/*!
 * iOS SDK
 *
 * Tencent is pleased to support the open source community by making
 * Hippy available.
 *
 * Copyright (C) 2019 THL A29 Limited, a Tencent company.
 * All rights reserved.
 *
 * 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 "HippyAsyncLocalStorage.h"
#import "HippyBridge.h"
#import "HippyDefines.h"
#import "HippyUtils.h"
#import "HippyAssert.h"
#import "HippyConvert.h"
#import "HippyLog.h"
#import "HippyUtils.h"

NSString *const HippyStorageDirectory = @"HippyAsyncLocalStorage_V1";
static NSString *const HippyManifestFileName = @"manifest.json";
static const NSUInteger HippyInlineValueThreshold = 1024;

NSUInteger HPLOCALSTORAGEIOTYPEREAD = 1000;

NSUInteger HPLOCALSTORAGEIOTYPEWRITE = 1001;

#pragma mark - Static helper functions

static NSDictionary *HippyErrorForKey(NSString *key) {
    if (![key isKindOfClass:[NSString class]]) {
        return HippyMakeAndLogError(@"Invalid key - must be a string.  Key: ", key, @ { @"key": key });
    } else if (key.length < 1) {
        return HippyMakeAndLogError(@"Invalid key - must be at least one character.  Key: ", key, @ { @"key": key });
    } else {
        return nil;
    }
}

static void HippyAppendError(NSDictionary *error, NSMutableArray<NSDictionary *> **errors) {
    if (error && errors) {
        if (!*errors) {
            *errors = [NSMutableArray new];
        }
        [*errors addObject:error];
    }
}

// Only merges objects - all other types are just clobbered (including arrays)
static BOOL HippyMergeRecursive(NSMutableDictionary *destination, NSDictionary *source) {
    BOOL modified = NO;
    for (NSString *key in source) {
        id sourceValue = source[key];
        id destinationValue = destination[key];
        if ([sourceValue isKindOfClass:[NSDictionary class]]) {
            if ([destinationValue isKindOfClass:[NSDictionary class]]) {
                if ([destinationValue classForCoder] != [NSMutableDictionary class]) {
                    destinationValue = [destinationValue mutableCopy];
                }
                if (HippyMergeRecursive(destinationValue, sourceValue)) {
                    destination[key] = destinationValue;
                    modified = YES;
                }
            } else {
                destination[key] = [sourceValue copy];
                modified = YES;
            }
        } else if (![source isEqual:destinationValue]) {
            destination[key] = [sourceValue copy];
            modified = YES;
        }
    }
    return modified;
}

// get mutable dictionary from a key
// dictionaries with same key share same memory
static NSMutableDictionary *mutableDictionaryForKey(NSString *key, BOOL *created) {
    static dispatch_once_t onceToken;
    static NSMapTable *mapTable = NULL;
    dispatch_once(&onceToken, ^{
        mapTable = [NSMapTable strongToWeakObjectsMapTable];
    });
    if (key) {
        NSMutableDictionary *dic = [mapTable objectForKey:key];
        if (!dic) {
            dic = [[NSMutableDictionary alloc] initWithCapacity:16];
            [mapTable setObject:dic forKey:key];
            *created = YES;
        } else {
            *created = NO;
        }
        return dic;
    }
    *created = YES;
    return [[NSMutableDictionary alloc] initWithCapacity:16];
}

static dispatch_queue_t HippyGetMethodQueue() {
    // We want all instances to share the same queue since they will be reading/writing the same files.
    static dispatch_queue_t queue;
    static dispatch_once_t onceToken;
    dispatch_once(&onceToken, ^{
        queue = dispatch_queue_create("com.tencent.hippy.AsyncLocalStorageQueue", DISPATCH_QUEUE_SERIAL);
    });
    return queue;
}

static NSCache *HippyGetCache() {
    // We want all instances to share the same cache since they will be reading/writing the same files.
    static NSCache *cache;
    static dispatch_once_t onceToken;
    dispatch_once(&onceToken, ^{
        cache = [NSCache new];
        cache.totalCostLimit = 2 * 1024 * 1024;  // 2MB

        // Clear cache in the event of a memory warning
        [[NSNotificationCenter defaultCenter] addObserverForName:UIApplicationDidReceiveMemoryWarningNotification object:nil queue:nil
                                                      usingBlock:^(__unused NSNotification *note) {
                                                          [cache removeAllObjects];
                                                      }];
    });
    return cache;
}

#pragma mark - HippyAsyncLocalStorage

@implementation HippyAsyncLocalStorage {
    BOOL _haveSetup;
    // The manifest is a dictionary of all keys with small values inlined.  Null values indicate values that are stored
    // in separate files (as opposed to nil values which don't exist).  The manifest is read off disk at startup, and
    // written to disk after all mutations.
    NSMutableDictionary<NSString *, NSString *> *_manifest;
    NSString *_storageDirectory;
    NSString *_manifestFilePath;
    BOOL _HippyHasCreatedStorageDirectory;
}
@synthesize bridge = _bridge;

