# Copyright 2021 Google LLC
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
#     https://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.

require "googleauth"
require "gapic/logging_concerns"
require "gapic/rest/faraday_middleware"
require "gapic/universe_domain_concerns"
require "faraday/retry"

module Gapic
  module Rest
    ##
    # A class for making REST calls through Faraday
    # ClientStub's responsibilities:
    #   - wrap Faraday methods with a bounded explicit interface
    #   - store service endpoint and create full url for the request
    #   - store credentials and add auth information to the request
    #
    class ClientStub
      include UniverseDomainConcerns
      include LoggingConcerns

      ##
      # Initializes with an endpoint and credentials
      #
      # @param endpoint [String] The endpoint of the API. Overrides any endpoint_template.
      # @param endpoint_template [String] The endpoint of the API, where the
      #   universe domain component of the hostname is marked by the string in
      #   the constant {UniverseDomainConcerns::ENDPOINT_SUBSTITUTION}.
      # @param universe_domain [String] The universe domain in which calls
      #   should be made. Defaults to `googleapis.com`.
      # @param credentials [Google::Auth::Credentials]
      #   Credentials to send with calls in form of a googleauth credentials object.
      #   (see the [googleauth docs](https://googleapis.dev/ruby/googleauth/latest/index.html))
      # @param numeric_enums [Boolean] Whether to signal the server to JSON-encode enums as ints
      # @param raise_faraday_errors [Boolean]
      #   Whether to raise Faraday errors instead of wrapping them in `Gapic::Rest::Error`
      #   Added for backwards compatibility.
      #   Default is `true`. All REST clients (except for old versions of `google-cloud-compute-v1`)
      #   should explicitly set this parameter to `false`.
      # @param logger [Logger,:default,nil] An explicit logger to use, or one
      #   of the values `:default` (the default) to construct a default logger,
      #   or `nil` to disable logging explicitly.
      #
      # @yield [Faraday::Connection]
      #
      def initialize credentials:,
                     endpoint: nil,
                     endpoint_template: nil,
                     universe_domain: nil,
                     numeric_enums: false,
                     raise_faraday_errors: true,
                     logging_system: nil,
                     service_name: nil,
                     logger: :default
        setup_universe_domain universe_domain: universe_domain,
                              endpoint: endpoint,
                              endpoint_template: endpoint_template,
                              credentials: credentials

        endpoint_url = self.endpoint
        endpoint_url = "https://#{endpoint_url}" unless /^https?:/.match? endpoint_url
        endpoint_url = endpoint_url.sub %r{/$}, ""

        setup_logging logger: logger,
                      system_name: logging_system,
                      service: service_name,
                      endpoint: endpoint_url,
                      client_id: object_id

        @numeric_enums = numeric_enums

        @raise_faraday_errors = raise_faraday_errors

        @connection = Faraday.new url: endpoint_url do |conn|
          conn.headers = { "Content-Type" => "application/json" }
          conn.request :google_authorization, self.credentials unless self.credentials.is_a? ::Symbol
          conn.request :retry
          conn.response :raise_error
          conn.adapter :net_http
        end

        yield @connection if block_given?
      end

      ##
      # Makes a GET request
      #
      # @param uri [String] uri to send this request to
      # @param params [Hash] query string parameters for the request
      # @param options [::Gapic::CallOptions,Hash] gapic options to be applied
      #     to the REST call. Currently only timeout and headers are supported.
      # @return [Faraday::Response]
      def make_get_request uri:, params: {}, options: {}, method_name: nil
        make_http_request :get, uri: uri, body: nil, params: params, options: options, method_name: method_name
      end

      ##
      # Makes a DELETE request
      #
      # @param uri [String] uri to send this request to
      # @param params [Hash] query string parameters for the request
      # @param options [::Gapic::CallOptions,Hash] gapic options to be applied
      #     to the REST call. Currently only timeout and headers are supported.
      # @return [Faraday::Response]
      def make_delete_request uri:, params: {}, options: {}, method_name: nil
        make_http_request :delete, uri: uri, body: nil, params: params, options: options, method_name: method_name
      end

      ##
      # Makes a PATCH request
      #
      # @param uri [String] uri to send this request to
      # @param body [String] a body to send with the request, nil for requests without a body
      # @param params [Hash] query string parameters for the request
      # @param options [::Gapic::CallOptions,Hash] gapic options to be applied
      #     to the REST call. Currently only timeout and headers are supported.
      # @return [Faraday::Response]
      def make_patch_request uri:, body:, params: {}, options: {}, method_name: nil
        make_http_request :patch, uri: uri, body: body, params: params, options: options, method_name: method_name
      end

      ##
      # Makes a POST request
      #
      # @param uri [String] uri to send this request to
      # @param body [String] a body to send with the request, nil for requests without a body
      # @param params [Hash] query string parameters for the request
      # @param options [::Gapic::CallOptions,Hash] gapic options to be applied
      #     to the REST call. Currently only timeout and headers are supported.
      # @return [Faraday::Response]
      def make_post_request uri:, body: nil, params: {}, options: {}, method_name: nil
        make_http_request :post, uri: uri, body: body, params: params, options: options, method_name: method_name
      end

      ##
      # Makes a PUT request
      #
      # @param uri [String] uri to send this request to
      # @param body [String] a body to send with the request, nil for requests without a body
      # @param params [Hash] query string parameters for the request
      # @param options [::Gapic::CallOptions,Hash] gapic options to be applied
      #     to the REST call. Currently only timeout and headers are supported.
      # @return [Faraday::Response]
      def make_put_request uri:, body: nil, params: {}, options: {}, method_name: nil
        make_http_request :put, uri: uri, body: body, params: params, options: options, method_name: method_name
      end

