require "http/server"
require "ecr/macros"
require "json"
require "yaml"
require "secure_random"
require "sqlite3"

module Guff
  VERSION = "20160715"
end

require "./guff/**"

private macro include_api_modules(modules)
  {% for mod in modules.resolve %}
    include {{ mod.id }}
  {% end %}
end

private macro api_method_dispatch(modules)
  case namespace
  {% for mod in modules.resolve %}
    {% mod_name = mod.resolve.name.gsub(/^.*:(.*)API$/, "\\1").downcase %}
    when {{ mod_name.stringify }}
    case method
    {% for mod_method in mod.resolve.methods %}
      {% method_name = mod_method.name.gsub(/^do_([^_]+)_/, "") %}
      when {{ method_name.stringify }}
        {{ mod_method.name.id }}(params)
    {% end %}
    else
      raise "unknown method: #{namespace}/#{method}"
    end
  {% end %}
  else
    raise "unknown namespace: #{namespace}"
  end
end

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

      protected def valid_origin_headers?(headers : HTTP::Headers)
        # FIXME: need to compare these against something rather than
        # just making sure that they are there
        %w{origin referer}.any? do |key|
          headers[key]? && headers[key].size > 0
        end
      end

      protected def get_site_id(host : String?) : Int64?
        @context.models.site.get_id(host)
      end
    end

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

      def call(context : HTTP::Server::Context)
        if @context.has_role?(@roles)
          authenticated_call(context)
        else
          call_next(context)
        end
      end

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

    class StubHandler < Handler
      def call(context : HTTP::Server::Context)
        STDERR.puts "%s %s" % [
          context.request.method,
          context.request.path.not_nil!
        ]

        call_next(context)
      end
    end

    class SessionHandler < Handler
      def call(context : HTTP::Server::Context)
        # clear session
        @context.session.clear

        if cookie = context.request.cookies[Guff::Session::COOKIE]?
          # load session
          @context.session.load(cookie.value)
        end

        call_next(context)

        if @context.session.valid?
          @context.session.save
        end
      end
    end

    class APIHandler < Handler
      PATH_RE = %r{^/guff/api/(?<namespace>[\w_-]+)/(?<method>[\w_-]+)$}

      API_MODULES = [
        APIs::PostAPI,
        APIs::UserAPI,
        APIs::PageAPI,
        APIs::ProjectAPI,
        APIs::BlogAPI,
        APIs::SiteAPI,
      ]

      include_api_modules(API_MODULES)

      def call(context : HTTP::Server::Context)
        if context.request.method == "POST" ||
           (@context.development? && context.request.method == "GET")
          if md = PATH_RE.match(context.request.path.not_nil!)
            namespace, method = %w{namespace method}.map { |k| md[k] }

            # get query parameteres
            params = if (context.request.method == "GET")
              context.request.query_params
            else
              HTTP::Params.parse(context.request.body || "")
            end

            code, data = begin
              { 200, api_method_dispatch(API_MODULES) }
            rescue err
              STDERR.puts "ERROR: #{err}"
              { 400, { "error": err.to_s } }
            end

            # send json response
            context.response.status_code = code
            context.response.content_type = "application/json; charset=utf-8"
            data.to_json(context.response)
          else
            call_next(context)
          end
        else
          call_next(context)
        end
      end
    end

    class AssetsHandler < Handler
      def initialize(context : Context)
        super(context)
        @etags = {} of String => String
      end

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

        if matching_request?(context.request.method, req_path) &&
           valid_origin_headers?(context.request.headers)
          # get expanded path to file
          if abs_path = expand_path(req_path)
            # get file digest
            etag = get_file_etag(abs_path)

            # check for cache header
            if context.request.headers["if-none-match"]? == etag
              # cached, send 304 not modified
              context.response.status_code = 304
            else
              # not cached, set code and send headers
              context.response.headers["x-frame-options"] = "SAMEORIGIN"
              context.response.status_code = 200
              context.response.content_type = AssetMimeType.from_path(abs_path)
              context.response.content_length = File.size(abs_path)
              context.response.headers["etag"] = etag

              if context.request.method == "GET"
                # send body for GET requests
                File.open(abs_path) do |fh|
                  STDERR.puts "sending #{abs_path}"
                  IO.copy(fh, context.response)
                  STDERR.puts "done sending #{abs_path}"
                end
              end
            end
          else
            # expanded path does not exist
            call_next(context)
          end
        else
          # not a matching request
          call_next(context)
        end
      end

