<?php
/*
 Plugin Name: Hum
 Plugin URI: http://github.com/willnorris/wordpress-hum
 Description: Personal URL shortener for WordPress
 Author: Will Norris
 Author URI: http://willnorris.com/
 Version: 1.1
 License: MIT (http://opensource.org/licenses/MIT)
 Text Domain: hum
 */


// if you have hum installed, then you probably actually care about short
// links, so we'll add it to the admin menu bar.
add_action('admin_bar_menu', 'wp_admin_bar_shortlink_menu', 90);


/**
 * Accept hum query variables.
 */
function hum_query_vars( $vars ) {
  $vars[] = 'hum';
  return $vars;
}
add_action('query_vars', 'hum_query_vars');


/**
 * Parse request for shortlink.
 *
 * @uses do_action() Calls 'hum_request_{$type}" action
 * @uses do_action() Calls 'hum_request" action
 */
function hum_parse_request( $wp ) {
  if ( array_key_exists( 'hum', $wp->query_vars ) ) {
    list($type, $id) = explode('/', $wp->query_vars['hum'], 2);
    do_action("hum_request_{$type}", $id);
    do_action('hum_request', $type, $id);

    // hum hasn't handled the request yet, so try again but strip common
    // punctuation that might appear after a URL in written text: . , )
    $clean_id = preg_replace('/[\.,\)]+$/', '', $id);
    if ($id != $clean_id) {
      do_action("hum_request_{$type}", $clean_id);
      do_action('hum_request', $type, $clean_id);
    }

    // hum didn't handle request, so issue 404.
    // manually setting query vars like this feels very fragile, but
    // $wp_query->set_404() doesn't do what we need here.
    $wp->query_vars['error'] = '404';
  }
}
add_action('parse_request', 'hum_parse_request');


/**
 * Redirect shortlinks that are for content hosted directly within WordPress.
 * The 'id' portion of these URLs is expected to be the sexagesimal post ID.
 *
 * @uses apply_filters() Calls 'hum_local_types' filter on prefixes for local
 *     WordPress hosted content
 * @param string $code the content-type prefix
 */
function hum_redirect_local( $type, $id ) {
  $local_types = array('b', 't');
  $local_types = apply_filters('hum_local_types', $local_types);

  if ( in_array($type, $local_types) ) {
    $p = sxg_to_num( $id );
    $permalink = get_permalink($p);

    if ( $permalink ) {
      wp_redirect( $permalink, 301 );
      exit;
    }
  }
}
add_filter('hum_request', 'hum_redirect_local', 20, 2);


/**
 * Handles /i/ URLs that have ISBN or ASIN subpaths by redirecting to Amazon.
 *
 * @uses do_action() Calls 'hum_request_i_{$subtype}' action
 * @uses apply_filters() Calls 'amazon_affiliate_id' filter
 *
 * @param string $path subpath of URL (after /i/)
 */
function hum_request_i( $path ) {
  list($subtype, $id) = preg_split('|/|', $path, 2);
  do_action("hum_request_i_{$subtype}", $id);
  switch ($subtype) {
    case 'a':
    case 'asin':
    case 'i':
    case 'isbn':
      $amazon_id = apply_filters('amazon_affiliate_id', false);
      if ($amazon_id) {
        wp_redirect('http://www.amazon.com/gp/redirect.html?ie=UTF8&location='
          . 'http%3A%2F%2Fwww.amazon.com%2Fdp%2F' . $id . '&tag=' . $amazon_id
          . '&linkCode=ur2&camp=1789&creative=9325');
      } else {
        wp_redirect('http://www.amazon.com/dp/' . $id );
      }
      exit;
      break;
  }
}
add_filter('hum_request_i', 'hum_request_i', 20);


/**
 * Allow for simple redirect rules for shortlink prefixes.  Users can provide a
 * filter to perform simple URL redirect for a given type prefix.  For example,
 * to redirect all /w/ shortlinks to your personal PBworks wiki, you could use:
 *
 *   add_filter('hum_redirect_base_w', 
 *     create_function('', 'return "http://willnorris.pbworks.com/";'));
 *
 * @uses apply_filters() Calls 'hum_redirect_base_{$type}' filter on redirect base URL
 */
function hum_redirect_request( $type, $id ) {
  $url = apply_filters("hum_redirect_base_{$type}", false);
  if ( $url ) {
    $url = trailingslashit($url) . $id;
    wp_redirect( $url );
    exit;
  }
}
add_action('hum_request', 'hum_redirect_request', 30, 2);


/**
 * Add rewrite rules for hum shortlinks.
 *
 * @param object $wp_rewrite
 */
function hum_rewrite_rules( $wp_rewrite ) {
  $hum_rules = array(
		'([a-z](/.*)?$)' => 'index.php?hum=$matches[1]',
  );

  $wp_rewrite->rules = $hum_rules + $wp_rewrite->rules;
}
add_action('generate_rewrite_rules', 'hum_rewrite_rules');


/**
 * Flush wp_rewrite rules.
 */
function hum_flush_rewrite_rules() {
  global $wp_rewrite;
  $wp_rewrite->flush_rules();
}
register_activation_hook(__FILE__, 'hum_flush_rewrite_rules');
register_deactivation_hook(__FILE__, 'hum_flush_rewrite_rules');


