| 1 | // SPDX-License-Identifier: AGPL-3.0-or-later |
| 2 | |
| 3 | package fork |
| 4 | |
| 5 | import ( |
| 6 | "context" |
| 7 | "errors" |
| 8 | "fmt" |
| 9 | |
| 10 | repogit "github.com/tenseleyFlow/shithub/internal/repos/git" |
| 11 | reposdb "github.com/tenseleyFlow/shithub/internal/repos/sqlc" |
| 12 | ) |
| 13 | |
| 14 | // AheadBehindStats describes how the fork's default branch relates |
| 15 | // to the source's default branch. Both numbers are commit counts: |
| 16 | // `Ahead` = commits in fork not in source; `Behind` = commits in |
| 17 | // source not in fork. |
| 18 | // |
| 19 | // `Comparable` is false when either side's default ref doesn't |
| 20 | // exist (e.g. an empty fork before its first push, or a source |
| 21 | // that's never been initialized). The UI renders "—" in that case. |
| 22 | type AheadBehindStats struct { |
| 23 | Ahead int |
| 24 | Behind int |
| 25 | Comparable bool |
| 26 | } |
| 27 | |
| 28 | // AheadBehind computes the stats by reading both default OIDs, |
| 29 | // then running `rev-list --left-right --count` inside the fork's |
| 30 | // bare repo. Because forks share object alternates with their |
| 31 | // source, the fork can resolve OIDs from the source without an |
| 32 | // explicit fetch — they're already reachable through the |
| 33 | // alternates link. |
| 34 | // |
| 35 | // This is the floor implementation. S36's perf-pass sprint adds |
| 36 | // caching keyed on `(fork_repo_id, fork_default_oid, |
| 37 | // upstream_default_oid)` so the rev-list shells out only on push |
| 38 | // (the deferral pointer is already in S36's spec). |
| 39 | func AheadBehind(ctx context.Context, deps Deps, forkRepoID int64) (AheadBehindStats, error) { |
| 40 | rq := reposdb.New() |
| 41 | fork, err := rq.GetRepoByID(ctx, deps.Pool, forkRepoID) |
| 42 | if err != nil { |
| 43 | return AheadBehindStats{}, fmt.Errorf("ahead-behind: load fork: %w", err) |
| 44 | } |
| 45 | if !fork.ForkOfRepoID.Valid { |
| 46 | return AheadBehindStats{}, ErrSourceNotFound |
| 47 | } |
| 48 | source, err := rq.GetRepoByID(ctx, deps.Pool, fork.ForkOfRepoID.Int64) |
| 49 | if err != nil { |
| 50 | return AheadBehindStats{}, ErrSourceNotFound |
| 51 | } |
| 52 | if source.DeletedAt.Valid { |
| 53 | return AheadBehindStats{}, ErrSourceDeleted |
| 54 | } |
| 55 | |
| 56 | forkOwner, err := ownerUsername(ctx, deps, fork) |
| 57 | if err != nil { |
| 58 | return AheadBehindStats{}, err |
| 59 | } |
| 60 | sourceOwner, err := ownerUsername(ctx, deps, source) |
| 61 | if err != nil { |
| 62 | return AheadBehindStats{}, err |
| 63 | } |
| 64 | forkPath, err := deps.RepoFS.RepoPath(forkOwner, fork.Name) |
| 65 | if err != nil { |
| 66 | return AheadBehindStats{}, err |
| 67 | } |
| 68 | sourcePath, err := deps.RepoFS.RepoPath(sourceOwner, source.Name) |
| 69 | if err != nil { |
| 70 | return AheadBehindStats{}, err |
| 71 | } |
| 72 | |
| 73 | // Resolve both default OIDs. Either side empty → not comparable. |
| 74 | forkOID, err := repogit.ResolveRefOID(ctx, forkPath, fork.DefaultBranch) |
| 75 | if err != nil { |
| 76 | if errors.Is(err, repogit.ErrRefNotFound) { |
| 77 | return AheadBehindStats{Comparable: false}, nil |
| 78 | } |
| 79 | return AheadBehindStats{}, fmt.Errorf("ahead-behind: resolve fork: %w", err) |
| 80 | } |
| 81 | sourceOID, err := repogit.ResolveRefOID(ctx, sourcePath, source.DefaultBranch) |
| 82 | if err != nil { |
| 83 | if errors.Is(err, repogit.ErrRefNotFound) { |
| 84 | return AheadBehindStats{Comparable: false}, nil |
| 85 | } |
| 86 | return AheadBehindStats{}, fmt.Errorf("ahead-behind: resolve source: %w", err) |
| 87 | } |
| 88 | if forkOID == sourceOID { |
| 89 | return AheadBehindStats{Comparable: true}, nil |
| 90 | } |
| 91 | |
| 92 | // Run the count inside the fork's repo. The fork's alternates |
| 93 | // give it visibility into source's objects, so passing |
| 94 | // `<forkOID>...<sourceOID>` resolves both ends. |
| 95 | ahead, behind, err := repogit.AheadBehind(ctx, forkPath, sourceOID, forkOID) |
| 96 | if err != nil { |
| 97 | return AheadBehindStats{}, fmt.Errorf("ahead-behind: rev-list: %w", err) |
| 98 | } |
| 99 | // repogit.AheadBehind's argument order is (base, head): ahead |
| 100 | // = "commits in head not in base"; we asked it for forkOID's |
| 101 | // ahead-of sourceOID. So the returned ahead/behind are already |
| 102 | // from the fork's perspective. |
| 103 | return AheadBehindStats{Ahead: ahead, Behind: behind, Comparable: true}, nil |
| 104 | } |
| 105 |