      VALID_METHODS = %w{GET HEAD}
      PATH_RE = %r{^/guff/assets/}

      private def matching_request?(method, path)
        VALID_METHODS.includes?(method) && PATH_RE.match(path)
      end

      private def expand_path(req_path : String) : String?
        # unescape path, check for nil byte
        path = URI.unescape(req_path)
        return nil if path.includes?('\0')

        # build absolute path
        r = File.join(
          @context.config.system_dir,
          "assets",
          File.expand_path(path.gsub(PATH_RE, ""), "/")
        )

        # return path if file exists, or nil otherwise
        File.file?(r) ? r : nil
      end

      private def get_file_etag(path : String) : String
        # FIXME: rather than a hash this should be an HMAC
        @etags[path] ||= OpenSSL::Digest.new("SHA1").file(path).hexdigest
      end
    end

    class AdminPageHandler < AuthenticatedHandler
      def initialize(context : Context)
        super(context, %w{admin editor})
      end

      PATH_RE = %r{^/guff/admin\.html$}

      def authenticated_call(context : HTTP::Server::Context)
        if context.request.path.not_nil!.match(PATH_RE)
          context.response.headers["x-frame-options"] = "SAMEORIGIN"
          context.response.content_type = "text/html; charset=utf-8"
          context.response.status_code = 200
          Views::AdminPageView.new(@context).to_s(context.response)
        else
          call_next(context)
        end
      end
    end

    class LoginPageHandler < Handler
      PATH_RE = %r{^/guff/login\.html$}
      VALID_METHODS = %w{GET POST}

      def call(context : HTTP::Server::Context)
        if VALID_METHODS.includes?(context.request.method) &&
           PATH_RE.match(context.request.path.not_nil!)
          case context.request.method
          when "GET"
            reply(context.response)
          when "POST"
            begin
              # check for valid origin or referer header
              unless valid_origin_headers?(context.request.headers)
                raise "missing origin and referer headers"
              end

              # create session
              session_id = @context.session.create({
                "user_id" => login(context.request.body).to_s,
              })

              # add cookie
              context.response.cookies << HTTP::Cookie.new(
                name:       Guff::Session::COOKIE,
                value:      session_id as String,
                http_only:  true,

                # TODO
                # expires:
                # secure:
              )

              # redirect to admin panel
              context.response.headers["location"] = "/guff/admin.html"
              context.response.status_code = 302
            rescue err
              # log error
              STDERR.puts "login failed: #{err}"
              reply(context.response, "invalid login")
            end
          else
            raise "invalid HTTP method"
          end
        else
          call_next(context)
        end
      end

      private def reply(
        response : HTTP::Server::Response,
        error : String? = nil
      )
        response.headers["x-frame-options"] = "SAMEORIGIN"
        response.content_type = "text/html; charset=utf-8"
        response.status_code = 200
        Views::LoginPageView.new(@context, error).to_s(response)
      end

      private def login(body : String?)
        # check body
        raise "empty request body" if body.nil? || body.size == 0

        # parse request parameters
        params = HTTP::Params.parse(body.not_nil!)

        # check login parameters
        raise "missing login parameters" unless %w{
          username
          password
          csrf_token
        }.all? do |key|
          params.has_key?(key) && params[key].size > 0
        end

        # check csrf token
        unless @context.models.csrf.use_token(params["csrf_token"])
          raise "invalid csrf token"
        end

        # try login
        user_id =  @context.models.user.login(
          params["username"],
          params["password"]
        )

        # check user id
        raise "invalid credentials" unless user_id

        # return user id
        user_id.not_nil!
      end
    end

    class LogoutPageHandler < Handler
      PATH_RE = %r{^/guff/logout\.html$}

      def call(context : HTTP::Server::Context)
        if context.request.method == "GET" &&
           PATH_RE.match(context.request.path.not_nil!) &&
           valid_origin_headers?(context.request.headers)
          # delete session
          @context.session.delete

          # clear cookie
          context.response.cookies << HTTP::Cookie.new(
            name:       Guff::Session::COOKIE,
            value:      "",
            expires:    Time.epoch(0),
            http_only:  true,
          )

