#
# Copyright:: 2009-2016, 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 'open-uri'

module Opscode
  module Aws
    module Ec2
      def ec2
        require 'aws-sdk'

        Chef::Log.debug('Initializing the EC2 Client')
        @ec2 ||= create_aws_interface(::Aws::EC2::Client)
      end

      def instance_id
        node['ec2']['instance_id']
      end

      def find_snapshot_id(volume_id = '', find_most_recent = false)
        response = ec2.describe_snapshots(
          filters: [
            { name: 'volume-id', values: [volume_id] },
            { name: 'status', values: ['completed'] },
          ]
        )
        snapshots = if find_most_recent
                      # bring the latest snapshot to the front
                      response.snapshots.sort { |a, b| b[:start_time] <=> a[:start_time] }
                    else
                      response.snapshots.sort { |a, b| a[:start_time] <=> b[:start_time] }
                    end

        raise 'Cannot find snapshot id!' if snapshots.empty?

        Chef::Log.debug("Snapshot ID is #{snapshots.first[:snapshot_id]}")
        snapshots.first[:snapshot_id]
      end

      # determine the AWS region of the node
      # Priority: resource property, user set node attribute -> ohai data -> us-east-1
      def aws_region
        # facilitate support for region in resource name
        if new_resource.region
          Chef::Log.debug("Using overridden region name, #{new_resource.region}, from resource")
          new_resource.region
        elsif node.attribute?('ec2')
          Chef::Log.debug("Using region #{node['ec2']['placement_availability_zone'].chop} from Ohai attributes")
          node['ec2']['placement_availability_zone'].chop
        else
          Chef::Log.debug('Falling back to region us-east-1 as Ohai data and resource defined region not present')
          'us-east-1'
        end
      end

      private

      # setup AWS instance using passed creds, iam profile, or assumed role
      def create_aws_interface(aws_interface)
        aws_interface_opts = { region: aws_region }

        if !new_resource.aws_access_key.to_s.empty? && !new_resource.aws_secret_access_key.to_s.empty?
          Chef::Log.debug('Using resource-defined credentials')
          aws_interface_opts[:credentials] = ::Aws::Credentials.new(
            new_resource.aws_access_key,
            new_resource.aws_secret_access_key,
            new_resource.aws_session_token)
        else
          Chef::Log.debug('Using local credential chain')
        end

        if !new_resource.aws_assume_role_arn.to_s.empty? && !new_resource.aws_role_session_name.to_s.empty?
          Chef::Log.debug("Assuming role #{new_resource.aws_assume_role_arn}")
          sts_client = ::Aws::STS::Client.new(region: aws_region,
                                              access_key_id: new_resource.aws_access_key,
                                              secret_access_key: new_resource.aws_secret_access_key)
          creds = ::Aws::AssumeRoleCredentials.new(client: sts_client, role_arn: new_resource.aws_assume_role_arn, role_session_name: new_resource.aws_role_session_name)
          aws_interface_opts[:credentials] = creds
        end
        aws_interface.new(aws_interface_opts)
      end

      # fetch the mac address of an interface.
      def query_mac_address(interface)
        node['network']['interfaces'][interface]['addresses'].select do |_, e|
          e['family'] == 'lladdr'
        end.keys.first.downcase
      end

      # fetch the private IP address of an interface from the metadata endpoint.
      def query_default_interface
        Chef::Log.debug("Default instance ID is #{node['network']['default_interface']}")
        node['network']['default_interface']
      end

      def query_private_ip_addresses(interface)
        mac = query_mac_address(interface)
        ip_addresses = open("http://169.254.169.254/latest/meta-data/network/interfaces/macs/#{mac}/local-ipv4s", options = { proxy: false }) { |f| f.read.split("\n") }
        Chef::Log.debug("#{interface} assigned local ipv4s addresses is/are #{ip_addresses.join(',')}")
        ip_addresses
      end

      # fetch the network interface ID of an interface from the metadata endpoint
      def query_network_interface_id(interface)
        mac = query_mac_address(interface)
        eni_id = open("http://169.254.169.254/latest/meta-data/network/interfaces/macs/#{mac}/interface-id", options = { proxy: false }, &:gets)
        Chef::Log.debug("#{interface} eni id is #{eni_id}")
        eni_id
      end
    end
  end
end
