require 'roda'
require 'securerandom'
require 'json'
require 'sequel'
require 'open-uri'

class App < Roda
  plugin :sessions, secret: ENV.delete('APP_SESSION_SECRET')
  plugin :render, escape: true
  plugin :flash
  plugin :json_parser
  plugin :request_headers

  DB = Sequel.sqlite("db/#{ENV['DB_NAME']}")
  links = DB[:links]

  route do |r|
    r.root do
      @message = flash['message'] || "Enter a URL"
      view :home
    end

    r.get String do | url_code |
      link = links.filter(:code => url_code)
      r.redirect link.first[:url] unless link.first.nil?
      @message = "Link #{url_code} doesn't exist"
      response.status = 404
      view :home
    end

    r.post "create" do
      url = r.params['url']
      if url.nil? or url.empty? 
        flash['message'] = "Please enter a valid URL";
        r.redirect '/'
      end
      if links.filter(:url => url).first.nil?
        code = SecureRandom.urlsafe_base64 4
        links.insert(url: url, code: code) 
        @message = "Link created"
      end
      code = links.filter(:url => url).first[:code]
      @message ||= "Link exists"
      @new_link = 'http://' + request.env['HTTP_HOST'] + '/' + code
      view :create   
    end
    r.on "links" do
      r.post do
        if 'application/json' != r.headers['CONTENT_TYPE']
          return {message: "Not a valid JSON request"}.to_json
        end

        url = r.params['url']
        if url.nil?
          response.status = 400
          return {message: "missing url parameter"}.to_json
        end

        if url.empty? 
          response.status = 400
          return {message: "invalid url parameter"}.to_json
        end

        begin
          OpenURI.open_uri(url)
        rescue URI::BadURIError
          response.status = 400
          return {message: "invalid url parameter"}.to_json
        rescue OpenURI::HTTPError
          response.status = 400
          return {message: "url not found"}.to_json
        rescue SocketError => e
          response.status = 400
          return {message: "url does not resolve"}.to_json
        end

        if links.filter(:url => url).first.nil?
          code = SecureRandom.urlsafe_base64 4
          links.insert(url: url, code: code) 
        end

        code = links.filter(:url => url).first[:code]
        @new_link = 'http://' + request.env['HTTP_HOST'] + '/' + code
        return {url: url, code: code, link: @new_link}.to_json
      end
    end
  end
end