<?php
class CurlHttpClient {
    /**
     * Default User-Agent
     * @var string
     */
    const DEFAULT_USER_AGENT = 'Instagram PHP Implementation http://mauriciocuenca.com/';

    /**
     * Used HTTP request methods
     */
    const GET = 'GET';
    const POST = 'POST';
    const DELETE = 'DELETE';

    /**
     * cURL handler
     * @var resource
     */
    private $handler;

    /**
     * Store the POST fields
     */
    private $postParams = array();

    /**
     * Initiate a cURL session
     * @param string $url
     */
    public function __construct($uri) {
        $this->handler = curl_init($uri);
        $this->_setOptions();
    }

    protected function _setOptions() {
        curl_setopt($this->handler, CURLOPT_RETURNTRANSFER, true);
        curl_setopt($this->handler, CURLOPT_FOLLOWLOCATION, true);
        curl_setopt($this->handler, CURLOPT_USERAGENT, self::DEFAULT_USER_AGENT);
    }

    /**
     * Set the URI
     * @param $uri
     */
    public function setUri($uri) {
        $this->handler = curl_init($uri);
        $this->_setOptions();
    }

    /**
     * Receive the response with full headers
     * @param boolean $value
     */
    public function setHeaders($value = true) {
        curl_setopt($this->handler, CURLOPT_HEADER, $value);
    }

    /**
     * Set the HTTP request method
     * @param string $method
     */
    public function setMethod($method = self::GET) {
        switch ($method) {
            case self::GET :
                curl_setopt($this->handler, CURLOPT_HTTPGET, true);
                break;
            case self::POST :
                curl_setopt($this->handler, CURLOPT_POST, true);
                break;
            case self::DELETE :
                curl_setopt($this->handler, CURLOPT_CUSTOMREQUEST, self::DELETE);
                break;
            default:
                throw new CurlHttpClientException('Method not supported');
        }
    }

    /**
     * Add a new post param to the set
     * @param string $name
     * @param mixed $value
     */
    public function setPostParam($name, $value) {
        $this->postParams[$name] = $value;
        curl_setopt($this->handler, CURLOPT_POSTFIELDS, $this->postParams);
    }

    /**
     * Get the response
     * @return string
     */
    public function getResponse() {
        $response = curl_exec($this->handler);
        curl_close($this->handler);

        return $response;
    }

    /**
     * Extract the headers from a response string
     *
     * @param string $response
     * @return mixed[]
     */
    protected function extractHeaders($response) {
        $headers = array();

        // First, split body and headers
        $parts = preg_split('|(?:\r?\n){2}|m', $response_str, 2);
        if (!$parts[0]) return $headers;

        // Split headers part to lines
        $lines = explode("\n", $parts[0]);
        unset($parts);
        $last_header = null;

        foreach($lines as $line) {
            $line = trim($line, "\r\n");
            if ($line == "") break;

            // Locate headers like 'Location: ...' and 'Location:...' (note the missing space)
            if (preg_match("|^([\w-]+):\s*(.+)|", $line, $m)) {
                unset($last_header);
                $h_name = strtolower($m[1]);
                $h_value = $m[2];

                if (isset($headers[$h_name])) {
                    if (! is_array($headers[$h_name])) {
                        $headers[$h_name] = array($headers[$h_name]);
                    }

                    $headers[$h_name][] = $h_value;
                } else {
                    $headers[$h_name] = $h_value;
                }
                $last_header = $h_name;
            } else if (preg_match("|^\s+(.+)$|", $line, $m) && $last_header !== null) {
                if (is_array($headers[$last_header])) {
                    end($headers[$last_header]);
                    $last_header_key = key($headers[$last_header]);
                    $headers[$last_header][$last_header_key] .= $m[1];
                } else {
                    $headers[$last_header] .= $m[1];
                }
            }
        }

        return $headers;
    }
}

class CurlHttpClientException extends Exception {}