Initial commit for Chrome metainstaller on Mac.

chrome/installer/mac/app/downloader.m

+// Copyright (c) 2016 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#import <Foundation/Foundation.h>
+#import "downloader.h"
+
+@implementation Downloader
+
+@synthesize chromeDownloadURLs;

[Mark Mentovai, 2016/06/28 15:42:51]

We synthesize things into instance variables with trailing underscores, so that
it’s clear in the code when you’re referring to an instance variable. You’d do:

@synthesize chromeDownloadURLs = chromeDownloadURLs_;

But actually, now that I see what you’re doing with these, they don’t look very
property-like at all. You might be better off with pure instance variables
instead of properties.

+@synthesize chromeImageFilename;
+
+- (id)init {
+  if ((self = [super init])) {
+    chromeDownloadURLs = [[NSMutableArray alloc] init];
+  }
+  return self;
+}
+
+- (void)parseXML:(NSData*)omahaResponseXML {
+  NSData *response = omahaResponseXML;
+  NSXMLParser *parser = [[NSXMLParser alloc] initWithData:response];
+  [parser setDelegate:self];
+  bool success = [parser parse];
+  if (!success) {
+    NSError *err = [parser parserError];
+    NSLog(@"%@",err);
+  }
+}
+
+- (void)appendFilenameToURL {
+  int count = [chromeDownloadURLs count];

[Mark Mentovai, 2016/06/28 15:42:50]

-[NSArray count] returns type NSUInteger, not int.

+  for (int i = 0; i < count; i++) {

[Mark Mentovai, 2016/06/28 15:42:51]

But to just walk over a NSArray in Objective-C, you can write

  for (id downloadURL in chromeDownloadURLs) {
  }

+    NSString *fullFilename = [[chromeDownloadURLs objectAtIndex:i]
+                              stringByAppendingString: chromeImageFilename];
+    [chromeDownloadURLs replaceObjectAtIndex:i withObject: fullFilename];
+  }
+}
+
+// Method implementation for XMLParserDelegate.
+// Will search the XML data for the tag "url" and the subsequent "codebase" attribute

[Mark Mentovai, 2016/06/28 15:42:50]

Watch the 80-column limit

+
+- (void)parser:(NSXMLParser *)parser
+didStartElement:(NSString *)elementName
+  namespaceURI:(NSString *)namespaceURI
+ qualifiedName:(NSString *)qName
+    attributes:(NSDictionary *)attributeDict {
+  if ([elementName isEqualToString:@"url"]) {
+    NSString *extractedURL = [attributeDict objectForKey:@"codebase"];
+    [chromeDownloadURLs addObject: extractedURL];
+  }
+  if ([elementName isEqualToString:@"package"]) {
+    chromeImageFilename = [attributeDict objectForKey:@"name"];
+  }
+}
+
+
+- (NSURL*)getChromeImageURL: (NSData*)chromeImageAsData {
+  [self parseXML:chromeImageAsData];
+  [self appendFilenameToURL];

[Mark Mentovai, 2016/06/28 15:42:50]

If the parse failed, chromeImageFilename might not be set at all, and then this
will try to use it. That can’t be good!

+
+  NSArray *downloadLinks = [NSArray arrayWithArray:chromeDownloadURLs];
+  if(!downloadLinks || [downloadLinks count] < 1) {
+    NSLog(@"There were no download links found.");
+    return nil;
+  }
+  NSString *chromeURLString = [downloadLinks firstObject];
+
+  return [NSURL URLWithString: chromeURLString];
+}
+
+//TODO(ivan): make this not suck using [NSURLSession downloadTaskWithURL:] instead 👍.

[Mark Mentovai, 2016/06/28 15:42:51]

I like the emoji!

+- (NSData*)downloadChromeAsData: (NSURL*)chromeURL {
+  return [NSData dataWithContentsOfURL:chromeURL];
+}
+
+- (NSString*)getDownloadsFilePath {
+  NSArray *downloadPaths = NSSearchPathForDirectoriesInDomains(
+                                                               NSDownloadsDirectory, NSUserDomainMask, YES);
+  NSString *filePathToDownloads = [downloadPaths objectAtIndex:0];
+  NSArray *filenameComposition = @[filePathToDownloads, @"GoogleChrome.dmg"];
+  NSString *completeFilePath = [NSString pathWithComponents: filenameComposition];
+  return completeFilePath;
+}
+
+- (void)writeChromeImageToDownloadsDirectory: (NSData*)chromeImageAsData {
+  if (chromeImageAsData) {
+    NSString *filePath = [self getDownloadsFilePath];
+    [chromeImageAsData writeToFile:filePath atomically:YES];

[Mark Mentovai, 2016/06/28 15:42:50]

What if it already exists, you overwrite it?

We’ll need to cope with this. Not necessarily now, but you should call it out in
a TODO.

+
+    NSLog(@"File was downloaded to %@.", filePath);
+  } else {
+    NSLog(@"Error downloading file.");
+  }
+}
+
+- (void)downloadChromeImageToDownloadsDirectory: (NSData*)responseXMLData {
+  NSURL *chromeURL = [self getChromeImageURL: responseXMLData];
+  NSData *chromeImageData = [self downloadChromeAsData: chromeURL];
+  [self writeChromeImageToDownloadsDirectory: chromeImageData];
+}
+
+@end