#
# Author:: Thom May (<thom@chef.io>)
# Copyright:: Copyright (c) 2016-2018, 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 "chef/resource"
require "chef/dsl/declare_resource"
require "chef/mixin/shell_out"
require "chef/http/simple"
require "chef/provider/noop"
require "tmpdir"

class Chef
  class Provider
    class AptRepository < Chef::Provider
      include Chef::Mixin::ShellOut

      provides :apt_repository, platform_family: "debian"

      LIST_APT_KEY_FINGERPRINTS = %w{apt-key adv --list-public-keys --with-fingerprint --with-colons}.freeze

      def load_current_resource
      end

      action :add do
        if new_resource.key.nil?
          logger.debug "No 'key' property specified skipping key import"
        else
          new_resource.key.each do |k|
            if is_key_id?(k) && !has_cookbook_file?(k)
              install_key_from_keyserver(k)
            else
              install_key_from_uri(k)
            end
          end
        end

        declare_resource(:execute, "apt-cache gencaches") do
          command %w{apt-cache gencaches}
          default_env true
          ignore_failure true
          action :nothing
        end

        declare_resource(:apt_update, new_resource.name) do
          ignore_failure true
          action :nothing
        end

        cleanup_legacy_file!

        repo = build_repo(
          new_resource.uri,
          new_resource.distribution,
          repo_components,
          new_resource.trusted,
          new_resource.arch,
          new_resource.deb_src
        )

        declare_resource(:file, "/etc/apt/sources.list.d/#{new_resource.repo_name}.list") do
          owner "root"
          group "root"
          mode "0644"
          content repo
          sensitive new_resource.sensitive
          action :create
          notifies :run, "execute[apt-cache gencaches]", :immediately
          notifies :update, "apt_update[#{new_resource.name}]", :immediately if new_resource.cache_rebuild
        end
      end

      action :remove do
        cleanup_legacy_file!
        if ::File.exist?("/etc/apt/sources.list.d/#{new_resource.repo_name}.list")
          converge_by "Removing #{new_resource.repo_name} repository from /etc/apt/sources.list.d/" do
            declare_resource(:file, "/etc/apt/sources.list.d/#{new_resource.repo_name}.list") do
              sensitive new_resource.sensitive
              action :delete
              notifies :update, "apt_update[#{new_resource.name}]", :immediately if new_resource.cache_rebuild
            end

            declare_resource(:apt_update, new_resource.name) do
              ignore_failure true
              action :nothing
            end
          end
        else
          logger.trace("/etc/apt/sources.list.d/#{new_resource.repo_name}.list does not exist. Nothing to do")
        end
      end

      # is the provided ID a key ID from a keyserver. Looks at length and HEX only values
      # @param [String] id the key value passed by the user that *may* be an ID
      def is_key_id?(id)
        id = id[2..-1] if id.start_with?("0x")
        id =~ /^\h+$/ && [8, 16, 40].include?(id.length)
      end

      # run the specified command and extract the fingerprints from the output
      # accepts a command so it can be used to extract both the current key's fingerprints
      # and the fingerprint of the new key
      # @param [Array<String>] cmd the command to run
      #
      # @return [Array] an array of fingerprints
      def extract_fingerprints_from_cmd(*cmd)
        so = shell_out(*cmd)
        so.stdout.split(/\n/).map do |t|
          if z = t.match(/^fpr:+([0-9A-F]+):/)
            z[1].split.join
          end
        end.compact
      end

      # validate the key against the apt keystore to see if that version is expired
      # @param [String] key
      #
      # @return [Boolean] is the key valid or not
      def key_is_valid?(key)
        valid = true

        so = shell_out("apt-key", "list")
        so.stdout.split(/\n/).map do |t|
          if t =~ %r{^\/#{key}.*\[expired: .*\]$}
            logger.debug "Found expired key: #{t}"
            valid = false
            break
          end
        end

        logger.debug "key #{key} #{valid ? "is valid" : "is not valid"}"
        valid
      end

      # return the specified cookbook name or the cookbook containing the
      # resource.
      #
      # @return [String] name of the cookbook
      def cookbook_name
        new_resource.cookbook || new_resource.cookbook_name
      end

      # determine if a cookbook file is available in the run
      # @param [String] fn the path to the cookbook file
      #
      # @return [Boolean] cookbook file exists or doesn't
      def has_cookbook_file?(fn)
        run_context.has_cookbook_file_in_cookbook?(cookbook_name, fn)
      end

      # determine if there are any new keys by comparing the fingerprints of installed
      # keys to those of the passed file
      # @param [String] file the keyfile of the new repository
      #
      # @return [Boolean] true: no new keys in the file. false: there are new keys
      def no_new_keys?(file)
        # Now we are using the option --with-colons that works across old os versions
        # as well as the latest (16.10). This for both `apt-key` and `gpg` commands
        installed_keys = extract_fingerprints_from_cmd(*LIST_APT_KEY_FINGERPRINTS)
        proposed_keys = extract_fingerprints_from_cmd("gpg", "--with-fingerprint", "--with-colons", file)
        (installed_keys & proposed_keys).sort == proposed_keys.sort
      end

      # Given the provided key URI determine what kind of chef resource we need
      # to fetch the key
      # @param [String] uri the uri of the gpg key (local path or http URL)
      #
      # @raise [Chef::Exceptions::FileNotFound] Key isn't remote or found in the current run
      #
      # @return [Symbol] :remote_file or :cookbook_file
      def key_type(uri)
        if uri.start_with?("http")
          :remote_file
        elsif has_cookbook_file?(uri)
          :cookbook_file
        else
          raise Chef::Exceptions::FileNotFound, "Cannot locate key file: #{uri}"
        end
      end

