $deductionAmount, Available: $currentBalance");
        }

        $stmtPassengerWallet = $con->prepare(
            "INSERT INTO `passengerWallet` (`passenger_id`, `balance`) 
             VALUES (:passenger_id, :balance)"
        );
        $stmtPassengerWallet->execute([
            ':passenger_id' => $passengerId,
            ':balance'      => (-1) * $deductionAmount,
        ]);

        if ($stmtPassengerWallet->rowCount() <= 0) {
            throw new Exception("Failed to deduct from passenger wallet.");
        }

        // 3c. Settle existing debt (use actual balance after deduction)
        $stmtBalanceAfter = $con->prepare(
            "SELECT COALESCE(SUM(balance), 0) AS balance_after
             FROM passengerWallet
             WHERE passenger_id = :passenger_id
             FOR UPDATE"
        );
        $stmtBalanceAfter->execute([':passenger_id' => $passengerId]);
        $balanceAfterRow = $stmtBalanceAfter->fetch(PDO::FETCH_ASSOC);
        $balanceAfter = floatval($balanceAfterRow['balance_after']);

        if ($balanceAfter < 0) {
            $stmtPassengerDebt = $con->prepare(
                "INSERT INTO `passengerWallet` (`passenger_id`, `balance`) 
                 VALUES (:passenger_id, :balance)"
            );
            $stmtPassengerDebt->execute([
                ':passenger_id' => $passengerId,
                ':balance'      => (-1) * $balanceAfter,
            ]);

            if ($stmtPassengerDebt->rowCount() <= 0) {
                throw new Exception("Failed to settle passenger debt.");
            }
        }
    }

    // 3d. Deduct driver points (8% of payment amount)
    $pointsSubtraction = floatval($paymentAmount) * (-0.08);
    $stmtDriverPoints = $con->prepare(
        "INSERT INTO `driverWallet` (`driverID`, `paymentID`, `amount`, `paymentMethod`)
         VALUES (:driverID, :paymentID, :amount, :paymentMethod)"
    );
    $stmtDriverPoints->execute([
        ':driverID'      => $driverId,
        ':paymentID'     => 'rideId' . $rideId,
        ':amount'        => number_format($pointsSubtraction, 0, '', ''),
        ':paymentMethod' => $paymentMethod,
    ]);

    if ($stmtDriverPoints->rowCount() <= 0) {
        throw new Exception("Failed to update driver wallet points.");
    }

    // --- All operations succeeded → Commit ---
    $con->commit();

    printSuccess("Payment processed successfully for ride $rideId.");

} catch (Exception $e) {
    // --- Any failure → Rollback all changes ---
    if (isset($con) && $con->inTransaction()) {
        $con->rollBack();
    }
    error_log("[process_ride_payments] Transaction FAILED for ride $rideId: " . $e->getMessage());
    printFailure("Transaction failed");
}