#!/usr/bin/env ruby

require 'sinatra'
require 'sinatra/multi_route'
require 'yaml'
require 'oj'
require 'faastruby-rpc'

module FaaStRuby
  class DoubleRenderError < StandardError; end
end

module FaaStRuby
  class Runner
    def initialize
      @rendered = false
    end

    def call(workspace_name, function_name, event, args)
      begin
        load "./#{workspace_name}/#{function_name}/handler.rb"
        response = handler(event, *args)
        return response if response.is_a?(FaaStRuby::Response)
        body = {
          'error' => "Please use the helpers 'render' or 'respond_with' as your function return value."
        }
        FaaStRuby::Response.new(body: Oj.dump(body), status: 500, headers: {'Content-Type' => 'application/json'})
      rescue Exception => e
        body = {
          'error' => e.message,
          'location' => e.backtrace&.first,
        }
        FaaStRuby::Response.new(body: Oj.dump(body), status: 500, headers: {'Content-Type' => 'application/json'})
      end
    end

    def rendered!
      @rendered = true
    end
    def rendered?
      @rendered
    end

    def respond_with(body, status: 200, headers: {})
      raise FaaStRuby::DoubleRenderError.new("You called 'render' or 'respond_with' twice in your handler method") if rendered?
      response = FaaStRuby::Response.new(body: body, status: status, headers: headers)
      rendered!
      response
    end

    def render(js: nil, body: nil, inline: nil, html: nil, json: nil, yaml: nil, text: nil, status: 200, headers: {}, content_type: nil)
      headers["Content-Type"] = content_type if content_type
      case
      when json
        headers["Content-Type"] ||= "application/json"
        resp_body = json.is_a?(String) ? json : Oj.dump(json)
      when html, inline
        headers["Content-Type"] ||= "text/html"
        resp_body = html
      when text
        headers["Content-Type"] ||= "text/plain"
        resp_body = text
      when yaml
        headers["Content-Type"] ||= "application/yaml"
        resp_body = yaml.is_a?(String) ? yaml : YAML.load(yaml)
      when body
        headers["Content-Type"] ||= "application/octet-stream"
        resp_body = raw
      when js
        headers["Content-Type"] ||= "text/javascript"
        resp_body = js
      end
      respond_with(resp_body, status: status, headers: headers)
    end
  end

  class Event < Struct
  end

  class Response
    attr_accessor :body, :status, :headers
    def initialize(body:, status: 200, headers: {})
      @body = body
      @status = status
      @headers = headers
    end
  end
end

class FaaStRubyServer < Sinatra::Application
  set :port, 3000
  set :bind, '0.0.0.0'
  case ARGV.shift
  when '-p'
    set :port, ARGV.shift
  when '-b'
    set :bind, ARGV.shift
  end
  set :server, %w[puma]
  set :run, false
  set :show_exceptions, true

  register Sinatra::MultiRoute
  route :get, :post, :put, :patch, :delete, '/:workspace_name/:function_name' do
    e = FaaStRuby::Event.new(:body, :query_params, :headers, :context)
    headers = env.select { |key, value| key.include?('HTTP_') || ['CONTENT_TYPE', 'CONTENT_LENGTH', 'REMOTE_ADDR', 'REQUEST_METHOD', 'QUERY_STRING'].include?(key) }
    if headers.has_key?("HTTP_FAASTRUBY_RPC")
      body = nil
      rpc_args = parse_body(request.body.read, headers['CONTENT_TYPE'], request.request_method) || []
    else
      body = parse_body(request.body.read, headers['CONTENT_TYPE'], request.request_method)
      rpc_args = []
    end
    query_params = parse_query(request.query_string)
    context = set_context(params[:workspace_name], params[:function_name])
    event = e.new(body, query_params, headers, context)
    response = FaaStRuby::Runner.new.call(params[:workspace_name], params[:function_name], event, rpc_args)
    status response.status
    headers response.headers
    body response.body
  end

  def parse_body(body, content_type, method)
    return nil if method == 'GET'
    return {} if body.nil? && method != 'GET'
    return Oj.load(body) if content_type == 'application/json'
    return body
  end

  def set_context(workspace_name, function_name)
    return nil unless File.file?('context.yml')
    yaml = YAML.load(File.read('context.yml'))
    return nil unless yaml.has_key?(workspace_name)
    yaml[workspace_name][function_name]
  end

  def parse_query(query_string)
    hash = {}
    query_string.split('&').each do |param|
      key, value = params.split('=')
      hash[key] = value
    end
    hash
  end
  def self.run?
    true
  end
end

FaaStRubyServer.run! rescue nil # this will suppress some of the errors messages