1 files changed, 56 insertions, 3 deletions

diff --git a/internal/db/repos.go b/internal/db/repos.go
index 7791a458..28a38148 100644
--- a/internal/db/repos.go
+++ b/internal/db/repos.go
@@ -19,8 +19,6 @@ import (
 )
 
 // ReposStore is the persistent interface for repositories.
-//
-// NOTE: All methods are sorted in alphabetical order.
 type ReposStore interface {
 	// Create creates a new repository record in the database. It returns
 	// ErrNameNotAllowed when the repository name is not allowed, or
@@ -48,6 +46,14 @@ type ReposStore interface {
 	// Touch updates the updated time to the current time and removes the bare state
 	// of the given repository.
 	Touch(ctx context.Context, id int64) error
+
+	// ListWatches returns all watches of the given repository.
+	ListWatches(ctx context.Context, repoID int64) ([]*Watch, error)
+	// Watch marks the user to watch the repository.
+	Watch(ctx context.Context, userID, repoID int64) error
+
+	// HasForkedBy returns true if the given repository has forked by the given user.
+	HasForkedBy(ctx context.Context, repoID, userID int64) bool
 }
 
 var Repos ReposStore
@@ -189,7 +195,7 @@ func (db *repos) Create(ctx context.Context, ownerID int64, opts CreateRepoOptio
 			return errors.Wrap(err, "create")
 		}
 
-		err = NewWatchesStore(tx).Watch(ctx, ownerID, repo.ID)
+		err = NewReposStore(tx).Watch(ctx, ownerID, repo.ID)
 		if err != nil {
 			return errors.Wrap(err, "watch")
 		}
@@ -371,3 +377,50 @@ func (db *repos) Touch(ctx context.Context, id int64) error {
 		}).
 		Error
 }
+
+func (db *repos) ListWatches(ctx context.Context, repoID int64) ([]*Watch, error) {
+	var watches []*Watch
+	return watches, db.WithContext(ctx).Where("repo_id = ?", repoID).Find(&watches).Error
+}
+
+func (db *repos) recountWatches(tx *gorm.DB, repoID int64) error {
+	/*
+		Equivalent SQL for PostgreSQL:
+
+		UPDATE repository
+		SET num_watches = (
+			SELECT COUNT(*) FROM watch WHERE repo_id = @repoID
+		)
+		WHERE id = @repoID
+	*/
+	return tx.Model(&Repository{}).
+		Where("id = ?", repoID).
+		Update(
+			"num_watches",
+			tx.Model(&Watch{}).Select("COUNT(*)").Where("repo_id = ?", repoID),
+		).
+		Error
+}
+
+func (db *repos) Watch(ctx context.Context, userID, repoID int64) error {
+	return db.WithContext(ctx).Transaction(func(tx *gorm.DB) error {
+		w := &Watch{
+			UserID: userID,
+			RepoID: repoID,
+		}
+		result := tx.FirstOrCreate(w, w)
+		if result.Error != nil {
+			return errors.Wrap(result.Error, "upsert")
+		} else if result.RowsAffected <= 0 {
+			return nil // Relation already exists
+		}
+
+		return db.recountWatches(tx, repoID)
+	})
+}
+
+func (db *repos) HasForkedBy(ctx context.Context, repoID, userID int64) bool {
+	var count int64
+	db.WithContext(ctx).Model(new(Repository)).Where("owner_id = ? AND fork_id = ?", userID, repoID).Count(&count)
+	return count > 0
+}