client/search: autocomplete negated tags in search fields

This doesn't apply to tag inputs that aren't for searching, like the tag
input box when editing a post.

client/js/controls/auto_complete_control.js

@@ -228,6 +228,13 @@ class AutoCompleteControl {
     }
 
     _updateResults(textToFind) {
+        if (this._options.isNegationAllowed && textToFind === "-") {
+            this._results = [];
+            this._activeResult = -1;
+            this._refreshList();
+            return;
+        }
+
         this._options.getMatches(textToFind).then((matches) => {
             const oldResults = this._results.slice();
             this._results = matches.slice(0, this._options.maxResults);

client/js/controls/pool_auto_complete_control.js

@@ -31,9 +31,9 @@ class PoolAutoCompleteControl extends AutoCompleteControl {
         options.getMatches = (text) => {
             const term = misc.escapeSearchTerm(text);
             const query =
-                (text.length < minLengthForPartialSearch
-                    ? term + "*"
-                    : "*" + term + "*") + " sort:post-count";
+                (text.length >= minLengthForPartialSearch
+                    ? "*" + term + "*"
+                    : term + "*") + " sort:post-count";
 
             return new Promise((resolve, reject) => {
                 PoolList.search(query, 0, this._options.maxResults, [

client/js/controls/tag_auto_complete_control.js

@@ -5,7 +5,7 @@ const views = require("../util/views.js");
 const TagList = require("../models/tag_list.js");
 const AutoCompleteControl = require("./auto_complete_control.js");
 
-function _tagListToMatches(tags, options) {
+function _tagListToMatches(tags, options, negated) {
     return [...tags]
         .sort((tag1, tag2) => {
             return tag2.usages - tag1.usages;
@@ -15,6 +15,9 @@ function _tagListToMatches(tags, options) {
             if (options.isTaggedWith(tag.names[0])) {
                 cssName += " disabled";
             }
+            if (negated) {
+                tag.names = tag.names.map((tagName) => "-"+tagName);
+            }
             const caption =
                 '<span class="' +
                 cssName +
@@ -35,16 +38,26 @@ class TagAutoCompleteControl extends AutoCompleteControl {
         options = Object.assign(
             {
                 isTaggedWith: (tag) => false,
+                isNegationAllowed: false,
             },
             options
         );
 
         options.getMatches = (text) => {
+            const negated = options.isNegationAllowed && text[0] === "-";
+            if (negated) text = text.substring(1);
+            if (!text) {
+                return new Promise((resolve, reject) => {
+                    (response) => resolve(null),
+                    reject
+                });
+            }
+
             const term = misc.escapeSearchTerm(text);
             const query =
-                (text.length < minLengthForPartialSearch
-                    ? term + "*"
-                    : "*" + term + "*") + " sort:usages";
+                (text.length >= minLengthForPartialSearch || (!options.isNegationAllowed && text[0] === "-")
+                    ? "*" + term + "*"
+                    : term + "*") + " sort:usages";
 
             return new Promise((resolve, reject) => {
                 TagList.search(query, 0, this._options.maxResults, [
@@ -54,7 +67,7 @@ class TagAutoCompleteControl extends AutoCompleteControl {
                 ]).then(
                     (response) =>
                         resolve(
-                            _tagListToMatches(response.results, this._options)
+                            _tagListToMatches(response.results, this._options, negated)
                         ),
                     reject
                 );

client/js/controls/tag_input_control.js

@@ -114,6 +114,7 @@ class TagInputControl extends events.EventTarget {
                 },
                 verticalShift: -2,
                 isTaggedWith: (tagName) => this.tags.isTaggedWith(tagName),
+                isNegationAllowed: false,
             }
         );
 

client/js/views/home_view.js

@@ -30,6 +30,7 @@ class HomeView {
                             misc.escapeSearchTerm(tag.names[0]),
                             true
                         ),
+                    isNegationAllowed: true,
                 }
             );
             this._formNode.addEventListener("submit", (e) =>

client/js/views/posts_header_view.js

@@ -186,6 +186,7 @@ class PostsHeaderView extends events.EventTarget {
                         misc.escapeSearchTerm(tag.names[0]),
                         true
                     ),
+                isNegationAllowed: true,
             }
         );