1# frozen_string_literal: true
2
3module MergeRequests
4  class CleanupRefsService
5    include BaseServiceUtility
6
7    TIME_THRESHOLD = 14.days
8
9    attr_reader :merge_request
10
11    def self.schedule(merge_request)
12      merge_request.create_cleanup_schedule(scheduled_at: TIME_THRESHOLD.from_now)
13    end
14
15    def initialize(merge_request)
16      @merge_request = merge_request
17      @repository = merge_request.project.repository
18      @ref_path = merge_request.ref_path
19      @merge_ref_path = merge_request.merge_ref_path
20      @ref_head_sha = @repository.commit(merge_request.ref_path)&.id
21      @merge_ref_sha = merge_request.merge_ref_head&.id
22    end
23
24    def execute
25      return error("Merge request is not scheduled to be cleaned up yet.") unless scheduled?
26      return error("Merge request has not been closed nor merged for #{TIME_THRESHOLD.inspect}.") unless eligible?
27
28      # Ensure that commit shas of refs are kept around so we won't lose them when GC runs.
29      keep_around
30
31      return error('Failed to create keep around refs.') unless kept_around?
32      return error('Failed to cache merge ref sha.') unless cache_merge_ref_sha
33
34      delete_refs if repository.exists?
35
36      return error('Failed to update schedule.') unless update_schedule
37
38      success
39    rescue Gitlab::Git::Repository::GitError, Gitlab::Git::CommandError => e
40      error(e.message)
41    end
42
43    private
44
45    attr_reader :repository, :ref_path, :merge_ref_path, :ref_head_sha, :merge_ref_sha
46
47    def scheduled?
48      merge_request.cleanup_schedule.present? && merge_request.cleanup_schedule.scheduled_at <= Time.current
49    end
50
51    def eligible?
52      return met_time_threshold?(merge_request.metrics&.latest_closed_at) if merge_request.closed?
53
54      merge_request.merged? && met_time_threshold?(merge_request.metrics&.merged_at)
55    end
56
57    def met_time_threshold?(attr)
58      attr.nil? || attr.to_i <= TIME_THRESHOLD.ago.to_i
59    end
60
61    def kept_around?
62      service = Gitlab::Git::KeepAround.new(repository)
63
64      [ref_head_sha, merge_ref_sha].compact.all? do |sha|
65        service.kept_around?(sha)
66      end
67    end
68
69    def keep_around
70      repository.keep_around(ref_head_sha, merge_ref_sha)
71    end
72
73    def cache_merge_ref_sha
74      return true if merge_ref_sha.nil?
75
76      # Caching the merge ref sha is needed before we delete the merge ref so
77      # we can still show the merge ref diff (via `MergeRequest#merge_ref_head`)
78      merge_request.update_column(:merge_ref_sha, merge_ref_sha)
79    end
80
81    def delete_refs
82      repository.delete_refs(ref_path, merge_ref_path)
83    end
84
85    def update_schedule
86      merge_request.cleanup_schedule.update(completed_at: Time.current)
87    end
88  end
89end
90