//
//  MBackup.m
//  CellLocations
//
//  Created by Simon Urbanek on 4/22/11.
//  Copyright 2011 Simon Urbanek. All rights reserved.
//

#import "MBackup.h"

#pragma pack(push)
#pragma pack(2)
typedef struct mbdx_record {
    unsigned char key[20];
    unsigned char offset[4];
    unsigned char mode[2];
} mbdx_record;
#pragma pack(pop)

@interface MBDXFile : NSObject
{
    NSInteger records;
    NSData *data;
    mbdx_record *index;
}
- (id) initWithPath: (NSString*) aPath;
- (NSString*) keyForOffset: (NSUInteger) off;
@end

@implementation MBDXFile
- (id) initWithPath: (NSString*) aPath
{
    if ((self = [super init])) {
	NSFileHandle *f = [NSFileHandle fileHandleForReadingAtPath:aPath];
	if (f) {
	    NSData *header = [f readDataOfLength:10];
	    const unsigned char *hd = (const unsigned char*) [header bytes];
	    if ([header length] == 10 && hd[0] == 'm' && hd[1] == 'b' &&
		hd[2] == 'd' && hd[3] == 'x') {
		records = ((unsigned int) hd[9]) |
		((unsigned int) hd[8]) << 8 |
		((unsigned int) hd[7]) << 16 |
		((unsigned int) hd[6]) << 24;
		data = [f readDataToEndOfFile];
		index = (mbdx_record*) [data bytes];
		if ([data length] < records * sizeof(mbdx_record)) {
		    NSLog(@"CellLocations.MBackup: truncated MBDX file %@ (expected %d, encountered %d)",
			  aPath, records * sizeof(mbdx_record), [data length]);
		    records = [data length] / sizeof(mbdx_record);
		}
		[data retain];
		NSLog(@" - %d records", records);
		return self;
	    }
	    [f closeFile];
	}
	[self release];
	self = nil;
    }
    return self;
}

- (void) dealloc
{
    if (data) [data release];
    [super dealloc];
}

- (NSString*) keyForOffset: (NSUInteger) off
{
    int i = 0;
    while (i < records) {
	unsigned int ro =
	((unsigned int)index[i].offset[3]) |
	((unsigned int)index[i].offset[2]) << 8 |
	((unsigned int)index[i].offset[1]) << 16 |
	((unsigned int)index[i].offset[0]) << 24;
	if (ro >= off && ro < off + 20) {
	    NSLog(@"keyForOffset: record %d at offset %x (matching %x)", i, ro, off);
	    char buf[42], *c = buf;
	    int j;
	    for (j = 0; j < 20; j++, c += 2)
		sprintf(c, "%02x", (int) index[i].key[j]);
	    buf[40] = 0;
	    return [NSString stringWithUTF8String:buf];
	}
	i++;
    }
    return nil;
}

@end

@implementation MBackup

- (id) initWithPath: (NSString*) aPath
{
    if ((self = [super init])) {
	path = [aPath copy];
	info = [NSDictionary dictionaryWithContentsOfFile:[path stringByAppendingString:@"/Info.plist"]];
	if (info) [info retain];
	mbdx = [[MBDXFile alloc] initWithPath:[path stringByAppendingString:@"/Manifest.mbdx"]];
    }
    return self;
}

- (void) dealloc
{
    if (path) [path release];
    if (info) [info release];
    if (mbdx) [mbdx release];
    [super dealloc];
}


- (BOOL) hasInfo
{ return (info != nil); }

- (BOOL) hasManifest
{ return (mbdx != nil); }

- (NSDictionary*) info
{ return info; }

- (NSString*) path
{ return path; }

- (NSString*) keyForPathContaining: (NSString*) substring
{
    if (!mbdx)
	return nil;
    NSFileHandle *fh = [NSFileHandle fileHandleForReadingAtPath:[path stringByAppendingString:@"/Manifest.mbdb"]];
    if (fh) {
	const char *csub = [substring UTF8String];
	if (csub) {
	    unsigned int sublen = strlen(csub);
	    NSData *cont = [fh readDataToEndOfFile];
	    const char *cc = [cont bytes], *oc = cc, *cs = cc + [cont length] - sublen;
	    while (cc < cs) {
		if (*cc == *csub && !memcmp(cc, csub, sublen)) {
		    NSLog(@"found match at %x", cc - oc);
		    /* rewind two NULs back - one for the path length and the other for the domain length.
		     * we are assuming that both involved strings are less than 256 characters long */
		    while (cc > oc && *cc) cc--; /* rewind to previous NUL */
		    if (cc > oc) cc--;
		    while (cc > oc && *cc) cc--; /* rewind to previous NUL */
		    NSLog(@" - records probably starts at %x", cc - oc);
		    return [mbdx keyForOffset: (cc - oc < 6) ? 0 : (cc - oc - 6)];
		}
		cc++;
	    }
	}
    }
    return nil;
}

@end