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

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

      def list_tags_v2(image)
        endpoint = "/v2/#{image}/tags/list"
        r = connection.get(path: endpoint)
        o = {}
        JSON.parse(r.body)['tags'].each do |tag|
          endpoint = "/v2/#{image}/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)
        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
        }
      end

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

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

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

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

      def self.get_login_basic(registry = 'docker.picsolve.net')
        dockercfg[registry]['auth']
      rescue StandardError
        nil
      end

      def self.repo_tag_unique(image_name)
        repo_tag = image_name.split(%r{/})[1..-1].join('/')
        repo_tag_split = repo_tag.split(/:/)
        repo = repo_tag_split[0]
        tag = repo_tag_split[1] || 'latest'

        headers = {}
        login_basic = get_login_basic
        headers['Authorization'] = "Basic #{login_basic}" \
          unless login_basic.nil?

        connection = Excon.new(
          'https://docker.picsolve.net',
          headers: headers,
          persistent: true
        )
        response = connection.get(path: "/v1/repositories/#{repo}/tags")

        tags = JSON.parse(response.body)

        hash = tags[tag]

        tags.each do |t, h|
          next if h != hash
          next if t == tag
          next unless t.match(/jenkins-[0-9]+/)
          return {
            tag_unique: "#{image_name.split(':').first}:#{t}",
            hash: hash
          }
        end

        fail "Can not find a uniqe tag for #{image_name}"
      end
    end
  end
end