require 'yaml'
require 'tmpdir'

require 'system'
require 'ostruct'
require 'fileutils'
require 'open3'

# make for: the user, system, package

# as regular user, if dependencies provided
# user: $HOME/.local
# as super user
# system: /
# package: /pkg/$name/$version/

module Make
    def self.rostruct(obj)
        case obj
        when Hash
            OpenStruct.new(obj.transform_values { |v| rostruct(v) })
        when Array
            obj.map { |v| rostruct(v) }
        else
            obj
        end
    end

    class Context
        attr_accessor :name, :use_cache, :environment, :steps, :packages, :repository
        attr_accessor :target

        def initialize(options: OpenStruct.new)
            @target = options.target || :user

            @name = options.name
            @use_cache = options.use_cache || false

            #System.detect_os
            # rbenv: brew install rbenv && rbenv install 3.0.0
            # asdf: asdf install ruby 3.0.0

            makefile_path = "#{ENV["DAT_ROOT"]}/recipes/#{@name}.yml"
            unless File.file?(makefile_path)
                makefile_path = "#{ENV["DAT_ROOT"]}/recipes/#{@name}/#{System.detect_os}.yml"
            end

            puts "recipe at: #{makefile_path}"
            makefile = YAML.load_file(makefile_path)
            
            # puts makefile_path
            # puts makefile

            @packages = makefile["packages"] || []
            @repository = Make.rostruct(makefile["repository"] || OpenStruct.new)
            @steps = makefile["steps"] || []

            @environment = ENV.to_h.merge(
                "PREFIX" => get_prefix
            )

            environment = makefile["environment"]

            if environment != nil
                @environment = environment.merge(@environment)
            end

            
        end

        def get_prefix
            case @target
            when :user
                "#{ENV["HOME"]}/.local"
            when :package
                "/pkg/#{@name}/#{@repository.branch}"
            when :system
                "/"
            end
        end

        # Root project directory
        def rpd
            puts  @repository
            if @use_cache
                path = "#{ENV["HOME"]}/.cache/dat/build/#{@name}/#{@repository.branch}"
                FileUtils.mkdir_p(path)
                yield path
            else 
                Dir.mktmpdir do |tmp_path|
                    yield tmp_path
                end
            end
        end

        def local_repo
            "#{ENV["HOME"]}/.cache/dat/repo/#{@name}.git"
        end

        def to_s
            vars = instance_variables.map do |var|
                "#{var.to_s.delete('@')}: #{instance_variable_get(var).inspect}"
            end
            "Context(#{vars.join(', ')})"
        end
    end

    class Builder
        attr_accessor :context, :cwd

        def initialize(context)
            @context = context
        end

        def execute(command)
            if command.strip.start_with?("cd ")
                eval_cmd = command.sub(/^cd /, 'echo ')
                # new_dir = `#{eval_cmd}`.strip
                new_dir, stderr, status = Open3.capture3(@context.environment, eval_cmd)
                begin
                    puts "Dir: #{Dir.pwd}"
                    # new_dir = File.expand_path(new_dir)
                    new_dir = new_dir.strip
                    puts "Exists #{new_dir} => #{Dir.exist?(new_dir)}"
                    Dir.chdir(new_dir)
                    puts "Changed directory to #{Dir.pwd}"
                rescue Errno::ENOENT
                    puts "Directory not found: #{new_dir}"
                end
            else
                system(@context.environment, command)
            end
        end

        def build
            install
            @context.rpd do | path |
                @cwd = path
                checkout
                puts "path: #{path}"
                Dir.chdir(path)

                @context.steps.each do |command|

                    # system(env, command)
                    execute(command)
                    # need to be refreshed
                    # rehash # hash -r # https://chatgpt.com/c/6880b3d6-b190-8330-9623-0458254d2881
                end
            end
        end

        def checkout
            repo_path = @context.local_repo
            repo_url = @context.repository.url
            branch = @context.repository.branch

            puts "Local bare git repo path: #{repo_path}"

            if Dir.exist?(repo_path) && !Dir.empty?(repo_path)
                puts "Bare repo exists, fetching updates..."
                Dir.chdir(repo_path) do
                    system("git fetch origin")
                end
            else
                puts "Cloning bare repository..."
                FileUtils.mkdir_p(repo_path)
                system("git clone --bare #{repo_url} #{repo_path}")
            end

            system("git --git-dir=#{repo_path} --work-tree=#{@cwd} checkout -f #{branch}")

        end

        def install
            System.install(context.packages)
        end
    end

    # dat make -t pkg --cache --name dry-run
    # dat make --name dry-run
    def self.command(options)
        context = Context.new(options: options)
        builder = Builder.new(context)
        builder.build
    end
end