Upstream most of the iOS WebUI support in ios/web/

ios/web/webui/crw_web_ui_page_builder.mm

+// Copyright 2015 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.
+
+#include "ios/web/webui/crw_web_ui_page_builder.h"
+
+#include <map>
+#include <string>
+#include <vector>
+
+#include "base/ios/weak_nsobject.h"
+#include "base/logging.h"
+#include "base/mac/bundle_locations.h"
+#include "base/mac/scoped_nsobject.h"
+#include "base/strings/sys_string_conversions.h"
+
+namespace {
+// Prefix for script tags. Used to locate JavaScript subresources.
+NSString* const kJSTagPrefix = @"<script src=\"";
+// Suffix for script tags. Used to locate JavaScript subresources.
+NSString* const kJSTagSuffix = @"\"></script>";
+// Prefix for stylesheet tags. Used to locate CSS subresources.
+NSString* const kCSSTagPrefix = @"<link rel=\"stylesheet\" href=\"";
+// Suffix for stylesheet tags. Used to locate CSS subresources.
+NSString* const kCSSTagSuffix = @"\">";
+// Template for creating inlined JavaScript tags.
+NSString* const kWebUIScriptTextTemplate = @"<script>%@</script>";
+// Template for creating inlined CSS tags.
+NSString* const kWebUIStyleTextTemplate = @"<style>%@</style>";
+// URL placeholder for WebUI messaging JavaScript.
+NSString* const kWebUICoreJSURL = @"chrome://resources/js/ios/core.js";
+}  // namespace
+
+@interface CRWWebUIPageBuilder ()
+
+// Builds WebUI page for URL with HTML as default resource.
+- (void)buildWebUIPageForHTML:(NSString*)HTML
+                     webUIURL:(const GURL&)URL
+            completionHandler:(web::WebUIPageCompletion)completionHandler;
+
+// Loads |resourceURL| by invoking _delegate.
+- (void)fetchResourceWithURL:(const GURL&)resourceURL
+           completionHandler:(web::WebUIDelegateCompletion)handler;
+
+// Loads |resourceURLs| by invoking _delegate. Members of resourceURLs must be
+// valid subresource URLs. |completionHandler| is called upon load of each
+// resource.
+- (void)fetchSubresourcesWithURLs:(const std::vector<GURL>&)resourceURLs
+                completionHandler:(web::WebUIDelegateCompletion)handler;
+
+// Looks for substrings surrounded by |prefix| and |suffix| in resource and
+// returns them as an NSSet.
+// For example, if prefix is "<a href='", suffix is "'>", and |resource|
+// includes substrings "<a href='http://www.apple.com'>" and
+// "<a href='chrome.html'>", return value will contain strings
+// "http://www.apple.com" and "chrome.html".
+- (NSSet*)URLStringsFromResource:(NSString*)resource
+                          prefix:(NSString*)prefix
+                          suffix:(NSString*)suffix;
+
+// Returns URL strings for subresources found in |HTML|. URLs are found by
+// searching for tags of the format <link rel="stylesheet" href="URLString">
+// and <script src="URLString">.
+- (NSSet*)URLStringsFromHTML:(NSString*)HTML;
+
+// Returns URL strings for subresources found in |CSS|. URLs are found by
+// searching for statements of the format @import(URLString).
+- (NSSet*)URLStringsFromCSS:(NSString*)CSS;
+
+// YES if subresourceURL is a valid subresource URL. Valid subresource URLs
+// include files with extension ".js" and ".css".
+- (BOOL)isValidSubresourceURL:(const GURL&)subresourceURL;
+
+// YES if subresourceURL is for a CSS resource.
+- (BOOL)isCSSSubresourceURL:(const GURL&)subresourceURL;
+
+// Prepends "<link rel="stylesheet" href="|URL|">" to the HTML link tag with
+// href=|sourceURL| in |HTML|.
+- (void)addCSSTagToHTML:(NSMutableString*)HTML
+                 forURL:(const GURL&)URL
+              sourceURL:(const GURL&)sourceURL;
+
+// Flattens HTML with provided map of URLs to resource strings.
+- (void)flattenHTML:(NSMutableString*)HTML
+    withSubresources:(std::map<GURL, std::string>)subresources;
+
+// Returns JavaScript needed for bridging WebUI chrome.send() messages to
+// the core.js defined message delivery system.
+- (NSString*)webUIJavaScript;
+
+@end
+
+@implementation CRWWebUIPageBuilder {
+  // Delegate for requesting resources.
