/*
 * Copyright @ 2019-present 8x8, Inc.
 *
 * 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 <React/RCTAssert.h>
#import <React/RCTLog.h>

#import "LogUtils.h"
#import "ReactUtils.h"

#pragma mark - Utility functions

/**
 * Merges 2 sets of props into a single one.
 */
NSMutableDictionary* mergeProps(NSDictionary *a, NSDictionary *b) {
    if (a == nil) {
        return [NSMutableDictionary dictionaryWithDictionary:b == nil ? @{} : b];
    }

    if (b == nil) {
        return [NSMutableDictionary dictionaryWithDictionary:a];
    }

    // Both have values, let's merge them, the strategy is to take the value from a first,
    // then override it with the one from b. If the value is a dictionary, merge them
    // recursively. Same goes for arrays.
    NSMutableDictionary *result = [NSMutableDictionary dictionaryWithDictionary:a];

    for (NSString *key in b) {
        id value = b[key];
        id aValue = result[key];

        if (aValue == nil) {
            result[key] = value;
            continue;
        }

        if ([value isKindOfClass:NSArray.class]) {
            result[key] = [aValue arrayByAddingObjectsFromArray:value];
        } else if ([value isKindOfClass:NSDictionary.class]) {
            result[key] = mergeProps(aValue, value);
        } else {
            result[key] = value;
        }
    }

    return result;
}

/**
 * A `RCTFatalHandler` implementation which swallows JavaScript errors. In the
 * Release configuration, React Native will (intentionally) raise an unhandled
 * `NSException` for an unhandled JavaScript error. This will effectively kill
 * the application. `_RCTFatal` is suitable to be in accord with the Web i.e.
 * not kill the application.
 */
RCTFatalHandler _RCTFatal = ^(NSError *error) {
    id jsStackTrace = error.userInfo[RCTJSStackTraceKey];
    NSString *name
        = [NSString stringWithFormat:@"%@: %@", RCTFatalExceptionName, error.localizedDescription];
    NSString *message
        = RCTFormatError(error.localizedDescription, jsStackTrace, -1);
    DDLogError(@"FATAL ERROR: %@\n%@", name, message);
};

/**
 * Helper function to register a fatal error handler for React. Our handler
 * won't kill the process, it will swallow JS errors and print stack traces
 * instead.
 */
void registerReactFatalErrorHandler() {
#if !DEBUG
    // In the Release configuration, React Native will (intentionally) raise an
    // unhandled `NSException` for an unhandled JavaScript error. This will
    // effectively kill the application. In accord with the Web, do not kill the
    // application.
    if (!RCTGetFatalHandler()) {
        RCTSetFatalHandler(_RCTFatal);
    }
#endif
}

/**
 * A `RTCLogFunction` implementation which uses CocoaLumberjack.
 */
RCTLogFunction _RCTLog
    = ^(RCTLogLevel level, __unused RCTLogSource source, NSString *fileName, NSNumber *lineNumber, NSString *message)
{
    // Convert RN log levels into Lumberjack's log flags.
    //
    DDLogFlag logFlag;
    switch (level) {
        case RCTLogLevelTrace:
            logFlag = DDLogFlagDebug;
            break;
        case RCTLogLevelInfo:
            logFlag = DDLogFlagInfo;
            break;
        case RCTLogLevelWarning:
            logFlag = DDLogFlagWarning;
            break;
        case RCTLogLevelError:
            logFlag = DDLogFlagError;
            break;
        case RCTLogLevelFatal:
            logFlag = DDLogFlagError;
            break;
        default:
            // Just in case more are added in the future.
            logFlag = DDLogFlagInfo;
            break;
    }

    // Build the message object we want to log.
    //
    DDLogMessage *logMessage
        = [[DDLogMessage alloc] initWithMessage:message
                                          level:LOG_LEVEL_DEF
                                           flag:logFlag
                                        context:0
                                           file:fileName
                                       function:nil
                                           line:[lineNumber integerValue]
                                            tag:nil
                                        options:0
                                      timestamp:nil];

    // Log the message. Errors are logged synchronously, and other async, as the Lumberjack defaults.
    //
    [DDLog log:logFlag != DDLogFlagError
       message:logMessage];
};

/**
 * Helper function which registers a React Native log handler.
 */
void registerReactLogHandler() {
    RCTSetLogFunction(_RCTLog);
    RCTSetLogThreshold(RCTLogLevelInfo);
}