# 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/>.

module Backend
  module Api
    module Schema
      @[GraphQL::Object]
      class Query < GraphQL::BaseQuery
        @[GraphQL::Field]
        # Retuns true
        def ok : Bool
          true
        end

        @[GraphQL::Field]
        # Public configuration of the API for frontend pre-validation
        def config : Config
          Config.new
        end

        @[GraphQL::Field]
        # Current authenticated user
        def me(context : Context) : User?
          context.authenticated!

          User.new(context.user.not_nil!)
        end

        @[GraphQL::Field]
        # User by ID
        def user(context : Context, id : Int32) : User?
          context.admin!

          User.from_id(id)
        end

        @[GraphQL::Field]
        # All users
        def users(context : Context) : Array(User)?
          context.admin!

          Db::User.query.map { |user| User.new(user) }
        end

        @[GraphQL::Field]
        def user_by_username(context : Context, username : String) : User?
          context.admin!

          User.new(Db::User.query.find { var(:username) == username }.not_nil!)
        end

        @[GraphQL::Field]
        # All admins
        def admins(context : Context) : Array(User)?
          context.admin!

          Db::User.query.where(admin: true).map { |user| User.new(user) }
        end

        @[GraphQL::Field]
        # Teacher by ID
        def teacher(id : Int32) : Teacher
          Teacher.new(Db::Teacher.find!(id))
        end

        @[GraphQL::Field]
        # All teachers
        def teachers : Array(Teacher)
          Db::Teacher.query.map { |teacher| Teacher.new(teacher) }
        end

        @[GraphQL::Field]
        # Student by ID
        def student(context : Context, id : Int32) : Student?
          context.admin!

          Student.new(Db::Student.find!(id))
        end

        @[GraphQL::Field]
        # All students
        def students(context : Context) : Array(Student)?
          context.admin!

          Db::Student.query.map { |student| Student.new(student) }
        end

        @[GraphQL::Field]
        # Vote by ID
        def vote(context : Context, id : Int32) : Vote?
          context.admin!

          Vote.new(Db::Vote.find!(id))
        end

        @[GraphQL::Field]
        # All votes
        def votes(context : Context) : Array(Vote)?
          context.admin!

          Db::Vote.query.map { |vote| Vote.new(vote) }
        end

        @[GraphQL::Field]
        # All students voted
        def all_students_voted(context : Context) : Bool?
          context.admin!

          votes = Db::Vote.query.count
          students = Db::Student.query.count

          students > 0 && votes >= students
        end

        @[GraphQL::Field]
        # Students can vote
        def students_can_vote : Bool
          teacher_role_count = Db::User.query.where(role: Db::UserRole::Teacher).count

          teacher_role_count > 0 && teacher_role_count == Db::Teacher.query.count
        end

        @[GraphQL::Field]
        # Teacher vote by ID
        def teacher_vote(context : Context, id : Int32) : TeacherVote?
          context.admin!

          TeacherVote.new(Db::TeacherVote.find!(id))
        end

        @[GraphQL::Field]
        # All teacher votes
        def teacher_votes(context : Context) : Array(TeacherVote)?
          context.admin!

          Db::TeacherVote.query.map { |vote| TeacherVote.new(vote) }
        end
      end
    end
  end
end