<?php

/**
 * URI management class
 *
 * @author     Time.ly Network Inc.
 * @since      2.0
 *
 * @package    AI1EC
 * @subpackage AI1EC.Routing
 */
class Ai1ec_Uri
{

    /**
     * Set direction separator
     */
    const DIRECTION_SEPARATOR = '~';

    /**
     * @var string Arguments (list) separator
     */
    protected $_arguments_separator = '/';

    /**
     * Parse page to internal URI representation
     *
     * @param string $page Page URI to parse
     *
     * @return array|bool Parsed URI or false on failure
     */
    public function parse( $page ) {
        $result = array(
            'base'  => '',
            'ai1ec' => array(),
            'args'  => null,
            'hash'  => null,
            '_type' => 'args', // enum: args,hash,pretty
        );
        if ( false === ( $parsed = parse_url( $page ) ) ) {
            return false;
        }

        if ( isset( $parsed['scheme'] ) ) {
            if ( !isset( $parsed['host'] ) ) {
                return false;
            }
            $result['base'] = $parsed['scheme'] . '://' . $parsed['host'];
        }

        if ( ! empty( $parsed['path'] ) ) {
            if ( false !== strpos( $parsed['path'], self::DIRECTION_SEPARATOR ) ) {
                $result['_type'] = 'pretty';
                $elements = explode(
                    $this->_arguments_separator,
                    $parsed['path']
                );
                foreach ( $elements as $particle ) {
                    $sep = strpos( $particle, self::DIRECTION_SEPARATOR );
                    if ( false !== $sep ) {
                        $key = substr( $particle, 0, $sep );
                        $result['ai1ec'][$key] = substr( $particle, $sep + 1 );
                    } else {
                        $result['base'] .= $this->_arguments_separator .
                            $particle;
                    }
                }
            }
        }

        $query_pos = array(
            'query'    => 'args',
            'fragment' => 'hash',
        );
        foreach ( $query_pos as $source => $destination ) {
            if ( 'hash' === $destination ) {
                $result['_type'] = $destination;
            }
            if ( ! empty( $parsed[$source] ) ) {
                $result = Ai1ec_Utility_Array::deep_merge(
                    $result,
                    $this->parse_query_str( $parsed[$source], $destination )
                );
            }
        }

        return $result;
    }

    /**
     * Produce query to use in URI
     *
     * @param array $parsed Internal query representation
     *
     * @return string Normalized URI
     */
    public function write( array $parsed ) {
        $uri = $parsed['base'];

        if ( 'pretty' == $parsed['_type'] ) {
            $uri = rtrim( $uri, $this->_arguments_separator );
            foreach ( $parsed['ai1ec'] as $key => $value ) {
                $uri .= $this->_arguments_separator .
                    $this->_clean_key( $key ) .
                    self::DIRECTION_SEPARATOR .
                    $this->_safe_uri_value( $value );
            }
        } else {
            $place  = $parsed['_type'];
            $action = isset( $parsed['ai1ec']['action'] )
                ? $parsed['ai1ec']['action']
                : NULL;
            if ( empty( $action ) ) {
                foreach ( array( 'args', 'hash' ) as $place ) {
                if ( ! empty( $parsed[$place]['action'] ) ) {
                    $action = $parsed[$place]['action'];
                    break;
                }
                }
            }
            if ( empty( $action ) ) {
                $action = 'uri_err';
            }
            if ( 0 !== strncmp( $action, 'ai1ec_', 6 ) ) {
                $action = 'ai1ec_' . $action;
            }
            $combined_ai1ec = array();
            foreach ( $parsed['ai1ec'] as $key => $value ) {
                $combined_ai1ec[] = $this->_clean_key( $key ) .
                    self::DIRECTION_SEPARATOR . $this->_safe_uri_value( $value );
            }
            $combined_ai1ec = implode( '|', $combined_ai1ec );
            $parsed[$place]['ai1ec'] = $combined_ai1ec;
            if ( 'hash' === $place ) {
                $parsed[$place]['action'] = $action;
            }
            unset( $combined_ai1ec, $place );
        }

        $arg_list = array(
          'args' => '?',
          'hash' => '#',
        );

        foreach ( $arg_list as $name => $separator ) {
            if ( ! empty( $parsed[$name] ) ) {
                $uri .= $separator . build_query( $parsed[$name] );
            }
        }

        return $uri;
    }

    /**
     * Convert query string to internal representation
     *
     * @param string $query Query to parse
     * @param string $name    Positional name (i.e. 'hash')
     *
     * @return array Parsed query map with 'ai1ec' and {$name} keys
     */
    public function parse_query_str( $query, $name ) {
        $result = array(
          'ai1ec' => array(),
          $name   => array(),
        );
        $parsed = null;
        parse_str( $query, $parsed );
        foreach ( $parsed as $key => $value ) {
            if ( 0 === strncmp( $key, 'ai1ec', 5 ) ) {
                $result['_type'] = $name;
                if ( ! is_array( $value ) ) {
                    if ( 'ai1ec' === $key ) {
                        $value_list = explode( '|', $value );
                        $value        = array();
                        foreach ( $value_list as $entry ) {
                            list( $sub_key, $sub_value ) = explode(
                                self::DIRECTION_SEPARATOR,
                                $entry
                            );
                            $value[$sub_key] = $sub_value;
                        }
                        unset( $value_list );
                    } else {
                        $value = array( substr($key, 6) => $value );
                    }
                }
                $result['ai1ec'] = array_merge(
                    $result['ai1ec'],
                    $value
                );
            } else {
                $result[$name][$key] = $value;
            }
        }
        unset( $parsed );
        return $result;
    }

    /**
     * Create URI-safe value (scalar)
     *
     * @param mixed $value Value provided for URL
     *
     * @return string Value to use in URI
     */
    protected function _safe_uri_value( $value ) {
        if ( is_array( $value ) ) {
            $value = implode(',', $value);
        }
        return $value;
    }

    /**
     * Clean AI1EC sub-element key
     *
     * @param string $key Key to clean
     *
     * @return string Cleaned key to output
     */
    protected function _clean_key( $key ) {
        if ( 0 === strncmp( $key, 'ai1ec_', 6 ) ) {
            $key = substr( $key, 6 );
        }
        return $key;
    }

}