first cut implementation at using public pixiv api

app/logical/pixiv_api_client.rb

@@ -0,0 +1,67 @@
+class PixivApiClient
+  CLIENT_ID = "bYGKuGVw91e0NMfPGp44euvGt59s"
+  CLIENT_SECRET = "HP3RmkgAmEGro0gn1x9ioawQE8WMfvLXDz3ZqxpK"
+
+  def works(illust_id)
+    headers = {
+      "Referer" => "http://www.pixiv.net",
+      "User-Agent" => "#{Danbooru.config.safe_app_name}/#{Danbooru.config.version}",
+      "Content-Type" => "application/x-www-form-urlencoded",
+      "Authorization" => "Bearer #{access_token}"
+    }
+    params = {
+      "image_sizes" => "large",
+      "include_stats" => "true"
+    }
+    url = URI.parse("https://public-api.secure.pixiv.net/v1/works/#{illust_id.to_i}.json")
+    url.query = URI.encode_www_form(params)
+    json = nil
+
+    Net::HTTP.start(url.host, url.port, :use_ssl => true) do |http|
+      resp = http.request_get(url.request_uri, headers)
+      if resp.is_a?(Net::HTTPSuccess)
+        json = JSON.parse(resp.body)
+      end
+    end
+
+    map(json)
+  end
+
+private
+
+  def map(raw_json)
+    {
+      :moniker => raw_json["response"][0]["user"]["account"],
+      :file_ext => File.extname(raw_json["response"][0]["image_urls"]["large"]),
+      :page_count => raw_json["response"][0]["page_count"]
+    }
+  end
+
+	def access_token
+    Cache.get("pixiv-papi-access-token", 3000) do
+      access_token = nil
+      headers = {
+        "Referer" => "http://www.pixiv.net"
+      }
+      params = {
+        "username" => Danbooru.config.pixiv_login,
+        "password" => Danbooru.config.pixiv_password,
+        "grant_type" => "password",
+        "client_id" => CLIENT_ID,
+        "client_secret" => CLIENT_SECRET
+      }
+      url = URI.parse("https://oauth.secure.pixiv.net/auth/token")
+
+      Net::HTTP.start(url.host, url.port, :use_ssl => true) do |http|
+        resp = http.request_post(url.request_uri, URI.encode_www_form(params), headers)
+
+        if resp.is_a?(Net::HTTPSuccess)
+          json = JSON.parse(resp.body)
+          access_token = json["response"]["access_token"]
+        end
+      end
+
+      access_token
+    end
+  end
+end