<?php
/**
 * Class WordPress Twitter API
 * 
 * @version 1.0.0
 */
class Wp_Twitter_Api {
  
	var $bearer_token,
		
	// Default credentials
	$args = array(
		'consumer_key'			=>	'default_consumer_key',
		'consumer_secret'		=>	'default_consumer_secret'
	),
	
	// Default type of the resource and cache duration
	$query_args = array(
		'type'				=>	'statuses/user_timeline',
		'cache'				=>	1800
	),

	$has_error = false;
	
	/**
	 * WordPress Twitter API Constructor
	 * 
	 * @param array $args
	 */
	public function __construct( $args = array() ) {
		
		if ( is_array( $args ) && !empty( $args ) )
			$this->args = array_merge( $this->args, $args );
		
		if ( ! $this->bearer_token = get_option( 'twitter_bearer_token' ) )
			$this->bearer_token = $this->get_bearer_token();
		
	}
	
	/**
	 * Get the token from oauth Twitter API
	 * 
	 * @return string Oauth Token
	 */
	private function get_bearer_token() {
		
		$bearer_token_credentials = $this->args['consumer_key'] . ':' . $this->args['consumer_secret'];
		$bearer_token_credentials_64 = base64_encode( $bearer_token_credentials );
		
		$args = array(
			'method'		=> 	'POST',
			'timeout'		=> 	5,
			'redirection'	=> 	5,
			'httpversion'	=> 	'1.0',
			'blocking'		=> 	true,
			'headers'		=> 	array(
				'Authorization'		=>	'Basic ' . $bearer_token_credentials_64,
				'Content-Type'		=> 	'application/x-www-form-urlencoded;charset=UTF-8',
				'Accept-Encoding'	=>	'gzip'
			),
			'body' 			=>  array( 'grant_type'		=>	'client_credentials' ),
			'cookies' 		=> 	array()
		);
		
		$response = wp_remote_post( 'https://api.twitter.com/oauth2/token', $args );
		
		if ( is_wp_error( $response ) || 200 != $response['response']['code'] )
			return $this->bail( __( 'Can\'t get the bearer token, check your credentials', 'wp_twitter_api' ), $response );
		
		$result = json_decode( $response['body'] );
		
		update_option( 'twitter_bearer_token', $result->access_token );
		
		return $result->access_token;
		
	}
	
	/**
	 * Query twitter's API
	 * 
	 * @uses $this->get_bearer_token() to retrieve token if not working
	 * 
	 * @param string $query Insert the query in the format "count=1&include_entities=true&include_rts=true&screen_name=micc1983!
	 * @param array $query_args Array of arguments: Resource type (string) and cache duration (int)
	 * @param bool $stop Stop the query to avoid infinite loop
	 * 
	 * @return bool|object Return an object containing the result
	 */
	public function query( $query, $query_args = array(), $stop = false ) {
		
		if ( $this->has_error )
			return false;
		
		if ( is_array( $query_args ) && !empty( $query_args ) )
			$this->query_args = array_merge( $this->query_args, $query_args );
		
		$transient_name = 'wta_' . md5( $query );
		
		if ( false !== ( $data = get_transient( $transient_name ) ) )
			return $data;
		
		$args = array(
			'method'		=> 	'GET',
			'timeout'		=> 	5,
			'redirection'	=> 	5,
			'httpversion'	=> 	'1.0',
			'blocking'		=> 	true,
			'headers'		=> 	array(
				'Authorization'		=>	'Bearer ' . $this->bearer_token,
				'Accept-Encoding'	=>	'gzip'
			),
			'body' 			=> 	null,
			'cookies' 		=> 	array()
		);
		
		$response = wp_remote_get( 'https://api.twitter.com/1.1/' . $this->query_args['type'] . '.json?' . $query, $args );
		
		if ( is_wp_error( $response ) || 200 != $response['response']['code'] ){
		
			if ( !$stop ){
				$this->bearer_token = $this->get_bearer_token();
				return $this->query( $query, $this->query_args, true );
			} else {
				return $this->bail( __( 'Bearer Token is good, check your query', 'wp_twitter_api' ), $response );
			}
			
		}
		
		$data = json_decode( $response['body'] );

		set_transient( $transient_name, $data, $this->query_args['cache'] );
		
		return $data;
		
	}
	
	/**
	 * Let's manage errors
	 * 
	 * WP_DEBUG has to be set to true to show errors
	 * 
	 * @param string $error_text Error message
	 * @param string $error_object Server response or wp_error
	 */
	private function bail( $error_text, $error_object = '' ) {
		
		$this->has_error = true;
		
		if ( is_wp_error( $error_object ) ){
			$error_text .= ' - Wp Error: ' . $error_object->get_error_message();
		} elseif ( !empty( $error_object ) && isset( $error_object['response']['message'] ) ) {
			$error_text .= ' ( Response: ' . $error_object['response']['message'] . ' )';
		}
		
		trigger_error( $error_text , E_USER_NOTICE );
		
	}
	
}