Chapter 11 - Chat App/ChatAppFinished/Pods/FirebaseDatabase/Firebase/Database/Utilities/FUtilities.m
/*
 * 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 <FirebaseCore/FIRLogger.h>
#import "FUtilities.h"
#import "FStringUtilities.h"
#import "FConstants.h"
#import "FAtomicNumber.h"

#define ARC4RANDOM_MAX 0x100000000
#define INTEGER_32_MIN (-2147483648)
#define INTEGER_32_MAX 2147483647

#pragma mark -
#pragma mark C functions

FIRLoggerService kFIRLoggerDatabase = @"[Firebase/Database]";
static FLogLevel logLevel = FLogLevelInfo; // Default log level is info
static NSMutableDictionary* options = nil;

BOOL FFIsLoggingEnabled(FLogLevel level) {
    return level >= logLevel;
}

void firebaseJobsTroll(void) {
    FFLog(@"I-RDB095001", @"password super secret; JFK conspiracy; Hello there! Having fun digging through Firebase? We're always hiring! jobs@firebase.com");
}

#pragma mark -
#pragma mark Private property and singleton specification

@interface FUtilities() {

}

@property (nonatomic, strong) FAtomicNumber* localUid;

+ (FUtilities*)singleton;

@end

@implementation FUtilities

@synthesize localUid;

- (id)init
{
    self = [super init];
    if (self) {
        self.localUid = [[FAtomicNumber alloc] init];
    }
    return self;
}

// TODO: We really want to be able to set the log level
+ (void) setLoggingEnabled:(BOOL)enabled {
    logLevel = enabled ? FLogLevelDebug : FLogLevelInfo;
}

+ (BOOL) getLoggingEnabled {
    return logLevel == FLogLevelDebug;
}

+ (FUtilities*) singleton
{
    static dispatch_once_t pred = 0;
    __strong static id _sharedObject = nil;
    dispatch_once(&pred, ^{
        _sharedObject = [[self alloc] init]; // or some other init method
    });
    return _sharedObject;
}

// Refactor as a category of NSString
+ (NSArray *) splitString:(NSString *) str intoMaxSize:(const unsigned int) size {
    if(str.length <= size) {
        return [NSArray arrayWithObject:str];
    }

    NSMutableArray* dataSegs = [[NSMutableArray alloc] init];
    for(int c = 0; c < str.length; c += size) {
        if (c + size > str.length) {
            int rangeStart = c;
            unsigned long rangeLength = size - ((c + size) - str.length);
            [dataSegs addObject:[str substringWithRange:NSMakeRange(rangeStart, rangeLength)]];
        }
        else {
            int rangeStart = c;
            int rangeLength = size;
            [dataSegs addObject:[str substringWithRange:NSMakeRange(rangeStart, rangeLength)]];
        }
    }
    return dataSegs;
}

+ (NSNumber *) LUIDGenerator {
    FUtilities* f = [FUtilities singleton];
    return [f.localUid getAndIncrement];
}

+ (NSString *) decodePath:(NSString *)pathString {
    NSMutableArray* decodedPieces = [[NSMutableArray alloc] init];
    NSArray* pieces = [pathString componentsSeparatedByString:@"/"];
    for (NSString* piece in pieces) {
        if (piece.length > 0) {
            [decodedPieces addObject:[FStringUtilities urlDecoded:piece]];
        }
    }
    return [NSString stringWithFormat:@"/%@", [decodedPieces componentsJoinedByString:@"/"]];
}

+ (FParsedUrl *) parseUrl:(NSString *)url {
    NSString* original = url;
    //NSURL* n = [[NSURL alloc] initWithString:url]

    NSString* host;
    NSString* namespace;
    bool secure;

    NSString* scheme = nil;
    FPath* path = nil;
    NSRange colonIndex = [url rangeOfString:@"//"];
    if (colonIndex.location != NSNotFound) {
        scheme = [url substringToIndex:colonIndex.location - 1];
        url = [url substringFromIndex:colonIndex.location + 2];
    }
    NSInteger slashIndex = [url rangeOfString:@"/"].location;
    if (slashIndex == NSNotFound) {
        slashIndex = url.length;
    }

    host = [[url substringToIndex:slashIndex] lowercaseString];
    if (slashIndex >= url.length) {
        url = @"";
    } else {
        url = [url substringFromIndex:slashIndex + 1];
    }

