Move tag autocomplete logic to new file

app/assets/javascripts/posts.js

@@ -6,10 +6,6 @@
   Danbooru.Post.initialize_all = function() {
     this.initialize_post_previews();
 
-    if (Danbooru.meta("enable-auto-complete") === "true") {
-      this.initialize_tag_autocomplete();
-    }
-
     if ($("#c-posts").length) {
       if (Danbooru.meta("enable-js-navigation") === "true") {
         this.initialize_shortcuts();
@@ -137,139 +133,6 @@
     $tag_string.css({"resize": "", "width": ""});
   }
 
-  Danbooru.Post.initialize_tag_autocomplete = function() {
-    var $fields_multiple = $(
-      "#tags,#post_tag_string,#upload_tag_string,#tag-script-field,#c-moderator-post-queues #query"
-    );
-    var $fields_single = $(
-      "#search_post_tags_match,#c-tags #search_name_matches,#c-tag-aliases #query,#c-tag-implications #query," +
-      "#wiki_page_title,#artist_name," +
-      "#tag_alias_request_antecedent_name,#tag_alias_request_consequent_name," +
-      "#tag_implication_request_antecedent_name,#tag_implication_request_consequent_name," +
-      "#tag_alias_antecedent_name,#tag_alias_consequent_name," +
-      "#tag_implication_antecedent_name,#tag_implication_consequent_name"
-    );
-
-    var prefixes = "-|~|general:|gen:|artist:|art:|copyright:|copy:|co:|character:|char:|ch:";
-
-    $fields_multiple.autocomplete({
-      delay: 100,
-      focus: function() {
-        return false;
-      },
-      select: function(event, ui) {
-        var before_caret_text = this.value.substring(0, this.selectionStart);
-        var after_caret_text = this.value.substring(this.selectionStart);
-
-        var regexp = new RegExp("(" + prefixes + ")?\\S+$", "g");
-        this.value = before_caret_text.replace(regexp, "$1" + ui.item.value + " ");
-
-        // Preserve original caret position to prevent it from jumping to the end
-        var original_start = this.selectionStart;
-        this.value += after_caret_text;
-        this.selectionStart = this.selectionEnd = original_start;
-
-        return false;
-      },
-      source: function(req, resp) {
-        var before_caret_text = req.term.substring(0, this.element.get(0).selectionStart);
-
-        if (before_caret_text.match(/ $/)) {
-          this.close();
-          return;
-        }
-
-        var term = before_caret_text.match(/\S+/g).pop();
-        var regexp = new RegExp("^(?:" + prefixes + ")(.*)$");
-        var match = term.match(regexp);
-        if (match) {
-          term = match[1];
-        }
-        if (term === "") {
-          return;
-        }
-
-        $.ajax({
-          url: "/tags.json",
-          data: {
-            "search[order]": "count",
-            "search[name_matches]": term + "*",
-            "limit": 10
-          },
-          method: "get",
-          success: function(data) {
-            resp($.map(data, function(tag) {
-              return {
-                label: tag.name.replace(/_/g, " "),
-                value: tag.name,
-                category: tag.category,
-                post_count: tag.post_count
-              };
-            }));
-          }
-        });
-      }
-    });
-
-    $fields_multiple.on("autocompleteselect", function() {
-      Danbooru.autocompleting = true;
-    });
-
-    $fields_multiple.on("autocompleteclose", function() {
-      // this is needed otherwise the var is disabled by the time the
-      // keydown is triggered
-      setTimeout(function() {Danbooru.autocompleting = false;}, 100);
-    });
-
-    $fields_single.autocomplete({
-      minLength: 1,
-      source: function(req, resp) {
-        $.ajax({
-          url: "/tags.json",
-          data: {
-            "search[order]": "count",
-            "search[name_matches]": req.term + "*",
-            "limit": 10
-          },
-          method: "get",
-          success: function(data) {
-            resp($.map(data, function(tag) {
-              return {
-                label: tag.name.replace(/_/g, " "),
-                value: tag.name,
-                category: tag.category,
-                post_count: tag.post_count
-              };
-            }));
-          }
-        });
-      }
-    });
-
-    var render_tag = function(list, tag) {
-      var $link = $("<a/>").addClass("tag-type-" + tag.category).text(tag.label);
-      $link.attr("href", "/posts?tags=" + encodeURIComponent(tag.value));
-      $link.click(function(e) {
-        e.preventDefault();
-      });
-
-      var count;
-      if (tag.post_count >= 1000) {
-        count = Math.floor(tag.post_count / 1000) + "k";
-      } else {
-        count = tag.post_count;
-      }
-      var $post_count = $("<span/>").addClass("post-count").css("float", "right").text(count);
-      $link.append($post_count);
-
-      return $("<li/>").data("item.autocomplete", tag).append($link).appendTo(list);
-    };
-
-    $.merge($fields_multiple, $fields_single).each(function(i, field) {
-      $(field).data("uiAutocomplete")._renderItem = render_tag;
-    });
-  }
-
   Danbooru.Post.initialize_similar = function() {
     $("#similar-button").click(function(e) {
       var old_source_name = $("#post_source").attr("name");