# Mentorenwahl: A fullstack application for assigning mentors to students based on their whishes.
# Copyright (C) 2022  Dominic Grimm

# This program is free software: you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.

# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License for more details.

# You should have received a copy of the GNU General Public License
# along with this program.  If not, see <https://www.gnu.org/licenses/>.

require "router"
require "http/server"
require "json"

module Backend
  module Api
    # Api webserver
    class WebServer
      include Router

      # GraphQL playground HTML code
      #
      # NOTE: Is minified in production
      GRAPHQL_PLAYGROUND = {{ flag?(:development) ? read_file("#{__DIR__}/playground.html") : run("./macros/minify_html.cr", read_file("#{__DIR__}/playground.html")).stringify }}

      # GraphQL request data serializer
      struct GraphQLQueryData
        include JSON::Serializable

        property query : String
        property variables : Hash(String, JSON::Any)?
        property operation_name : String?
      end

      # "Draws" (creates) routes
      def draw_routes : Nil
        # enable graphql playground when in development mode or explicitly enabled
        if Backend.config.api.graphql_playground_fully_enabled?
          Log.info { "GraphQL playground enabled" }

          get "/" do |context|
            context.response.content_type = "text/html"
            context.response.puts(GRAPHQL_PLAYGROUND)

            context
          end
        end

        post "/" do |context|
          context.response.content_type = "application/json"

          data = GraphQLQueryData.from_json(context.request.body.not_nil!.gets.not_nil!)
          context.response.print(
            Schema::SCHEMA.execute(
              data.query,
              data.variables,
              data.operation_name,
              Context.new(context.request)
            )
          )

          context
        end
      end

      # Runs the webserver with according middleware
      def run : Nil
        draw_routes

        server = HTTP::Server.new(
          [
            HTTP::LogHandler.new,
            HTTP::ErrorHandler.new,
            HTTP::CompressHandler.new,
            route_handler,
          ]
        )
        server.bind_tcp("0.0.0.0", 80, true)
        server.listen
      end
    end
  end
end