require 'net/http'
require 'net/https'
require 'uri'
require 'rack/utils'
require 'json'

module Appsignal
  class Transmitter
    CONTENT_TYPE = 'application/json; charset=UTF-8'.freeze
    CONTENT_ENCODING = 'gzip'.freeze

    HTTP_ERRORS = [
      EOFError,
      Errno::ECONNREFUSED,
      Errno::ECONNRESET,
      Errno::EINVAL,
      Net::HTTPBadResponse,
      Net::HTTPHeaderSyntaxError,
      Net::ProtocolError,
      Timeout::Error,
      OpenSSL::SSL::SSLError
    ]

    attr_reader :config, :action

    def initialize(action, config=Appsignal.config)
      @action = action
      @config = config
    end

    def uri
      @uri ||= URI("#{config[:endpoint]}/1/#{action}").tap do |uri|
        uri.query = ::Rack::Utils.build_query({
          :api_key => config[:push_api_key],
          :name => config[:name],
          :environment => config.env,
          :hostname => config[:hostname],
          :gem_version => Appsignal::VERSION
        })
      end
    end

    def transmit(payload)
      config.logger.debug "Transmitting payload to #{uri}"
      http_client.request(http_post(payload)).code
    end

    protected

    def http_post(payload)
      Net::HTTP::Post.new(uri.request_uri).tap do |request|
        request['Content-Type'] = CONTENT_TYPE
        request['Content-Encoding'] = CONTENT_ENCODING
        request.body = Zlib::Deflate.deflate(
          Appsignal::Utils.json_generate(payload),
          Zlib::BEST_SPEED
        )
      end
    end

    def http_client
      client = if config[:http_proxy]
        Net::HTTP.new(uri.host, uri.port, proxy_addr, proxy_port)
      else
        Net::HTTP.new(uri.host, uri.port)
      end

      client.tap do |http|
        if uri.scheme == 'https'
          http.use_ssl     = true
          http.ssl_version = :TLSv1
          http.verify_mode = OpenSSL::SSL::VERIFY_PEER

          ca_file = config[:ca_file_path]
          if ca_file && File.exist?(ca_file) && File.readable?(ca_file)
            http.ca_file = ca_file
          else
            config.logger.warn "Ignoring non-existing or unreadable "\
              "`ca_file_path`: #{ca_file}"
          end
        end
      end
    end

    def proxy_uri
      @proxy_uri ||= URI.parse(config[:http_proxy])
    end

    def proxy_addr
      if config[:http_proxy]
        proxy_uri.host
      else
        nil
      end
    end

    def proxy_port
      if config[:http_proxy]
        proxy_uri.port
      else
        nil
      end
    end
  end
end