/*
 * Copyright (C) 2014 Dominik Schürmann <dominik@dominikschuermann.de>
 *
 * 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 org.openintents.openpgp.util;

import android.annotation.TargetApi;
import android.content.Context;
import android.content.Intent;
import android.os.AsyncTask;
import android.os.Build;
import android.os.ParcelFileDescriptor;
import android.util.Log;

import org.openintents.openpgp.IOpenPgpService;
import org.openintents.openpgp.OpenPgpError;

import java.io.InputStream;
import java.io.OutputStream;

public class OpenPgpApi {

    public static final String TAG = "OpenPgp API";

    public static final String SERVICE_INTENT = "org.openintents.openpgp.IOpenPgpService";

    /**
     * Version history
     * ---------------
     * <p/>
     * 3:
     * - first public stable version
     * <p/>
     * 4:
     * - No changes to existing methods -> backward compatible
     * - Introduction of ACTION_DECRYPT_METADATA, RESULT_METADATA, EXTRA_ORIGINAL_FILENAME, and OpenPgpMetadata parcel
     * - Introduction of internal NFC extras: EXTRA_NFC_SIGNED_HASH, EXTRA_NFC_SIG_CREATION_TIMESTAMP
     * 5:
     * - OpenPgpSignatureResult: new consts SIGNATURE_KEY_REVOKED and SIGNATURE_KEY_EXPIRED
     * - OpenPgpSignatureResult: ArrayList<String> userIds
     */
    public static final int API_VERSION = 5;

    /**
     * General extras
     * --------------
     *
     * required extras:
     * int           EXTRA_API_VERSION           (always required)
     *
     * returned extras:
     * int           RESULT_CODE                 (RESULT_CODE_ERROR, RESULT_CODE_SUCCESS or RESULT_CODE_USER_INTERACTION_REQUIRED)
     * OpenPgpError  RESULT_ERROR                (if RESULT_CODE == RESULT_CODE_ERROR)
     * PendingIntent RESULT_INTENT               (if RESULT_CODE == RESULT_CODE_USER_INTERACTION_REQUIRED)
     */

    /**
     * Sign only
     * <p/>
     * optional extras:
     * boolean       EXTRA_REQUEST_ASCII_ARMOR   (request ascii armor for output)
     * String        EXTRA_PASSPHRASE            (key passphrase)
     */
    public static final String ACTION_SIGN = "org.openintents.openpgp.action.SIGN";

    /**
     * Encrypt
     * <p/>
     * required extras:
     * String[]      EXTRA_USER_IDS              (=emails of recipients, if more than one key has a user_id, a PendingIntent is returned via RESULT_INTENT)
     * or
     * long[]        EXTRA_KEY_IDS
     * <p/>
     * optional extras:
     * boolean       EXTRA_REQUEST_ASCII_ARMOR   (request ascii armor for output)
     * String        EXTRA_PASSPHRASE            (key passphrase)
     * String        EXTRA_ORIGINAL_FILENAME     (original filename to be encrypted as metadata)
     */
    public static final String ACTION_ENCRYPT = "org.openintents.openpgp.action.ENCRYPT";

    /**
     * Sign and encrypt
     * <p/>
     * required extras:
     * String[]      EXTRA_USER_IDS              (=emails of recipients, if more than one key has a user_id, a PendingIntent is returned via RESULT_INTENT)
     * or
     * long[]        EXTRA_KEY_IDS
     * <p/>
     * optional extras:
     * boolean       EXTRA_REQUEST_ASCII_ARMOR   (request ascii armor for output)
     * String        EXTRA_PASSPHRASE            (key passphrase)
     * String        EXTRA_ORIGINAL_FILENAME     (original filename to be encrypted as metadata)
     */
    public static final String ACTION_SIGN_AND_ENCRYPT = "org.openintents.openpgp.action.SIGN_AND_ENCRYPT";

    /**
     * Decrypts and verifies given input stream. This methods handles encrypted-only, signed-and-encrypted,
     * and also signed-only input.
     * <p/>
     * If OpenPgpSignatureResult.getStatus() == OpenPgpSignatureResult.SIGNATURE_KEY_MISSING
     * in addition a PendingIntent is returned via RESULT_INTENT to download missing keys.
     * <p/>
     * optional extras:
     * boolean       EXTRA_REQUEST_ASCII_ARMOR   (request ascii armor for output)
     * <p/>
     * returned extras:
     * OpenPgpSignatureResult   RESULT_SIGNATURE
     * OpenPgpDecryptMetadata   RESULT_METADATA
     */
    public static final String ACTION_DECRYPT_VERIFY = "org.openintents.openpgp.action.DECRYPT_VERIFY";

    /**
     * Decrypts the header of an encrypted file to retrieve metadata such as original filename.
     * <p/>
     * This does not decrypt the actual content of the file.
     * <p/>
     * returned extras:
     * OpenPgpDecryptMetadata   RESULT_METADATA
     */
    public static final String ACTION_DECRYPT_METADATA = "org.openintents.openpgp.action.DECRYPT_METADATA";

    /**
     * Get key ids based on given user ids (=emails)
     * <p/>
     * required extras:
     * String[]      EXTRA_USER_IDS
     * <p/>
     * returned extras:
     * long[]        RESULT_KEY_IDS
     */
    public static final String ACTION_GET_KEY_IDS = "org.openintents.openpgp.action.GET_KEY_IDS";

    /**
     * This action returns RESULT_CODE_SUCCESS if the OpenPGP Provider already has the key
     * corresponding to the given key id in its database.
     * <p/>
     * It returns RESULT_CODE_USER_INTERACTION_REQUIRED if the Provider does not have the key.
     * The PendingIntent from RESULT_INTENT can be used to retrieve those from a keyserver.
     * <p/>
     * required extras:
     * long        EXTRA_KEY_ID
     */
    public static final String ACTION_GET_KEY = "org.openintents.openpgp.action.GET_KEY";

