/*
 * Copyright (C) 2007 The Android Open Source Project
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package android.widget;

import android.content.Context;
import android.text.Editable;
import android.text.SpannableString;
import android.text.Spanned;
import android.text.TextUtils;
import android.text.method.QwertyKeyListener;
import android.util.AttributeSet;

An editable text view, extending AutoCompleteTextView, that can show completion suggestions for the substring of the text where the user is typing instead of necessarily for the entire thing. 
 You must provide a Tokenizer to distinguish the various substrings. 
The following code snippet shows how to create a text view which suggests
various countries names while the user is typing:
public class CountriesActivity extends Activity {
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.autocomplete_7);
        ArrayAdapter<String> adapter = new ArrayAdapter<String>(this,
                android.R.layout.simple_dropdown_item_1line, COUNTRIES);
        MultiAutoCompleteTextView textView = findViewById(R.id.edit);
        textView.setAdapter(adapter);
        textView.setTokenizer(new MultiAutoCompleteTextView.CommaTokenizer());
    }
    private static final String[] COUNTRIES = new String[] {
        "Belgium", "France", "Italy", "Germany", "Spain"
    };
}
/**
 * An editable text view, extending {@link AutoCompleteTextView}, that
 * can show completion suggestions for the substring of the text where
 * the user is typing instead of necessarily for the entire thing.
 * <p>
 * You must provide a {@link Tokenizer} to distinguish the
 * various substrings.
 *
 * <p>The following code snippet shows how to create a text view which suggests
 * various countries names while the user is typing:</p>
 *
 * <pre class="prettyprint">
 * public class CountriesActivity extends Activity {
 *     protected void onCreate(Bundle savedInstanceState) {
 *         super.onCreate(savedInstanceState);
 *         setContentView(R.layout.autocomplete_7);
 *
 *         ArrayAdapter&lt;String&gt; adapter = new ArrayAdapter&lt;String&gt;(this,
 *                 android.R.layout.simple_dropdown_item_1line, COUNTRIES);
 *         MultiAutoCompleteTextView textView = findViewById(R.id.edit);
 *         textView.setAdapter(adapter);
 *         textView.setTokenizer(new MultiAutoCompleteTextView.CommaTokenizer());
 *     }
 *
 *     private static final String[] COUNTRIES = new String[] {
 *         "Belgium", "France", "Italy", "Germany", "Spain"
 *     };
 * }</pre>
 */

public class MultiAutoCompleteTextView extends AutoCompleteTextView {
    private Tokenizer mTokenizer;

    public MultiAutoCompleteTextView(Context context) {
        this(context, null);
    }

    public MultiAutoCompleteTextView(Context context, AttributeSet attrs) {
        this(context, attrs, com.android.internal.R.attr.autoCompleteTextViewStyle);
    }

    public MultiAutoCompleteTextView(Context context, AttributeSet attrs, int defStyleAttr) {
        this(context, attrs, defStyleAttr, 0);
    }

    public MultiAutoCompleteTextView(
            Context context, AttributeSet attrs, int defStyleAttr, int defStyleRes) {
        super(context, attrs, defStyleAttr, defStyleRes);
    }

    /* package */ void finishInit() { }

    
Sets the Tokenizer that will be used to determine the relevant
range of the text where the user is typing.
/**
     * Sets the Tokenizer that will be used to determine the relevant
     * range of the text where the user is typing.
     */
    public void setTokenizer(Tokenizer t) {
        mTokenizer = t;
    }

    
Instead of filtering on the entire contents of the edit box, this subclass method filters on the range from Tokenizer.findTokenStart to TextView.getSelectionEnd if the length of that range meets or exceeds AutoCompleteTextView.getThreshold. /**
     * Instead of filtering on the entire contents of the edit box,
     * this subclass method filters on the range from
     * {@link Tokenizer#findTokenStart} to {@link #getSelectionEnd}
     * if the length of that range meets or exceeds {@link #getThreshold}.
     */
    @Override
    protected void performFiltering(CharSequence text, int keyCode) {
        if (enoughToFilter()) {
            int end = getSelectionEnd();
            int start = mTokenizer.findTokenStart(text, end);

            performFiltering(text, start, end, keyCode);
        } else {
            dismissDropDown();

            Filter f = getFilter();
            if (f != null) {
                f.filter(null);
            }
        }
    }

    
Instead of filtering whenever the total length of the text exceeds the threshhold, this subclass filters only when the length of the range from Tokenizer.findTokenStart to TextView.getSelectionEnd meets or exceeds AutoCompleteTextView.getThreshold. /**
     * Instead of filtering whenever the total length of the text
     * exceeds the threshhold, this subclass filters only when the
     * length of the range from
     * {@link Tokenizer#findTokenStart} to {@link #getSelectionEnd}
     * meets or exceeds {@link #getThreshold}.
     */
    @Override
    public boolean enoughToFilter() {
        Editable text = getText();

        int end = getSelectionEnd();
        if (end < 0 || mTokenizer == null) {
            return false;
        }

        int start = mTokenizer.findTokenStart(text, end);

        if (end - start >= getThreshold()) {
            return true;
        } else {
            return false;
        }
    }

