apps/Tag/src/com/android/apps/tag/SmartPoster.java

/*
 * Copyright (C) 2010 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 com.android.apps.tag;

import com.google.common.base.Preconditions;
import com.google.common.collect.Iterables;
import com.trustedlogic.trustednfc.android.NdefMessage;
import com.trustedlogic.trustednfc.android.NdefRecord;
import com.trustedlogic.trustednfc.android.NfcException;

import javax.annotation.Nullable;
import java.net.URI;
import java.util.Arrays;

/**
 * A representation of an NFC Forum "Smart Poster".
 */
public class SmartPoster {

    /**
     * NFC Forum Smart Poster Record Type Definition section 3.2.1.
     *
     * "The Title record for the service (there can be many of these in
     * different languages, but a language MUST NOT be repeated).
     * This record is optional."

     */
    private final String titleRecord;

    /**
     * NFC Forum Smart Poster Record Type Definition section 3.2.1.
     *
     * "The URI record. This is the core of the Smart Poster, and all other
     * records are just metadata about this record. There MUST be one URI
     * record and there MUST NOT be more than one."
     */
    private final URI uriRecord;

    private SmartPoster(URI uri, @Nullable String title) {
        uriRecord = Preconditions.checkNotNull(uri);
        titleRecord = title;
    }

    public URI getURI() {
        return uriRecord;
    }

    /**
     * Returns the title of the smartposter.  This may be {@code null}.
     */
    public String getTitle() {
        return titleRecord;
    }

    public static SmartPoster from(NdefRecord record) {
        Preconditions.checkArgument(record.getTnf() == NdefRecord.TNF_WELL_KNOWN_TYPE);
        Preconditions.checkArgument(Arrays.equals(record.getType(), NdefRecord.TYPE_SMART_POSTER));
        try {
            NdefMessage subRecords = new NdefMessage(record.getPayload());
            URI uri = Iterables.getOnlyElement(NdefUtil.getURIs(subRecords));
            Iterable<String> textFields = NdefUtil.getTextFields(subRecords);
            String title = null;
            if (!Iterables.isEmpty(textFields)) {
                title = Iterables.get(textFields, 0);
            }

            return new SmartPoster(uri, title);
        } catch (NfcException e) {
            throw new IllegalArgumentException(e);
        }
    }

    public static boolean isPoster(NdefRecord record) {
        try {
            from(record);
            return true;
        } catch (IllegalArgumentException e) {
            return false;
        }
    }
}