require 'yaml'

class ::Hash
    def deep_merge(second)
        merger = proc { |_, v1, v2| Hash === v1 && Hash === v2 ? v1.merge(v2, &merger) : Array === v1 && Array === v2 ? v1 | v2 : [:undefined, nil, :nil].include?(v2) ? v1 : v2 }
        merge(second.to_h, &merger)
    end
end

module Comfpile
    class ConfigArtefact < Artefact
        attr_reader :loaded_config
        attr_reader :config

        attr_reader :mtime

        def initialize(*args, **opts)
            super(*args, **opts)

            @loaded_config = {}
            
            unless @target == '.' or @target == ''
                parent_artefact :config_file, File.dirname(@target) 
            end

            @config_file_artefact = craft_artefact(:sourcefile, File.join(@target, "comf.yml"))
            wait_on @config_file_artefact 

            add_step do
                unless @config_file_artefact.nil?
                    @loaded_config = YAML.load_file(@config_file_artefact.file)
    
                    log "Config file found and loaded for directory #{@target}!"
                end
                
                fail! "Config YAML file is not a hash!" unless @loaded_config.is_a? Hash

                if @parent_artefact.nil?
                    @config = @loaded_config
                    @mtime = @config_file_artefact.mtime
                else
                    defaults = @loaded_config['defaults'] || {}

                    @config = defaults.deep_merge(@parent_artefact.config.deep_merge(@loaded_config))
                    @mtime = [@config_file_artefact.mtime, @parent_artefact.mtime].max
                end
            end
        end

        def [](key)
            @config[key]
        end

        undef []=
    end

    class ConfigLoaderEngine < ArtefactEngine
        def initialize(core, **options)
            super(core, **options)

        end

        def craft(stage, target, context)
            return unless stage == :config_file

            ConfigArtefact.new(@core, self, stage, target, context)
        end
    end
end