# 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 "env_config"

module Backend
  extend self

  @@config = Config.new(ENV, prefix: "BACKEND")

  # Global configuration
  def config : Config
    @@config
  end

  # Environment based configuration class
  class Config
    include EnvConfig

    # Types of environments program can compiled for / with
    enum BuildEnv
      Release
      Development
    end

    # Type of environment program is running in
    def build_env : BuildEnv
      {{ flag?(:release) }} ? BuildEnv::Release : BuildEnv::Development
    end

    # Release mode
    #
    # `true` if the build environment is `BuildEnv::Release`
    def release? : Bool
      build_env.production?
    end

    # Development mode
    #
    # `true` if the build environment is `BuildEnv::Development`
    def development? : Bool
      build_env.development?
    end

    # Base URL of application
    getter url : String

    # Minimum teacher selection count
    getter minimum_teacher_selection_count : Int32

    # Assignment possibility count
    getter assignment_possibility_count : UInt32

    @[EnvConfig::Setting(key: "api")]
    # Configuration for `Api`
    getter api : ApiConfig

    @[EnvConfig::Setting(key: "smtp")]
    # Configuration for `Mailers`
    getter smtp : SmtpConfig

    @[EnvConfig::Setting(key: "db")]
    # Configuration for `Db`
    getter db : DbConfig

    @[EnvConfig::Setting(key: "redis")]
    getter redis : RedisConfig

    @[EnvConfig::Setting(key: "ldap")]
    # Configuration for `Ldap`
    getter ldap : LdapConfig

    @[EnvConfig::Setting(key: "auth")]
    # Configuration for authorization provider
    getter auth : AuthConfig

    # Configuration for `Api`
    class ApiConfig
      include EnvConfig

      # JWT signing key
      getter jwt_secret : String

      # JWT expiration time in minutes
      getter jwt_expiration : Int32

      # Returns true of `playground` flag was set on compile time
      def graphql_playground? : Bool
        flag?(:playground)
      end
    end

    # Configuration for `Mailers`
    class SmtpConfig
      include EnvConfig

      # SMTP host HELO
      #
      # NOTE: HELOs are [FQDNs](https://en.wikipedia.org/wiki/Fully_qualified_domain_name), so this should be a domain name
      getter helo : String

      # SMTP hostname
      getter host : String

      # SMTP port
      getter port : Int32

      # Name to send from
      getter name : String

      # SMTP username
      getter username : String

      # SMTP password
      getter password : String
    end

    # Configuration for `Db`
    class DbConfig
      include EnvConfig

      # Database URL
      getter url : String

      # Allow old database migrations to be used
      getter allow_old_schema : Bool
    end

    # Configuration for `REDIS`
    class RedisConfig
      include EnvConfig

      # Redis host
      getter host : String

      # Redis port
      getter port : Int32

      # Redis URL
      def url : String
        "redis://#{host}:#{port}"
      end
    end

    # Configuration for `Ldap`
    class LdapConfig
      include EnvConfig

      # LDAP hostname
      getter host : String

      # LDAP port
      getter port : Int32

      # LDAP base DN
      getter base_dn : String

      # LDAP user base DN
      getter base_user_dn : String

      # LDAP bind DN
      #
      # NOTE: This is the DN to search with
      getter bind_dn : String

      # LDAP bind password
      getter bind_password : String

      # Periodical cache refresh interval
      getter cache_refresh_interval : Int32
    end

    # Configuration for authoriuation API
    class AuthConfig
      include EnvConfig

      # Auth API URL
      getter url : String
    end
  end
end