module Eco
  module API
    class Session
      class Config
        class Api < Hash

          class << self

            def to_version(str)
              case str.to_sym
              when :external, :v1
                :v1
              when :v2, :oozes
                :v2
              else # :internal, :v0
                :v0
              end
            end

            def api_class(version = :v0)
              case to_version(version)
              when :v0
                Ecoportal::API::Internal
              when :v1
                Ecoportal::API::V1
              when :v2
                Ecoportal::API::V2
              else
              end
            end

          end

          def initialize(name, key:, host:, version:, mode: :local, root:, user_key: nil, external_key: nil)
            super(nil)
            @root = root
            @apis = {}
            self["name"]         = name
            self["key"]          = key
            self["host"]         = host
            self["version"]      = version
            self["mode"]         = mode
            self["user_key"]     = user_key
            self["external_key"] = external_key
          end

          # @return [Eco::API::Session::Config] the `root` config
          def config
            @root.config
          end

          # Obtain an `API` object of a specific `version`.
          # @param version [Symbol] any of the available `API` versions [`:v0`, `:v1`, `:v2`].
          # @param logger [Logger] the logger that will be used with this api instance.
          # @return [Ecoportal::API::Internal, Ecoportal::API::V2, Ecoportal::API::V1]
          def api(version: nil, logger: nil)
            version       = version ? version : self.version
            switch_logger = (logger != @logger)
            @logger       = logger if logger

            if (current = get(version)) && !switch_logger
              return current
            end

            unless api_params?(version)
              raise "The api configuration for '#{name}' is missing data for the api version '#{self.version(version)}'"
            end

            new_api(version).tap do |pi|
              set(version, pi)
            end
          end

          def set(version, api)
            @apis[self.version(version)] = api
          end

          def get(version)
            @apis[self.version(version)]
          end

          def name
            self["name"]
          end

          def key
            self["key"]
          end

          def user_key
            self["user_key"] || @root.default_user_key
          end

          def external_key
            self["external_key"] || ([:v1, :v2].include?(version) && key)
          end

          def internal_key
            (version == :v0) && self["key"]
          end

          def host
            self["host"]
          end

          # @param mode [Symbol] to define if running on `:remote` or `:local`
          def mode=(mode)
            self["mode"] = (mode == :remote)? :remote : :local
          end

          # @return [Symbol] if running on `:remote` or `:local`
          def mode
            self["mode"]
          end

          def local?
            mode == :local
          end

          def remote?
            !local?
          end

          def version(value = nil)
            self.class.to_version(value || self["version"])
          end

          # if no low level connection messages: use `IO::NULL`
          def logger
            @logger ||= ::Logger.new(IO::NULL)
            log_connection? ? @logger : ::Logger.new(IO::NULL)
          end

          private

          # Generates a **new** `API` object of version `version`.
          def new_api(version)
            klass = self.class.api_class(version)
            case self.version(version)
            when :v0
              klass.new(internal_key, host: host, logger: logger)
            when :v1
              klass.new(external_key, host: host, logger: logger)
            when :v2
              klass.new(user_key: user_key, org_key: external_key, host: host, logger: logger)
            end.tap do |api|
              unless !api || log_connection?
                @logger.info("Created api#{self.version(version)} connection on '#{name}' enviro, pointing to '#{host}' in '#{mode}' mode")
                api.logger.level = ::Logger::UNKNOWN
              end
            end
          end

          # Checks if the necessary parameters for a specific `API` version are available.
          def api_params?(version)
            case self.class.to_version(version)
            when :v0
              internal_key && host
            when :v1
              external_key && host
            when :v2
              external_key && user_key
            end
          end

          def log_connection?
            config.logger.log_connection?
          end

        end
      end
    end
  end
end