+  base::WeakNSProtocol<id<CRWWebUIPageBuilderDelegate>> _delegate;
+}
+
+#pragma mark - Public Methods
+
+- (instancetype)init {
+  NOTREACHED();
+  return self;
+}
+
+- (instancetype)initWithDelegate:(id<CRWWebUIPageBuilderDelegate>)delegate {
+  if (self = [super init]) {
+    _delegate.reset(delegate);
+  }
+  return self;
+}
+
+- (void)buildWebUIPageForURL:(const GURL&)webUIURL
+           completionHandler:(web::WebUIPageCompletion)completionHandler {
+  [self fetchResourceWithURL:webUIURL
+           completionHandler:^(NSString* webUIHTML, const GURL& URL) {
+             [self buildWebUIPageForHTML:webUIHTML
+                                webUIURL:URL
+                       completionHandler:completionHandler];
+           }];
+}
+
+#pragma mark - Private Methods
+
+- (void)buildWebUIPageForHTML:(NSString*)HTML
+                     webUIURL:(const GURL&)pageURL
+            completionHandler:(web::WebUIPageCompletion)completionHandler {
+  __block base::scoped_nsobject<NSMutableString> webUIHTML([HTML mutableCopy]);
+  NSSet* subresourceURLStrings = [self URLStringsFromHTML:webUIHTML];
+  __block NSUInteger pendingSubresourceCount = [subresourceURLStrings count];
+  if (!pendingSubresourceCount) {
+    completionHandler(webUIHTML);
+    return;
+  }
+  __block std::map<GURL, std::string> subresources;
+  base::WeakNSObject<CRWWebUIPageBuilder> weakSelf(self);
+  // Completion handler for subresource loads.
+  __block web::WebUIDelegateCompletion subresourceHandler = nil;
+  subresourceHandler = [[^(NSString* subresource, const GURL& subresourceURL) {
+    // Import statements in CSS resources are also loaded.
+    if ([self isCSSSubresourceURL:subresourceURL]) {
+      NSSet* URLStrings = [weakSelf URLStringsFromCSS:subresource];
+      for (NSString* URLString in URLStrings) {
+        GURL URL(subresourceURL.Resolve(base::SysNSStringToUTF8(URLString)));
+        [weakSelf addCSSTagToHTML:webUIHTML
+                           forURL:URL
+                        sourceURL:subresourceURL];
+        pendingSubresourceCount++;
+        [weakSelf fetchResourceWithURL:URL
+                     completionHandler:subresourceHandler];
+      }
+    }
+    subresources[subresourceURL] = base::SysNSStringToUTF8(subresource);
+    pendingSubresourceCount--;
+    // When subresource loading is complete, flatten the default resource
+    // and invoke the completion handler.
+    if (!pendingSubresourceCount) {
+      [weakSelf flattenHTML:webUIHTML withSubresources:subresources];
+      completionHandler(webUIHTML);
+    }
+  } copy] autorelease];
+
+  for (NSString* URLString in subresourceURLStrings) {
+    // chrome://resources/js/ios/core.js is skipped because it is
+    // retrieved via webUIJavaScript rather than the net stack.
+    if ([URLString isEqualToString:kWebUICoreJSURL]) {
+      pendingSubresourceCount--;
+      if (!pendingSubresourceCount) {
+        [weakSelf flattenHTML:webUIHTML withSubresources:subresources];
+        completionHandler(webUIHTML);
+      }
+      continue;
+    }
+    GURL URL(pageURL.Resolve(base::SysNSStringToUTF8(URLString)));
+    // If the resolved URL is different from URLString, replace URLString in
+    // webUIHTML so that it will be located appropriately when flattening
+    // occurs.
+    if (URL.spec() != base::SysNSStringToUTF8(URLString)) {
+      [webUIHTML replaceOccurrencesOfString:URLString
+                                 withString:base::SysUTF8ToNSString(URL.spec())
+                                    options:0
+                                      range:NSMakeRange(0, [HTML length])];
+    }
+    [self fetchResourceWithURL:URL completionHandler:subresourceHandler];
+  }
+}
+
+- (void)fetchResourceWithURL:(const GURL&)resourceURL
+           completionHandler:(web::WebUIDelegateCompletion)handler {
+  [_delegate webUIPageBuilder:self
+         fetchResourceWithURL:resourceURL
+            completionHandler:handler];
+}
+
+- (void)fetchSubresourcesWithURLs:(const std::vector<GURL>&)resourceURLs
+                completionHandler:(web::WebUIDelegateCompletion)handler {
+  for (const GURL& URL : resourceURLs) {
+    DCHECK([self isValidSubresourceURL:URL]);
+    [self fetchResourceWithURL:URL completionHandler:handler];
+  }
+}
+
+- (NSSet*)URLStringsFromResource:(NSString*)resource
+                          prefix:(NSString*)prefix
+                          suffix:(NSString*)suffix {
+  DCHECK(resource);
+  DCHECK(prefix);
+  DCHECK(suffix);
+  NSMutableSet* URLStrings = [NSMutableSet set];
+  NSError* error = nil;
