module Construi
  module Config
    module Image
      def image
        image_configured :image
      end

      def build
        image_configured :build
      end

      def privileged?
        key?(:privileged) ? yaml['privileged'] : with_parent(false, &:privileged?)
      end

      def image_configured?
        key?(:build) || key?(:image)
      end

      def image_configured(what)
        image_configured? ? yaml[what.to_s] : with_parent(&what)
      end
    end

    module Files
      class File
        attr_reader :container, :permissions

        def initialize(host, container, permissions)
          @host = host
          @container = container
          @permissions = permissions
        end

        def host
          @host.gsub(/\$(\w+)/) { ENV[$1] }
        end

        def self.parse(str)
          split = str.split(':')
          File.new split[0], split[1], split[2]
        end
      end

      def files_configured?
        key? :files
      end

      def files
        fs = files_configured? ? yaml['files'].map { |str| File.parse(str) } : []

        with_parent([], &:files).concat fs
      end
    end

    module Environment
      include Image
      include Files

      def parent
        nil
      end

      def key?(key)
        yaml.is_a?(Hash) && yaml.key?(key.to_s)
      end

      def with_parent(or_else = nil)
        parent ? yield(parent) : or_else
      end
    end

    class Global
      include Environment

      attr_reader :yaml

      def initialize(yaml)
        @yaml = yaml
      end

      def env
        return [] if yaml['environment'].nil?

        yaml['environment'].reduce([]) do |acc, e|
          key = e.partition('=').first
          value = e.partition('=').last

          value = ENV[key] if value.empty?

          acc << "#{key}=#{value}" unless value.nil? or value.empty?
          acc
        end
      end

      def target(target)
        targets = yaml['targets']

        return nil if targets.nil?

        return Target.new yaml['targets'][target], self
      end
    end

    class Target
      include Environment

      attr_reader :yaml, :parent

      def initialize(yaml, parent)
        @yaml = yaml
        @parent = parent
      end

      def commands
        Array(@yaml.is_a?(Hash) ? @yaml['run'] : @yaml)
      end

      def options
        { env: parent.env, privileged: parent.privileged? }
      end
    end

    def self.load(content)
      Global.new YAML.load(content)
    end

    def self.load_file(path)
      Global.new YAML.load_file(path)
    end
  end
end