<?php

/**
 * This class handles generations of href for links.
 *
 * @author       Time.ly Network, Inc.
 * @instantiator Ai1ec_Factory_Html.create_href_helper_instance
 * @since        2.0
 * @package      Ai1EC
 * @subpackage   Ai1EC.Html
 */
class Ai1ec_Html_Element_Href {

	/**
	 * @var array the parameters that are used in the urls
	 */
	private $used_paramaters = array(
		'action',
		'page_offset',
		'month_offset',
		'oneday_offset',
		'week_offset',
		'time_limit',
		'exact_date',
		'cat_ids',
		'auth_ids',
		'post_ids',
		'tag_ids',
		'instance_ids',
		'events_limit',
		'request_format',
	);

	/**
	 * @var boolean
	 */
	private $is_category;

	/**
	 * @var boolean
	 */
	private $is_tag;

	/**
	 * @var boolean
	 */
	private $is_author;

	/**
	 * @var boolean
	 */
	private $is_custom_filter;

	/**
	 * @var array the arguments to parse
	 */
	private $args;

	/**
	 * @var int
	 */
	private $term_id;

	/**
	 * @var string
	 */
	private $calendar_page;

	/**
	 * @var boolean
	 */
	private $pretty_permalinks_enabled;

	/**
	 * @var string
	 */
	private $uri_particle = null;

	/**
	 * @param boolean $pretty_permalinks_enabled
	 */
	public function set_pretty_permalinks_enabled( $pretty_permalinks_enabled ) {
		$this->pretty_permalinks_enabled = $pretty_permalinks_enabled;
		if ( $pretty_permalinks_enabled ) {
			$this->calendar_page = trim( (string)$this->calendar_page, '/' )
				. '/';
		}
	}

	/**
	 * @param number $term_id
	 */
	public function set_term_id( $term_id ) {
		$this->term_id = $term_id;
	}

	public function __construct( array $args, $calendar ) {
		$this->args = $args;
		$this->calendar_page = $calendar;
		if ( isset( $args['_extra_used_parameters'] ) ) {
			$this->used_paramaters = array_merge(
				$this->used_paramaters,
				$args['_extra_used_parameters']
			);
		}
		$this->used_paramaters = array_merge(
			$this->used_paramaters,
			apply_filters(
				'ai1ec_view_args_for_view',
				array()
			)
		);
	}

	/**
	 * @param boolean $is_category
	 */
	public function set_is_category( $is_category ) {
		$this->is_category = $is_category;
	}

	/**
	 * @param boolean $is_tag
	 */
	public function set_is_tag( $is_tag ) {
		$this->is_tag = $is_tag;
	}

	/**
	 * @param boolean $is_author
	 */
	public function set_is_author( $is_author ) {
		$this->is_author = $is_author;
	}

	/**
	 * Generate the correct href for the view.
	 * This takes into account special filters for categories and tags
	 *
	 * @return string
	 */
	public function generate_href() {
		$href = '';
		$to_implode = array();
		foreach ( $this->used_paramaters as $key ) {
			if ( ! empty( $this->args[$key] ) ) {
				$value = $this->args[$key];
				if( is_array( $this->args[$key] ) ) {
					$value = implode( ',', $this->args[$key] );
				}
				$to_implode[$key] = $key . Ai1ec_Uri::DIRECTION_SEPARATOR .
					$value;
			}
		}
		if (
			$this->is_category ||
			$this->is_tag ||
			$this->is_author ||
			$this->is_custom_filter
		) {
			$to_implode = $this->add_or_remove_category_from_href(
				$to_implode
			);
		}
		if ( $this->pretty_permalinks_enabled ) {
			$href .= implode( '/', $to_implode );
			if ( ! empty( $href ) ) {
				$href .=  '/';
			}
		} else {
			$href .= $this->get_param_delimiter_char( $this->calendar_page );
			$href .= 'ai1ec=' . implode( '|', $to_implode );
		}
		$full_url = $this->calendar_page . $href;
		// persist the `lang` parameter if present
		if ( isset( $_REQUEST['lang'] ) ) {
			$full_url = add_query_arg( 'lang', $_REQUEST['lang'], $full_url );
		}
		return $full_url;
	}

	/**
	 * Sets that class is used for custom filter.
	 *
	 * @param bool   $value        Expected true or false.
	 * @param string $uri_particle URI particle identifier.
	 *
	 * @return void Method does not return.
	 */
	public function set_custom_filter( $value, $uri_particle = null ) {
		$this->is_custom_filter = $value;
		$this->uri_particle     = $uri_particle;
	}

	/**
	 * Perform some extra manipulation for filter href. Basically if the current
	 * category is part of the filter, the href will not contain it (because
	 * clicking on it will actually mean "remove that one from the filter")
	 * otherwise it will be preserved.
	 *
	 * @param array $to_implode
	 * @return array
	 */
	private function add_or_remove_category_from_href( array $to_implode ) {
		$array_key = $this->uri_particle;
		if ( null === $this->uri_particle ) {
			$array_key = $this->_current_array_key();
		}
		// Let's copy the origina cat_ids or tag_ids so we do not affect it
		$copy      = array();
		if ( isset( $this->args[$array_key] ) ) {
			$copy  = (array)$this->args[$array_key];
		}
		$key       = array_search( $this->term_id, $copy );
		// Let's check if we are already filtering for tags / categorys
		if( isset( $to_implode[$array_key] ) ) {
			if( $key !== false ) {
				unset( $copy[$key] );
			} else {
				$copy[] = $this->term_id;
			}
			if( empty( $copy ) ) {
				unset( $to_implode[$array_key] );
			} else {
				$to_implode[$array_key] = $array_key . Ai1ec_Uri::DIRECTION_SEPARATOR .
					implode( ',', $copy );
			}
		} else {
			$to_implode[$array_key] = $array_key . Ai1ec_Uri::DIRECTION_SEPARATOR . $this->term_id;
		}
		return $to_implode;
	}

	/**
	 * Match current argument key
	 *
	 * @return string Name of current argument key
	 */
	protected function _current_array_key() {
		$map = array(
			'category' => 'cat',
			'tag'      => 'tag',
			'author'   => 'auth',
		);
		$use_name = '';
		foreach ( $map as $value => $name ) {
			if ( $this->{'is_' . $value} ) {
				$use_name = $name;
				break;
			}
		}
		return $use_name . '_ids';
	}

	/**
	 * Returns the delimiter character to use if a new query string parameter is
	 * going to be appended to the URL.
	 *
	 * @param string $url URL to parse
	 *
	 * @return string
	 */
	public static function get_param_delimiter_char( $url ) {
		return strpos( $url, '?' ) === false ? '?' : '&';
	}

}