          # build remaining headers
          context.response.headers["x-frame-options"] = "SAMEORIGIN"
          context.response.content_type = "text/html; charset=utf-8"
          context.response.status_code = 200

          # draw page
          Views::LogoutPageView.new(@context).to_s(context.response)
        else
          call_next(context)
        end
      end
    end

    class PageHandler < Handler
      PATH_RE = %r{^/(?<slug>[^/]+)\.html$}

      def call(context : HTTP::Server::Context)
        if post_id = get_post_id(context.request)
          # TODO: render page
          context.response.headers["x-frame-options"] = "SAMEORIGIN"
          context.response.content_type = "text/html; charset=utf-8"
          context.response.status_code = 200
          context.response << "page: #{post_id}"
        else
          # unknown page
          call_next(context)
        end
      end

      private def get_post_id(request : HTTP::Request) : Int64?
        r = nil

        if request.method == "GET"
          if md = PATH_RE.match(request.path.not_nil!)
            if site_id = get_site_id(request.headers["host"]?)
              r = @context.models.page.get_id(
                site_id: site_id,
                slug: md["slug"],
              )
            end
          end
        end

        # return result
        r
      end
    end

    class ProjectHandler < Handler
      PATH_RE = %r{^/(?<slug>[^/]+)/?$}

      def call(context : HTTP::Server::Context)
        if post_id = get_post_id(context.request)
          path = context.request.path.not_nil!

          if /\/$/.match(path)
            # TODO: render page
            context.response.headers["x-frame-options"] = "SAMEORIGIN"
            context.response.content_type = "text/html; charset=utf-8"
            context.response.status_code = 200
            context.response << "project: #{post_id}"
          else
            # redirect to project
            context.response.headers["location"] = path + "/"
            context.response.status_code = 302
          end
        else
          # unknown page
          call_next(context)
        end
      end

      private def get_post_id(request : HTTP::Request) : Int64?
        r = nil

        if request.method == "GET"
          if md = PATH_RE.match(request.path.not_nil!)
            if site_id = get_site_id(request.headers["host"]?)
              r = @context.models.project.get_id(
                site_id: site_id,
                slug: md["slug"],
              )
            end
          end
        end

        # return result
        r
      end
    end

    class BlogPostHandler < Handler
      PATH_RE = %r{^
        (/blog)?
        /(?<year>\d{4})
        /(?<month>\d{2})
        /(?<day>\d{2})
        /(?<slug>[^/]+)\.html
      $}x

      def call(context : HTTP::Server::Context)
        if id = get_id(context.request)
          # TODO: render page
          context.response.headers["x-frame-options"] = "SAMEORIGIN"
          context.response.content_type = "text/html; charset=utf-8"
          context.response.status_code = 200
          context.response << "blog post id: #{id}"
        else
          # unknown page
          call_next(context)
        end
      end

      private def get_id(request : HTTP::Request) : Int64?
        r = nil

        if request.method == "GET"
          if md = PATH_RE.match(request.path.not_nil!)
            if site_id = get_site_id(request.headers["host"]?)
              r = @context.models.blog.get_id(
                site_id:  site_id,
                year:     md["year"].to_i,
                month:    md["month"].to_i,
                day:      md["day"].to_i,
                slug:     md["slug"],
              )
            end
          end
        end

        # return result
        r
      end
    end

    class BlogListHandler < Handler
      # TODO: make index page configurable
      PATH_RE = %r{^/
        (blog/?)?
        (
          (?<year>\d{4})/
          (
            (?<month>\d{2})/
            ((?<day>\d{2})/)?
          )?
        )?
      $}x

      def call(context : HTTP::Server::Context)
        if ids = get_ids(context.request)
          # TODO: render page
          context.response.headers["x-frame-options"] = "SAMEORIGIN"
          context.response.content_type = "text/html; charset=utf-8"
          context.response.status_code = 200

