package store

import (
	"context"
	"fmt"
)

// SyncState tracks how far back into Garmin history a backfill has already
// reached. Since activities are immutable once recorded, this lets a repeat
// backfill skip everything already covered instead of re-fetching it.
type SyncState struct {
	EarliestSyncedDate *string // "YYYY-MM-DD", nil if backfill has never run
	BackfillComplete   bool    // true once backfill has reached the configured horizon (or Garmin's own history start)
}

// GetSyncState returns the current backfill watermark for userID.
func (db *DB) GetSyncState(ctx context.Context, userID int64) (SyncState, error) {
	var s SyncState
	err := db.QueryRowContext(ctx, `SELECT earliest_synced_date, backfill_complete FROM sync_state WHERE user_id = ?`, userID).
		Scan(&s.EarliestSyncedDate, &s.BackfillComplete)
	if err != nil {
		return SyncState{}, fmt.Errorf("get sync state for user %d: %w", userID, err)
	}
	return s, nil
}

// UpdateSyncState records progress of a backfill run for userID.
func (db *DB) UpdateSyncState(ctx context.Context, userID int64, earliestSyncedDate string, complete bool) error {
	_, err := db.ExecContext(ctx, `
		UPDATE sync_state SET earliest_synced_date = ?, backfill_complete = ? WHERE user_id = ?`,
		earliestSyncedDate, complete, userID)
	if err != nil {
		return fmt.Errorf("update sync state for user %d: %w", userID, err)
	}
	return nil
}