require_relative 'error'
require_relative 'check'
require_relative 'proc_check'
require 'set'

module Remon
  class CheckDsl

    def initialize(load_paths = [])
      @load_paths = load_paths
      @checks = {}
    end

    def defcheck(name = nil, &block)
      return define_klass(&block) if not name
      name = name.to_s
      validate_name(name)
      if @checks[name]
        raise Error, "check #{name} already defined"
      end
      klass = define_klass(&block)
      klass.name = name
      @checks[name] = klass
    end

    def check(name)
      name = name.to_s
      validate_name(name)
      @checks[name] || load_check(name)
    end

    def proc_check(name = nil, &block)
      ProcCheck.new(name, block)
    end

    private

    def validate_name(name)
      regex = /\A[a-zA-Z0-9_:]+\z/
      if not name =~ regex
        raise Error, "only alphanumeric, _, : characters allowed for check name"
      end
      if name.scan(/:/).size > 1
        raise Error, "nested namespacing not allowed in check names"
      end
    end

    def define_klass(&block)
      Class.new(Check, &block)
    end

    def load_file(f)
      instance_eval File.read(f), f
    end

    def load_check(name)
      file = find_check_file(name)
      load_file file
      if a = @checks[name]
        return a
      else
        raise Error, "unable to find check: #{name} in #{file}"
      end
    end

    def find_check_file(name)
      files = check_files(name)
      combination = files.product(@load_paths).find { |f, d| Dir.glob("#{d}/#{f}").first }
      if not combination
        raise Error, "unable to find check: #{name} in PATH: #{@load_paths.join(":")}"
      end
      dir = combination[1]
      file = combination[0]
      path = "#{dir}/#{file}"
    end

    def check_files(name)
      files = []
      if name.include? ":"
        part = name.partition(":")
        namespace = part[0]
        rest = part[2]
        files << "#{namespace}/#{rest}.rb"
        files << "#{namespace}.rb"
      else
        files << "#{name}.rb"
      end
      files
    end

  end
end