require_relative '../artefact.rb'
require_relative '../artefact_engine.rb'

module Comfpile
    class ParserArtefact < Comfpile::Artefact
        attr_reader :parsed_parameters
        attr_reader :parsed_dependencies

        def initialize(*args, search_regexes: nil, **opts)
            super(*args, **opts)

            @search_regexes = search_regexes

            @parsed_parameters = {}
            @parsed_dependencies = {}

            parent_artefact :sourcefile, @target
            require_artefact :config_file, File.dirname(@target)

            add_step do
                sourcefile_parse_step
                sourcefile_dependency_step
            end

        end

        # Attempts to find the set of values for a given 
        # parameter key.
        #
        # @param [String, Array<String>] keys Key, or array of keys, to look for
        #
        # @return [Array<String>] Array of values found for this key
        #
        def find_parsed_parameters(keys)
            if keys.is_a? Array
                output = []
                keys.each do |key|
                    output += @parsed_parameters[key] || []
                end

                output
            else
                @parsed_parameters[keys] || []
            end
        end

        def find_parsed_parameter(key)
            find_parsed_parameters(key).last
        end

        # Try to find a relative or absolute source file 
        # artefact.
        # Used to resolve the include, require and reference
        # statements and find relative and/or absolute source 
        # files with matching name. Similar to how C++'s 
        # include statement it will check relative, then 
        # globally.
        #
        # @param [String, Array<String>] name Path of the sourcefile to look for
        # @param [Boolean] optional If true, will also check for absolute
        #  source file, and will discard the file if it can't be found.
        #  Useful for e.g. C/C++ header files that may not be in the search
        #  path of comfpile.
        #  
        # @return [String] Resolved path of the sourcefile. Relative
        #  if a relative file is found, else absolute.
        #
        def resolve_sourcefile(name, optional: false)
            if(name.is_a? Array)
                name.map do |n|
                    resolve_sourcefile(n, optional: optional)
                end.compact
            else
                own_dir = File.dirname(@target)
                relative_file = File.join(own_dir, name).gsub(/^\.\//, '')

                if not craft_artefact(:sourcefile, relative_file).nil?
                    relative_file
                elsif not craft_artefact(:sourcefile, name).nil?
                    name
                elsif not optional
                    relative_file
                else
                    nil
                end
            end
        end

        def sourcefile_parse_step
            log "Parsing file #{@target}..."

            param_count = 0

            File.readlines(@parent_artefact.file).each do |line|
                @search_regexes.each do |r|
                    next if r[:regex].nil?

                    match = r[:regex].match line
                    next if match.nil?
                    match = match.named_captures

                    key = match['key'] || r[:key]
                    value = match['value'] || r[:value]

                    next if key.nil?

                    log "Found k/v pair: '#{key}' '#{value}'", :debug
                    param_count += 1

                    @parsed_parameters[key] ||= []
                    @parsed_parameters[key] << value
                end
            end

            log "Parsing completed, found #{param_count} parameters!"
        end

        def sourcefile_dependency_step            
            ['include', 'require', 'reference'].map do |key|
                key_artefacts = resolve_sourcefile(find_parsed_parameters(key), optional: key == 'include')

                @parsed_dependencies[key] = key_artefacts.map { |key| craft_artefact(:parsed, key) }
            end

            log "Generated dependencies. #{@parsed_dependencies.map { |k, v| "#{k}: #{v.size}" }.join(', ')}."
        end
    end

    class DependencyAnalysisArtefact < Artefact
        attr_reader :dependencies
        attr_reader :mtime

        def initialize(*args, traverse: nil, **opts)
            super(*args, **opts)

            parent_artefact :parsed, @target

            @dependencies = []

            @dependency_processed_artefacts = {}
            @dependency_waiting_on = [ @parent_artefact ]
            
            @traverse = traverse || ['include', 'require', 'reference']

            add_step do
                iterative_dependency_wait_step
            end

            add_step do
                @mtime = @dependencies.map(&:mtime).max
            end
        end

        def iterative_dependency_wait_step
            dependency_unfurl = @dependency_waiting_on
            @dependency_waiting_on = []

            loop do
                break if dependency_unfurl.empty?

                artefact = dependency_unfurl.pop
                
                next if @dependency_processed_artefacts[artefact.target]
                
                @dependencies << artefact
                @dependency_processed_artefacts[artefact.target] = true

                artefact.parsed_dependencies.each do |key, dep_list|
                    next unless @traverse.nil? or @traverse.include? key

                    dep_list.each do |dep_artefact|
                        if wait_on dep_artefact
                            @dependency_waiting_on << dep_artefact
                        else
                            dependency_unfurl << dep_artefact
                        end
                    end
                end
            end

            retry_step! unless @dependency_waiting_on.empty?
        end
    end

    class ParserEngine < ArtefactEngine
        #
        # Initialize a new ParserEngine
        #
        # This engine has the task of generating single-file parser artefacts,
        # which check for comfpile parameters that will be extracted from the sourcefile.
        # Each file will recursively craft other files it requires and add them, either as
        # fully included, required, or referenced file.
        #
        # @param [<Type>] core <description>
        # @param [<Type>] **options <description>
        #
        def initialize(core, **options)
            super(core, **options)

            @input_file_regex = options[:file_regex]
            @search_regexes = options[:search_regexes]

            raise ArgumentError, "Missing input file regex!" unless @input_file_regex.is_a? Regexp
            raise ArgumentError, "Missing regex parsing array!" unless @search_regexes.is_a? Array
        end

        def generate_parser_artefact(stage, target)
            match = @input_file_regex.match target
            return nil if match.nil?

            ParserArtefact.new(@core, self, stage, target,
                search_regexes: @search_regexes)
        end

        def generate_dependency_analysis_artefact(stage, target, **opts)
            match = @input_file_regex.match target
            return nil if match.nil?

            DependencyAnalysisArtefact.new(@core, self, stage, target, **opts)
        end

        def craft(stage, target)
            case stage
            when :parsed
                generate_parser_artefact(stage, target)
            when /^dependency_analysis(?:_(.+))?$/
                traverse = $1&.split('_')
                generate_dependency_analysis_artefact(stage, target, traverse: traverse)
            else 
                nil
            end
        end
    end
end