# frozen_string_literal: true

module Telnyx
  # TelnyxClient executes requests against the Telnyx API and allows a user to
  # recover both a resource a call returns as well as a response object that
  # contains information on the HTTP call.
  class TelnyxClient
    attr_accessor :conn

    # Initializes a new TelnyxClient. Expects a Faraday connection object, and
    # uses a default connection unless one is passed.
    def initialize(conn = nil)
      self.conn = conn || self.class.default_conn
      @system_profiler = SystemProfiler.new
      @last_request_metrics = nil
    end

    def self.active_client
      Thread.current[:telnyx_client] || default_client
    end

    def self.default_client
      Thread.current[:telnyx_client_default_client] ||= TelnyxClient.new(default_conn)
    end

    # A default Faraday connection to be used when one isn't configured. This
    # object should never be mutated, and instead instantiating your own
    # connection and wrapping it in a TelnyxClient object should be preferred.
    def self.default_conn
      # We're going to keep connections around so that we can take advantage
      # of connection re-use, so make sure that we have a separate connection
      # object per thread.
      Thread.current[:telnyx_client_default_conn] ||= begin
        conn = Faraday.new do |builder|
          builder.use Faraday::Request::Multipart
          builder.use Faraday::Request::UrlEncoded
          builder.use Faraday::Response::RaiseError

          # Net::HTTP::Persistent doesn't seem to do well on Windows or JRuby,
          # so fall back to default there.
          if Gem.win_platform? || RUBY_PLATFORM == "java"
            builder.adapter :net_http
          else
            builder.adapter :net_http_persistent
          end
        end

        if Telnyx.verify_ssl_certs
          conn.ssl.verify = true
        else
          conn.ssl.verify = false

          unless @verify_ssl_warned
            @verify_ssl_warned = true
            $stderr.puts("WARNING: Running without SSL cert verification. " \
              "You should never do this in production. " \
              "Execute 'Telnyx.verify_ssl_certs = true' to enable verification.")
          end
        end

        conn
      end
    end

    # Checks if an error is a problem that we should retry on. This includes both
    # socket errors that may represent an intermittent problem and some special
    # HTTP statuses.
    def self.should_retry?(e, num_retries)
      return false if num_retries >= Telnyx.max_network_retries

      # Retry on timeout-related problems (either on open or read).
      return true if e.is_a?(Faraday::TimeoutError)

      # Destination refused the connection, the connection was reset, or a
      # variety of other connection failures. This could occur from a single
      # saturated server, so retry in case it's intermittent.
      return true if e.is_a?(Faraday::ConnectionFailed)

      false
    end

    def self.sleep_time(num_retries)
      # Apply exponential backoff with initial_network_retry_delay on the
      # number of num_retries so far as inputs. Do not allow the number to exceed
      # max_network_retry_delay.
      sleep_seconds = [Telnyx.initial_network_retry_delay * (2**(num_retries - 1)), Telnyx.max_network_retry_delay].min

      # Apply some jitter by randomizing the value in the range of (sleep_seconds
      # / 2) to (sleep_seconds).
      sleep_seconds *= (0.5 * (1 + rand))

      # But never sleep less than the base sleep seconds.
      sleep_seconds = [Telnyx.initial_network_retry_delay, sleep_seconds].max

      sleep_seconds
    end

    # Executes the API call within the given block. Usage looks like:
    #
    #     client = TelnyxClient.new
    #     messaging_profile, resp = client.request { MessagingProfile.create }
    #
    def request
      @last_response = nil
      old_telnyx_client = Thread.current[:telnyx_client]
      Thread.current[:telnyx_client] = self

      begin
        res = yield
        [res, @last_response]
      ensure
        Thread.current[:telnyx_client] = old_telnyx_client
      end
    end

    def execute_request(method, path,
                        api_base: nil, api_key: nil, headers: {}, params: {})
      api_base ||= Telnyx.api_base
      api_key ||= Telnyx.api_key

      check_api_key!(api_key)

      params = Util.objects_to_ids(params)
      url = api_url(path, api_base)

      body = nil
      query_params = nil

      case method.to_s.downcase.to_sym
      when :get, :head, :delete
        query_params = params
      else
        body = if headers[:content_type] && headers[:content_type] == "multipart/form-data"
                 params
               else
                 JSON.generate(params)
               end
      end

