module Omnitest
  class Psychic
    class MagicTaskFactory
      include Omnitest::Core::Logger
      extend Forwardable
      def_delegators :psychic, :cwd, :env, :logger

      TASK_PRIORITY = 5

      attr_reader :known_tasks, :tasks, :hints, :priority, :psychic

      class << self
        def register_task_factory
          Omnitest::Psychic::TaskFactoryManager.register_factory(self)
        end

        def magic_file_patterns
          @magic_file_patterns ||= []
        end

        def magic_file(pattern) # rubocop:disable Style/TrivialAccessors
          magic_file_patterns << pattern
        end

        def magic_env_vars
          @magic_env_vars ||= []
        end

        def magic_env_var(var)
          magic_env_vars << var
        end

        def known_tasks
          @known_tasks ||= []
        end

        def tasks
          @tasks ||= {}
        end

        def task(name, &block)
          name = name.to_s
          tasks[name] = block
          known_tasks << name
        end
      end

      def initialize(psychic, opts = {})
        @psychic = psychic
        @opts = opts
        @priority = self.class::TASK_PRIORITY
        init_attr(:known_tasks) { self.class.known_tasks }
        init_attr(:tasks) { self.class.tasks }
      end

      def task(task_alias, *_args)
        task_alias = task_alias.to_s
        task = tasks[task_alias] if tasks.include? task_alias
        task = instance_eval(&task) if task.respond_to? :call
        fail Omnitest::Psychic::TaskNotImplementedError, task_alias if task.nil?
        task
      end

      def active?
        self.class.magic_file_patterns.each do | pattern |
          return true unless Dir.glob("#{cwd}/#{pattern}", File::FNM_CASEFOLD).empty?
        end
        self.class.magic_env_vars.each do | var |
          return true if ENV[var]
        end
        false
      end

      def known_task?(task_alias)
        known_tasks.include?(task_alias.to_s)
      end

      def priority_for_task(task_alias)
        priority if known_task? task_alias
      end

      private

      def init_attr(var)
        var_name = "@#{var}"
        var_value = @opts[var]
        var_value = yield if var_value.nil? && block_given?
        instance_variable_set(var_name, var_value)
      end

      def init_attrs(*vars)
        vars.each do | var |
          init_attr var
        end
      end
    end
  end
end