/**
 * Get the base URL for hum shortlinks.  Defaults to the WordPress home url.
 * Users can define HUM_SHORTLINK_BASE or provide a filter to use a custom
 * domain for shortlinks.
 *
 * @uses apply_filters() Calls 'hum_shortlink_base' filter on base URL
 * @return string
 */
function hum_shortlink_base() {
  $base = get_option('hum_shortlink_base');
  if ( empty( $base ) ) {
    $base = home_url();
  }
  return apply_filters( 'hum_shortlink_base', $base );
}


/**
 * Allow the constant named 'HUM_SHORTLINK_BASE' to override the base URL for shortlinks.
 */
function _config_hum_shortlink_base( $url = '' ) {
  if ( defined( 'HUM_SHORTLINK_BASE') ) {
    return untrailingslashit( HUM_SHORTLINK_BASE );
  }
  return $url;
}
add_filter('pre_option_hum_shortlink_base', '_config_hum_shortlink_base');


/**
 * Get the shortlink for a post, page, attachment, or blog.
 *
 * @param string $link the current shortlink for the post
 * @param int $id post ID
 * @param string $context
 * @param boolean $allow_slugs
 * @return string
 */
function hum_get_shortlink($link, $id, $context, $allow_slugs) {
  $post_id = 0;
  if ( 'query' == $context ) {
    if ( is_front_page() ) {
      $link = trailingslashit( hum_shortlink_base() );
    } elseif ( is_singular() ) {
      $post_id = get_queried_object_id();
    }
  } elseif ( 'post' == $context ) {
    $post = get_post($id);
    $post_id = $post->ID;
  }

  if ( !empty($post_id) ) {
    $type = hum_type_prefix($post_id);
    $sxg_id = num_to_sxg($post_id);
    $link = trailingslashit( hum_shortlink_base() ) . $type . '/' . $sxg_id;
  }

  return $link;
}
add_filter('pre_get_shortlink', 'hum_get_shortlink', 10, 4);


/**
 * Get the content-type prefix for the specified post.
 *
 * @see http://ttk.me/w/Whistle#design
 * @uses apply_filters() Calls 'hum_type_prefix' on the content type prefix
 *
 * @param int|object $post A post
 * @return string the content type prefix for the post
 */
function hum_type_prefix( $post ) {
  $prefix = 'b';

  $post_format = get_post_format( $post );
  switch($post_format) {
    case 'aside': 
      $prefix = 't'; break;
    case 'status': 
      $prefix = 't'; break;
  }

  return apply_filters('hum_type_prefix', $prefix, $post);
}


// Admin Settings


/**
 * Register admin settings for Hum.
 */
function hum_admin_init() {
  register_setting('general', 'hum_shortlink_base');
}
add_action('admin_init', 'hum_admin_init');


/**
 * Add admin settings fields for Hum.
 */
function hum_admin_menu() {
  add_settings_field('hum_shortlink_base', __('Shortlink Base (URL)', 'hum'), 'hum_admin_shortlink_base', 'general');
}
add_action('admin_menu', 'hum_admin_menu');


/**
 * Admin UI for setting the shortlink base URL.
 */
function hum_admin_shortlink_base() {
?>
  <input name="hum_shortlink_base" type="text" id="hum_shortlink_base" value="<?php form_option('hum_shortlink_base'); ?>"<?php disabled( defined( 'HUM_SHORTLINK_BASE') ); ?> class="regular-text code<?php if ( defined( 'HUM_SHORTLINK_BASE') ) echo ' disabled' ?>" />
  <p class="description">
    If you have a custom domain you want to use for shortlinks, enter the address here.
  </p>

  <script>
    // move adjacent to other URL properties
    jQuery('input#hum_shortlink_base').parents('tr')
      .insertAfter( jQuery('input#home').parents('tr') );
  </script>
<?php
}


// New Base 60 - see http://ttk.me/w/NewBase60
//
// slightly modified from Cassis Project (http://cassisproject.com/)
// Copyright 2010 Tantek Çelik, released under Creative Commons by-sa 3.0

if ( !function_exists( 'num_to_sxg' ) ):
/**
 * Convert base-10 number to sexagesimal.
 */
function num_to_sxg($n) {
  $s = "";
  $m = "0123456789ABCDEFGHJKLMNPQRSTUVWXYZ_abcdefghijkmnopqrstuvwxyz";
  if ($n===null || $n===0) { return 0; }
  while ($n>0) {
    $d = $n % 60;
    $s = $m[$d] . $s;
    $n = ($n-$d)/60;
  }
  return $s;
}
endif;


if ( !function_exists( 'sxg_to_num' ) ):
/**
 * Convert sexagesimal to base-10 number.
 */
function sxg_to_num($s) {
  $n = 0;
  $j = strlen($s);
  for ($i=0;$i<$j;$i++) { // iterate from first to last char of $s
    $c = ord($s[$i]); //  put current ASCII of char into $c  
    if ($c>=48 && $c<=57) { $c=$c-48; }
    else if ($c>=65 && $c<=72) { $c-=55; }
    else if ($c==73 || $c==108) { $c=1; } // typo capital I, lowercase l to 1
    else if ($c>=74 && $c<=78) { $c-=56; }
    else if ($c==79) { $c=0; } // error correct typo capital O to 0
    else if ($c>=80 && $c<=90) { $c-=57; }
    else if ($c==95) { $c=34; } // underscore
    else if ($c>=97 && $c<=107) { $c-=62; }
    else if ($c>=109 && $c<=122) { $c-=63; }
    else { $c = 0; } // treat all other noise as 0
    $n = 60*$n + $c;
  }
  return $n;
}
endif;