      # This works around an edge case where we end up with both query
      # parameters in `query_params` and query parameters that are appended
      # onto the end of the given path. In this case, Faraday will silently
      # discard the URL's parameters which may break a request.
      #
      # Here we decode any parameters that were added onto the end of a path
      # and add them to `query_params` so that all parameters end up in one
      # place and all of them are correctly included in the final request.
      u = URI.parse(path)
      unless u.query.nil?
        query_params ||= {}
        query_params = Hash[URI.decode_www_form(u.query)].merge(query_params)

        # Reset the path minus any query parameters that were specified.
        path = u.path
      end

      headers = request_headers(api_key, method)
                .update(Util.normalize_headers(headers))

      # stores information on the request we're about to make so that we don't
      # have to pass as many parameters around for logging.
      context = RequestLogContext.new
      context.api_key         = api_key
      context.body            = body
      context.method          = method
      context.path            = path
      context.query_params    = query_params ? Util.encode_parameters(query_params) : nil

      http_resp = execute_request_with_rescues(api_base, context) do
        conn.run_request(method, url, body, headers) do |req|
          req.options.open_timeout = Telnyx.open_timeout
          req.options.timeout = Telnyx.read_timeout
          req.params = query_params unless query_params.nil?
        end
      end

      begin
        resp = TelnyxResponse.from_faraday_response(http_resp)
      rescue JSON::ParserError
        raise general_api_error(http_resp.status, http_resp.body)
      end

      # Allows TelnyxClient#request to return a response object to a caller.
      @last_response = resp
      [resp, api_key]
    end

    private

    def api_url(url = "", api_base = nil)
      (api_base || Telnyx.api_base) + url
    end

    def check_api_key!(api_key)
      unless api_key
        raise AuthenticationError, "No API key provided. " \
          'Set your API key using "Telnyx.api_key = <API-KEY>". ' \
          "You can generate API keys from the Telnyx web interface. " \
          "See https://telnyx.com/api for details, or email support@telnyx.com " \
          "if you have any questions."
      end

      return unless api_key =~ /\s/

      raise AuthenticationError, "Your API key is invalid, as it contains " \
        "whitespace. (HINT: You can double-check your API key from the " \
        "Telnyx web interface. See https://telnyx.com/api for details, or " \
        "email support@telnyx.com if you have any questions.)"
    end

    def execute_request_with_rescues(api_base, context)
      num_retries = 0
      begin
        request_start = Time.now
        log_request(context, num_retries)
        resp = yield
        context = context.dup_from_response(resp)
        log_response(context, request_start, resp.status, resp.body)

      # We rescue all exceptions from a request so that we have an easy spot to
      # implement our retry logic across the board. We'll re-raise if it's a type
      # of exception that we didn't expect to handle.
      rescue StandardError => e
        # If we modify context we copy it into a new variable so as not to
        # taint the original on a retry.
        error_context = context

        if e.respond_to?(:response) && e.response
          error_context = context.dup_from_response(e.response)
          log_response(error_context, request_start,
                       e.response[:status], e.response[:body])
        else
          log_response_error(error_context, request_start, e)
        end

        if self.class.should_retry?(e, num_retries)
          num_retries += 1
          sleep self.class.sleep_time(num_retries)
          retry
        end

        case e
        when Faraday::ClientError
          if e.response
            handle_error_response(e.response, error_context)
          else
            handle_network_error(e, error_context, num_retries, api_base)
          end

        # Only handle errors when we know we can do so, and re-raise otherwise.
        # This should be pretty infrequent.
        else
          raise
        end
      end

      resp
    end

    def general_api_error(status, body)
      APIError.new("Invalid response object from API: #{body.inspect} " \
                   "(HTTP response code was #{status})",
                   http_status: status, http_body: body)
    end