HIPPY_EXPORT_MODULE(StorageModule)

- (dispatch_queue_t)methodQueue {
    return HippyGetMethodQueue();
}

+ (void)clearAllData {
    NSString *docDir = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES).firstObject;
    NSString *storageDirectory = [docDir stringByAppendingPathComponent:HippyStorageDirectory];
    // begin delete all files from 'storageDirectory'
    dispatch_async(HippyGetMethodQueue(), ^{
        NSError *error = nil;
        NSArray<NSString *> *allFiles = [[NSFileManager defaultManager] contentsOfDirectoryAtPath:storageDirectory error:&error];
        for (NSString *fileName in allFiles) {
            NSString *filePath = [storageDirectory stringByAppendingPathComponent:fileName];
            [[NSFileManager defaultManager] removeItemAtPath:filePath error:&error];
        }
    });
}

- (NSDictionary *)HippyDeleteStorageDirectory {
    NSError *error;
    [[NSFileManager defaultManager] removeItemAtPath:[self HippyGetStorageDirectory] error:&error];
    _HippyHasCreatedStorageDirectory = NO;
    return error ? HippyMakeError(@"Failed to delete storage directory.", error, nil) : nil;
}

- (NSString *)HippyGetManifestFilePath {
    if (_manifestFilePath == nil) {
        _manifestFilePath = [[self HippyGetStorageDirectory] stringByAppendingPathComponent:HippyManifestFileName];
    }
    return _manifestFilePath;
}

- (void)invalidate {
    if (_clearOnInvalidate) {
        [HippyGetCache() removeAllObjects];
        [self HippyDeleteStorageDirectory];
    }
    _clearOnInvalidate = NO;
    //    [_manifest removeAllObjects];
    _haveSetup = NO;
}

- (BOOL)isValid {
    return _haveSetup;
}

- (void)dealloc {
    [self invalidate];
}

- (NSString *)_filePathForKey:(NSString *)key {
    NSString *safeFileName = HippyMD5Hash(key);
    return [[self HippyGetStorageDirectory] stringByAppendingPathComponent:safeFileName];
}

- (NSDictionary *)_ensureSetup {
    HippyAssertThread(HippyGetMethodQueue(), @"Must be executed on storage thread");

    NSError *error = nil;
    if (!_HippyHasCreatedStorageDirectory) {
        [[NSFileManager defaultManager] createDirectoryAtPath:[self HippyGetStorageDirectory] withIntermediateDirectories:YES attributes:nil
                                                        error:&error];
        if (error) {
            return HippyMakeError(@"Failed to create storage directory.", error, nil);
        }
        _HippyHasCreatedStorageDirectory = YES;
    }
    if (!_haveSetup) {
        BOOL created = NO;
        _manifest = mutableDictionaryForKey(self.bridge.moduleName, &created);
        if (created) {
            NSDictionary *errorOut;
            NSString *serialized = [self _readFileFromPath:[self HippyGetManifestFilePath] key:nil error:&errorOut];
            NSMutableDictionary *tmpDic = serialized ? HippyJSONParseMutable(serialized, &error) : [NSMutableDictionary new];
            if (error) {
                HippyLogWarn(@"Failed to parse manifest - creating new one.\n\n%@", error);
                tmpDic = [NSMutableDictionary new];
            }
            [_manifest addEntriesFromDictionary:tmpDic];
        }
        _haveSetup = YES;
    }
    return nil;
}

- (NSDictionary *)_writeManifest:(NSMutableArray<NSDictionary *> **)errors {
    NSError *error;
    NSString *serialized = HippyJSONStringify(_manifest, &error);
    [serialized writeToFile:[self HippyGetManifestFilePath] atomically:YES encoding:NSUTF8StringEncoding error:&error];
    NSDictionary *errorOut;
    if (error) {
        errorOut = HippyMakeError(@"Failed to write manifest file.", error, nil);
        HippyAppendError(errorOut, errors);
    }
    return errorOut;
}

- (NSString *)_getValueForKey:(NSString *)key errorOut:(NSDictionary **)errorOut {
    NSString *value = _manifest[key];  // nil means missing, null means there may be a data file, else: NSString
    if (value == (id)kCFNull) {
        value = [HippyGetCache() objectForKey:key];
        if (!value) {
            NSString *filePath = [self _filePathForKey:key];
            value = [self _readFileFromPath:filePath key:key error:errorOut];
            if (value) {
                [HippyGetCache() setObject:value forKey:key cost:value.length];
            } else {
                // file does not exist after all, so remove from manifest (no need to save
                // manifest immediately though, as cost of checking again next time is negligible)
                [_manifest removeObjectForKey:key];
            }
        }
    }
    return value;
}

