/**
 * Copyright (c) 2013, 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.proxyhandler;

import android.os.RemoteException;
import android.util.Log;

import com.android.net.IProxyPortListener;
import com.google.android.collect.Lists;

import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.net.InetSocketAddress;
import java.net.Proxy;
import java.net.ProxySelector;
import java.net.ServerSocket;
import java.net.Socket;
import java.net.SocketException;
import java.net.URI;
import java.net.URISyntaxException;
import java.util.List;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;

/**
 * @hide
 */
public class ProxyServer extends Thread {

    private static final String CONNECT = "CONNECT";
    private static final String HTTP_OK = "HTTP/1.1 200 OK\n";

    private static final String TAG = "ProxyServer";

    private ExecutorService threadExecutor;

    public boolean mIsRunning = false;

    private ServerSocket serverSocket;
    private int mPort;
    private IProxyPortListener mCallback;

    private class ProxyConnection implements Runnable {
        private Socket connection;

        private ProxyConnection(Socket connection) {
            this.connection = connection;
        }

        @Override
        public void run() {
            try {
                String requestLine = getLine(connection.getInputStream());
                if (requestLine == null) {
                    connection.close();
                    return;
                }
                String[] splitLine = requestLine.split(" ");
                if (splitLine.length < 3) {
                    connection.close();
                    return;
                }
                String requestType = splitLine[0];
                String urlString = splitLine[1];

                String host = "";
                int port = 80;

                if (requestType.equals(CONNECT)) {
                    String[] hostPortSplit = urlString.split(":");
                    host = hostPortSplit[0];
                    try {
                        port = Integer.parseInt(hostPortSplit[1]);
                    } catch (NumberFormatException nfe) {
                        port = 443;
                    }
                    urlString = "Https://" + host + ":" + port;
                } else {
                    try {
                        URI url = new URI(urlString);
                        host = url.getHost();
                        port = url.getPort();
                        if (port < 0) {
                            port = 80;
                        }
                    } catch (URISyntaxException e) {
                        connection.close();
                        return;
                    }
                }

                List<Proxy> list = Lists.newArrayList();
                try {
                    list = ProxySelector.getDefault().select(new URI(urlString));
                } catch (URISyntaxException e) {
                    e.printStackTrace();
                }
                Socket server = null;
                for (Proxy proxy : list) {
                    try {
                        if (!proxy.equals(Proxy.NO_PROXY)) {
                            // Only Inets created by PacProxySelector.
                            InetSocketAddress inetSocketAddress =
                                    (InetSocketAddress)proxy.address();
                            server = new Socket(inetSocketAddress.getHostName(),
                                    inetSocketAddress.getPort());
                            sendLine(server, requestLine);
                        } else {
                            server = new Socket(host, port);
                            if (requestType.equals(CONNECT)) {
                                while (getLine(connection.getInputStream()).length() != 0);
                                // No proxy to respond so we must.
                                sendLine(connection, HTTP_OK);
                            } else {
                                sendLine(server, requestLine);
                            }
                        }
                    } catch (IOException ioe) {

                    }
                    if (server != null) {
                        break;
                    }
                }
                if (server == null) {
                    server = new Socket(host, port);
                    if (requestType.equals(CONNECT)) {
                        while (getLine(connection.getInputStream()).length() != 0);
                        // No proxy to respond so we must.
                        sendLine(connection, HTTP_OK);
                    } else {
                        sendLine(server, requestLine);
                    }
                }
                // Pass data back and forth until complete.
                SocketConnect.connect(connection, server);
            } catch (IOException e) {
                Log.d(TAG, "Problem Proxying", e);
            }
            try {
                connection.close();
            } catch (IOException ioe) {

            }
        }

        private String getLine(InputStream inputStream) throws IOException {
            StringBuffer buffer = new StringBuffer();
            int byteBuffer = inputStream.read();
            if (byteBuffer < 0) return "";
            do {
                if (byteBuffer != '\r') {
                    buffer.append((char)byteBuffer);
                }
                byteBuffer = inputStream.read();
            } while ((byteBuffer != '\n') && (byteBuffer >= 0));

            return buffer.toString();
        }

        private void sendLine(Socket socket, String line) throws IOException {
            OutputStream os = socket.getOutputStream();
            os.write(line.getBytes());
            os.write('\r');
            os.write('\n');
            os.flush();
        }
    }

    public ProxyServer() {
        threadExecutor = Executors.newCachedThreadPool();
        mPort = -1;
        mCallback = null;
    }

    @Override
    public void run() {
        try {
            serverSocket = new ServerSocket(0);

            if (serverSocket != null) {
                setPort(serverSocket.getLocalPort());

                while (mIsRunning) {
                    try {
                        Socket socket = serverSocket.accept();
                        // Only receive local connections.
                        if (socket.getInetAddress().isLoopbackAddress()) {
                            ProxyConnection parser = new ProxyConnection(socket);

                            threadExecutor.execute(parser);
                        } else {
                            socket.close();
                        }
                    } catch (IOException e) {
                        e.printStackTrace();
                    }
                }
            }
        } catch (SocketException e) {
            Log.e(TAG, "Failed to start proxy server", e);
        } catch (IOException e1) {
            Log.e(TAG, "Failed to start proxy server", e1);
        }

        mIsRunning = false;
    }

    public synchronized void setPort(int port) {
        if (mCallback != null) {
            try {
                mCallback.setProxyPort(port);
            } catch (RemoteException e) {
                Log.w(TAG, "Proxy failed to report port to PacManager", e);
            }
        }
        mPort = port;
    }

    public synchronized void setCallback(IProxyPortListener callback) {
        if (mPort != -1) {
            try {
                callback.setProxyPort(mPort);
            } catch (RemoteException e) {
                Log.w(TAG, "Proxy failed to report port to PacManager", e);
            }
        }
        mCallback = callback;
    }

    public synchronized void startServer() {
        mIsRunning = true;
        start();
    }

    public synchronized void stopServer() {
        mIsRunning = false;
        if (serverSocket != null) {
            try {
                serverSocket.close();
                serverSocket = null;
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
    }

    public boolean isBound() {
        return (mPort != -1);
    }

    public int getPort() {
        return mPort;
    }
}