    # Formats a plugin "app info" hash into a string that we can tack onto the
    # end of a User-Agent string where it'll be fairly prominent in places like
    # the Dashboard. Note that this formatting has been implemented to match
    # other libraries, and shouldn't be changed without universal consensus.
    def format_app_info(info)
      str = info[:name]
      str = "#{str}/#{info[:version]}" unless info[:version].nil?
      str = "#{str} (#{info[:url]})" unless info[:url].nil?
      str
    end

    def handle_error_response(http_resp, context)
      begin
        resp = TelnyxResponse.from_faraday_hash(http_resp)
        error_list = resp.data[:errors]

        raise TelnyxError, "Indeterminate error" unless error_list
      rescue JSON::ParserError, TelnyxError
        raise general_api_error(http_resp[:status], http_resp[:body])
      end

      error = specific_api_error(resp, error_list, context)

      error.response = resp
      raise(error)
    end

    def specific_api_error(resp, error_list, context)
      error_list.each do |error|
        Util.log_error("Telnyx API error",
                       status: resp.http_status,
                       error_code: error[:code],
                       error_detail: error[:detail],
                       error_source: error[:source],
                       error_title: error[:title],
                       request_id: context.request_id)
      end

      # The standard set of arguments that can be used to initialize most of
      # the exceptions.
      opts = {
        http_body: resp.http_body,
        http_headers: resp.http_headers,
        http_status: resp.http_status,
        json_body: resp.data,
      }

      case resp.http_status
      when 400
        InvalidRequestError.new(error_list, opts)
      when 401
        AuthenticationError.new(error_list, opts)
      when 403
        PermissionError.new(error_list, opts)
      when 404
        ResourceNotFoundError.new(error_list, opts)
      when 405
        MethodNotSupportedError.new(error_list, opts)
      when 408
        TimeoutError.new(error_list, opts)
      when 422
        InvalidParametersError.new(error_list, opts)
      when 429
        RateLimitError.new(error_list, opts)
      when 500
        APIError.new(error_list, opts)
      when 503
        ServiceUnavailableError.new(error_list, opts)
      else
        APIError.new(error_list, opts)
      end
    end

    def handle_network_error(e, context, num_retries, api_base = nil)
      Util.log_error("Telnyx network error",
                     error_message: e.message,
                     request_id: context.request_id)

      case e
      when Faraday::ConnectionFailed
        message = "Unexpected error communicating when trying to connect to Telnyx. " \
          "You may be seeing this message because your DNS is not working. " \
          "To check, try running 'host telnyx.com' from the command line."

      when Faraday::SSLError
        message = "Could not establish a secure connection to Telnyx, you may " \
                  "need to upgrade your OpenSSL version. To check, try running " \
                  "'openssl s_client -connect api.telnyx.com:443' from the " \
                  "command line."

      when Faraday::TimeoutError
        api_base ||= Telnyx.api_base
        message = "Could not connect to Telnyx (#{api_base}). " \
          "Please check your internet connection and try again. " \
          "If this problem persists, you should check Telnyx's service status at " \
          "https://twitter.com/telnyxstatus, or let us know at support@telnyx.com."

      else
        message = "Unexpected error communicating with Telnyx. " \
          "If this problem persists, let us know at support@telnyx.com."

      end

      message += " Request was retried #{num_retries} times." if num_retries > 0

      raise APIConnectionError, message + "\n\n(Network error: #{e.message})"
    end

    def request_headers(api_key, _method)
      user_agent = "Telnyx/v2 RubyBindings/#{Telnyx::VERSION}"
      unless Telnyx.app_info.nil?
        user_agent += " " + format_app_info(Telnyx.app_info)
      end

      headers = {
        "User-Agent" => user_agent,
        "Authorization" => "Bearer #{api_key}",
        "Content-Type" => "application/json",
      }

      user_agent = @system_profiler.user_agent
      begin
        headers.update(
          "X-Telnyx-Client-User-Agent" => JSON.generate(user_agent)
        )
      rescue StandardError => e
        headers.update(
          "X-Telnyx-Client-Raw-User-Agent" => user_agent.inspect,
          :error => "#{e} (#{e.class})"
        )
      end