- (NSDictionary *)_writeEntry:(NSArray<NSString *> *)entry changedManifest:(BOOL *)changedManifest {
    if (entry.count != 2) {
        return HippyMakeAndLogError(@"Entries must be arrays of the form [key: string, value: string], got: ", entry, nil);
    }
    NSString *key = entry[0];
    NSDictionary *errorOut = HippyErrorForKey(key);
    if (errorOut) {
        return errorOut;
    }
    NSString *value = entry[1];
    NSString *filePath = [self _filePathForKey:key];
    NSError *error;
    if (value.length <= HippyInlineValueThreshold) {
        if (_manifest[key] == (id)kCFNull) {
            // If the value already existed but wasn't inlined, remove the old file.
            [[NSFileManager defaultManager] removeItemAtPath:filePath error:nil];
            [HippyGetCache() removeObjectForKey:key];
        }
        *changedManifest = YES;
        _manifest[key] = value;
        return nil;
    }
    NSInteger maxLimit = [self maxWriteDataSize];
    if ([value length] > maxLimit) {
        if (![self handleDataSizeExceedForIOType:HPLOCALSTORAGEIOTYPEWRITE moduleName:self.bridge.moduleName key:key dataLength:[value length]]) {
            return HippyMakeError(@"write data length exceed range", error, @{ @"key": key?:@"nilkey" , @"length": @([value length])});;
        }
    }
    [value writeToFile:filePath atomically:YES encoding:NSUTF8StringEncoding error:&error];
    [HippyGetCache() setObject:value forKey:key cost:value.length];
    if (error) {
        errorOut = HippyMakeError(@"Failed to write value.", error, @{ @"key": key });
    } else if (_manifest[key] != (id)kCFNull) {
        *changedManifest = YES;
        _manifest[key] = (id)kCFNull;
    }
    return errorOut;
}

- (NSString *)_readFileFromPath:(NSString *)filePath key:(NSString *)key error:(NSDictionary **)errorOut {
    BOOL isDirectory = NO;
    if ([[NSFileManager defaultManager] fileExistsAtPath:filePath isDirectory:&isDirectory] && !isDirectory) {
        NSDictionary<NSString*, id> *fileAttribute =
            [[NSFileManager defaultManager] attributesOfItemAtPath:filePath error:nil];
        NSUInteger fileSize = [fileAttribute[NSFileSize] unsignedIntegerValue];
        NSUInteger maxReadFileSize = [self maxReadDataSize];
        if (fileSize > maxReadFileSize) {
            if (![self handleDataSizeExceedForIOType:HPLOCALSTORAGEIOTYPEREAD moduleName:self.bridge.moduleName
                                                 key:key dataLength:fileSize]) {
                *errorOut = HippyMakeError(@"read data length exceed range", nil, @{ @"key": key?:@"nilkey" , @"length": @(fileSize)});;
                return nil;
            }
        }
        NSError *error;
        NSStringEncoding encoding;
        NSString *entryString = [NSString stringWithContentsOfFile:filePath usedEncoding:&encoding error:&error];
        if (error) {
            *errorOut = HippyMakeError(@"Failed to read storage file.", error, @ { @"key": key });
        } else if (encoding != NSUTF8StringEncoding) {
            *errorOut = HippyMakeError(@"Incorrect encoding of storage file: ", @(encoding), @ { @"key": key });
        } else {
            return entryString;
        }
    }
    return nil;
}

- (NSString *)HippyGetStorageDirectory {
    if (nil == _storageDirectory) {
        _storageDirectory = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES).firstObject;
        /** HippyAsyncLocalStorage writes configuration into disk
         *  HippyAsyncLocalStorage will create folder named [HippyBridge moduleName].
         *  HippyBridge.moduleName must be set.
         *  If not, HippyAsyncLocalStorage will write configuration into public file
         */
        NSAssert([[self bridge] moduleName], @"HippyBridge.moduleName must not be null");
        _storageDirectory =
            [[_storageDirectory stringByAppendingPathComponent:HippyStorageDirectory] stringByAppendingPathComponent:[self bridge].moduleName];
    }
    return _storageDirectory;
}

- (NSUInteger)maxReadDataSize {
    return NSUIntegerMax;
}

- (NSUInteger)maxWriteDataSize {
    return NSUIntegerMax;
}

- (BOOL)handleDataSizeExceedForIOType:(NSUInteger)IOType moduleName:(NSString *)moduleName
                                  key:(NSString *)key dataLength:(NSUInteger)length {
    return YES;
}

