PHP: Consuming a REST API with `cURL` and Error Handling

<?php

/**
 * Fetches data from a REST API using cURL.
 *
 * @param string $url The API endpoint URL.
 * @param string $method HTTP method (GET, POST, PUT, DELETE).
 * @param array $headers Optional HTTP headers.
 * @param array|string|null $data Optional request body data (for POST/PUT).
 * @param int $timeout Timeout for the cURL request in seconds.
 * @return array|false Returns the decoded JSON response as an array on success, false on failure.
 */
function callRestApi(string $url, string $method = 'GET', array $headers = [], $data = null, int $timeout = 30)
{
    $ch = curl_init();

    curl_setopt($ch, CURLOPT_URL, $url);
    curl_setopt($ch, CURLOPT_RETURNTRANSFER, true); // Return the response as a string
    curl_setopt($ch, CURLOPT_HTTPHEADER, $headers); // Set custom headers
    curl_setopt($ch, CURLOPT_TIMEOUT, $timeout);
    
    // Handle SSL certificate verification (recommended for production)
    // curl_setopt($ch, CURLOPT_SSL_VERIFYPEER, true);
    // curl_setopt($ch, CURLOPT_SSL_VERIFYHOST, 2);
    // curl_setopt($ch, CURLOPT_CAINFO, '/path/to/your/cacert.pem'); // Path to CA certificate bundle

    switch (strtoupper($method)) {
        case 'POST':
            curl_setopt($ch, CURLOPT_POST, true);
            if ($data) {
                curl_setopt($ch, CURLOPT_POSTFIELDS, is_array($data) ? json_encode($data) : $data);
            }
            break;
        case 'PUT':
            curl_setopt($ch, CURLOPT_CUSTOMREQUEST, 'PUT');
            if ($data) {
                curl_setopt($ch, CURLOPT_POSTFIELDS, is_array($data) ? json_encode($data) : $data);
            }
            break;
        case 'DELETE':
            curl_setopt($ch, CURLOPT_CUSTOMREQUEST, 'DELETE');
            break;
        case 'GET':
        default:
            // GET is default, no specific options needed for method itself
            break;
    }

    $response = curl_exec($ch);
    $httpCode = curl_getinfo($ch, CURLINFO_HTTP_CODE);
    $curlError = curl_error($ch);

    if ($curlError) {
        error_log("cURL Error for {$url}: {$curlError}");
        curl_close($ch);
        return false;
    }

    curl_close($ch);

    if ($httpCode >= 200 && $httpCode < 300) {
        $decodedResponse = json_decode($response, true);
        if (json_last_error() === JSON_ERROR_NONE) {
            return $decodedResponse;
        } else {
            error_log("JSON Decoding Error for {$url}: " . json_last_error_msg());
            return false;
        }
    } else {
        error_log("API Call Failed for {$url} with HTTP Status: {$httpCode}. Response: {$response}");
        return false;
    }
}

// --- Example Usage ---

// 1. GET Request
$get_url = 'https://jsonplaceholder.typicode.com/posts/1';
$get_headers = [
    'Accept: application/json',
    // 'Authorization: Bearer YOUR_API_TOKEN'
];
$get_result = callRestApi($get_url, 'GET', $get_headers);

if ($get_result) {
    echo "GET Request Successful:
";
    print_r($get_result);
} else {
    echo "GET Request Failed.
";
}

echo "
--------------------------------

";

// 2. POST Request
$post_url = 'https://jsonplaceholder.typicode.com/posts';
$post_data = [
    'title' => 'foo',
    'body' => 'bar',
    'userId' => 1,
];
$post_headers = [
    'Content-Type: application/json',
    'Accept: application/json',
];
$post_result = callRestApi($post_url, 'POST', $post_headers, $post_data);

if ($post_result) {
    echo "POST Request Successful:
";
    print_r($post_result);
} else {
    echo "POST Request Failed.
";
}

echo "
--------------------------------

";

// 3. Error Handling Example (e.g., non-existent endpoint)
$error_url = 'https://jsonplaceholder.typicode.com/non-existent-endpoint';
$error_result = callRestApi($error_url, 'GET');

if (!$error_result) {
    echo "Error handling test: API call correctly failed for {$error_url}. Check logs for details.
";
}

?>