projection

type OffsetStore interface {
	// Get retrieves the last applied version for a projection.
	// Returns nil if no offset has been stored yet (start from beginning).
	Get(ctx context.Context, name string) (synckit.Version, error)

	// Set updates the last applied version for a projection.
	// This should be called atomically after successfully applying events.
	Set(ctx context.Context, name string, v synckit.Version) error
}

type ProjectionMetrics struct {
	// contains filtered or unexported fields
}

type ProjectionMetricsOption func(*ProjectionMetrics)

type Projector interface {
	// Name returns a stable identifier used for offset bookkeeping.
	// This name should be unique across all projectors in an application.
	Name() string

	// Apply applies a batch of events to the read model.
	// Must be idempotent - applying the same events multiple times should be safe.
	// Events are provided in order and should be processed sequentially.
	Apply(ctx context.Context, batch []synckit.EventWithVersion) error
}

type Runner interface {
	// ApplySince applies all events since the last saved offset.
	// Returns the number of events applied, the last processed version, and any error.
	// This method is idempotent and can be called multiple times safely.
	ApplySince(ctx context.Context) (applied int, last synckit.Version, err error)

	// ApplyBatch applies a specific batch of events directly.
	// This is useful for server-side hooks that want to apply events immediately
	// after they are committed to storage.
	ApplyBatch(ctx context.Context, batch []synckit.EventWithVersion) error
}

type RunnerOption func(*runner)