<?php

/**
 * Generate an OAuth 2.0 access token for authenticating with PayPal REST APIs.
 *
 * @see https://developer.paypal.com/api/rest/authentication/
 * @return string|null
 */
function generateAccessToken()
{
    if (!PAYPAL_CLIENT_ID || !PAYPAL_CLIENT_SECRET) {
        throw new \Exception("MISSING_API_CREDENTIALS");
    }

    $url = PAYPAL_BASE_URL . "/v1/oauth2/token";
    $payload = [
        "grant_type" => "client_credentials",
    ];
    $ch = curl_init();

    curl_setopt($ch, CURLOPT_URL, $url);
    curl_setopt($ch, CURLOPT_POST, 1);
    curl_setopt($ch, CURLOPT_POSTFIELDS, http_build_query($payload));
    curl_setopt($ch, CURLOPT_HTTPAUTH, CURLAUTH_BASIC);
    curl_setopt($ch, CURLOPT_HTTPHEADER, [
        "Content-Type: application/x-www-form-urlencoded",
        "Authorization: Basic " .
        base64_encode(PAYPAL_CLIENT_ID . ":" . PAYPAL_CLIENT_SECRET),
        // Uncomment one of these to force an error for negative testing (in sandbox mode only).
    ]);

    curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
    $response = curl_exec($ch);
    $response_code = curl_getinfo($ch, CURLINFO_HTTP_CODE);
    curl_close($ch);

    // Further processing ...
    if ($response_code === 200) {
        return json_decode($response)->access_token;
    } else {
        header("Content-Type: application/json");
        http_response_code($response_code);
        echo $response;
        die();
    }
}

/**
 * Create an order to start the transaction.
 *
 * @see https://developer.paypal.com/docs/api/orders/v2/#orders_create
 * @param array $cart
 * @return array
 */
function createOrder($cart)
{
    try {
        $access_token = generateAccessToken();
        if (!$access_token) {
            http_response_code(500);
            header("Content-Type: application/json");
            echo json_encode(["error" => "Failed to obtain access token."]);
            die();
        }

        $url = PAYPAL_BASE_URL . "/v2/checkout/orders";

        $payload = [
            "intent" => "CAPTURE",
            "purchase_units" => [
                [
                    "amount" => [
                        "currency_code" => $cart[0]->unit_amount->currency_code,
                        "value" => $cart[0]->unit_amount->value,
                        "breakdown" => [
                            "item_total" => [
                                "currency_code" =>
                                    $cart[0]->unit_amount->currency_code,
                                "value" => $cart[0]->unit_amount->value,
                            ],
                        ],
                    ],
                    "items" => [
                        [
                            "name" => $cart[0]->description,
                            "description" => $cart[0]->description,
                            "unit_amount" => [
                                "currency_code" =>
                                    $cart[0]->unit_amount->currency_code,
                                "value" => $cart[0]->unit_amount->value,
                            ],
                            "quantity" => 1,
                        ],
                    ],
                ],
            ],
        ];

        $ch = curl_init();

        curl_setopt($ch, CURLOPT_URL, $url);
        curl_setopt($ch, CURLOPT_POST, 1);
        curl_setopt($ch, CURLOPT_POSTFIELDS, json_encode($payload));
        curl_setopt($ch, CURLOPT_HTTPAUTH, CURLAUTH_BASIC);
        curl_setopt($ch, CURLOPT_HTTPHEADER, [
            "Content-Type: application/json",
            "Authorization: Bearer $access_token",
        ]);
        // Uncomment one of these to force an error for negative testing (in sandbox mode only).
        // Documentation: https://developer.paypal.com/tools/sandbox/negative-testing/request-headers/
        // 'PayPal-Mock-Response' => '{"mock_application_codes": "MISSING_
        curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
        $response = curl_exec($ch);
        $response_code = curl_getinfo($ch, CURLINFO_HTTP_CODE);
        curl_close($ch);

        // Further processing ...
        if ($response_code === 200) {
            header("Content-Type: application/json");
            http_response_code($response_code);
            echo $response;
            die();
        } else {
            header("Content-Type: application/json");
            http_response_code($response_code);
            echo $response;
            die();
        }
    } catch (\Exception $error) {
        header("Content-Type: application/json");
        http_response_code(500);
        echo json_encode(["error" => "Failed to create order."]);
        die();
    }
}

/**
 * Capture payment for the given order
 *
 * @see https://developer.paypal.com/docs/api/orders/v2/#orders_capture
 * @param array $cart
 * @return array
 */
function captureOrder($order_id)
{
    $url = PAYPAL_BASE_URL . "/v2/checkout/orders/{$order_id}/capture";
    // Http::fake(function ($request) {
    //     // Capture and log request headers
    //     $headers = $request->headers();

    //     // Log headers for inspection
    //     \Log::info('Captured Request Headers', $headers);

    //     return Http::response('', 200, [
    //         'X-Custom-Response-Header' => 'HeaderValue'
    //     ]);
    // });
    $auth = base64_encode(PAYPAL_CLIENT_ID . ":" . PAYPAL_CLIENT_SECRET);

    $ch = curl_init();

    curl_setopt($ch, CURLOPT_URL, $url);
    curl_setopt($ch, CURLOPT_POST, 1);
    curl_setopt($ch, CURLOPT_HTTPAUTH, CURLAUTH_BASIC);
    curl_setopt($ch, CURLOPT_HTTPHEADER, [
        "Content-Type: application/json",
        "Authorization: Basic $auth",
    ]);
    // Uncomment one of these to force an error for negative testing (in sandbox mode only).
    // Documentation: https://developer.paypal.com/tools/sandbox/negative-testing/request-headers/
    // 'PayPal-Mock-Response' => '{"mock_application_codes": "MISSING_
    curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
    $response = curl_exec($ch);
    $response_code = curl_getinfo($ch, CURLINFO_HTTP_CODE);
    curl_close($ch);

    // Further processing ...
    if ($response_code === 200) {
        header("Content-Type: application/json");
        http_response_code($response_code);
        echo $response;
        die();
    } else {
        header("Content-Type: application/json");
        http_response_code($response_code);
        echo $response;
        die();
    }
}

if (
    $_SERVER["REQUEST_METHOD"] === "POST" &&
    $_SERVER["REQUEST_URI"] === "/api/orders"
) {
    $body = file_get_contents("php://input");
    $cart = json_decode($body)->cart;
    createOrder($cart);
}

if ($_SERVER["REQUEST_METHOD"] === "POST") {
    $order_id = substr($_SERVER["REQUEST_URI"], 12, 17);
    captureOrder($order_id);
}

if ($_SERVER["REQUEST_METHOD"] !== "POST") {
    http_response_code(404);
    die();
}