#import "SDFileAttributeHelper.h"
#import <sys/xattr.h>

@implementation SDFileAttributeHelper

+ (NSArray*)extendedAttributeNamesAtPath:(NSString *)path traverseLink:(BOOL)follow error:(NSError **)err {
    int flags = follow? 0 : XATTR_NOFOLLOW;
    
    
    ssize_t nameBuffLen = listxattr([path fileSystemRepresentation], NULL, 0, flags);
    if (nameBuffLen == -1) {
        if (err) *err = [NSError errorWithDomain:NSPOSIXErrorDomain code:errno userInfo:
                         @{
                             @"error": [NSString stringWithUTF8String:strerror(errno)],
                             @"function": @"listxattr",
                             @":path": path,
                             @":traverseLink": @(follow)
                         }
                         ];
        return nil;
    } else if (nameBuffLen == 0) return @[];
    
    
    NSMutableData *nameBuff = [NSMutableData dataWithLength:nameBuffLen];
    listxattr([path fileSystemRepresentation], [nameBuff mutableBytes], nameBuffLen, flags);
    
    
    NSMutableArray * names = [NSMutableArray arrayWithCapacity:5];
    char *nextName, *endOfNames = [nameBuff mutableBytes] + nameBuffLen;
    for(nextName = [nameBuff mutableBytes]; nextName < endOfNames; nextName += 1+strlen(nextName))
        [names addObject:[NSString stringWithUTF8String:nextName]];
    return names.copy;
}

+ (BOOL)hasExtendedAttribute:(NSString *)name atPath:(NSString *)path traverseLink:(BOOL)follow error:(NSError **)err {
    int flags = follow? 0 : XATTR_NOFOLLOW;
    
    
    ssize_t nameBuffLen = listxattr([path fileSystemRepresentation], NULL, 0, flags);
    if (nameBuffLen == -1) {
        if (err) *err = [NSError errorWithDomain:NSPOSIXErrorDomain code:errno userInfo:
                         @{
                             @"error": [NSString stringWithUTF8String:strerror(errno)],
                             @"function": @"listxattr",
                             @":path": path,
                             @":traverseLink": @(follow)
                         }
                         ];
        return NO;
    } else if (nameBuffLen == 0) return NO;
    
    
    NSMutableData *nameBuff = [NSMutableData dataWithLength:nameBuffLen];
    listxattr([path fileSystemRepresentation], [nameBuff mutableBytes], nameBuffLen, flags);
    
    
    char *nextName, *endOfNames = [nameBuff mutableBytes] + nameBuffLen;
    for(nextName = [nameBuff mutableBytes]; nextName < endOfNames; nextName += 1+strlen(nextName))
        if (strcmp(nextName, [name UTF8String]) == 0) return YES;
    return NO;
}

+ (NSData *)extendedAttribute:(NSString *)name atPath:(NSString *)path traverseLink:(BOOL)follow error:(NSError **)err {
    int flags = follow? 0 : XATTR_NOFOLLOW;
    
    ssize_t attrLen = getxattr([path fileSystemRepresentation], [name UTF8String], NULL, 0, 0, flags);
    if (attrLen == -1) {
        if (err) *err = [NSError errorWithDomain:NSPOSIXErrorDomain code:errno userInfo:
                         @{
                             @"error": [NSString stringWithUTF8String:strerror(errno)],
                             @"function": @"getxattr",
                             @":name": name,
                             @":path": path,
                             @":traverseLink": @(follow)
                         }
                         ];
        return nil;
    }
    
    
    NSMutableData *attrData = [NSMutableData dataWithLength:attrLen];
    getxattr([path fileSystemRepresentation], [name UTF8String], [attrData mutableBytes], attrLen, 0, flags);
    return attrData;
}

+ (BOOL)setExtendedAttribute:(NSString *)name value:(NSData *)value atPath:(NSString *)path traverseLink:(BOOL)follow overwrite:(BOOL)overwrite error:(NSError **)err {
    int flags = (follow? 0 : XATTR_NOFOLLOW) | (overwrite? 0 : XATTR_CREATE);
    if (0 == setxattr([path fileSystemRepresentation], [name UTF8String], [value bytes], [value length], 0, flags)) return YES;
    
    if (err) *err = [NSError errorWithDomain:NSPOSIXErrorDomain code:errno userInfo:
                     @{
                         @"error": [NSString stringWithUTF8String:strerror(errno)],
                         @"function": @"setxattr",
                         @":name": name,
                         @":value.length": @(value.length),
                         @":path": path,
                         @":traverseLink": @(follow),
                         @":overwrite": @(overwrite)
                     }
                     ];
    return NO;
}

+ (BOOL)removeExtendedAttribute:(NSString *)name atPath:(NSString *)path traverseLink:(BOOL)follow error:(NSError **)err {
    int flags = (follow? 0 : XATTR_NOFOLLOW);
    if (0 == removexattr([path fileSystemRepresentation], [name UTF8String], flags)) return YES;
    
    if (err) *err = [NSError errorWithDomain:NSPOSIXErrorDomain code:errno userInfo:
                     @{
                         @"error": [NSString stringWithUTF8String:strerror(errno)],
                         @"function": @"removexattr",
                         @":name": name,
                         @":path": path,
                         @":traverseLink": @(follow)
                     }
                     ];
    return NO;
}

@end