/*

 File: ZipDocument.m

 Abstract: ZipDocument is the NSDocument subclass representing

 a zip archive and serving as the browser's delegate.

 Version: 1.1

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 */ 

#import "ZipDocument.h"

#import "ZipEntry.h"

#import "ZipEntryView.h"

#define MIN_DIRECTORY_END_OFFSET    20

#define MAX_DIRECTORY_END_OFFSET    66000

#define DIRECTORY_END_TAG           0x06054b50

@implementation ZipDocument

/* Initialization and setup methods */

- (id)init {

    self = [super init];

    if (self) {

        rootEntry = [ZipEntry rootEntry];

    }

    return self;

}

- (NSString *)windowNibName {

    return @"ZipDocument";

}

- (void)windowControllerDidLoadNib:(NSWindowController *)aController {

    [super windowControllerDidLoadNib:aController];

    // Set up state associated with the preview column

    previewViewController = [[NSViewController alloc] initWithNibName:nil bundle:nil];

    previewEntryView = [[ZipEntryView alloc] initWithFrame:NSMakeRect(0, 0, 200, 200)];

    [previewViewController setView:previewEntryView];

    [previewEntryView setViewController:previewViewController];

}

/* Document reading methods */

- (BOOL)readFromURL:(NSURL *)absoluteURL ofType:(NSString *)typeName error:(NSError **)error {

    BOOL retval = NO;

    NSData *data = [NSData dataWithContentsOfURL:absoluteURL options:0 error:error];

    const uint8_t *bytes = [data bytes];

    unsigned i, length = [data length], directoryEntriesEnd = 0;

    unsigned numberOfDirectoryEntries = 0;

    unsigned potentialTag, directoryEntriesStart = 0, directoryIndex;

    NSString *path;

    ZipEntry *entry;

    if (data) {

        for (i = MIN_DIRECTORY_END_OFFSET; directoryEntriesEnd == 0 && i < MAX_DIRECTORY_END_OFFSET && i < length; i++) {

            potentialTag = NSSwapLittleIntToHost(*(uint32_t *)(bytes + length - i));

            if (potentialTag == DIRECTORY_END_TAG) {

                directoryEntriesEnd = length - i;

                numberOfDirectoryEntries = NSSwapLittleShortToHost(*(uint16_t *)(bytes + directoryEntriesEnd + 8));

                directoryEntriesStart = NSSwapLittleIntToHost(*(uint32_t *)(bytes + directoryEntriesEnd + 16));

            }

        }

        for (i = 0, directoryIndex = directoryEntriesStart; i < numberOfDirectoryEntries; i++) {

            unsigned compression, namelen, extralen, commentlen;

            unsigned crcval, csize, usize, headeridx;

            compression = NSSwapLittleShortToHost(*(uint16_t *)(bytes + directoryIndex + 10));

            crcval = NSSwapLittleIntToHost(*(uint32_t *)(bytes + directoryIndex + 16));

            csize = NSSwapLittleIntToHost(*(uint32_t *)(bytes + directoryIndex + 20));

            usize = NSSwapLittleIntToHost(*(uint32_t *)(bytes + directoryIndex + 24));

            namelen = NSSwapLittleShortToHost(*(uint16_t *)(bytes + directoryIndex + 28));

            extralen = NSSwapLittleShortToHost(*(uint16_t *)(bytes + directoryIndex + 30));

            commentlen = NSSwapLittleShortToHost(*(uint16_t *)(bytes + directoryIndex + 32));

            headeridx = NSSwapLittleIntToHost(*(uint32_t *)(bytes + directoryIndex + 42));

            path = [[NSFileManager defaultManager] stringWithFileSystemRepresentation:(const char *)(bytes + directoryIndex + 46) length:namelen];

            if (path) {

                entry = [[ZipEntry alloc] initWithPath:path headerOffset:headeridx CRC:crcval compressedSize:csize uncompressedSize:usize compressionType:compression];

                [entry addToRootEntry:rootEntry];

                retval = YES;

            } else {

                break;

            }

            directoryIndex += 46 + namelen + extralen + commentlen;

        }

        if (!retval && error) *error = [NSError errorWithDomain:NSCocoaErrorDomain code:NSFileReadCorruptFileError userInfo:[NSDictionary dictionaryWithObjectsAndKeys:absoluteURL, NSURLErrorKey, nil]];

    }

    return retval;

}

/* Browser support methods */

- (id)rootItemForBrowser:(NSBrowser *)browser {

    return rootEntry;

}

- (int)browser:(NSBrowser *)browser numberOfChildrenOfItem:(id)item {

    return [[(ZipEntry *)item childEntries] count];

}    

- (id)browser:(NSBrowser *)browser child:(int)index ofItem:(id)item {

    return [[(ZipEntry *)item childEntries] objectAtIndex:index];

}

- (BOOL)browser:(NSBrowser *)browser isLeafItem:(id)item {

    return [(ZipEntry *)item isLeaf];

}

- (id)browser:(NSBrowser *)browser objectValueForItem:(id)item {

    return [(ZipEntry *)item name];

}

- (NSViewController *)browser:(NSBrowser *)browser previewViewControllerForLeafItem:(id)item {

    return previewViewController;

}

@end