#pragma mark - Exported JS Functions

HIPPY_EXPORT_METHOD(multiGet:(NSArray<NSString *> *)keys
                  callback:(HippyResponseSenderBlock)callback) {
    NSDictionary *errorOut = [self _ensureSetup];
    if (errorOut) {
        callback(@[@[errorOut], (id)kCFNull]);
        return;
    }
    NSMutableArray<NSDictionary *> *errors;
    NSMutableArray<NSArray<NSString *> *> *result = [[NSMutableArray alloc] initWithCapacity:keys.count];
    for (NSString *key in keys) {
        id keyError;
        id value = [self _getValueForKey:key errorOut:&keyError];
        [result addObject:@[key, HippyNullIfNil(value)]];
        HippyAppendError(keyError, &errors);
    }
    callback(@[HippyNullIfNil(errors), result]);
}

HIPPY_EXPORT_METHOD(multiSet:(NSArray<NSArray<NSString *> *> *)kvPairs
                  callback:(HippyResponseSenderBlock)callback) {
    NSDictionary *errorOut = [self _ensureSetup];
    if (errorOut) {
        callback(@[@[errorOut]]);
        return;
    }
    BOOL changedManifest = NO;
    NSMutableArray<NSDictionary *> *errors;
    for (NSArray<NSString *> *entry in kvPairs) {
        NSDictionary *keyError = [self _writeEntry:entry changedManifest:&changedManifest];
        HippyAppendError(keyError, &errors);
    }
    if (changedManifest) {
        [self _writeManifest:&errors];
    }
    callback(@[HippyNullIfNil(errors)]);
}

HIPPY_EXPORT_METHOD(multiMerge:(NSArray<NSArray<NSString *> *> *)kvPairs
                  callback:(HippyResponseSenderBlock)callback) {
    NSDictionary *errorOut = [self _ensureSetup];
    if (errorOut) {
        callback(@[@[errorOut]]);
        return;
    }
    BOOL changedManifest = NO;
    NSMutableArray<NSDictionary *> *errors;
    for (__strong NSArray<NSString *> *entry in kvPairs) {
        NSDictionary *keyError;
        NSString *value = [self _getValueForKey:entry[0] errorOut:&keyError];
        if (!keyError) {
            if (value) {
                NSError *jsonError;
                NSMutableDictionary *mergedVal = HippyJSONParseMutable(value, &jsonError);
                if (HippyMergeRecursive(mergedVal, HippyJSONParse(entry[1], &jsonError))) {
                    entry = @[entry[0], HippyNullIfNil(HippyJSONStringify(mergedVal, NULL))];
                }
                if (jsonError) {
                    keyError = HippyJSErrorFromNSError(jsonError);
                }
            }
            if (!keyError) {
                keyError = [self _writeEntry:entry changedManifest:&changedManifest];
            }
        }
        HippyAppendError(keyError, &errors);
    }
    if (changedManifest) {
        [self _writeManifest:&errors];
    }
    callback(@[HippyNullIfNil(errors)]);
}

HIPPY_EXPORT_METHOD(multiRemove:(NSArray<NSString *> *)keys
                  callback:(HippyResponseSenderBlock)callback) {
    NSDictionary *errorOut = [self _ensureSetup];
    if (errorOut) {
        callback(@[@[errorOut]]);
        return;
    }
    NSMutableArray<NSDictionary *> *errors;
    BOOL changedManifest = NO;
    for (NSString *key in keys) {
        NSDictionary *keyError = HippyErrorForKey(key);
        if (!keyError) {
            if (_manifest[key] == (id)kCFNull) {
                NSString *filePath = [self _filePathForKey:key];
                [[NSFileManager defaultManager] removeItemAtPath:filePath error:nil];
                [HippyGetCache() removeObjectForKey:key];
                // remove the key from manifest, but no need to mark as changed just for
                // this, as the cost of checking again next time is negligible.
                [_manifest removeObjectForKey:key];
            } else if (_manifest[key]) {
                changedManifest = YES;
                [_manifest removeObjectForKey:key];
            }
        }
        HippyAppendError(keyError, &errors);
    }
    if (changedManifest) {
        [self _writeManifest:&errors];
    }
    callback(@[HippyNullIfNil(errors)]);
}

HIPPY_EXPORT_METHOD(clear:(HippyResponseSenderBlock)callback) {
    [_manifest removeAllObjects];
    [HippyGetCache() removeAllObjects];
    NSDictionary *error = [self HippyDeleteStorageDirectory];
    callback(@[HippyNullIfNil(error)]);
}

HIPPY_EXPORT_METHOD(getAllKeys:(HippyResponseSenderBlock)callback) {
    NSDictionary *errorOut = [self _ensureSetup];
    if (errorOut) {
        callback(@[errorOut, (id)kCFNull]);
    } else {
        callback(@[(id)kCFNull, _manifest.allKeys]);
    }
}

@end