# PHP Example for Calling API

#### Prerequisites

* [You need a valid **API Key** and **API Secret**](/en/getting-started/buy-energy-via-api-on-catfee/api-overview.md#apply-api-info).
* Ensure that your PHP environment has the **cURL** extension installed (most PHP installations include it by default).

***

#### Example Code

```php
<?php

$API_KEY = "your_api_key";  // Replace with your actual API Key
$API_SECRET = "your_api_secret";  // Replace with your actual API Secret
$BASE_URL = "https://api.catfee.io";

// Generate the current timestamp in ISO 8601 format
function generateTimestamp() {
    return gmdate("Y-m-d\TH:i:s.000\Z");
}

// Build the request path, including query parameters
function buildRequestPath($path, $queryParams) {
    if (empty($queryParams)) {
        return $path;
    }
    $queryString = http_build_query($queryParams);
    return $path . '?' . $queryString;
}

// Generate the HMAC-SHA256 signature
function generateSignature($timestamp, $method, $requestPath) {
    $signString = $timestamp . $method . $requestPath;
    return base64_encode(hash_hmac('sha256', $signString, $GLOBALS['API_SECRET'], true));
}

// Create and send the HTTP request
function createRequest($url, $method, $timestamp, $signature) {
    $headers = [
        "Content-Type: application/json",
        "CF-ACCESS-KEY: " . $GLOBALS['API_KEY'],
        "CF-ACCESS-SIGN: " . $signature,
        "CF-ACCESS-TIMESTAMP: " . $timestamp
    ];

    $ch = curl_init();
    
    curl_setopt($ch, CURLOPT_URL, $url);
    curl_setopt($ch, CURLOPT_HTTPHEADER, $headers);
    curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);

    switch (strtoupper($method)) {
        case "POST":
            curl_setopt($ch, CURLOPT_POST, true);
            break;
        case "GET":
            curl_setopt($ch, CURLOPT_HTTPGET, true);
            break;
        case "PUT":
            curl_setopt($ch, CURLOPT_CUSTOMREQUEST, "PUT");
            break;
        case "DELETE":
            curl_setopt($ch, CURLOPT_CUSTOMREQUEST, "DELETE");
            break;
        default:
            throw new Exception("Unsupported HTTP method: $method");
    }

    $response = curl_exec($ch);

    // Check for errors
    if (curl_errno($ch)) {
        throw new Exception("cURL error: " . curl_error($ch));
    }

    curl_close($ch);
    
    return $response;
}

function main() {
    $method = "POST";  // Change to "GET", "PUT", or "DELETE" as needed
    $path = "/v1/order";

    // Example: Create order
    $queryParams = [
        "quantity" => "65000",
        "receiver" => "TRON_ADDRESS",
        "duration" => "1h"
    ];

    $timestamp = generateTimestamp();
    $requestPath = buildRequestPath($path, $queryParams);
    $signature = generateSignature($timestamp, $method, $requestPath);
    $url = $BASE_URL . $requestPath;

    try {
        $response = createRequest($url, $method, $timestamp, $signature);
        echo "Response Code: 200\n";
        echo "Response Body: $response\n";
    } catch (Exception $e) {
        echo "Error: " . $e->getMessage() . "\n";
    }
}

// Run the main function
main();

?>
```

***

#### Code Explanation

**generateTimestamp()**:\
Generates the current UTC timestamp in ISO 8601 format using `gmdate("Y-m-d\TH:i:s.000\Z")`.

**buildRequestPath()**:\
Builds the request path including query parameters (if any), using `http_build_query()` for URL encoding. Note that the query string is not sorted.

**generateSignature()**:\
Concatenates `timestamp + method + requestPath` as the signing string, then uses `hash_hmac()` with HMAC-SHA256 and encodes the result with Base64.

**createRequest()**:\
Sends an HTTP request using the appropriate method (`POST`, `GET`, `PUT`, or `DELETE`). Headers are set via `curl_setopt()` and the response is returned by `curl_exec()`.

**main()**:\
The entry point of the script. Sets the HTTP method, constructs the request path and signature, sends the request, and prints the response.

***

#### Notes

**API Key & Secret**:\
Make sure to replace `API_KEY` and `API_SECRET` with the actual credentials from CatFee.IO.

**Error Handling**:\
Errors from `curl_exec()` are caught with `try-catch` and displayed.

**HTTP Methods**:\
The example supports `POST`, `GET`, `PUT`, and `DELETE`. Adjust based on your specific API endpoint.

**Response Handling**:\
The response from `curl_exec()` is printed directly. You may want to parse it (e.g., using `json_decode()`) depending on the expected format.

***

#### Summary

This example demonstrates how to securely call the CatFee.IO Rest API using PHP. It uses HMAC-SHA256 for request signing, and cURL to send HTTP requests. The code supports multiple HTTP methods and is flexible for integration with different API endpoints.


---

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