implement post change report

app/logical/google_big_query/base.rb

@@ -0,0 +1,36 @@
+require "big_query"
+
+module GoogleBigQuery
+  class Base
+    def query(q)
+      client.query(q)
+    end
+
+    def escape(s)
+      Regexp.escape(s).gsub(/\\/, '\0\0').gsub(/['"]/, '\\\\\0')
+    end
+
+    def client
+      @_client ||= BigQuery::Client.new(
+        "json_key" => client_options[:google_key_path],
+        "project_id" => google_config["project_id"],
+        "dataset" => client_options[:google_data_set]
+      )
+    end
+
+    def client_options
+      @_client_options ||= {
+        google_key_path: Danbooru.config.google_api_json_key_path,
+        google_data_set: "danbooru_#{Rails.env}"
+      }
+    end
+
+    def google_config
+      @_google_config ||= JSON.parse(File.read(client_options[:google_key_path]))
+    end
+
+    def data_set
+      client_options[:google_data_set]
+    end
+  end
+end

app/logical/google_big_query/post_version.rb

@@ -0,0 +1,15 @@
+module GoogleBigQuery
+  class PostVersion < Base
+    def find_removed(tag, limit = 1_000)
+      tag = escape(tag)
+      limit = limit.to_i
+      query("select id, post_id, updated_at, updater_id, updater_ip_addr, tags, added_tags, removed_tags, parent_id, rating, source from [#{data_set}.post_versions] where regexp_match(removed_tags, \"(?:^| )#{tag}(?:$| )\") order by updated_at desc limit #{limit}")
+    end
+
+    def find_added(tag, limit = 1_000)
+      tag = escape(tag)
+      limit = limit.to_i
+      query("select id, post_id, updated_at, updater_id, updater_ip_addr, tags, added_tags, removed_tags, parent_id, rating, source from [#{data_set}.post_versions] where regexp_match(added_tags, \"(?:^| )#{tag}(?:$| )\") order by updated_at desc limit #{limit}")
+    end
+  end
+end