// Copyright 2015 The Vanadium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package watchable

// GetOp represents a store get operation.
type GetOp struct {
	Key []byte
}

// ScanOp represents a store scan operation.
type ScanOp struct {
	Start []byte
	Limit []byte
}

// PutOp represents a store put operation.  The new version is written instead
// of the value to avoid duplicating the user data in the store.  The version
// is used to access the user data of that specific mutation.
type PutOp struct {
	Key     []byte
	Version []byte
}

// DeleteOp represents a store delete operation.
type DeleteOp struct {
	Key []byte
}

// SyncGroupOp represents a change in SyncGroup tracking, adding or removing
// key prefixes to sync.  SyncGroup prefixes cannot be changed, this is used
// to track changes due to SyncGroup create/join/leave/destroy.
type SyncGroupOp struct {
	Prefixes []string
	Remove   bool
}

// SyncSnapshotOp represents a snapshot operation when creating and joining a
// SyncGroup.  The sync watcher needs to get a snapshot of the Database at the
// point of creating/joining a SyncGroup.  A SyncSnapshotOp entry is written to
// the log for each Database key that falls within the SyncGroup prefixes.  This
// allows sync to initialize its metadata at the correct versions of the objects
// when they become syncable.  These log entries should be filtered by the
// client-facing Watch interface because the user data did not actually change.
type SyncSnapshotOp struct {
	Key     []byte
	Version []byte
}

// Op represents a store operation.
type Op union {
	Get          GetOp
	Scan         ScanOp
	Put          PutOp
	Delete       DeleteOp
	SyncGroup    SyncGroupOp
	SyncSnapshot SyncSnapshotOp
}

// LogEntry represents a single store operation. This operation may have been
// part of a transaction, as signified by the Continued boolean. Read-only
// operations (and read-only transactions) are not logged.
type LogEntry struct {
	// The store operation that was performed.
	Op Op

	// Time when the operation was committed.
	CommitTimestamp int64

	// Operation came from sync (used for echo suppression).
	FromSync bool

	// If true, this entry is followed by more entries that belong to the same
	// commit as this entry.
	Continued bool
}