[Enhanced Bookmark]Rewrite initialization logic

chrome/android/java/src/org/chromium/chrome/browser/enhancedbookmarks/EnhancedBookmarkUIState.java

Index: chrome/android/java/src/org/chromium/chrome/browser/enhancedbookmarks/EnhancedBookmarkUIState.java
diff --git a/chrome/android/java/src/org/chromium/chrome/browser/enhancedbookmarks/EnhancedBookmarkUIState.java b/chrome/android/java/src/org/chromium/chrome/browser/enhancedbookmarks/EnhancedBookmarkUIState.java
new file mode 100644
index 0000000000000000000000000000000000000000..20dbdf0d3f5087de37abcadd5f9d1c021f810f3a
--- /dev/null
+++ b/chrome/android/java/src/org/chromium/chrome/browser/enhancedbookmarks/EnhancedBookmarkUIState.java
@@ -0,0 +1,158 @@
+// 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.
+
+package org.chromium.chrome.browser.enhancedbookmarks;
+
+import android.net.Uri;
+import android.text.TextUtils;
+
+import org.chromium.chrome.browser.UrlConstants;
+import org.chromium.components.bookmarks.BookmarkId;
+
+/**
+ * A class representing the UI state of the {@link EnhancedBookmarkManager}. All
+ * states can be uniquely identified by a URL.
+ */
+class EnhancedBookmarkUIState {
+    static final String URI_PERSIST_QUERY_NAME = "persist";
+
+    static final int STATE_LOADING = 1;
+    static final int STATE_ALL_BOOKMARKS = 2;
+    static final int STATE_FOLDER = 3;
+    static final int STATE_FILTER = 4;
+    private static final int STATE_INVALID = 0;
+
+    /**
+     * One of the STATE_* constants.
+     */
+    int mState;
+    String mUrl;
+    /** Whether this state should be persisted as user's last location. */
+    boolean mShouldPersist = true;
+    BookmarkId mFolder;
+    EnhancedBookmarkFilter mFilter;
+
+    static EnhancedBookmarkUIState createLoadingState() {
+        EnhancedBookmarkUIState state = new EnhancedBookmarkUIState();
+        state.mState = STATE_LOADING;
+        state.mShouldPersist = false;
+        state.mUrl = "";
+        return state;
+    }
+
+    static EnhancedBookmarkUIState createAllBookmarksState(EnhancedBookmarksModel bookmarkModel) {
+        return createStateFromUrl(Uri.parse(UrlConstants.BOOKMARKS_URL), bookmarkModel);
+    }
+
+    static EnhancedBookmarkUIState createFolderState(BookmarkId folder,
+            EnhancedBookmarksModel bookmarkModel) {
+        return createStateFromUrl(createFolderUrl(folder), bookmarkModel);
+    }
+
+    static EnhancedBookmarkUIState createFilterState(
+            EnhancedBookmarkFilter filter, EnhancedBookmarksModel bookmarkModel) {
+        return createStateFromUrl(createFilterUrl(filter, true), bookmarkModel);
+    }
+
+    /**
+     * @see #createStateFromUrl(Uri, EnhancedBookmarksModel)
+     */
+    static EnhancedBookmarkUIState createStateFromUrl(String url,
+            EnhancedBookmarksModel bookmarkModel) {
+        return createStateFromUrl(Uri.parse(url), bookmarkModel);
+    }
+
+    /**
+     * @return A state corresponding to the URI object. If the URI is not valid,
+     *         return all_bookmarks.
+     */
+    static EnhancedBookmarkUIState createStateFromUrl(Uri uri,
+            EnhancedBookmarksModel bookmarkModel) {
+        EnhancedBookmarkUIState state = new EnhancedBookmarkUIState();
+        state.mState = STATE_INVALID;
+        state.mUrl = uri.toString();
+        state.mShouldPersist = shouldPersist(uri);
+
+        if (state.mUrl.equals(UrlConstants.BOOKMARKS_URL)) {
+            state.mState = STATE_ALL_BOOKMARKS;
+        } else if (state.mUrl.startsWith(UrlConstants.BOOKMARKS_FOLDER_URL)) {
+            String path = uri.getLastPathSegment();
+            if (!path.isEmpty()) {
+                state.mFolder = BookmarkId.getBookmarkIdFromString(path);
+                state.mState = STATE_FOLDER;
+            }
+        } else if (state.mUrl.startsWith(UrlConstants.BOOKMARKS_FILTER_URL)) {
+            String path = uri.getLastPathSegment();
+            if (!path.isEmpty()) {
+                state.mState = STATE_FILTER;
+                state.mFilter = EnhancedBookmarkFilter.valueOf(path);
+            }
+        }
+
+        if (!state.isValid(bookmarkModel)) {
+            state.mState = STATE_ALL_BOOKMARKS;
+            state.mUrl = UrlConstants.BOOKMARKS_URL;
+        }
+
+        return state;
+    }
+
+    static Uri createFolderUrl(BookmarkId folderId) {
+        return createUrl(UrlConstants.BOOKMARKS_FOLDER_URL, folderId.toString(), true);
+    }
+
+    static Uri createFilterUrl(EnhancedBookmarkFilter filter, boolean shouldPersist) {
+        return createUrl(UrlConstants.BOOKMARKS_FILTER_URL, filter.value, shouldPersist);
+    }
+
+    /**
+     * Encodes the path and appends it to the base url. A simple appending
+     * does not work because there might be spaces in suffix.
+     * @param shouldPersist Whether this url should be saved to preferences as
+     *                      user's last location.
+     */
+    private static Uri createUrl(String baseUrl, String pathSuffix, boolean shouldPersist) {
+        Uri.Builder builder = Uri.parse(baseUrl).buildUpon();
+        builder.appendPath(pathSuffix);
+        if (!shouldPersist) {
+            builder.appendQueryParameter(URI_PERSIST_QUERY_NAME, "0");
+        }
+        return builder.build();
+    }
+
+    private static boolean shouldPersist(Uri uri) {
+        String queryString = uri.getQueryParameter(URI_PERSIST_QUERY_NAME);
+        return !("0".equals(queryString));
+    }
+
+    private EnhancedBookmarkUIState() {}
+
+    @Override
+    public int hashCode() {
+        return 31 * mUrl.hashCode() + mState;
+    }
+
+    @Override
+    public boolean equals(Object obj) {
+        if (!(obj instanceof EnhancedBookmarkUIState)) return false;
+        EnhancedBookmarkUIState other = (EnhancedBookmarkUIState) obj;
+        return mState == other.mState && TextUtils.equals(mUrl, other.mUrl);
+    }
+
+    /**
+     * @return Whether this state is valid.
+     */
+    boolean isValid(EnhancedBookmarksModel bookmarkModel) {
+        if (mUrl == null || mState == STATE_INVALID) return false;
+
+        if (mState == STATE_FOLDER) {
+            return mFolder != null && bookmarkModel.doesBookmarkExist(mFolder)
+                    && !mFolder.equals(bookmarkModel.getRootFolderId());
+        }
+
+        if (mState == STATE_FILTER && mFilter == null) return false;
+
+        return true;
+    }
+}