<?php

if (!function_exists('curl_init')) {
    throw new Exception('Forrst API needs the cURL PHP extension.');
}
if (!function_exists('json_decode')) {
    throw new Exception('Forrst API needs the JSON PHP extension.');
}

/**
 * Thrown when an API call returns an exception.
 *
 * @author Martin Bean <hide@address.com>
 **/
class ForrstApiException extends Exception
{
    /**
     * The result from the API that represents the exception information.
     *
     * @var array
     **/
    protected $result;
    
    /**
     * Make a new API exception with the given result.
     *
     * @param array $result from the API
     * @return void
    **/
    public function __construct($result)
    {
        $this->result = $result;
        $code = isset($result['code']) ? $result['code'] : 0;
        $message = $result['message'];
        parent::__construct($message, $code);
    }
    
    /**
     * Return the associated result object returned by the API.
     *
     * @return array
     **/
    public function getResult()
    {
        return $this->result;
    }
    
    /**
     * Returns the associated type for the error.
     *
     * @return string
     **/
    public function getType()
    {
        return $this->result['type'];
    }
}

/**
 * Provides access to the Forrst API.
 *
 * @author Martin Bean <hide@address.com>
 */
class ForrstApi
{
    /**
     * Default options for cURL.
     *
     * @var array
     **/
    public static $CURL_OPTS = array(
        CURLOPT_CONNECTTIMEOUT => 10,
        CURLOPT_RETURNTRANSFER => true,
        CURLOPT_TIMEOUT        => 60,
        CURLOPT_USERAGENT      => 'forrst-php-api-client'
    );
    
    /**
     * Forrst API base URL.
     *
     * @var string
     **/
    protected $baseUrl = 'http://forrst.com/api/v2';
    
    /**
     * Forrst API access token.
     *
     * @var string
     **/
    protected $accessToken;
    
    
    /**
     * Constructor.
     *
     * @return void
     **/
    public function __construct() {}
    
    /**
     * Set base URL.
     *
     * @param string $url
     * @return void
     **/
    public function setBaseUrl($url)
    {
        $this->baseUrl = $url;
    }
    
    /**
     * Set access token.
     *
     * @param string $token
     * @return void
     **/
    public function setAccessToken($token)
    {
        $this->accessToken = $token;
    }
    
    /**
     * Makes an HTTP request.
     * This method can be overriden by subclasses if developers want to use something other than cURL.
     *
     * @param string $url
     * @param array $params
     * @param string $method
     * @return string
     * @throws ForrstApiException
     **/
    protected function makeRequest($url, $params=array(), $method='GET')
    {
        $ch = curl_init();
        $opts = self::$CURL_OPTS;
        $opts[CURLOPT_URL] = $this->baseUrl . $url;
        switch (strtolower($method)) {
            case 'get':
                $opts[CURLOPT_URL].= '?'.http_build_query($params, null, '&');
            break;
            case 'post':
                $opts[CURLOPT_CUSTOMREQUEST] = 'POST';
                $opts[CURLOPT_POSTFIELDS] = $params;
            break;
        }
        curl_setopt_array($ch, $opts);
        $result = curl_exec($ch);
        $result = json_decode($result);
        if ($result === false) {
            $e = new ForrstApiException(array(
                'type' => 'CurlExcpetion',
                'code' => curl_errno(),
                'message' => curl_error()
            ));
            curl_close($ch);
            throw $e;
        }
        if (is_object($result) && $result->stat == 'fail') {
            $e = new ForrstApiException(array(
                'type' => 'ForrstApiException',
                'code' => curl_getinfo($ch, CURLINFO_HTTP_CODE),
                'message' => $result->resp->error,
                'url' => $opts[CURLOPT_URL]
            ));
            curl_close($ch);
            throw $e;
        }
        curl_close($ch);
        return $result;
    }
    
    /**
     * Returns stats about your API usage.
     *
     * @return object
     **/
    public function getStats()
    {
        return $this->makeRequest('/stats');
    }
    
    /**
     * User authentication.
     * Provide an email/username and password and get an access token back.
     *
     * @param string $email_or_username
     * @param string $password
     * @return string
     **/
    public function authenticateUser($email_or_username, $password)
    {
        $params = array(
            'email_or_username' => $email_or_username,
            'password' => $password
        );
        $response = $this->makeRequest('/users/auth', $params, 'POST');
        $this->setAccessToken($response->resp->token);
        return $response->resp->token;
    }
    
    /**
     * Returns user information.
     *
     * @param integer $id
     * @param string $username
     * @return object
     **/
    public function getUsersInfo($id, $username)
    {
        $params = array(
            'id' => $id,
            'username' => $username
        );
        return $this->makeRequest('/users/info', $params);
    }
    
    /**
     * Returns a user's posts.
     *
     * @param integer $id
     * @param string $username
     * @param string $type (one of code, snap, link, question)
     * @param integer $limit
     * @param integer $after
     * @return object
     **/
    public function getUserPosts($id=null, $username=null, $type=null, $limit=10, $after=null)
    {
        $params = array(
            'id' => $id,
            'username' => $username,
            'type' => $type,
            'limit' => $limit,
            'after' => $after
        );
        return $this->makeRequest('/user/posts', $params);
    }
    
    /**
     * Return data about a single post.
     * For questions, content is the question.
     * For code, content contains the code snippet.
     * For code, snaps, and links, description is the post description; it is not used for questions.
     *
     * @param integer $id
     * @param string $tiny_id
     * @return object
     **/
    public function showPost($id, $tiny_id)
    {
        $params = array(
            'id' => $id,
            'tiny_id' => $tiny_id
        );
        return $this->makeRequest('/posts/show', $params);
    }
    
    /**
     * Returns a list of posts of a given type.
     *
     * @param string $post_type (one of code, snap, link, question)
     * @param string $sort (one of recent, popular, best (staff picks))
     * @param integer $page
     * @return object
     **/
    public function listPosts($post_type, $sort='recent', $page=1)
    {
        $params = array(
            'post_type' => $post_type,
            'sort' => $sort,
            'page' => $page
        );
        return $this->makeRequest('/posts/list', $params);
    }
    
    /**
     * Returns a post's comments.
     *
     * @param integer $id
     * @param string $tiny_id
     * @return object
     **/
    public function getPostComments($id, $tiny_id)
    {
        $params = array(
            'id' => $id,
            'tiny_id' => $tiny_id,
            'access_token' => $this->accessToken
        );
        return $this->makeRequest('/post/comments', $params);
    }
}