require 'grape/middleware/base'
require 'multi_json'

module Grape
  module Middleware
    class Error < Base

      def default_options
      {
        :default_status => 403, # default status returned on error
        :default_message => "",
        :format => :txt,
        :formatters => {},
        :error_formatters => {},
        :rescue_all => false, # true to rescue all exceptions
        :rescue_options => { :backtrace => false }, # true to display backtrace
        :rescue_handlers => {}, # rescue handler blocks
        :rescued_errors => []
      }
      end

      def call!(env)
        @env = env

        begin
          error_response(catch(:error){
            return @app.call(@env)
          })
        rescue Exception => e
          is_rescuable = rescuable?(e.class)
          if e.is_a?(Grape::Exceptions::Base) && !is_rescuable
            handler = lambda {|e| error_response(e) }
          else
            raise unless is_rescuable
            handler = options[:rescue_handlers][e.class] || options[:rescue_handlers][:all]
          end
          handler.nil? ? handle_error(e) : self.instance_exec(e, &handler)
        end
      end

      def rescuable?(klass)
        options[:rescue_all] || (options[:rescued_errors] || []).include?(klass)
      end

      def handle_error(e)
        error_response({ :message => e.message, :backtrace => e.backtrace })
      end

      def error_response(error = {})
        status = error[:status] || options[:default_status]
        message = error[:message] || options[:default_message]
        headers = {'Content-Type' => content_type}
        headers.merge!(error[:headers]) if error[:headers].is_a?(Hash)
        backtrace = error[:backtrace] || []
        rack_response(format_message(message, backtrace), status, headers)
      end

      def rack_response(message, status = options[:default_status], headers = { 'Content-Type' => content_type })
        Rack::Response.new([ message ], status, headers).finish
      end

      def format_message(message, backtrace)
        format = env['api.format'] || options[:format]
        formatter = Grape::ErrorFormatter::Base.formatter_for(format, options)
        throw :error, :status => 406, :message => "The requested format #{format} is not supported." unless formatter
        formatter.call(message, backtrace, options, env)
      end

    end
  end
end