/*
 * 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 "FMockStorageEngine.h"

#import "FWriteRecord.h"
#import "FCompoundWrite.h"
#import "FNode.h"
#import "FEmptyNode.h"
#import "FTrackedQuery.h"
#import "FPruneForest.h"
#import "FCompoundWrite.h"

@interface FMockStorageEngine ()

@property (nonatomic) BOOL closed;
@property (nonatomic, strong) NSMutableDictionary *userWritesDict;
@property (nonatomic, strong) FCompoundWrite *serverCache;
@property (nonatomic, strong) NSMutableDictionary *trackedQueries;
@property (nonatomic, strong) NSMutableDictionary *trackedQueryKeys;

@end

@implementation FMockStorageEngine

- (id)init {
    self = [super init];
    if (self != nil) {
        self->_userWritesDict = [NSMutableDictionary dictionary];
        self->_serverCache = [FCompoundWrite emptyWrite];
        self->_trackedQueries = [NSMutableDictionary dictionary];
        self->_trackedQueryKeys = [NSMutableDictionary dictionary];
    }
    return self;
}

- (void)close {
    self.closed = YES;
}

- (void)saveUserOverwrite:(id<FNode>)node atPath:(FPath *)path writeId:(NSUInteger)writeId {
    FWriteRecord *writeRecord = [[FWriteRecord alloc] initWithPath:path overwrite:node writeId:writeId visible:YES];
    self.userWritesDict[@(writeId)] = writeRecord;
}

- (void)saveUserMerge:(FCompoundWrite *)merge atPath:(FPath *)path writeId:(NSUInteger)writeId {
    FWriteRecord *writeRecord = [[FWriteRecord alloc] initWithPath:path merge:merge writeId:writeId];
    self.userWritesDict[@(writeId)] = writeRecord;
}

- (void)removeUserWrite:(NSUInteger)writeId {
    [self.userWritesDict removeObjectForKey:@(writeId)];
}

- (void)removeAllUserWrites {
    [self.userWritesDict removeAllObjects];
}

- (NSArray *)userWrites {
    return [[self.userWritesDict allValues] sortedArrayUsingComparator:^NSComparisonResult(FWriteRecord *obj1, FWriteRecord *obj2) {
        if (obj1.writeId < obj2.writeId) {
            return NSOrderedAscending;
        } else if (obj1.writeId > obj2.writeId) {
            return NSOrderedDescending;
        } else {
            return NSOrderedSame;
        }
    }];
}

- (id<FNode>)serverCacheAtPath:(FPath *)path {
    return [[self.serverCache childCompoundWriteAtPath:path] applyToNode:[FEmptyNode emptyNode]];
}

- (id<FNode>)serverCacheForKeys:(NSSet *)keys atPath:(FPath *)path {
    __block id<FNode> children = [FEmptyNode emptyNode];
    id<FNode> fullNode = [[self.serverCache childCompoundWriteAtPath:path] applyToNode:[FEmptyNode emptyNode]];
    [keys enumerateObjectsUsingBlock:^(NSString *key, BOOL *stop) {
        children = [children updateImmediateChild:key withNewChild:[fullNode getImmediateChild:key]];
    }];
    return children;
}

- (void)updateServerCache:(id<FNode>)node atPath:(FPath *)path merge:(BOOL)merge {
    if (merge) {
        [node enumerateChildrenUsingBlock:^(NSString *key, id<FNode> childNode, BOOL *stop) {
            self.serverCache = [self.serverCache addWrite:childNode atPath:[path childFromString:key]];
        }];
    } else {
        self.serverCache = [self.serverCache addWrite:node atPath:path];
    }
}

- (void)updateServerCacheWithMerge:(FCompoundWrite *)merge atPath:(FPath *)path {
    self.serverCache = [self.serverCache addCompoundWrite:merge atPath:path];
}

- (NSUInteger)serverCacheEstimatedSizeInBytes {
    id data = [[self.serverCache applyToNode:[FEmptyNode emptyNode]] valForExport:YES];
    return [NSJSONSerialization dataWithJSONObject:data options:0 error:nil].length;
}

- (void)pruneCache:(FPruneForest *)pruneForest atPath:(FPath *)prunePath {
    [self.serverCache enumerateWrites:^(FPath *absolutePath, id<FNode> node, BOOL *stop) {
        NSAssert([prunePath isEqual:absolutePath] || ![absolutePath contains:prunePath], @"Pruning at %@ but we found data higher up!", prunePath);
        if ([prunePath contains:absolutePath]) {
            FPath *relativePath = [FPath relativePathFrom:prunePath to:absolutePath];
            if ([pruneForest shouldPruneUnkeptDescendantsAtPath:relativePath]) {
                __block FCompoundWrite *newCache = [FCompoundWrite emptyWrite];
                [[pruneForest childAtPath:relativePath] enumarateKeptNodesUsingBlock:^(FPath *keepPath) {
                    newCache = [newCache addWrite:[node getChild:keepPath] atPath:keepPath];
                }];
                self.serverCache = [[self.serverCache removeWriteAtPath:absolutePath] addCompoundWrite:newCache atPath:absolutePath];
            } else {
                // NOTE: This is technically a valid scenario (e.g. you ask to prune at / but only want to prune
                // 'foo' and 'bar' and ignore everything else).  But currently our pruning will explicitly
                // prune or keep everything we know about, so if we hit this it means our tracked queries and
                // the server cache are out of sync.
                NSAssert([pruneForest shouldKeepPath:relativePath], @"We have data at %@ that is neither pruned nor kept.", relativePath);
            }
        }
    }];
}

- (NSArray *)loadTrackedQueries {
    return self.trackedQueries.allValues;
}

- (void)removeTrackedQuery:(NSUInteger)queryId {
    [self.trackedQueries removeObjectForKey:@(queryId)];
    [self.trackedQueryKeys removeObjectForKey:@(queryId)];
}

- (void)saveTrackedQuery:(FTrackedQuery *)query {
    self.trackedQueries[@(query.queryId)] = query;
}

- (void)setTrackedQueryKeys:(NSSet *)keys forQueryId:(NSUInteger)queryId {
    self.trackedQueryKeys[@(queryId)] = keys;
}

- (void)updateTrackedQueryKeysWithAddedKeys:(NSSet *)added removedKeys:(NSSet *)removed forQueryId:(NSUInteger)queryId {
    NSSet *oldKeys = [self trackedQueryKeysForQuery:queryId];
    NSMutableSet *newKeys = [NSMutableSet setWithSet:oldKeys];
    [newKeys minusSet:removed];
    [newKeys unionSet:added];
    self.trackedQueryKeys[@(queryId)] = newKeys;
}

- (NSSet *)trackedQueryKeysForQuery:(NSUInteger)queryId {
    NSSet *keys = self.trackedQueryKeys[@(queryId)];
    return keys != nil ? keys : [NSSet set];
}

@end