/*
 * Copyright 2017 Google
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

#import <Foundation/Foundation.h>

#import "Firestore/Source/Core/FSTTypes.h"
#import "Firestore/Source/Model/FSTDocumentVersionDictionary.h"

#include "Firestore/core/src/firebase/firestore/model/document_key.h"
#include "Firestore/core/src/firebase/firestore/model/document_key_set.h"
#include "Firestore/core/src/firebase/firestore/model/snapshot_version.h"

@class FSTMutation;
@class FIRTimestamp;
@class FSTMutationResult;
@class FSTMutationBatchResult;

NS_ASSUME_NONNULL_BEGIN

/**
 * A BatchID that was searched for and not found or a batch ID value known to be before all known
 * batches.
 *
 * FSTBatchID values from the local store are non-negative so this value is before all batches.
 */
extern const FSTBatchID kFSTBatchIDUnknown;

/**
 * A batch of mutations that will be sent as one unit to the backend. Batches can be marked as a
 * tombstone if the mutation queue does not remove them immediately. When a batch is a tombstone
 * it has no mutations.
 */
@interface FSTMutationBatch : NSObject

/** Initializes a mutation batch with the given batchID, localWriteTime, and mutations. */
- (instancetype)initWithBatchID:(FSTBatchID)batchID
                 localWriteTime:(FIRTimestamp *)localWriteTime
                      mutations:(NSArray<FSTMutation *> *)mutations NS_DESIGNATED_INITIALIZER;

- (id)init NS_UNAVAILABLE;

/**
 * Applies all the mutations in this FSTMutationBatch to the specified document.
 *
 * @param maybeDoc The document to apply mutations to.
 * @param documentKey The key of the document to apply mutations to.
 * @param mutationBatchResult The result of applying the MutationBatch to the backend. If omitted
 *   it's assumed that this is a local (latency-compensated) application and documents will have
 *   their hasLocalMutations flag set.
 */
- (FSTMaybeDocument *_Nullable)applyTo:(FSTMaybeDocument *_Nullable)maybeDoc
                           documentKey:(const firebase::firestore::model::DocumentKey &)documentKey
                   mutationBatchResult:(FSTMutationBatchResult *_Nullable)mutationBatchResult;

/**
 * A helper version of applyTo for applying mutations locally (without a mutation batch result from
 * the backend).
 */
- (FSTMaybeDocument *_Nullable)applyTo:(FSTMaybeDocument *_Nullable)maybeDoc
                           documentKey:(const firebase::firestore::model::DocumentKey &)documentKey;

/**
 * Returns YES if this mutation batch has already been removed from the mutation queue.
 *
 * Note that not all implementations of the FSTMutationQueue necessarily use tombstones as a part
 * of their implementation and generally speaking no code outside the mutation queues should really
 * care about this.
 */
- (BOOL)isTombstone;

/** Converts this batch to a tombstone. */
- (FSTMutationBatch *)toTombstone;

/** Returns the set of unique keys referenced by all mutations in the batch. */
- (firebase::firestore::model::DocumentKeySet)keys;

@property(nonatomic, assign, readonly) FSTBatchID batchID;
@property(nonatomic, strong, readonly) FIRTimestamp *localWriteTime;
@property(nonatomic, strong, readonly) NSArray<FSTMutation *> *mutations;

@end

#pragma mark - FSTMutationBatchResult

/** The result of applying a mutation batch to the backend. */
@interface FSTMutationBatchResult : NSObject

- (instancetype)init NS_UNAVAILABLE;

/**
 * Creates a new FSTMutationBatchResult for the given batch and results. There must be one result
 * for each mutation in the batch. This static factory caches a document=>version mapping
 * (as docVersions).
 */
+ (instancetype)resultWithBatch:(FSTMutationBatch *)batch
                  commitVersion:(firebase::firestore::model::SnapshotVersion)commitVersion
                mutationResults:(NSArray<FSTMutationResult *> *)mutationResults
                    streamToken:(nullable NSData *)streamToken;

- (const firebase::firestore::model::SnapshotVersion &)commitVersion;

@property(nonatomic, strong, readonly) FSTMutationBatch *batch;
@property(nonatomic, strong, readonly) NSArray<FSTMutationResult *> *mutationResults;
@property(nonatomic, strong, readonly, nullable) NSData *streamToken;
@property(nonatomic, strong, readonly) FSTDocumentVersionDictionary *docVersions;

@end

NS_ASSUME_NONNULL_END