+  NSString* tagPattern = [NSString
+      stringWithFormat:@"%@(.*?)%@",
+                       [NSRegularExpression escapedPatternForString:prefix],
+                       [NSRegularExpression escapedPatternForString:suffix]];
+  NSRegularExpression* tagExpression = [NSRegularExpression
+      regularExpressionWithPattern:tagPattern
+                           options:NSRegularExpressionCaseInsensitive
+                             error:&error];
+  if (error) {
+    DLOG(WARNING) << "Error: " << error.description.UTF8String;
+  }
+  NSArray* matches =
+      [tagExpression matchesInString:resource
+                             options:0
+                               range:NSMakeRange(0, [resource length])];
+  for (NSTextCheckingResult* match in matches) {
+    NSRange matchRange = [match rangeAtIndex:1];
+    DCHECK(matchRange.length);
+    NSString* URLString = [resource substringWithRange:matchRange];
+    [URLStrings addObject:URLString];
+  }
+  return URLStrings;
+}
+
+- (NSSet*)URLStringsFromHTML:(NSString*)HTML {
+  NSSet* JS = [self URLStringsFromResource:HTML
+                                    prefix:kJSTagPrefix
+                                    suffix:kJSTagSuffix];
+  NSSet* CSS = [self URLStringsFromResource:HTML
+                                     prefix:kCSSTagPrefix
+                                     suffix:kCSSTagSuffix];
+  return [JS setByAddingObjectsFromSet:CSS];
+}
+
+- (NSSet*)URLStringsFromCSS:(NSString*)CSS {
+  NSString* prefix = @"@import url(";
+  NSString* suffix = @");";
+  return [self URLStringsFromResource:CSS prefix:prefix suffix:suffix];
+}
+
+- (BOOL)isValidSubresourceURL:(const GURL&)subresourceURL {
+  base::FilePath resourcePath(subresourceURL.ExtractFileName());
+  std::string extension = resourcePath.Extension();
+  return extension == ".css" || extension == ".js";
+}
+
+- (BOOL)isCSSSubresourceURL:(const GURL&)subresourceURL {
+  base::FilePath resourcePath(subresourceURL.ExtractFileName());
+  std::string extension = resourcePath.Extension();
+  return extension == ".css";
+}
+
+- (void)addCSSTagToHTML:(NSMutableString*)HTML
+                 forURL:(const GURL&)URL
+              sourceURL:(const GURL&)sourceURL {
+  NSString* URLString = base::SysUTF8ToNSString(URL.spec());
+  NSString* sourceURLString = base::SysUTF8ToNSString(sourceURL.spec());
+  NSString* sourceTag =
+      [NSString stringWithFormat:@"%@%@%@", kCSSTagPrefix, sourceURLString,
+                                 kCSSTagSuffix];
+  NSString* extendedTag = [[NSString
+      stringWithFormat:@"%@%@%@", kCSSTagPrefix, URLString, kCSSTagSuffix]
+      stringByAppendingString:sourceTag];
+  [HTML replaceOccurrencesOfString:sourceTag
+                        withString:extendedTag
+                           options:0
+                             range:NSMakeRange(0, [HTML length])];
+}
+
+- (void)flattenHTML:(NSMutableString*)HTML
+    withSubresources:(std::map<GURL, std::string>)subresources {
+  // Add core.js script to resources.
+  GURL webUIJSURL("chrome://resources/js/ios/core.js");
+  subresources[webUIJSURL] = base::SysNSStringToUTF8([self webUIJavaScript]);
+  for (auto it = subresources.begin(); it != subresources.end(); it++) {
+    NSString* linkTemplate = @"";
+    NSString* textTemplate = @"";
+    if ([self isCSSSubresourceURL:it->first]) {
+      linkTemplate =
+          [NSString stringWithFormat:@"%@%%@%@", kCSSTagPrefix, kCSSTagSuffix];
+      textTemplate = kWebUIStyleTextTemplate;
+    } else {  // JavaScript.
+      linkTemplate =
+          [NSString stringWithFormat:@"%@%%@%@", kJSTagPrefix, kJSTagSuffix];
+      textTemplate = kWebUIScriptTextTemplate;
+    }
+    NSString* resourceURLString = base::SysUTF8ToNSString(it->first.spec());
+    NSString* linkTag =
+        [NSString stringWithFormat:linkTemplate, resourceURLString];
+    NSString* resource = base::SysUTF8ToNSString(it->second);
+    NSString* textTag = [NSString stringWithFormat:textTemplate, resource];
+    [HTML replaceOccurrencesOfString:linkTag
+                          withString:textTag
+                             options:0
+                               range:NSMakeRange(0, [HTML length])];
+  }
+}
+
+- (NSString*)webUIJavaScript {
+  NSBundle* bundle = base::mac::FrameworkBundle();
+  NSString* path = [bundle pathForResource:@"web_ui" ofType:@"js"];
+  DCHECK(path) << "web_ui.js file not found";
+  return [NSString stringWithContentsOfFile:path
+                                   encoding:NSUTF8StringEncoding
+                                      error:nil];
+}
+
+@end