          Views::Blog::ListView.new(@context, ids).to_s(context.response)
        else
          # unknown page
          call_next(context)
        end
      end

      private def get_ids(request : HTTP::Request) : Array(Int64)?
        r = nil

        if request.method == "GET"
          if md = PATH_RE.match(request.path.not_nil!)
            if site_id = get_site_id(request.headers["host"]?)
              # get request parameters
              params = request.query_params

              r = @context.models.blog.get_ids(
                site_id:  site_id,
                year:     md["year"]? ? md["year"].to_i : nil,
                month:    md["month"]? ? md["month"].to_i : nil,
                day:      md["day"]? ? md["day"].to_i : nil,
                page:     params["page"]? ? params["page"].to_i : nil,
              )
            end
          end
        end

        # return result
        r
      end
    end

    HANDLERS = [{
      :dev  => true,
      :id   => :stub,
    }, {
      :dev  => true,
      :id   => :error,
    }, {
      :dev  => false,
      :id   => :log,
    }, {
      :dev  => false,
      :id   => :deflate,
    }, {
      :dev  => false,
      :id   => :assets,
    }, {
      :dev  => false,
      :id   => :page,
    }, {
      :dev  => false,
      :id   => :project,
    }, {
      :dev  => false,
      :id   => :blog_post,
    }, {
      :dev  => false,
      :id   => :blog_list,
    }, {
      :dev  => false,
      :id   => :login,
    }, {
      :dev  => false,
      :id   => :session,
    }, {
      :dev  => false,
      :id   => :api,
    }, {
      :dev  => false,
      :id   => :admin,
    }, {
      :dev  => false,
      :id   => :logout,
    }]

    def self.get(context : Context) : Array(HTTP::Handler)
      HANDLERS.select { |row|
        !(row[:dev] as Bool) || context.development?
      }.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 :stub
        StubHandler.new(context)
      when :error
        HTTP::ErrorHandler.new
      when :log
        HTTP::LogHandler.new
      when :deflate
        HTTP::DeflateHandler.new
      when :session
        SessionHandler.new(context)
      when :api
        APIHandler.new(context)
      when :assets
        AssetsHandler.new(context)
      when :admin
        AdminPageHandler.new(context)
      when :login
        LoginPageHandler.new(context)
      when :logout
        LogoutPageHandler.new(context)
      when :page
        PageHandler.new(context)
      when :blog_post
        BlogPostHandler.new(context)
      when :blog_list
        BlogListHandler.new(context)
      when :project
        ProjectHandler.new(context)
      else
        raise "unknown handler id: #{handler_id}"
      end
    end
  end

  module CLI
    module Actions
      abstract class Action
        def self.run(config : Config)
          new(config).run
        end

        def initialize(@config : Config)
        end

        abstract def run
      end

      class InitAction < Action
        class Data
          YAML.mapping({
            init_sql:   Array(String),
            add_user:   String,
            test_posts: Array(String),
          })

          def self.load(system_dir : String) : Data
            self.from_yaml(File.read(File.join(system_dir, "init.yaml")))
          end
        end

        def initialize(config : Config)
          super(config)

          # read init data
          @data = Data.load(@config.system_dir)
        end

        def run
          STDERR.puts "Initializing data directory"
          Dir.mkdir(@config.data_dir) unless Dir.exists?(@config.data_dir)

          Guff::Database.new(@config.db_path) do |db|
            @data.init_sql.each do |sql|
              db.query(sql)
            end

            # gen random password and add admin user
            # TODO: move these to init.yaml
            password = Password.random_password
            add_user(db, "Admin", "admin@admin", password)
            add_user(db, "Test", "test@test", "test")
            add_test_posts(db)

            STDERR.puts "admin user: admin@admin, password: #{password}"
          end
        end

        private def add_user(
          db        : Database,
          name      : String,
          email     : String,
          password  : String
        ) : Int64
          db.query(@data.add_user, [
            name,
            email,
            Password.create(password),
            "admin",
          ])
          db.last_insert_row_id.to_i64
        end

        private def add_test_posts(db)
          # STDERR.puts "DEBUG: adding test data"
          @data.test_posts.each do |sql|
            db.query(sql)
          end
        end
      end

      class RunAction < Action
        def run
          STDERR.puts "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
          {
            system: @config.system_dir,
            data:   @config.data_dir,
          }.each do |name, dir|
            unless Dir.exists?(dir)
              raise "missing #{name} directory: \"#{dir}\""
            end
          end
        end
      end
    end

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

        case config.mode
        when "init"
          Actions::InitAction.run(config)
        when "run"
          Actions::RunAction.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)