    
Instead of validating the entire text, this subclass method validates
each token of the text individually.  Empty tokens are removed.
/**
     * Instead of validating the entire text, this subclass method validates
     * each token of the text individually.  Empty tokens are removed.
     */
    @Override
    public void performValidation() {
        Validator v = getValidator();

        if (v == null || mTokenizer == null) {
            return;
        }

        Editable e = getText();
        int i = getText().length();
        while (i > 0) {
            int start = mTokenizer.findTokenStart(e, i);
            int end = mTokenizer.findTokenEnd(e, start);

            CharSequence sub = e.subSequence(start, end);
            if (TextUtils.isEmpty(sub)) {
                e.replace(start, i, "");
            } else if (!v.isValid(sub)) {
                e.replace(start, i,
                          mTokenizer.terminateToken(v.fixText(sub)));
            }

            i = start;
        }
    }

    
Starts filtering the content of the drop down list. The filtering
pattern is the specified range of text from the edit box. Subclasses may
override this method to filter with a different pattern, for
instance a smaller substring of text.
/**
     * <p>Starts filtering the content of the drop down list. The filtering
     * pattern is the specified range of text from the edit box. Subclasses may
     * override this method to filter with a different pattern, for
     * instance a smaller substring of <code>text</code>.</p>
     */
    protected void performFiltering(CharSequence text, int start, int end,
                                    int keyCode) {
        getFilter().filter(text.subSequence(start, end), this);
    }

    
Performs the text completion by replacing the range from Tokenizer.findTokenStart to TextView.getSelectionEnd by the the result of passing text through Tokenizer.terminateToken. In addition, the replaced region will be marked as an AutoText substition so that if the user immediately presses DEL, the completion will be undone. Subclasses may override this method to do some different insertion of the content into the edit box.
Params:
text – the selected suggestion in the drop down list/**
     * <p>Performs the text completion by replacing the range from
     * {@link Tokenizer#findTokenStart} to {@link #getSelectionEnd} by the
     * the result of passing <code>text</code> through
     * {@link Tokenizer#terminateToken}.
     * In addition, the replaced region will be marked as an AutoText
     * substition so that if the user immediately presses DEL, the
     * completion will be undone.
     * Subclasses may override this method to do some different
     * insertion of the content into the edit box.</p>
     *
     * @param text the selected suggestion in the drop down list
     */
    @Override
    protected void replaceText(CharSequence text) {
        clearComposingText();

        int end = getSelectionEnd();
        int start = mTokenizer.findTokenStart(getText(), end);

        Editable editable = getText();
        String original = TextUtils.substring(editable, start, end);

        QwertyKeyListener.markAsReplaced(editable, start, end, original);
        editable.replace(start, end, mTokenizer.terminateToken(text));
    }

    @Override
    public CharSequence getAccessibilityClassName() {
        return MultiAutoCompleteTextView.class.getName();
    }

    public static interface Tokenizer {
        
Returns the start of the token that ends at offset
cursor within text.
/**
         * Returns the start of the token that ends at offset
         * <code>cursor</code> within <code>text</code>.
         */
        public int findTokenStart(CharSequence text, int cursor);

        
Returns the end of the token (minus trailing punctuation)
that begins at offset cursor within text.
/**
         * Returns the end of the token (minus trailing punctuation)
         * that begins at offset <code>cursor</code> within <code>text</code>.
         */
        public int findTokenEnd(CharSequence text, int cursor);

        
Returns text, modified, if necessary, to ensure that
it ends with a token terminator (for example a space or comma).
/**
         * Returns <code>text</code>, modified, if necessary, to ensure that
         * it ends with a token terminator (for example a space or comma).
         */
        public CharSequence terminateToken(CharSequence text);
    }

    
This simple Tokenizer can be used for lists where the items are
separated by a comma and one or more spaces.
/**
     * This simple Tokenizer can be used for lists where the items are
     * separated by a comma and one or more spaces.
     */
    public static class CommaTokenizer implements Tokenizer {
        public int findTokenStart(CharSequence text, int cursor) {
            int i = cursor;

            while (i > 0 && text.charAt(i - 1) != ',') {
                i--;
            }
            while (i < cursor && text.charAt(i) == ' ') {
                i++;
            }

            return i;
        }

        public int findTokenEnd(CharSequence text, int cursor) {
            int i = cursor;
            int len = text.length();

            while (i < len) {
                if (text.charAt(i) == ',') {
                    return i;
                } else {
                    i++;
                }
            }

            return len;
        }

        public CharSequence terminateToken(CharSequence text) {
            int i = text.length();

            while (i > 0 && text.charAt(i - 1) == ' ') {
                i--;
            }

            if (i > 0 && text.charAt(i - 1) == ',') {
                return text;
            } else {
                if (text instanceof Spanned) {
                    SpannableString sp = new SpannableString(text + ", ");
                    TextUtils.copySpansFrom((Spanned) text, 0, text.length(),
                                            Object.class, sp, 0);
                    return sp;
                } else {
                    return text + ", ";
                }
            }
        }
    }
}