feat: track watchlist completions

internal/database/database_test.go

@@ -7,6 +7,7 @@ import (
 	"testing"
 
 	_ "github.com/mattn/go-sqlite3"
+	"github.com/pressly/goose/v3"
 )
 
 func TestRunMigrationsCreatesHotPathIndexes(t *testing.T) {
@@ -45,6 +46,116 @@ func TestRunMigrationsCreatesHotPathIndexes(t *testing.T) {
 	}
 }
 
+func TestWatchlistCompletionDateFollowsCompletedStatus(t *testing.T) {
+	sqlDB := newMigratedTestDB(t)
+	defer closeTestDB(t, sqlDB)
+
+	ctx := context.Background()
+	mustExecTestSQL(t, sqlDB, `INSERT INTO user (id, username, password_hash) VALUES ('user-1', 'alice', 'hash')`)
+	mustExecTestSQL(t, sqlDB, `INSERT INTO anime (id, title_original, image_url) VALUES (1, 'Anime', 'image.jpg')`)
+
+	queries := db.New(sqlDB)
+	upsertTestWatchlistStatus(ctx, t, queries, "completed")
+	completedAt, estimated := testWatchlistCompletion(ctx, t, sqlDB)
+	if !completedAt.Valid {
+		t.Fatalf("completed status should record completed_at")
+	}
+	if estimated {
+		t.Fatalf("new completion date should be exact")
+	}
+
+	upsertTestWatchlistStatus(ctx, t, queries, "watching")
+	completedAt, estimated = testWatchlistCompletion(ctx, t, sqlDB)
+	if completedAt.Valid || estimated {
+		t.Fatalf("watching status completion = %v estimated=%v, want empty", completedAt, estimated)
+	}
+
+	upsertTestWatchlistStatus(ctx, t, queries, "completed")
+	completedAt, estimated = testWatchlistCompletion(ctx, t, sqlDB)
+	if !completedAt.Valid || estimated {
+		t.Fatalf("re-completed status completion = %v estimated=%v, want exact date", completedAt, estimated)
+	}
+}
+
+func TestCompletionDateMigrationMarksHistoricalEstimates(t *testing.T) {
+	sqlDB, err := sql.Open("sqlite3", ":memory:")
+	if err != nil {
+		t.Fatalf("open sqlite: %v", err)
+	}
+	defer closeTestDB(t, sqlDB)
+	sqlDB.SetMaxOpenConns(1)
+
+	goose.SetBaseFS(migrationsFS)
+	goose.SetLogger(goose.NopLogger())
+	if err := goose.SetDialect("sqlite3"); err != nil {
+		t.Fatalf("set goose dialect: %v", err)
+	}
+	if err := goose.UpTo(sqlDB, "migrations", 25); err != nil {
+		t.Fatalf("migrate to version 25: %v", err)
+	}
+
+	ctx := context.Background()
+	mustExecTestSQL(t, sqlDB, `INSERT INTO user (id, username, password_hash) VALUES ('user-1', 'alice', 'hash')`)
+	mustExecTestSQL(t, sqlDB, `INSERT INTO anime (id, title_original, image_url) VALUES (1, 'Audited', '1.jpg'), (2, 'Estimated', '2.jpg')`)
+	mustExecTestSQL(t, sqlDB, `
+INSERT INTO watch_list_entry (id, user_id, anime_id, status, updated_at)
+VALUES
+    ('entry-1', 'user-1', 1, 'completed', '2026-06-20 20:00:00'),
+    ('entry-2', 'user-1', 2, 'completed', '2026-06-21 21:00:00')`)
+	mustExecTestSQL(t, sqlDB, `
+INSERT INTO audit_log (id, occurred_at, user_id, action, resource_type, resource_id)
+VALUES ('audit-1', '2026-06-19 19:00:00', 'user-1', 'watch_completed', 'anime', '1')`)
+
+	if err := goose.UpTo(sqlDB, "migrations", 26); err != nil {
+		t.Fatalf("migrate to version 26: %v", err)
+	}
+
+	assertHistoricalCompletion(ctx, t, sqlDB, 1, "2026-06-19T19:00:00Z", false)
+	assertHistoricalCompletion(ctx, t, sqlDB, 2, "2026-06-21T21:00:00Z", true)
+}
+
+func mustExecTestSQL(t *testing.T, sqlDB *sql.DB, query string) {
+	t.Helper()
+	if _, err := sqlDB.ExecContext(context.Background(), query); err != nil {
+		t.Fatalf("execute test SQL: %v", err)
+	}
+}
+
+func upsertTestWatchlistStatus(ctx context.Context, t *testing.T, queries *db.Queries, status string) {
+	t.Helper()
+	_, err := queries.UpsertWatchListEntry(ctx, db.UpsertWatchListEntryParams{
+		ID:      "entry-1",
+		UserID:  "user-1",
+		AnimeID: 1,
+		Status:  status,
+	})
+	if err != nil {
+		t.Fatalf("upsert %s watchlist entry: %v", status, err)
+	}
+}
+
+func testWatchlistCompletion(ctx context.Context, t *testing.T, sqlDB *sql.DB) (sql.NullTime, bool) {
+	t.Helper()
+	var completedAt sql.NullTime
+	var estimated bool
+	if err := sqlDB.QueryRowContext(ctx, `SELECT completed_at, completed_at_estimated FROM watch_list_entry WHERE user_id = 'user-1' AND anime_id = 1`).Scan(&completedAt, &estimated); err != nil {
+		t.Fatalf("query completion date: %v", err)
+	}
+	return completedAt, estimated
+}
+
+func assertHistoricalCompletion(ctx context.Context, t *testing.T, sqlDB *sql.DB, animeID int64, wantTime string, wantEstimated bool) {
+	t.Helper()
+	var completedAt string
+	var estimated bool
+	if err := sqlDB.QueryRowContext(ctx, `SELECT completed_at, completed_at_estimated FROM watch_list_entry WHERE anime_id = ?`, animeID).Scan(&completedAt, &estimated); err != nil {
+		t.Fatalf("query completion for anime %d: %v", animeID, err)
+	}
+	if completedAt != wantTime || estimated != wantEstimated {
+		t.Fatalf("anime %d completion = %q estimated=%v, want %q estimated=%v", animeID, completedAt, estimated, wantTime, wantEstimated)
+	}
+}
+
 func TestCleanupExpiredJikanCache(t *testing.T) {
 	sqlDB := newMigratedTestDB(t)
 	defer closeTestDB(t, sqlDB)