#--
# Author:: Daniel DeLeo (<dan@chef.io>)
# Copyright:: Copyright (c) Chef Software Inc.
# License:: Apache License, Version 2.0
#
# 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
#
#     http://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_relative "auth_credentials"
require_relative "../exceptions"
require "openssl" unless defined?(OpenSSL)

class Chef
  class HTTP
    class Authenticator

      DEFAULT_SERVER_API_VERSION = "2".freeze

      attr_reader :signing_key_filename
      attr_reader :raw_key
      attr_reader :attr_names
      attr_reader :auth_credentials
      attr_reader :version_class
      attr_reader :api_version

      attr_accessor :sign_request

      def initialize(opts = {})
        @raw_key = nil
        @sign_request = true
        @signing_key_filename = opts[:signing_key_filename]
        @key = load_signing_key(opts[:signing_key_filename], opts[:raw_key])
        @auth_credentials = AuthCredentials.new(opts[:client_name], @key, use_ssh_agent: opts[:ssh_agent_signing])
        @version_class = opts[:version_class]
        @api_version = opts[:api_version]
      end

      def handle_request(method, url, headers = {}, data = false)
        headers["X-Ops-Server-API-Version"] = request_version
        headers.merge!(authentication_headers(method, url, data, headers)) if sign_requests?
        [method, url, headers, data]
      end

      def handle_response(http_response, rest_request, return_value)
        [http_response, rest_request, return_value]
      end

      def stream_response_handler(response)
        nil
      end

      def handle_stream_complete(http_response, rest_request, return_value)
        [http_response, rest_request, return_value]
      end

      def request_version
        if version_class
          version_class.best_request_version
        elsif api_version
          api_version
        elsif Chef::ServerAPIVersions.instance.negotiated?
          Chef::ServerAPIVersions.instance.max_server_version.to_s
        else
          DEFAULT_SERVER_API_VERSION
        end
      end

      def sign_requests?
        auth_credentials.sign_requests? && @sign_request
      end

      def client_name
        @auth_credentials.client_name
      end

      def load_signing_key(key_file, raw_key = nil)
        if !!key_file
          @raw_key = IO.read(key_file).strip
        elsif !!raw_key
          @raw_key = raw_key.strip
        else
          return nil
        end
        # Pass in '' as the passphrase to avoid OpenSSL prompting on the TTY if
        # given an encrypted key. This also helps if using a single file for
        # both the public and private key with ssh-agent mode.
        @key = OpenSSL::PKey::RSA.new(@raw_key, "")
      rescue SystemCallError, IOError => e
        Chef::Log.warn "Failed to read the private key #{key_file}: #{e.inspect}"
        raise Chef::Exceptions::PrivateKeyMissing, "I cannot read #{key_file}, which you told me to use to sign requests!"
      rescue OpenSSL::PKey::RSAError
        msg = "The file #{key_file} or :raw_key option does not contain a correctly formatted private key or the key is encrypted.\n"
        msg << "The key file should begin with '-----BEGIN RSA PRIVATE KEY-----' and end with '-----END RSA PRIVATE KEY-----'"
        raise Chef::Exceptions::InvalidPrivateKey, msg
      end

      def authentication_headers(method, url, json_body = nil, headers = nil)
        request_params = {
          http_method: method,
          path: url.path,
          body: json_body,
          host: "#{url.host}:#{url.port}",
          headers: headers,
        }
        request_params[:body] ||= ""
        auth_credentials.signature_headers(request_params)
      end
    end
  end
end