require 'set'
require_relative 'error'
require_relative 'ext/num_ext'
require_relative 'check_dsl'
require 'forwardable'

module Remon
  class Config
    using NumExt

    LOAD_PATHS = ["#{__dir__}/checks"]

    extend Forwardable

    def initialize(config_file: nil, config_dir: nil, load_paths: [])
      @config_file = config_file
      @config_dir = config_dir
      @schedule = {}
      @scheduler_offset = 0
      @workers = 1
      @task_group = { interval: 0, offset: 15, randomize: false }
      load_paths = Set.new(load_paths).merge(LOAD_PATHS)
      @dsl = CheckDsl.new load_paths.to_a
    end

    def config
      @config_read ||= begin
        read_config
        true
      end
      {
        schedule: @schedule,
        scheduler_offset: @scheduler_offset,
        process_proc: @process_proc,
        workers: @workers
      }
    end

    private

    def_delegators :@dsl, :check, :defcheck, :proc_check

    def host(host)
      Remon.host = host
    end

    def every(secs, randomize: false, offset: 0, &block)
      raise Error, "offset must be less than interval" if offset > secs
      before = @task_group
      @task_group = { interval: secs, offset: offset, randomize: randomize }
      yield
    ensure
      @task_group = before
    end

    def scheduler_offset(offset)
      @scheduler_offset = offset
    end

    def process_event(&block)
      @process_proc = block
    end

    def workers(workers)
      @workers = workers
    end

    def schedule_check(check, args = [], kwargs = {})
      @schedule[@task_group] ||= Set.new
      if not check.is_a? Check
        kwargs[:ttl] ||= default_ttl(@task_group[:interval])
        klass = self.check(check)
        check = klass.new(*args, **kwargs)
      end
      @schedule[@task_group] << check
    end

    def default_ttl(interval)
      3 * interval
    end

    def read_config
      read_config_file @config_file if @config_file
      if @config_dir
        Dir.glob("#{@config_dir}/*.rb").each { |f| read_config_file f }
      end
    end

    def read_config_file(file)
      if not File.readable? file
        raise Error, "config #{file} not readable"
      end
      instance_eval(File.read(file))
    rescue NoMethodError => e
      raise Error, "invalid option used in config: #{e.name}"
    end

    alias_method :run_check, :schedule_check

  end
end