twitter: fix parsing of the artist name from the url.

Fixes URLs like https://twitter.com/intent/user?user_id=123 being
incorrectly normalized to http://twitter.com/intent/ in artist entries.

Also fixes the artist name to be taken from the url when it can't be
obtained from the api (when the tweet is deleted).

app/logical/sources/strategies/base.rb

@@ -132,7 +132,7 @@ module Sources
       # The url to use for artist finding purposes. This will be stored in the
       # artist entry. Normally this will be the profile url.
       def normalize_for_artist_finder
-        profile_url || url
+        profile_url.presence || url
       end
 
       # A unique identifier for the artist. This is used for artist creation.

app/logical/sources/strategies/twitter.rb

@@ -2,6 +2,12 @@ module Sources::Strategies
   class Twitter < Base
     PAGE = %r!\Ahttps?://(?:mobile\.)?twitter\.com!i
     ASSET = %r!\A(https?://(?:video|pbs)\.twimg\.com/media/)!i
+    PROFILE = %r!\Ahttps?://(?:mobile\.)?twitter.com/(?<username>[a-z0-9_]+)!i
+
+    # Twitter provides a list but it's inaccurate; some names ('intent') aren't
+    # included and other names in the list aren't actually reserved.
+    # https://developer.twitter.com/en/docs/developer-utilities/configuration/api-reference/get-help-configuration
+    RESERVED_USERNAMES = %w[home i intent search]
 
     def self.match?(*urls)
       urls.compact.any? { |x| x =~ PAGE || x =~ ASSET}
@@ -17,6 +23,14 @@ module Sources::Strategies
       return nil
     end
 
+    def self.artist_name_from_url(url)
+      if url =~ PROFILE && !$~[:username].in?(RESERVED_USERNAMES)
+        $~[:username]
+      else
+        nil
+      end
+    end
+
     def site_name
       "Twitter"
     end
@@ -53,22 +67,18 @@ module Sources::Strategies
     end
 
     def profile_url
-      if url =~ %r{\Ahttps?://(?:mobile\.)?twitter\.com/(\w+)}i
-        if $1 != "i"
-          return "https://twitter.com/#{$1}"
-        end
-      end
-
-      if artist_name.present?
-        return "https://twitter.com/" + artist_name
-      end
-
-      ""
+      return "" if artist_name.blank?
+      "https://twitter.com/#{artist_name}"
     end
 
     def artist_name
-      return "" if api_response.blank?
-      api_response.attrs[:user][:screen_name]
+      if artist_name_from_url.present?
+        artist_name_from_url
+      elsif api_response.present?
+        api_response.attrs[:user][:screen_name]
+      else
+        ""
+      end
     end
 
     def artist_commentary_title
@@ -85,7 +95,7 @@ module Sources::Strategies
     end
 
     def normalize_for_artist_finder
-      profile_url.try(:downcase)
+      profile_url.try(:downcase).presence || url
     end
 
     def tags
@@ -135,5 +145,9 @@ module Sources::Strategies
       [url, referer_url].map {|x| self.class.status_id_from_url(x)}.compact.first
     end
     memoize :status_id
+
+    def artist_name_from_url
+      [url, referer_url].map {|x| self.class.artist_name_from_url(x)}.compact.first
+    end
   end
 end

test/unit/artist_url_test.rb

@@ -152,6 +152,12 @@ class ArtistUrlTest < ActiveSupport::TestCase
       assert_equal("http://twitter.com/aoimanabu/", url.normalized_url)
     end
 
+    should "normalize https://twitter.com/intent/user?user_id=* urls" do
+      url = FactoryBot.create(:artist_url, :url => "https://twitter.com/intent/user?user_id=2784590030")
+      assert_equal("https://twitter.com/intent/user?user_id=2784590030", url.url)
+      assert_equal("http://twitter.com/intent/user?user_id=2784590030/", url.normalized_url)
+    end
+
     should "normalize nijie urls" do
       url = FactoryBot.create(:artist_url, url: "https://pic03.nijie.info/nijie_picture/236014_20170620101426_0.png")
       assert_equal("http://nijie.info/members.php?id=161703/", url.normalized_url)

test/unit/sources/twitter_test.rb

@@ -91,7 +91,6 @@ module Sources
       setup do
         skip "Twitter key is not set" unless Danbooru.config.twitter_api_key
         @site = Sources::Strategies.find("https://mobile.twitter.com/Strangestone/status/556440271961858051")
-        
       end
 
       should "get the image url" do
@@ -177,6 +176,17 @@ module Sources
       end
     end
 
+    context "A deleted tweet" do
+      should "still find the artist name" do
+        @site = Sources::Strategies.find("https://twitter.com/masayasuf/status/870734961778630656")
+        @artist = FactoryBot.create(:artist, name: "masayasuf", url_string: @site.url)
+
+        assert_equal("masayasuf", @site.artist_name)
+        assert_equal("https://twitter.com/masayasuf", @site.profile_url)
+        assert_equal([@artist], @site.artists)
+      end
+    end
+
     context "A tweet" do
       setup do
         skip "Twitter key is not set" unless Danbooru.config.twitter_api_key