    NSArray *parts = [host componentsSeparatedByString:@"."];
    if([parts count] == 3) {
        NSInteger colonIndex = [[parts objectAtIndex:2] rangeOfString:@":"].location;
        if (colonIndex != NSNotFound) {
            // we have a port, use the provided scheme
            secure = [scheme isEqualToString:@"https"];
        } else {
            secure = YES;
        }

        namespace = [[parts objectAtIndex:0] lowercaseString];
        NSString* pathString = [self decodePath:[NSString stringWithFormat:@"/%@", url]];
        path = [[FPath alloc] initWith:pathString];
    }
    else {
        [NSException raise:@"No Firebase database specified." format:@"No Firebase database found for input: %@", url];
    }

    FRepoInfo* repoInfo = [[FRepoInfo alloc] initWithHost:host isSecure:secure withNamespace:namespace];

    FFLog(@"I-RDB095002", @"---> Parsed (%@) to: (%@,%@); ns=(%@); path=(%@)", original, [repoInfo description], [repoInfo connectionURL], repoInfo.namespace, [path description]);

    FParsedUrl* parsedUrl = [[FParsedUrl alloc] init];
    parsedUrl.repoInfo = repoInfo;
    parsedUrl.path = path;

    return parsedUrl;
}

/*
 case str: JString => priString + "string:" + str.s;
 case bool: JBool => priString + "boolean:" + bool.value;
 case double: JDouble => priString + "number:" + double.num;
 case int: JInt => priString + "number:" + int.num;
 case _ => {
 error("Leaf node has value '" + data.value + "' of invalid type '" + data.value.getClass.toString + "'");
 "";
 }
 */

+ (NSString *) getJavascriptType:(id)obj {
    if ([obj isKindOfClass:[NSDictionary class]]) {
        return kJavaScriptObject;
    } else if([obj isKindOfClass:[NSString class]]) {
        return kJavaScriptString;
    }
    else if ([obj isKindOfClass:[NSNumber class]]) {
        // We used to just compare to @encode(BOOL) as suggested at
        // http://stackoverflow.com/questions/2518761/get-type-of-nsnumber, but on arm64, @encode(BOOL) returns "B"
        // instead of "c" even though objCType still returns 'c' (signed char).  So check both.
        if(strcmp([obj objCType], @encode(BOOL)) == 0 ||
           strcmp([obj objCType], @encode(signed char)) == 0) {
            return kJavaScriptBoolean;
        }
        else {
            return kJavaScriptNumber;
        }
    }
    else {
        return kJavaScriptNull;
    }
}

+ (NSError *) errorForStatus:(NSString *)status andReason:(NSString *)reason {
    static dispatch_once_t pred = 0;
    __strong static NSDictionary* errorMap = nil;
    __strong static NSDictionary* errorCodes = nil;
    dispatch_once(&pred, ^{
        errorMap = @{
            @"permission_denied": @"Permission Denied",
            @"unavailable": @"Service is unavailable",
            kFErrorWriteCanceled: @"Write cancelled by user"
        };
        errorCodes = @{
            @"permission_denied": @1,
            @"unavailable": @2,
            kFErrorWriteCanceled: @3
        };
    });

    if ([status isEqualToString:kFWPResponseForActionStatusOk]) {
        return nil;
    } else {
        NSInteger code;
        NSString* desc = nil;
        if (reason) {
            desc = reason;
        } else if ([errorMap objectForKey:status] != nil) {
            desc = [errorMap objectForKey:status];
        } else {
            desc = status;
        }

        if ([errorCodes objectForKey:status] != nil) {
            NSNumber* num = [errorCodes objectForKey:status];
            code = [num integerValue];
        } else {
            // XXX what to do here?
            code = 9999;
        }

        return [[NSError alloc] initWithDomain:kFErrorDomain code:code userInfo:@{NSLocalizedDescriptionKey: desc}];
    }
}

