1/*
2 * Copyright (C) 2009 The Android Open Source Project
3 *
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
7 *
8 *      http://www.apache.org/licenses/LICENSE-2.0
9 *
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
15 */
16
17package com.android.quicksearchbox;
18
19import com.google.common.annotations.VisibleForTesting;
20
21import android.database.DataSetObservable;
22import android.database.DataSetObserver;
23
24import java.util.ArrayList;
25import java.util.Collection;
26import java.util.HashSet;
27
28/**
29 * A SuggestionCursor that is backed by a list of Suggestions.
30 */
31public class ListSuggestionCursor extends AbstractSuggestionCursorWrapper {
32
33    private static final int DEFAULT_CAPACITY = 16;
34
35    private final DataSetObservable mDataSetObservable = new DataSetObservable();
36
37    private final ArrayList<Entry> mSuggestions;
38
39    private HashSet<String> mExtraColumns;
40
41    private int mPos = 0;
42
43    public ListSuggestionCursor(String userQuery) {
44        this(userQuery, DEFAULT_CAPACITY);
45    }
46
47    @VisibleForTesting
48    public ListSuggestionCursor(String userQuery, Suggestion...suggestions) {
49        this(userQuery, suggestions.length);
50        for (Suggestion suggestion : suggestions) {
51            add(suggestion);
52        }
53    }
54
55    public ListSuggestionCursor(String userQuery, int capacity) {
56        super(userQuery);
57        mSuggestions = new ArrayList<Entry>(capacity);
58    }
59
60    /**
61     * Adds a suggestion from another suggestion cursor.
62     *
63     * @return {@code true} if the suggestion was added.
64     */
65    public boolean add(Suggestion suggestion) {
66        mSuggestions.add(new Entry(suggestion));
67        return true;
68    }
69
70    public void close() {
71        mSuggestions.clear();
72    }
73
74    public int getPosition() {
75        return mPos;
76    }
77
78    public void moveTo(int pos) {
79        mPos = pos;
80    }
81
82    public boolean moveToNext() {
83        int size = mSuggestions.size();
84        if (mPos >= size) {
85            // Already past the end
86            return false;
87        }
88        mPos++;
89        return mPos < size;
90    }
91
92    public void removeRow() {
93        mSuggestions.remove(mPos);
94    }
95
96    public void replaceRow(Suggestion suggestion) {
97        mSuggestions.set(mPos, new Entry(suggestion));
98    }
99
100    public int getCount() {
101        return mSuggestions.size();
102    }
103
104    @Override
105    protected Suggestion current() {
106        return mSuggestions.get(mPos).get();
107    }
108
109    @Override
110    public String toString() {
111        return getClass().getSimpleName() + "{[" + getUserQuery() + "] " + mSuggestions + "}";
112    }
113
114    /**
115     * Register an observer that is called when changes happen to this data set.
116     *
117     * @param observer gets notified when the data set changes.
118     */
119    public void registerDataSetObserver(DataSetObserver observer) {
120        mDataSetObservable.registerObserver(observer);
121    }
122
123    /**
124     * Unregister an observer that has previously been registered with
125     * {@link #registerDataSetObserver(DataSetObserver)}
126     *
127     * @param observer the observer to unregister.
128     */
129    public void unregisterDataSetObserver(DataSetObserver observer) {
130        mDataSetObservable.unregisterObserver(observer);
131    }
132
133    protected void notifyDataSetChanged() {
134        mDataSetObservable.notifyChanged();
135    }
136
137    @Override
138    public SuggestionExtras getExtras() {
139        // override with caching to avoid re-parsing the extras
140        return mSuggestions.get(mPos).getExtras();
141    }
142
143   public Collection<String> getExtraColumns() {
144        if (mExtraColumns == null) {
145            mExtraColumns = new HashSet<String>();
146            for (Entry e : mSuggestions) {
147                SuggestionExtras extras = e.getExtras();
148                Collection<String> extraColumns = extras == null ? null
149                        : extras.getExtraColumnNames();
150                if (extraColumns != null) {
151                    for (String column : extras.getExtraColumnNames()) {
152                        mExtraColumns.add(column);
153                    }
154                }
155            }
156        }
157        return mExtraColumns.isEmpty() ? null : mExtraColumns;
158    }
159
160    /**
161     * This class exists purely to cache the suggestion extras.
162     */
163    private static class Entry {
164        private final Suggestion mSuggestion;
165        private SuggestionExtras mExtras;
166        public Entry(Suggestion s) {
167            mSuggestion = s;
168        }
169        public Suggestion get() {
170            return mSuggestion;
171        }
172        public SuggestionExtras getExtras() {
173            if (mExtras == null) {
174                mExtras = mSuggestion.getExtras();
175            }
176            return mExtras;
177        }
178    }
179
180}
181