my_own_api_gateway_wrapper.rb

# frozen_string_literal: true

require 'sinatra/base'
require 'active_support/core_ext/string'
require 'dotenv/load'

# My rack lambda facade application ohh yeah
class App < Sinatra::Base
  def self.parse_route(route_key)
    method, route = route_key.split('-')
    route = route.gsub(/{([_0-9a-z\+]+)}/, ':\1')
    route = route.gsub(':cors+', '*')
    [method.upcase, route]
  end

  helpers do
    def request_headers
      # rubocop:disable EachWithObject
      env.inject({}) do |acc, (k, v)|
        # rubocop:disable PerlBackrefs
        acc[$1.downcase.tr('_', '-')] = v if k =~ /^http_(.*)/i
        # rubocop:enable PerlBackrefs
        acc
      end
      # rubocop:enable EachWithObject
    end

    def parse_event(route_key)
      method, route = route_key.split('-')
      method = method.upcase
      path = env['REQUEST_PATH']
      {
        'resource' => route, 'path' => path, 'httpMethod' => method,
        'headers' => request_headers, 'pathParameters' => {},
        'queryStringParameters' => params, 'requestContext' => {
          'resourcePath' => route, 'httpMethod' => method, 'path' => path
        }, 'body' => request.body.read.force_encoding('utf-8')
      }
    end
  end

  Dir['./app/requests/*.rb'].each do |file|
    name = File.basename(file, '.*')
    require file
    class_name = "Requests::#{name.camelize}"
    route_class = class_name.constantize
    route_class.routes.each do |route_key, _value|
      method, path = parse_route(route_key)
      puts "   Registring #{method} #{path}"
      send(method.downcase.to_sym, path) do
        event = parse_event(route_key)
        response = route_class.handler(event: event, context: nil)
        content_type :json
        headers \
          response[:headers].stringify_keys
        status response[:statusCode]
        body response[:body]
      end
    end
  end
end