    /* Intent extras */
    public static final String EXTRA_API_VERSION = "api_version";

    public static final String EXTRA_ACCOUNT_NAME = "account_name";

    // SIGN, ENCRYPT, SIGN_AND_ENCRYPT, DECRYPT_VERIFY
    // request ASCII Armor for output
    // OpenPGP Radix-64, 33 percent overhead compared to binary, see http://tools.ietf.org/html/rfc4880#page-53)
    public static final String EXTRA_REQUEST_ASCII_ARMOR = "ascii_armor";

    // ENCRYPT, SIGN_AND_ENCRYPT
    public static final String EXTRA_USER_IDS = "user_ids";
    public static final String EXTRA_KEY_IDS = "key_ids";
    // optional extras:
    public static final String EXTRA_PASSPHRASE = "passphrase";
    public static final String EXTRA_ORIGINAL_FILENAME = "original_filename";

    // internal NFC states
    public static final String EXTRA_NFC_SIGNED_HASH = "nfc_signed_hash";
    public static final String EXTRA_NFC_SIG_CREATION_TIMESTAMP = "nfc_sig_creation_timestamp";
    public static final String EXTRA_NFC_DECRYPTED_SESSION_KEY = "nfc_decrypted_session_key";

    // GET_KEY
    public static final String EXTRA_KEY_ID = "key_id";
    public static final String RESULT_KEY_IDS = "key_ids";

    /* Service Intent returns */
    public static final String RESULT_CODE = "result_code";

    // get actual error object from RESULT_ERROR
    public static final int RESULT_CODE_ERROR = 0;
    // success!
    public static final int RESULT_CODE_SUCCESS = 1;
    // get PendingIntent from RESULT_INTENT, start PendingIntent with startIntentSenderForResult,
    // and execute service method again in onActivityResult
    public static final int RESULT_CODE_USER_INTERACTION_REQUIRED = 2;

    public static final String RESULT_ERROR = "error";
    public static final String RESULT_INTENT = "intent";

    // DECRYPT_VERIFY
    public static final String RESULT_SIGNATURE = "signature";
    public static final String RESULT_METADATA = "metadata";

    IOpenPgpService mService;
    Context mContext;

    public OpenPgpApi(Context context, IOpenPgpService service) {
        this.mContext = context;
        this.mService = service;
    }

    public interface IOpenPgpCallback {
        void onReturn(final Intent result);
    }

    private class OpenPgpAsyncTask extends AsyncTask<Void, Integer, Intent> {
        Intent data;
        InputStream is;
        OutputStream os;
        IOpenPgpCallback callback;

        private OpenPgpAsyncTask(Intent data, InputStream is, OutputStream os, IOpenPgpCallback callback) {
            this.data = data;
            this.is = is;
            this.os = os;
            this.callback = callback;
        }

        @Override
        protected Intent doInBackground(Void... unused) {
            return executeApi(data, is, os);
        }

        protected void onPostExecute(Intent result) {
            callback.onReturn(result);
        }

    }

    @TargetApi(Build.VERSION_CODES.HONEYCOMB)
    public void executeApiAsync(Intent data, InputStream is, OutputStream os, IOpenPgpCallback callback) {
        OpenPgpAsyncTask task = new OpenPgpAsyncTask(data, is, os, callback);

        // don't serialize async tasks!
        // http://commonsware.com/blog/2012/04/20/asynctask-threading-regression-confirmed.html
        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.HONEYCOMB) {
            task.executeOnExecutor(AsyncTask.THREAD_POOL_EXECUTOR, (Void[]) null);
        } else {
            task.execute((Void[]) null);
        }
    }

    public Intent executeApi(Intent data, InputStream is, OutputStream os) {
        try {
            data.putExtra(EXTRA_API_VERSION, OpenPgpApi.API_VERSION);

            Intent result;

            // pipe the input and output
            ParcelFileDescriptor input = null;
            if (is != null) {
                input = ParcelFileDescriptorUtil.pipeFrom(is,
                        new ParcelFileDescriptorUtil.IThreadListener() {

                            @Override
                            public void onThreadFinished(Thread thread) {
                                //Log.d(OpenPgpApi.TAG, "Copy to service finished");
                            }
                        }
                );
            }
            ParcelFileDescriptor output = null;
            if (os != null) {
                output = ParcelFileDescriptorUtil.pipeTo(os,
                        new ParcelFileDescriptorUtil.IThreadListener() {

                            @Override
                            public void onThreadFinished(Thread thread) {
                                //Log.d(OpenPgpApi.TAG, "Service finished writing!");
                            }
                        }
                );
            }

            // blocks until result is ready
            result = mService.execute(data, input, output);
            // close() is required to halt the TransferThread
            if (output != null) {
                output.close();
            }
            // TODO: close input?

            // set class loader to current context to allow unparcelling
            // of OpenPgpError and OpenPgpSignatureResult
            // http://stackoverflow.com/a/3806769
            result.setExtrasClassLoader(mContext.getClassLoader());

            return result;
        } catch (Exception e) {
            Log.e(OpenPgpApi.TAG, "Exception in executeApi call", e);
            Intent result = new Intent();
            result.putExtra(RESULT_CODE, RESULT_CODE_ERROR);
            result.putExtra(RESULT_ERROR,
                    new OpenPgpError(OpenPgpError.CLIENT_SIDE_ERROR, e.getMessage()));
            return result;
        }
    }

}