#
# Author:: Jesse Campbell (<hikeit@gmail.com>)
# Author:: Lamont Granquist (<lamont@chef.io>)
# Copyright:: Copyright 2013-2016, Jesse Campbell
# 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 "../../digester"
require_relative "../remote_file"
require_relative "cache_control_data"

class Chef
  class Provider
    class RemoteFile

      class HTTP

        attr_reader :uri
        attr_reader :new_resource
        attr_reader :current_resource
        attr_reader :logger

        # Parse the uri into instance variables
        def initialize(uri, new_resource, current_resource, logger = Chef::Log.with_child)
          @uri = uri
          @new_resource = new_resource
          @current_resource = current_resource
          @logger = logger
        end

        def events
          new_resource.events
        end

        def headers
          conditional_get_headers.merge(new_resource.headers)
        end

        def conditional_get_headers
          cache_control_headers = {}
          if (last_modified = cache_control_data.mtime) && want_mtime_cache_control?
            cache_control_headers["if-modified-since"] = last_modified
          end
          if (etag = cache_control_data.etag) && want_etag_cache_control?
            cache_control_headers["if-none-match"] = etag
          end
          logger.trace("Cache control headers: #{cache_control_headers.inspect}")
          cache_control_headers
        end

        def fetch
          http = TargetIO::HTTP.new(uri, http_client_opts)
          orig_tempfile = Chef::FileContentManagement::Tempfile.new(@new_resource).tempfile
          if want_progress?
            tempfile = http.streaming_request_with_progress(uri, headers, orig_tempfile) do |size, total|
              events.resource_update_progress(new_resource, size, total, progress_interval)
            end
          else
            tempfile = http.streaming_request(uri, headers, orig_tempfile)
          end
          if tempfile
            update_cache_control_data(tempfile, http.last_response)
            tempfile.close
          else
            # cache_control shows the file is unchanged, so we got back nil from the streaming_request above, and it is
            # now our responsibility to unlink the tempfile we created
            orig_tempfile.close
            orig_tempfile.unlink
          end
          tempfile
        end

        private

        def update_cache_control_data(tempfile, response)
          cache_control_data.checksum = Chef::Digester.checksum_for_file(tempfile.path)
          cache_control_data.mtime = last_modified_time_from(response)
          cache_control_data.etag = etag_from(response)
          cache_control_data.save
        end

        def cache_control_data
          @cache_control_data ||= CacheControlData.load_and_validate(uri, current_resource.checksum)
        end

        def want_progress?
          !ChefConfig::Config.target_mode? && events.formatter? && (Chef::Config[:show_download_progress] || !!new_resource.show_progress)
        end

        def progress_interval
          Chef::Config[:download_progress_interval]
        end

        def want_mtime_cache_control?
          new_resource.use_last_modified
        end

        def want_etag_cache_control?
          new_resource.use_etag
        end

        def last_modified_time_from(response)
          response["last-modified"] || response["date"]
        end

        def etag_from(response)
          response["etag"]
        end

        def http_client_opts
          opts = {}
          # CHEF-3140
          # 1. If it's already compressed, trying to compress it more will
          # probably be counter-productive.
          # 2. Some servers are misconfigured so that you GET $URL/file.tgz but
          # they respond with content type of tar and content encoding of gzip,
          # which tricks Chef::REST into decompressing the response body. In this
          # case you'd end up with a tar archive (no gzip) named, e.g., foo.tgz,
          # which is not what you wanted.
          if /gz$/.match?(uri.to_s)
            logger.trace("Turning gzip compression off due to filename ending in gz")
            opts[:disable_gzip] = true
          end
          if new_resource.ssl_verify_mode
            opts[:ssl_verify_mode] = new_resource.ssl_verify_mode
          end
          opts.merge(new_resource.http_options)
        end

      end
    end
  end
end
