/*
 * Copyright (C) 2011 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.nfc_extras;

import java.io.IOException;

import android.annotation.SdkConstant;
import android.annotation.SdkConstant.SdkConstantType;
import android.content.Context;
import android.nfc.INfcAdapterExtras;
import android.nfc.NfcAdapter;
import android.os.Binder;
import android.os.Bundle;
import android.os.IBinder;
import android.os.RemoteException;

public class NfcExecutionEnvironment {
    private final INfcAdapterExtras mService;

    /**
     * Broadcast Action: An ISO-DEP AID was selected.
     *
     * <p>This happens as the result of a 'SELECT AID' command from an
     * external NFC reader/writer.
     *
     * <p>Always contains the extra field {@link #EXTRA_AID}
     *
     * <p class="note">
     * Requires the {@link android.Manifest.permission#WRITE_SECURE_SETTINGS} permission
     * to receive.
     */
    @SdkConstant(SdkConstantType.BROADCAST_INTENT_ACTION)
    public static final String ACTION_AID_SELECTED =
        "com.android.nfc_extras.action.AID_SELECTED";

    /**
     * Mandatory byte array extra field in {@link #ACTION_AID_SELECTED}.
     *
     * <p>Contains the AID selected.
     * @hide
     */
    public static final String EXTRA_AID = "com.android.nfc_extras.extra.AID";

    NfcExecutionEnvironment(INfcAdapterExtras service) {
        mService = service;
    }

    /**
     * Open the NFC Execution Environment on its contact interface.
     *
     * <p>Only one process may open the secure element at a time. If it is
     * already open, an {@link IOException} is thrown.
     *
     * <p>All other NFC functionality is disabled while the NFC-EE is open
     * on its contact interface, so make sure to call {@link #close} once complete.
     *
     * <p class="note">
     * Requires the {@link android.Manifest.permission#WRITE_SECURE_SETTINGS} permission.
     *
     * @throws IOException if the NFC-EE is already open, or some other error occurs
     */
    public void open() throws IOException {
        try {
            Bundle b = mService.open(new Binder());
            throwBundle(b);
        } catch (RemoteException e) {
            return;
        }
    }

    /**
     * Close the NFC Execution Environment on its contact interface.
     *
     * <p class="note">
     * Requires the {@link android.Manifest.permission#WRITE_SECURE_SETTINGS} permission.
     *
     * @throws IOException if the NFC-EE is already open, or some other error occurs
     */
    public void close() throws IOException {
        try {
            throwBundle(mService.close());
        } catch (RemoteException e) {
            return;
        }
    }

    /**
     * Send raw commands to the NFC-EE and receive the response.
     *
     * <p class="note">
     * Requires the {@link android.Manifest.permission#WRITE_SECURE_SETTINGS} permission.
     *
     * @throws IOException if the NFC-EE is not open, or some other error occurs
     */
    public byte[] transceive(byte[] in) throws IOException {
        Bundle b;
        try {
            b = mService.transceive(in);
        } catch (RemoteException e) {
            throw new IOException(e.getMessage());
        }
        throwBundle(b);
        return b.getByteArray("out");
    }

    private static void throwBundle(Bundle b) throws IOException {
        if (b.getInt("e") == -1) {
            throw new IOException(b.getString("m"));
        }
    }
}