<?php

/**
 * Date/Time format parser
 *
 * @author       Time.ly Network, Inc.
 * @since        2.0
 * @package      Ai1EC
 * @subpackage   Ai1EC.Parser
 */
class Ai1ec_Parser_Date {

    /**
     * @var string Character separating tokens.
     */
    protected $_token_separator;

    /**
     * @var string Character specifying need for localization.
     */
    protected $_localize_indicator;

    /**
     * @var array Map of input and parsed formats.
     */
    protected $_parsed             = array();

    /**
     * @var array Map of I18n-able format specifiers.
     */
    protected $_i18nable_formats = array(
        'D' => array( 'w', null ),
        'F' => array( 'm', 'get_month' ),
        'l' => array( 'w', 'get_weekday' ),
        'M' => array( 'm', null ),
        'a' => array( 'a', 'get_meridiem' ),
        'A' => array( 'A', 'get_meridiem' ),
    );

    /**
     * Constructor.
     *
     * @return void Method does not return.
     */
    public function __construct() {
        $this->_token_separator    = chr( 12 );
        $this->_localize_indicator = chr( 11 );
    }

    /**
     * Get i18n-safe format string.
     *
     * NOTICE: this method caches result of {@see self::parse()} call.
     *
     * @param string $format Requested format.
     *
     * @return string Format to use in `date`-like calls.
     */
    public function get_format( $format ) {
        if ( ! isset( $this->_parsed[$format] ) ) {
            $this->_parsed[$format] = $this->parse( $format );
        }
        return $this->_parsed[$format];
    }

    /**
     * Parse date-time into i18n-safe format string.
     *
     * @param string $format Input format.
     *
     * @return string Format to use in `date`-like calls.
     */
    public function parse( $format ) {
        $parsed = '';
        $case   = 0;
        for ( $idx = 0, $len = strlen( $format ); $idx < $len; $idx++ ) {
            $char = $format[$idx];
            if ( 1 !== $case ) {
                if ( '\\' === $char ) {
                    $case = 2;
                } else {
                    $char = $this->get_i18n_name( $char );
                }
            }
            $parsed .= $char;
            if ( $case > 0 ) {
                --$case;
            }
        }
        return trim( $parsed, $this->_token_separator );
    }

    /**
     * Remove binary characters and add I18n values to formatted string.
     *
     * @param string $formatted Formatted datetime string.
     *
     * @return string Safe for use format value.
     */
    public function squeeze( $formatted ) {
        $output = '';
        $tokens = explode( $this->_token_separator, $formatted );
        foreach ( $tokens as $token ) {
            $output .= $this->get_i18n_value( $token );
        }
        return $output;
    }

    /**
     * Return rendering-ready formatted string token value.
     *
     * Method uses {@see self::localize()} to actually format I18n
     * parts when needed.
     *
     * @param string $token Formatting token.
     *
     * @return string I18n-ized value.
     */
    public function get_i18n_value( $token ) {
        if ( isset( $token[0] ) && $this->_localize_indicator === $token[0] ) {
            $format = $token[1];
            $value  = substr( $token, 2 );
            $token  = $this->localize( $format, $value );
        }
        return $token;
    }

    /**
     * Get I18n value for token.
     *
     * @param string $format Original format specifier.
     * @param string $value  Value to use in I18n query.
     *
     * @return string I18n-formatted string.
     */
    public function localize( $format, $value ) {
        global $wp_locale;
        if (
            isset( $this->_i18nable_formats[$format] ) &&
            isset( $this->_i18nable_formats[$format][1] )
        ) {
            return $wp_locale->{$this->_i18nable_formats[$format][1]}( $value );
        }
        switch ( $format ) {
            case 'M':
                return $wp_locale->get_month_abbrev(
                    $wp_locale->get_month( $value )
                );
                break;

            case 'D':
                return $wp_locale->get_weekday_abbrev(
                    $wp_locale->get_weekday( $value )
                );
                break;

            default:
                // nop
        }
        return $value; // fail-safe
    }

    /**
     * Get optionally binary-quoted string for formatting inputs.
     *
     * @param string $format Originally requested formatting token.
     *
     * @return string Token to use in formatting query.
     */
    public function get_i18n_name( $format ) {
        if ( isset( $this->_i18nable_formats[$format] ) ) {
            return $this->_token_separator .
                $this->_localize_indicator . // speed parsing token
                '\\' . $format . // backslashed value for recovery
                $this->_i18nable_formats[$format][0] . // formattable token
                $this->_token_separator;
        }
        return $format;
    }

}