/*

 Copyright (C) 2016 Apple Inc. All Rights Reserved.

 See LICENSE.txt for this sample’s licensing information

 Abstract:

 Implements ZIP functionality for PIV standard

 */

#import <Foundation/Foundation.h>

#import <zlib.h>

#import <zconf.h>

#import "Token.h"

NS_ASSUME_NONNULL_BEGIN

@implementation NSData(Zip)

- (int)getWindowSize {

    int windowSize = MAX_WBITS;

    uint8_t *bytes = (uint8_t *)self.bytes;

    if (self.length > 2 && bytes[0] == 0x1F && bytes[1] == 0x8B) //gzip

        windowSize += 0x10;

    else

        windowSize += 0x20;

    return windowSize;

}

- (nullable NSData *)inflate {

    z_stream dstream;

    int windowSize = [self getWindowSize];

    dstream.zalloc = (alloc_func)0;

    dstream.zfree = (free_func)0;

    dstream.opaque = (voidpf)0;

    /* Input not altered , so de-const-casting ok*/

    dstream.next_in  = (Bytef*)self.bytes;

    dstream.avail_in = (uInt)self.length;

    int err = inflateInit2(&dstream, windowSize);

    if (err != Z_OK)

        return nil;

    NSUInteger offset = 0;

    NSMutableData *data = [NSMutableData dataWithLength:1024];

    for (;;) {

        dstream.next_out = [data mutableBytes] + offset;

        dstream.avail_out = (uInt)(data.length - offset);

        err = inflate(&dstream, Z_NO_FLUSH);

        if (err == Z_OK) {

            offset = data.length;

            [data setLength:data.length + data.length / 2];

        }

        else if (err == Z_STREAM_END) {

            break;

        }

        else {

            inflateEnd(&dstream);

            return nil;

        }

    }

    [data setLength:dstream.total_out];

    inflateEnd(&dstream);

    return data;

}

@end

NS_ASSUME_NONNULL_END