require 'picsolve_docker_builder/base'
require 'excon'
require 'json'
require 'base64'
require 'picsolve_docker_builder/helpers/repository'

module PicsolveDockerBuilder
  module Helpers
    # This represents a remote registry, that is queried for
    # for informations about images
    class Registry
      include PicsolveDockerBuilder::Base

      attr_reader :config

      def self.creds(image = nil)
        if image.nil?
          registry = 'https://docker.picsolve.net'
        else
          registry = "https://#{image.split('/')[0]}"
        end
        new(registry).creds
      end

      def initialize(registry)
        @registry = registry
      end

      def api_version_unsupported
        fail 'No supported version found at registry'
      end

      def api_version
        return @api_version unless @api_version.nil?
        if connection.get(path: '/v2/').status == 200
          @api_version = :v2
        elsif connection.get(path: '/v1/_ping').status == 200
          @api_version = :v1
        else
          api_version_unsupported
        end
        log.info "Detected api version #{@api_version} on registry #{@registry}"
        @api_version
      end

      def list_tags_v1(image)
        base_url = "/v1/repositories/#{image.user}/#{image.repo}"
        endpoint = "#{base_url}/tags"
        r = connection.get(path: endpoint)
        JSON.parse(r.body)
      end

      def list_tags_v2(image)
        base_url = "/v2/#{image.user}/#{image.repo}"
        endpoint = "#{base_url}/tags/list"
        r = connection.get(path: endpoint)
        o = {}
        JSON.parse(r.body)['tags'].each do |tag|
          endpoint = "#{base_url}/manifests/#{tag}"
          r = connection.get(path: endpoint)
          digest = Digest::SHA2.new(256)
          JSON.parse(r.body)['fsLayers'].each do |fs_hash|
            digest.update(fs_hash['blobSum'])
          end
          o[tag] = digest.to_s
        end
        o
      end

      def unique_tag(image, tag)
        tags = list_tags(image)
        fail "tag '#{tag}' not found" unless tags.include? tag
        tags.each do |my_tag, hash|
          # next if not right name
          next unless my_tag.match(/^jenkins-/)
          # next hash not matching
          next if hash != tags[tag]
          # return tag name now
          return my_tag
        end
        fail "no unique tag found for tag=#{tag}"
      end

      def list_tags(image)
        image = Repository.new image
        if api_version == :v1
          list_tags_v1(image)
        elsif api_version == :v2
          list_tags_v2(image)
        else
          api_version_unsupported
        end
      end

      def http_host
        URI(@registry).host
      end

      def headers
        {
          'Host' => http_host,
          'Authorization' => "Basic #{login_basic}"
        }
      end

      def connection
        @connection ||= Excon.new(
          @registry,
          headers: headers
        )
      end

      def dockercfg_path
        File.expand_path '~/.dockercfg'
      end

      def dockercfg
        JSON.parse(
          File.open(
            dockercfg_path
          ).read
        )
      end

      def creds
        auth = Base64.decode64(login_basic).split(':')
        {
          'username' => auth[0],
          'password' => auth[1]
        }
      end

      def login_basic
        dockercfg[http_host]['auth']
      rescue StandardError
        nil
      end
    end
  end
end