fixed bugs in icon selection view

download icon button now is only enabled for nodes
delete icon call now has saveguards to not run into assertions
delete icon context menu action gets disabled if not applicable
feedback for errors when downloading a icon
better error handling when download for icons fails

MacPass/MPIconSelectViewController.m

@@ -26,21 +26,33 @@
 #import "MPCollectionView.h"
 #import "MPCollectionViewItem.h"
 
+typedef NS_ENUM(NSInteger, MPIconDownloadStatus) {
+  MPIconDownloadStatusNone,
+  MPIconDownloadStatusProgress,
+  MPIconDownloadStatusError
+};
+
 @interface MPIconSelectViewController () <NSCollectionViewDelegate>
 
 /* UI properties */
 @property (weak) IBOutlet MPCollectionView *iconCollectionView;
 @property (weak) IBOutlet NSButton *imageButton;
+@property (weak) IBOutlet NSButton *downloadIconButton;
+@property (assign) MPIconDownloadStatus downloadStatus;
 
 @end
 
 @implementation MPIconSelectViewController
 
+@dynamic downloadStatus;
+
 - (NSString *)nibName {
   return @"IconSelection";
 }
 
 - (void)viewDidLoad {
+  KPKNode *node = self.representedObject;
+  self.downloadIconButton.enabled = (nil != node.asEntry);
   self.iconCollectionView.backgroundColors = @[NSColor.clearColor];
   self.iconCollectionView.selectable = YES;
   self.iconCollectionView.allowsMultipleSelection = NO;
@@ -64,35 +76,70 @@
 }
 
 - (IBAction)downloadIcon:(id)sender {
+  //self.downloadStatus = MPIconDownloadStatusProgress;
   KPKNode *node = self.representedObject;
   if(!node.asEntry) {
     return;
   }
-  NSString *rawURL = node.asEntry.url;
-  if([rawURL hasPrefix:@"http://"] || ![rawURL hasPrefix:@"https://"]) {
-    rawURL = [@"https://" stringByAppendingString:rawURL];
+  [self _downloadIconForURL:node.asEntry.url];
+}
+
+- (void)setDownloadStatus:(MPIconDownloadStatus)status {
+  switch (status) {
+    case MPIconDownloadStatusNone:
+      self.downloadIconButton.image = nil;
+      break;
+    case MPIconDownloadStatusError:
+      self.downloadIconButton.image = [NSImage imageNamed:NSImageNameCaution];
+      break;
+    case MPIconDownloadStatusProgress:
+      self.downloadIconButton.image = [NSImage imageNamed:NSImageNameRefreshTemplate];
+      break;
+  }
+}
+
+- (void)_downloadIconForURL:(NSString *)URLString {
+  if([URLString hasPrefix:@"http://"] || ![URLString hasPrefix:@"https://"]) {
+    URLString = [@"https://" stringByAppendingString:URLString];
   }
   
-  NSURL *url = [NSURL URLWithString:rawURL];
+  NSURL *url = [NSURL URLWithString:URLString];
   if(!url) {
+    self.downloadStatus = MPIconDownloadStatusError;
     return;
   }
   
   NSString *urlString = [NSString stringWithFormat:@"%@://%@/favicon.ico", url.scheme, url.host ? url.host : @""];
   NSURL *favIconURL = [NSURL URLWithString:urlString];
   if(!favIconURL) {
+    self.downloadStatus = MPIconDownloadStatusError;
     return;
   }
   
   KPKMetaData *metaData = ((MPDocument *)[NSDocumentController sharedDocumentController].currentDocument).tree.metaData;
   NSURLSessionTask *task = [[NSURLSession sharedSession] dataTaskWithURL:favIconURL completionHandler:^(NSData * _Nullable data, NSURLResponse * _Nullable response, NSError * _Nullable error) {
-    if(data) {
+    if(error) {
+      dispatch_async(dispatch_get_main_queue(), ^{
+        self.downloadStatus = MPIconDownloadStatusError;
+        [NSApp presentError:error];
+      });
+    }
+    if(data.length > 0) {
       dispatch_async(dispatch_get_main_queue(), ^{
         KPKIcon *newIcon = [[KPKIcon alloc] initWithImageData:data];
         if(newIcon) {
+          self.downloadStatus = MPIconDownloadStatusNone;
           [metaData addCustomIcon:newIcon];
           [self _updateCollectionViewContent];
         }
+        else {
+          self.downloadStatus = MPIconDownloadStatusError;
+        }
+      });
+    }
+    else {
+      dispatch_async(dispatch_get_main_queue(), ^{
+        self.downloadStatus = MPIconDownloadStatusError;
       });
     }
   }];
@@ -105,6 +152,9 @@
   if(index < firstCustomIndex) {
     return;
   }
+  if(index >= self.iconCollectionView.content.count) {
+    return;
+  }
   MPDocument *document = [NSDocumentController sharedDocumentController].currentDocument;
   KPKIcon *icon = self.iconCollectionView.content[index];
   [document.tree.metaData removeCustomIcon:icon];
@@ -127,6 +177,21 @@
   [self.view.window performClose:sender];
 }
 
+- (BOOL)validateMenuItem:(NSMenuItem *)menuItem {
+  if(menuItem.action == @selector(deleteIcon:)) {
+    NSUInteger index = self.iconCollectionView.contextMenuIndex;
+    NSUInteger firstCustomIndex = [MPIconHelper databaseIcons].count;
+    if(index < firstCustomIndex) {
+      return NO;
+    }
+    if(index >= self.iconCollectionView.content.count) {
+      return NO;
+    }
+    return YES;
+  }
+  return NO;
+}
+
 - (void)didSelectCollectionViewItem:(id)sender {
   if(![sender isKindOfClass:[NSCollectionViewItem class]]) {
     return;