search: apply aliases after parsing searches.

Make PostQueryBuilder apply aliases earlier, immediately after parsing
the search.

On the post index page there are multiple places where we need to apply
aliases:

* When running the search with PostQueryBuilder#build.
* When calculating the search count with PostQueryBuilder#fast_count.
* When calculating the related tags for the sidebar.
* When tracking missed searches and popular searches for Reportbooru.
* When looking up wiki excerpts.

Applying aliases after parsing ensures we only have to apply aliases
once for all of these things.

We also normalize the order of tags in searches and strip repeated tags.
This is so that we have consistent cache keys for fast_count.

* Fixes searches for aliased tags being counted as missed searches (fixes #4433).
* Fixes wiki excerpts not showing up when searching for aliased tags.

test/functional/posts_controller_test.rb

@@ -68,6 +68,17 @@ class PostsControllerTest < ActionDispatch::IntegrationTest
           assert_select "#show-excerpt-link", count: 0
         end
 
+        should "render for an aliased tag" do
+          create(:tag_alias, antecedent_name: "/lav", consequent_name: "looking_at_viewer")
+          as(@user) { create(:wiki_page, title: "looking_at_viewer") }
+          @post = create(:post, tag_string: "looking_at_viewer", rating: "s")
+
+          get posts_path, params: { tags: "/lav" }
+          assert_response :success
+          assert_select "#post_#{@post.id}", count: 1
+          assert_select "#excerpt .wiki-link[href='/wiki_pages/looking_at_viewer']", count: 1
+        end
+
         should "render for a wildcard tag search" do
           create(:post, tag_string: "1girl solo")
           get posts_path(tags: "*girl*")

test/unit/post_query_builder_test.rb

@@ -1018,7 +1018,7 @@ class PostQueryBuilderTest < ActiveSupport::TestCase
   context "Parsing:" do
     should "split a query" do
       assert_equal(%w(aaa bbb), PostQueryBuilder.new("aaa bbb").split_query)
-      assert_equal(%w(~aaa -bbb* -bbb*), PostQueryBuilder.new("~AAa -BBB* -bbb*").split_query)
+      assert_equal(%w(~aaa -bbb*), PostQueryBuilder.new("~AAa -BBB* -bbb*").split_query)
     end
 
     should "not strip out valid characters when scanning" do
@@ -1054,19 +1054,18 @@ class PostQueryBuilderTest < ActiveSupport::TestCase
     should "work" do
       create(:tag_alias, antecedent_name: "gray", consequent_name: "grey")
 
-      assert_equal("foo", PostQueryBuilder.new("foo").normalize_query)
-      assert_equal("foo", PostQueryBuilder.new(" foo ").normalize_query)
-      assert_equal("foo", PostQueryBuilder.new("FOO").normalize_query)
-      assert_equal("foo", PostQueryBuilder.new("foo foo").normalize_query)
-      assert_equal("gray", PostQueryBuilder.new("gray").normalize_query)
-      assert_equal("grey", PostQueryBuilder.new("gray").normalize_query(normalize_aliases: true))
-      assert_equal("aaa bbb", PostQueryBuilder.new("bbb aaa").normalize_query)
-      assert_equal("-aaa bbb", PostQueryBuilder.new("bbb -aaa").normalize_query)
-      assert_equal("~aaa ~bbb", PostQueryBuilder.new("~bbb ~aaa").normalize_query)
-      assert_equal("bbb commentary:true", PostQueryBuilder.new("bbb commentary:true").normalize_query)
-      assert_equal('bbb commentary:"true"', PostQueryBuilder.new("bbb commentary:'true'").normalize_query)
-      assert_equal('-commentary:true bbb', PostQueryBuilder.new("bbb -commentary:true").normalize_query)
-      assert_equal('-commentary:"true" bbb', PostQueryBuilder.new("bbb -commentary:'true'").normalize_query)
+      assert_equal("foo", PostQueryBuilder.new("foo").to_s)
+      assert_equal("foo", PostQueryBuilder.new(" foo ").to_s)
+      assert_equal("foo", PostQueryBuilder.new("FOO").to_s)
+      assert_equal("foo", PostQueryBuilder.new("foo foo").to_s)
+      assert_equal("grey", PostQueryBuilder.new("gray").to_s)
+      assert_equal("aaa bbb", PostQueryBuilder.new("bbb aaa").to_s)
+      assert_equal("-aaa bbb", PostQueryBuilder.new("bbb -aaa").to_s)
+      assert_equal("~aaa ~bbb", PostQueryBuilder.new("~bbb ~aaa").to_s)
+      assert_equal("commentary:true bbb", PostQueryBuilder.new("bbb commentary:true").to_s)
+      assert_equal('commentary:"true" bbb', PostQueryBuilder.new("bbb commentary:'true'").to_s)
+      assert_equal('-commentary:true bbb', PostQueryBuilder.new("bbb -commentary:true").to_s)
+      assert_equal('-commentary:"true" bbb', PostQueryBuilder.new("bbb -commentary:'true'").to_s)
     end
   end
 
@@ -1107,7 +1106,7 @@ class PostQueryBuilderTest < ActiveSupport::TestCase
 
     context "for a multi-tag search" do
       should "return the cached count, if it exists" do
-        PostQueryBuilder.new(nil).set_count_in_cache("aaa score:42", 100)
+        PostQueryBuilder.new(nil).set_count_in_cache("score:42 aaa", 100)
         assert_fast_count(100, "aaa score:42")
       end
 
@@ -1116,7 +1115,7 @@ class PostQueryBuilderTest < ActiveSupport::TestCase
       end
 
       should "set the expiration time" do
-        Cache.expects(:put).with(PostQueryBuilder.new(nil).count_cache_key("aaa score:42"), 1, 180)
+        Cache.expects(:put).with(PostQueryBuilder.new(nil).count_cache_key("score:42 aaa"), 1, 180)
         PostQueryBuilder.new("aaa score:42").fast_count
       end