package store

import (
	"context"
	"testing"
)

func userVersion(t *testing.T, s *Store) int {
	t.Helper()
	var v int
	if err := s.db.QueryRowContext(context.Background(), "PRAGMA user_version").Scan(&v); err != nil {
		t.Fatalf("read user_version: %v", err)
	}
	return v
}

func TestMigrateAppliesOnceAndIsIdempotent(t *testing.T) {
	ctx := context.Background()
	s := newTestStore(t)

	// The 1 migration in the built-in slice (tools scope) was applied on Open.
	startVer := len(migrations)
	if v := userVersion(t, s); v != startVer {
		t.Fatalf("fresh DB user_version = %d, want %d", v, startVer)
	}

	// Append a fake migration and run it: creates a throwaway table, bumps by 1.
	migrations = append(migrations, `CREATE TABLE migrate_probe (id INTEGER PRIMARY KEY)`)
	t.Cleanup(func() { migrations = migrations[:len(migrations)-1] })

	if err := migrate(ctx, s.db); err != nil {
		t.Fatalf("migrate: %v", err)
	}
	want := startVer + 1
	if v := userVersion(t, s); v != want {
		t.Fatalf("after migrate user_version = %d, want %d", v, want)
	}
	if _, err := s.db.ExecContext(ctx, "INSERT INTO migrate_probe DEFAULT VALUES"); err != nil {
		t.Fatalf("probe table not created: %v", err)
	}

	// Second run is a no-op — re-running the CREATE would error (no IF NOT EXISTS).
	if err := migrate(ctx, s.db); err != nil {
		t.Fatalf("migrate second run not idempotent: %v", err)
	}
	if v := userVersion(t, s); v != want {
		t.Fatalf("after re-migrate user_version = %d, want %d", v, want)
	}
}