      # Fetch the key using either cookbook_file or remote_file, validate it,
      # and install it with apt-key add
      # @param [String] key the key to install
      #
      # @raise [RuntimeError] Invalid key which can't verify the apt repository
      #
      # @return [void]
      def install_key_from_uri(key)
        key_name = key.gsub(/[^0-9A-Za-z\-]/, "_")
        cached_keyfile = ::File.join(Chef::Config[:file_cache_path], key_name)
        tmp_dir = Dir.mktmpdir(".gpg")
        at_exit { FileUtils.remove_entry(tmp_dir) }

        declare_resource(key_type(key), cached_keyfile) do
          source key
          mode "0644"
          sensitive new_resource.sensitive
          action :create
          verify "gpg --homedir #{tmp_dir} %{path}"
        end

        declare_resource(:execute, "apt-key add #{cached_keyfile}") do
          command [ "apt-key", "add", cached_keyfile ]
          default_env true
          sensitive new_resource.sensitive
          action :run
          not_if { no_new_keys?(cached_keyfile) }
          notifies :run, "execute[apt-cache gencaches]", :immediately
        end
      end

      # build the apt-key command to install the keyserver
      # @param [String] key the key to install
      # @param [String] keyserver the key server to use
      #
      # @return [String] the full apt-key command to run
      def keyserver_install_cmd(key, keyserver)
        cmd = "apt-key adv --no-tty --recv"
        cmd << " --keyserver-options http-proxy=#{new_resource.key_proxy}" if new_resource.key_proxy
        cmd << " --keyserver "
        cmd << if keyserver.start_with?("hkp://")
                 keyserver
               else
                 "hkp://#{keyserver}:80"
               end

        cmd << " #{key}"
        cmd
      end

      # @param [String] key
      # @param [String] keyserver
      #
      # @raise [RuntimeError] Invalid key which can't verify the apt repository
      #
      # @return [void]
      def install_key_from_keyserver(key, keyserver = new_resource.keyserver)
        declare_resource(:execute, "install-key #{key}") do
          command keyserver_install_cmd(key, keyserver)
          default_env true
          sensitive new_resource.sensitive
          not_if do
            present = extract_fingerprints_from_cmd(*LIST_APT_KEY_FINGERPRINTS).any? do |fp|
              fp.end_with? key.upcase
            end
            present && key_is_valid?(key.upcase)
          end
          notifies :run, "execute[apt-cache gencaches]", :immediately
        end

        raise "The key #{key} is invalid and cannot be used to verify an apt repository." unless key_is_valid?(key.upcase)
      end

      # @param [String] owner
      # @param [String] repo
      #
      # @raise [RuntimeError] Could not access the Launchpad PPA API
      #
      # @return [void]
      def install_ppa_key(owner, repo)
        url = "https://launchpad.net/api/1.0/~#{owner}/+archive/#{repo}"
        key_id = Chef::HTTP::Simple.new(url).get("signing_key_fingerprint").delete('"')
        install_key_from_keyserver(key_id, "keyserver.ubuntu.com")
      rescue Net::HTTPClientException => e
        raise "Could not access Launchpad ppa API: #{e.message}"
      end

      # determine if the repository URL is a PPA
      # @param [String] url the url of the repository
      #
      # @return [Boolean] is the repo URL a PPA
      def is_ppa_url?(url)
        url.start_with?("ppa:")
      end

      # determine the repository's components:
      #  - "components" property if defined
      #  - "main" if "components" not defined and the repo is a PPA URL
      #  - otherwise nothing
      #
      # @return [String] the repository component
      def repo_components
        if is_ppa_url?(new_resource.uri) && new_resource.components.empty?
          "main"
        else
          new_resource.components
        end
      end

      # given a PPA return a PPA URL in http://ppa.launchpad.net format
      # @param [String] ppa the ppa URL
      #
      # @return [String] full PPA URL
      def make_ppa_url(ppa)
        owner, repo = ppa[4..-1].split("/")
        repo ||= "ppa"

        install_ppa_key(owner, repo)
        "http://ppa.launchpad.net/#{owner}/#{repo}/ubuntu"
      end

      # build complete repo text that will be written to the config
      # @param [String] uri
      # @param [Array] components
      # @param [Boolean] trusted
      # @param [String] arch
      # @param [Boolean] add_src
      #
      # @return [String] complete repo config text
      def build_repo(uri, distribution, components, trusted, arch, add_src = false)
        uri = make_ppa_url(uri) if is_ppa_url?(uri)

        uri = '"' + uri + '"' unless uri.start_with?("'", '"')
        components = Array(components).join(" ")
        options = []
        options << "arch=#{arch}" if arch
        options << "trusted=yes" if trusted
        optstr = unless options.empty?
                   "[" + options.join(" ") + "]"
                 end
        info = [ optstr, uri, distribution, components ].compact.join(" ")
        repo =  "deb      #{info}\n"
        repo << "deb-src  #{info}\n" if add_src
        repo
      end

      # clean up a potentially legacy file from before we fixed the usage of
      # new_resource.name vs. new_resource.repo_name. We might have the
      # name.list file hanging around and need to clean it up.
      #
      # @return [void]
      def cleanup_legacy_file!
        legacy_path = "/etc/apt/sources.list.d/#{new_resource.name}.list"
        if new_resource.name != new_resource.repo_name && ::File.exist?(legacy_path)
          converge_by "Cleaning up legacy #{legacy_path} repo file" do
            declare_resource(:file, legacy_path) do
              action :delete
              # Not triggering an update since it isn't super likely to be needed.
            end
          end
        end
      end
    end
  end
end

Chef::Provider::Noop.provides :apt_repository