require "option_parser"
require "http/server"
require "./guff/*"

module Guff
  class Config
    property :mode, :env, :host, :port, :data_dir, :assets_dir

    DEFAULTS = {
      mode:       "help",
      env:        "production",
      host:       "127.0.0.1",
      port:       "8989",
      data_dir:   "./data",
      assets_dir: "/usr/local/share/guff",
    }

    def initialize
      @mode        = DEFAULTS[:mode] as String
      @env         = (ENV["GUFF_ENVIRONMENT"]? || DEFAULTS[:env]) as String
      @host        = (ENV["GUFF_HOST"]? || DEFAULTS[:host]) as String
      @port        = (ENV["GUFF_PORT"]? || DEFAULTS[:port]) as String
      @data_dir    = (ENV["GUFF_DATA_DIR"]? || DEFAULTS[:data_dir]) as String
      @assets_dir  = (ENV["GUFF_ASSETS_DIR"]? || DEFAULTS[:assets_dir]) as String
    end

    VALID_MODES = %w{init run help}

    def mode=(mode : String)
      raise "unknown mode: \"#{mode}\"" unless VALID_MODES.includes?(mode)
      @mode = mode
    end

    VALID_ENVS = %w{development production}

    def env=(env : String)
      raise "unknown environment: \"#{env}\"" unless VALID_ENVS.includes?(env)
      @env = env
    end

    def port=(port : String)
      val = port.to_i
      raise "invalid port: #{port}" unless val > 0 && val < 65535
      @port = port
    end

    def assets_dir=(dir : String)
      raise "missing assets dir: \"#{dir}\"" unless Dir.exists?(dir)
      @assets_dir = dir
    end

    def self.parse(
      app   : String,
      args  : Array(String)
    ) : Config
      r = Config.new

      raise "missing mode" unless args.size > 0

      # get mode
      r.mode = case mode = args.shift
      when "-h", "--help"
        "help"
      else
        mode
      end

      # parse arguments
      p = OptionParser.parse(args) do |p|
        p.banner = "Usage: #{app} [mode] <args>"

        p.separator
        p.separator("Run Options:")

        p.on(
          "-H HOST", "--host HOST",
          "TCP host (defaults to \"#{DEFAULTS[:host]}\")"
        ) do |arg|
          r.host = arg
        end

        p.on(
          "-p PORT", "--port PORT",
          "TCP port (defaults to \"#{DEFAULTS[:port]}\")"
        ) do |arg|
          r.port = arg
        end

        p.separator
        p.separator("Directory Options:")

        p.on(
          "-D DIR", "--data-dir DIR",
          "Data directory (defaults to \"#{DEFAULTS[:data_dir]}\")"
        ) do |arg|
          r.data_dir = arg
        end

        p.on(
          "-A DIR", "--assets-dir DIR",
          "Guff assets directory (defaults to \"#{DEFAULTS[:assets_dir]}\")"
        ) do |arg|
          r.assets_dir = arg
        end

        p.separator
        p.separator("Development Options:")

        p.on(
          "-E ENV", "--environment ENV",
          "Environment (defaults to \"#{DEFAULTS[:env]})\""
        ) do |arg|
          r.env = arg
        end

        p.separator
        p.separator("Other Options:")

        p.on("-h", "--help", "Print usage.") do
          r.mode = "help"
        end
      end

      case r.mode
      when "init"
        # shortcut for -D parameter
        r.data_dir = args.shift if args.size > 0
      when "help"
        # print help
        puts p
      end

      # return config
      r
    end
  end

  abstract class ModeRunner
    def self.run(config : Config)
      new(config).run
    end

    def initialize(@config : Config)
    end

    abstract def run
  end

  class Builder < ModeRunner
    def run
      STDERR.puts "TODO: building directory"
    end
  end

  class Context
    property :config #, :models

    def initialize(@config : Config)
      # @models = nil
    end
  end

  module Handlers
    abstract class Handler < HTTP::Handler
      def initialize(@context : Context)
        super()
      end
    end

    abstract class AuthenticatedHandler < Handler
      def initialize(context : Context, roles : Array(String))
        super(context)
        @roles = roles
      end

      def call(context : HTTP::Server::Context)
        role = context.request.headers["x-guff-role"]?

        if role && @roles.includes?(role)
          authenticated_call(context)
        else
          call_next(context)
        end
      end

      abstract def authenticated_call(context : HTTP::Server::Context)
    end

    class SessionHandler < Guff::Handlers::Handler
      def call(context : HTTP::Server::Context)
        if @context.config.env == "development"
          # TODO: add handler support
          context.request.headers["x-guff-user-id"] = "0"
          context.request.headers["x-guff-role"] = "admin"
        end

        call_next(context)
      end
    end

    class AssetsHandler < AuthenticatedHandler
      PATH_RE = %r{^/_guff/assets/}

      def authenticated_call(context : HTTP::Server::Context)
        path = context.request.path.not_nil!

        if path.match(PATH_RE)
          # TODO
        else
          call_next(context)
        end
      end
    end

    HANDLERS = [{
      dev:  true,
      id:   :error,
    }, {
      dev:  false,
      id:   :log,
    }, {
      dev:  false,
      id:   :deflate,
    }, {
      dev:  false,
      id:   :session,
    }, {
      dev:  false,
      id:   :assets,
    }]

    def self.get(context : Context) : Array(HTTP::Handler)
      is_dev = (context.config.env == "development")
      
      HANDLERS.select { |row|
        !(row[:dev] as Bool) || is_dev
      }.map { |row|
        make_handler(row[:id] as Symbol, context)
      }
    end

    def self.make_handler(
      handler_id : Symbol,
      context : Context
    ) : HTTP::Handler
      case handler_id
      when :error
        HTTP::ErrorHandler.new
      when :log
        HTTP::LogHandler.new
      when :deflate
        HTTP::DeflateHandler.new
      when :session
        SessionHandler.new(context)
      when :assets
        AssetsHandler.new(context, %w{admin editor})
      else
        raise "unknown handler id: #{handler_id}"
      end
    end
  end

  class Server < ModeRunner
    def run
      STDERR.puts "TODO: running web server"
      check_dirs

      # create context
      context = Context.new(@config)

      STDERR.puts "listening on %s:%s" % [@config.host, @config.port]

      # run server
      HTTP::Server.new(
        @config.host,
        @config.port.to_i,
        Handlers.get(context)
      ).listen
    end

    private def check_dirs
      raise "missing assets directory: \"#{@config.assets_dir}\"" unless Dir.exists?(@config.assets_dir)
      raise "missing data directory: \"#{@config.data_dir}\"" unless Dir.exists?(@config.data_dir)
    end
  end

  module CLI
    def self.print_usage(app : String)
      STDERR.puts "Usage: #{app} [mode] <args>"
    end

    def self.run(app : String, args : Array(String))
      begin
        begin
          config = Config.parse(app, args)
        rescue err
          raise "#{err}.  Use --help for usage"
        end

        case config.mode
        when "init"
          Builder.run(config)
        when "run"
          Server.run(config)
        when "help"
          # do nothing
        else
          # never reached
          raise "unknown mode: #{config.mode}"
        end
      rescue err
        STDERR.puts "ERROR: #{err}."
        exit -1
      end
    end
  end
end

Guff::CLI.run($0, ARGV)