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1 // Copyright (c) 2010 The Chromium Authors. All rights reserved.
2 // Use of this source code is governed by a BSD-style license that can be
3 // found in the LICENSE file.
4 
5 // BookmarkCodec is responsible for encoding and decoding the BookmarkModel
6 // into JSON values. The encoded values are written to disk via the
7 // BookmarkService.
8 
9 #ifndef CHROME_BROWSER_BOOKMARKS_BOOKMARK_CODEC_H_
10 #define CHROME_BROWSER_BOOKMARKS_BOOKMARK_CODEC_H_
11 #pragma once
12 
13 #include <set>
14 #include <string>
15 
16 #include "base/basictypes.h"
17 #include "base/md5.h"
18 #include "base/string16.h"
19 
20 class BookmarkModel;
21 class BookmarkNode;
22 class DictionaryValue;
23 class ListValue;
24 class Value;
25 
26 // BookmarkCodec is responsible for encoding/decoding bookmarks into JSON
27 // values. BookmarkCodec is used by BookmarkService.
28 
29 class BookmarkCodec {
30  public:
31   // Creates an instance of the codec. During decoding, if the IDs in the file
32   // are not unique, we will reassign IDs to make them unique. There are no
33   // guarantees on how the IDs are reassigned or about doing minimal
34   // reassignments to achieve uniqueness.
35   BookmarkCodec();
36   ~BookmarkCodec();
37 
38   // Encodes the model to a JSON value. It's up to the caller to delete the
39   // returned object. This is invoked to encode the contents of the bookmark bar
40   // model and is currently a convenience to invoking Encode that takes the
41   // bookmark bar node and other folder node.
42   Value* Encode(BookmarkModel* model);
43 
44   // Encodes the bookmark bar and other folders returning the JSON value. It's
45   // up to the caller to delete the returned object.
46   // This method is public for use by StarredURLDatabase in migrating the
47   // bookmarks out of the database.
48   Value* Encode(const BookmarkNode* bookmark_bar_node,
49                 const BookmarkNode* other_folder_node);
50 
51   // Decodes the previously encoded value to the specified nodes as well as
52   // setting |max_node_id| to the greatest node id. Returns true on success,
53   // false otherwise. If there is an error (such as unexpected version) all
54   // children are removed from the bookmark bar and other folder nodes. On exit
55   // |max_node_id| is set to the max id of the nodes.
56   bool Decode(BookmarkNode* bb_node,
57               BookmarkNode* other_folder_node,
58               int64* max_node_id,
59               const Value& value);
60 
61   // Returns the checksum computed during last encoding/decoding call.
computed_checksum()62   const std::string& computed_checksum() const { return computed_checksum_; }
63 
64   // Returns the checksum that's stored in the file. After a call to Encode,
65   // the computed and stored checksums are the same since the computed checksum
66   // is stored to the file. After a call to decode, the computed checksum can
67   // differ from the stored checksum if the file contents were changed by the
68   // user.
stored_checksum()69   const std::string& stored_checksum() const { return stored_checksum_; }
70 
71   // Returns whether the IDs were reassigned during decoding. Always returns
72   // false after encoding.
ids_reassigned()73   bool ids_reassigned() const { return ids_reassigned_; }
74 
75   // Names of the various keys written to the Value.
76   static const char* kRootsKey;
77   static const char* kRootFolderNameKey;
78   static const char* kOtherBookmarkFolderNameKey;
79   static const char* kVersionKey;
80   static const char* kChecksumKey;
81   static const char* kIdKey;
82   static const char* kTypeKey;
83   static const char* kNameKey;
84   static const char* kDateAddedKey;
85   static const char* kURLKey;
86   static const char* kDateModifiedKey;
87   static const char* kChildrenKey;
88 
89   // Possible values for kTypeKey.
90   static const char* kTypeURL;
91   static const char* kTypeFolder;
92 
93  private:
94   // Encodes node and all its children into a Value object and returns it.
95   // The caller takes ownership of the returned object.
96   Value* EncodeNode(const BookmarkNode* node);
97 
98   // Helper to perform decoding.
99   bool DecodeHelper(BookmarkNode* bb_node,
100                     BookmarkNode* other_folder_node,
101                     const Value& value);
102 
103   // Decodes the children of the specified node. Returns true on success.
104   bool DecodeChildren(const ListValue& child_value_list,
105                       BookmarkNode* parent);
106 
107   // Reassigns bookmark IDs for all nodes.
108   void ReassignIDs(BookmarkNode* bb_node, BookmarkNode* other_node);
109 
110   // Helper to recursively reassign IDs.
111   void ReassignIDsHelper(BookmarkNode* node);
112 
113   // Decodes the supplied node from the supplied value. Child nodes are
114   // created appropriately by way of DecodeChildren. If node is NULL a new
115   // node is created and added to parent (parent must then be non-NULL),
116   // otherwise node is used.
117   bool DecodeNode(const DictionaryValue& value,
118                   BookmarkNode* parent,
119                   BookmarkNode* node);
120 
121   // Updates the check-sum with the given string.
122   void UpdateChecksum(const std::string& str);
123   void UpdateChecksum(const string16& str);
124 
125   // Updates the check-sum with the given contents of URL/folder bookmark node.
126   // NOTE: These functions take in individual properties of a bookmark node
127   // instead of taking in a BookmarkNode for efficiency so that we don't convert
128   // various data-types to UTF16 strings multiple times - once for serializing
129   // and once for computing the check-sum.
130   // The url parameter should be a valid UTF8 string.
131   void UpdateChecksumWithUrlNode(const std::string& id,
132                                  const string16& title,
133                                  const std::string& url);
134   void UpdateChecksumWithFolderNode(const std::string& id,
135                                     const string16& title);
136 
137   // Initializes/Finalizes the checksum.
138   void InitializeChecksum();
139   void FinalizeChecksum();
140 
141   // Whether or not IDs were reassigned by the codec.
142   bool ids_reassigned_;
143 
144   // Whether or not IDs are valid. This is initially true, but set to false
145   // if an id is missing or not unique.
146   bool ids_valid_;
147 
148   // Contains the id of each of the nodes found in the file. Used to determine
149   // if we have duplicates.
150   std::set<int64> ids_;
151 
152   // MD5 context used to compute MD5 hash of all bookmark data.
153   MD5Context md5_context_;
154 
155   // Checksums.
156   std::string computed_checksum_;
157   std::string stored_checksum_;
158 
159   // Maximum ID assigned when decoding data.
160   int64 maximum_id_;
161 
162   DISALLOW_COPY_AND_ASSIGN(BookmarkCodec);
163 };
164 
165 #endif  // CHROME_BROWSER_BOOKMARKS_BOOKMARK_CODEC_H_
166