      ##
      # @private
      # Sends a http request via Faraday
      # @param verb [Symbol] http verb
      # @param uri [String] uri to send this request to
      # @param body [String, nil] a body to send with the request, nil for requests without a body
      # @param params [Hash] query string parameters for the request
      # @param options [::Gapic::CallOptions,Hash] gapic options to be applied to the REST call.
      # @param is_server_streaming [Boolean] flag if method is streaming
      # @yieldparam chunk [String] The chunk of data received during server streaming.
      # @return [Faraday::Response]
      def make_http_request verb,
                            uri:, body:, params:, options:,
                            is_server_streaming: false, method_name: nil,
                            &block
        # Converts hash and nil to an options object
        options = ::Gapic::CallOptions.new(**options.to_h) unless options.is_a? ::Gapic::CallOptions
        deadline = calculate_deadline options
        retried_exception = nil
        next_timeout = get_timeout deadline
        request_id = LoggingConcerns.random_uuid4
        try_number = 1

        begin
          log_request method_name, request_id, try_number, body, options.metadata
          response = base_make_http_request verb: verb, uri: uri, body: body,
                                            params: params, metadata: options.metadata,
                                            timeout: next_timeout,
                                            is_server_streaming: is_server_streaming,
                                            &block
          log_response method_name, request_id, try_number, response, is_server_streaming
          response
        rescue ::Faraday::TimeoutError => e
          log_response method_name, request_id, try_number, e, is_server_streaming
          raise if @raise_faraday_errors
          raise Gapic::Rest::DeadlineExceededError.wrap_faraday_error e, root_cause: retried_exception
        rescue ::Faraday::Error => e
          log_response method_name, request_id, try_number, e, is_server_streaming
          next_timeout = get_timeout deadline

          if check_retry?(next_timeout) && options.retry_policy.call(e)
            retried_exception = e
            try_number += 1
            retry
          end

          raise if @raise_faraday_errors
          raise ::Gapic::Rest::Error.wrap_faraday_error e
        end
      end

      ##
      # @private
      # Sends a http request via Faraday
      #
      # @param verb [Symbol] http verb
      # @param uri [String] uri to send this request to
      # @param body [String, nil] a body to send with the request, nil for requests without a body
      # @param params [Hash] query string parameters for the request
      # @param metadata [Hash] additional headers for the request
      # @param is_server_streaming [Boolean] flag if method is streaming
      # @yieldparam chunk [String] The chunk of data received during server streaming.
      # @return [Faraday::Response]
      def base_make_http_request verb:, uri:, body:, params:, metadata:,
                                 timeout:, is_server_streaming: false
        if @numeric_enums && (!params.key?("$alt") || params["$alt"] == "json")
          params = params.merge({ "$alt" => "json;enum-encoding=int" })
        end

        @connection.send verb, uri do |req|
          req.params = params if params.any?
          req.body = body unless body.nil?
          req.headers = req.headers.merge metadata
          req.options.timeout = timeout if timeout&.positive?
          if is_server_streaming
            req.options.on_data = proc do |chunk, _overall_received_bytes|
              yield chunk
            end
          end
        end
      end

      private

      ##
      # Calculates deadline
      #
      # @param options [Gapic::CallOptions] call options for this call
      #
      # @return [Numeric, nil] Deadline against a POSIX clock_gettime()
      def calculate_deadline options
        return if options.timeout.nil?
        return if options.timeout.negative?

        Process.clock_gettime(Process::CLOCK_MONOTONIC) + options.timeout
      end

      ##
      # Calculates timeout (seconds) to use as a Faraday timeout
      #
      # @param deadline [Numeric, nil] deadline
      #
      # @return [Numeric, nil] Timeout (seconds)
      def get_timeout deadline
        return if deadline.nil?
        deadline - Process.clock_gettime(Process::CLOCK_MONOTONIC)
      end

      ##
      # Whether the timeout should be retried
      #
      # @param timeout [Numeric, nil]
      #
      # @return [Boolean] whether the timeout should be retried
      def check_retry? timeout
        return true if timeout.nil?

        timeout.positive?
      end

      def log_request method_name, request_id, try_number, body, metadata
        return unless stub_logger
        stub_logger.info do |entry|
          entry.set_system_name
          entry.set_service
          entry.set "rpcName", method_name
          entry.set "retryAttempt", try_number
          entry.set "requestId", request_id
          entry.message = "Sending request to #{entry.service}.#{method_name} (try #{try_number})"
        end
        body = body.to_s
        metadata = metadata.to_h rescue {}
        return if body.empty? && metadata.empty?
        stub_logger.debug do |entry|
          entry.set "requestId", request_id
          entry.set "request", body
          entry.set "headers", metadata
          entry.message = "(request payload as JSON)"
        end
      end

      def log_response method_name, request_id, try_number, response, is_server_streaming
        return unless stub_logger
        stub_logger.info do |entry|
          entry.set_system_name
          entry.set_service
          entry.set "rpcName", method_name
          entry.set "retryAttempt", try_number
          entry.set "requestId", request_id
          if response.is_a? StandardError
            entry.set "exception", response.to_s
            entry.message = "Received error for #{entry.service}.#{method_name} (try #{try_number}): #{response}"
          elsif is_server_streaming
            entry.message = "Receiving stream for #{entry.service}.#{method_name} (try #{try_number})"
          else
            entry.message = "Received response for #{entry.service}.#{method_name} (try #{try_number})"
          end
        end
        return if is_server_streaming || !response.respond_to?(:body)
        body = response.body.to_s
        return if body.empty?
        stub_logger.debug do |entry|
          entry.set "requestId", request_id
          entry.set "response", body
          entry.message = "(response payload as JSON)"
        end
      end
    end
  end
end