+ (NSNumber *) intForString:(NSString *)string {
    static NSCharacterSet *notDigits = nil;
    if (!notDigits) {
        notDigits = [[NSCharacterSet decimalDigitCharacterSet] invertedSet];
    }
    if ([string rangeOfCharacterFromSet:notDigits].length == 0) {
        NSInteger num;
        NSScanner* scanner = [NSScanner scannerWithString:string];
        if ([scanner scanInteger:&num]) {
            return [NSNumber numberWithInteger:num];
        }
    }
    return nil;
}

+ (NSString *) ieee754StringForNumber:(NSNumber *)val {
    double d = [val doubleValue];
    NSData* data = [NSData dataWithBytes:&d length:sizeof(double)];
    NSMutableString* str = [[NSMutableString alloc] init];
    const unsigned char* buffer = (const unsigned char*)[data bytes];
    for (int i = 0; i < data.length; i++) {
        unsigned char byte = buffer[7 - i];
        [str appendFormat:@"%02x", byte];
    }
    return str;
}

static inline BOOL tryParseStringToInt(__unsafe_unretained NSString* str, NSInteger* integer) {
    // First do some cheap checks (NOTE: The below checks are significantly faster than an equivalent regex :-( ).
    NSUInteger length = str.length;
    if (length > 11 || length == 0) {
        return NO;
    }
    long long value = 0;
    BOOL negative = NO;
    NSUInteger i = 0;
    if ([str characterAtIndex:0] == '-') {
        if (length == 1) {
            return NO;
        }
        negative = YES;
        i = 1;
    }
    for(; i < length; i++) {
        unichar c = [str characterAtIndex:i];
        // Must be a digit, or '-' if it's the first char.
        if (c < '0' || c > '9') {
            return NO;
        } else {
            int charValue = c - '0';
            value = value*10 + charValue;
        }
    }

    value = (negative) ? -value : value;

    if (value < INTEGER_32_MIN || value > INTEGER_32_MAX) {
        return NO;
    } else {
        *integer = (NSInteger)value;
        return YES;
    }
}

+ (NSString *) maxName {
    static dispatch_once_t once;
    static NSString *maxName;
    dispatch_once(&once, ^{
        maxName = [[NSString alloc] initWithFormat:@"[MAX_NAME]"];
    });
    return maxName;
}

+ (NSString *) minName {
    static dispatch_once_t once;
    static NSString *minName;
    dispatch_once(&once, ^{
        minName = [[NSString alloc] initWithFormat:@"[MIN_NAME]"];
    });
    return minName;
}

+ (NSComparisonResult) compareKey:(NSString *)a toKey:(NSString *)b {
    if (a == b) {
        return NSOrderedSame;
    } else if (a == [FUtilities minName] || b == [FUtilities maxName]) {
        return NSOrderedAscending;
    } else if (b == [FUtilities minName] || a == [FUtilities maxName]) {
        return NSOrderedDescending;
    } else {
        NSInteger aAsInt, bAsInt;
        if (tryParseStringToInt(a, &aAsInt)) {
            if (tryParseStringToInt(b, &bAsInt)) {
                if (aAsInt > bAsInt) {
                    return NSOrderedDescending;
                } else if (aAsInt < bAsInt) {
                    return NSOrderedAscending;
                } else if (a.length > b.length) {
                    return NSOrderedDescending;
                } else if (a.length < b.length) {
                    return NSOrderedAscending;
                } else {
                    return NSOrderedSame;
                }
            } else {
                return (NSComparisonResult) NSOrderedAscending;
            }
        } else if (tryParseStringToInt(b, &bAsInt)) {
            return (NSComparisonResult) NSOrderedDescending;
        } else {
            // Perform literal character by character search to prevent a > b && b > a issues.
            // Note that calling -(NSString *)decomposedStringWithCanonicalMapping also works.
            return [a compare:b options:NSLiteralSearch];
        }
    }
}

+ (NSComparator) keyComparator {
    return ^NSComparisonResult(__unsafe_unretained NSString *a, __unsafe_unretained NSString *b) {
        return [FUtilities compareKey:a toKey:b];
    };
}

+ (NSComparator) stringComparator {
    return ^NSComparisonResult(__unsafe_unretained NSString *a, __unsafe_unretained NSString *b) {
        return [a compare:b];
    };
}

+ (double) randomDouble {
    return ((double) arc4random() / ARC4RANDOM_MAX);
}

@end