      headers
    end

    def log_request(context, num_retries)
      Util.log_info("Request to Telnyx API",
                    method: context.method,
                    num_retries: num_retries,
                    path: context.path)
      Util.log_debug("Request details",
                     body: context.body,
                     query_params: context.query_params)
    end
    private :log_request

    def log_response(context, request_start, status, body)
      Util.log_info("Response from Telnyx API",
                    elapsed: Time.now - request_start,
                    method: context.method,
                    path: context.path,
                    request_id: context.request_id,
                    status: status)
      Util.log_debug("Response details",
                     body: body,
                     request_id: context.request_id)

      return unless context.request_id
    end
    private :log_response

    def log_response_error(context, request_start, e)
      Util.log_error("Request error",
                     elapsed: Time.now - request_start,
                     error_message: e.message,
                     method: context.method,
                     path: context.path)
    end
    private :log_response_error

    # RequestLogContext stores information about a request that's begin made so
    # that we can log certain information. It's useful because it means that we
    # don't have to pass around as many parameters.
    class RequestLogContext
      attr_accessor :body
      attr_accessor :api_key
      attr_accessor :method
      attr_accessor :path
      attr_accessor :query_params
      attr_accessor :request_id

      # The idea with this method is that we might want to update some of
      # context information because a response that we've received from the API
      # contains information that's more authoritative than what we started
      # with for a request. For example, we should trust whatever came back in
      # a `Telnyx-Version` header beyond what configuration information that we
      # might have had available.
      def dup_from_response(resp)
        return self if resp.nil?

        # Faraday's API is a little unusual. Normally it'll produce a response
        # object with a `headers` method, but on error what it puts into
        # `e.response` is an untyped `Hash`.
        headers = if resp.is_a?(Faraday::Response)
                    resp.headers
                  else
                    resp[:headers]
                  end

        context = dup
        context.request_id = headers["X-Request-Id"]
        context
      end
    end

    # SystemProfiler extracts information about the system that we're running
    # in so that we can generate a rich user agent header to help debug
    # integrations.
    class SystemProfiler
      def self.uname
        if ::File.exist?("/proc/version")
          ::File.read("/proc/version").strip
        else
          case RbConfig::CONFIG["host_os"]
          when /linux|darwin|bsd|sunos|solaris|cygwin/i
            uname_from_system
          when /mswin|mingw/i
            uname_from_system_ver
          else
            "unknown platform"
          end
        end
      end

      def self.uname_from_system
        (`uname -a 2>/dev/null` || "").strip
      rescue Errno::ENOENT
        "uname executable not found"
      rescue Errno::ENOMEM # couldn't create subprocess
        "uname lookup failed"
      end

      def self.uname_from_system_ver
        (`ver` || "").strip
      rescue Errno::ENOENT
        "ver executable not found"
      rescue Errno::ENOMEM # couldn't create subprocess
        "uname lookup failed"
      end

      def initialize
        @uname = self.class.uname
      end

      def user_agent
        lang_version = "#{RUBY_VERSION} p#{RUBY_PATCHLEVEL} (#{RUBY_RELEASE_DATE})"

        {
          application: Telnyx.app_info,
          bindings_version: Telnyx::VERSION,
          lang: "ruby",
          lang_version: lang_version,
          platform: RUBY_PLATFORM,
          engine: defined?(RUBY_ENGINE) ? RUBY_ENGINE : "",
          publisher: "telnyx",
          uname: @uname,
          hostname: Socket.gethostname,
        }.delete_if { |_k, v| v.nil? }
      end
    end

    # TelnyxRequestMetrics tracks metadata to be reported to telnyx for metrics collection
    class TelnyxRequestMetrics
      # The Telnyx request ID of the response.
      attr_accessor :request_id

      # Request duration in milliseconds
      attr_accessor :request_duration_ms

      def initialize(request_id, request_duration_ms)
        self.request_id = request_id
        self.request_duration_ms = request_duration_ms
      end

      def payload
        { request_id: request_id, request_duration_ms: request_duration_ms }
      end
    end
  end
end