/*
 * 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.net;

import android.annotation.SdkConstant;
import android.annotation.SdkConstant.SdkConstantType;
import android.content.ContentResolver;
import android.content.Context;
import android.database.ContentObserver;
import android.net.ProxyProperties;
import android.os.Handler;
import android.os.SystemProperties;
import android.text.TextUtils;
import android.provider.Settings;
import android.util.Log;

import java.net.InetAddress;
import java.net.InetSocketAddress;
import java.net.ProxySelector;
import java.net.SocketAddress;
import java.net.URI;
import java.net.UnknownHostException;
import java.util.concurrent.locks.ReadWriteLock;
import java.util.concurrent.locks.ReentrantReadWriteLock;
import java.util.List;
import java.util.regex.Matcher;
import java.util.regex.Pattern;

import junit.framework.Assert;

import org.apache.http.conn.routing.HttpRoute;
import org.apache.http.conn.routing.HttpRoutePlanner;
import org.apache.http.conn.scheme.SchemeRegistry;
import org.apache.http.HttpHost;
import org.apache.http.HttpRequest;
import org.apache.http.impl.conn.ProxySelectorRoutePlanner;
import org.apache.http.protocol.HttpContext;

/**
 * A convenience class for accessing the user and default proxy
 * settings.
 */
public final class Proxy {

    // Set to true to enable extra debugging.
    private static final boolean DEBUG = false;
    private static final String TAG = "Proxy";

    /**
     * Used to notify an app that's caching the default connection proxy
     * that either the default connection or its proxy has changed.
     * The intent will have the following extra value:</p>
     * <ul>
     *   <li><em>EXTRA_PROXY_INFO</em> - The ProxyProperties for the proxy.  Non-null,
     *                                   though if the proxy is undefined the host string
     *                                   will be empty.
     * </ul>
     *
     * <p class="note">This is a protected intent that can only be sent by the system
     */
    @SdkConstant(SdkConstantType.BROADCAST_INTENT_ACTION)
    public static final String PROXY_CHANGE_ACTION = "android.intent.action.PROXY_CHANGE";
    /** {@hide} **/
    public static final String EXTRA_PROXY_INFO = "proxy";

    private static ConnectivityManager sConnectivityManager = null;

    // Hostname / IP REGEX validation
    // Matches blank input, ips, and domain names
    private static final String NAME_IP_REGEX =
        "[a-zA-Z0-9]+(\\-[a-zA-Z0-9]+)*(\\.[a-zA-Z0-9]+(\\-[a-zA-Z0-9]+)*)*";

    private static final String HOSTNAME_REGEXP = "^$|^" + NAME_IP_REGEX + "$";

    private static final Pattern HOSTNAME_PATTERN;

    private static final String EXCLLIST_REGEXP = "$|^(.?" + NAME_IP_REGEX
        + ")+(,(.?" + NAME_IP_REGEX + "))*$";

    private static final Pattern EXCLLIST_PATTERN;

    static {
        HOSTNAME_PATTERN = Pattern.compile(HOSTNAME_REGEXP);
        EXCLLIST_PATTERN = Pattern.compile(EXCLLIST_REGEXP);
    }

    /**
     * Return the proxy object to be used for the URL given as parameter.
     * @param ctx A Context used to get the settings for the proxy host.
     * @param url A URL to be accessed. Used to evaluate exclusion list.
     * @return Proxy (java.net) object containing the host name. If the
     *         user did not set a hostname it returns the default host.
     *         A null value means that no host is to be used.
     * {@hide}
     */
    public static final java.net.Proxy getProxy(Context ctx, String url) {
        String host = "";
        if (url != null) {
            URI uri = URI.create(url);
            host = uri.getHost();
        }

        if (!isLocalHost(host)) {
            if (sConnectivityManager == null) {
                sConnectivityManager = (ConnectivityManager)ctx.getSystemService(
                        Context.CONNECTIVITY_SERVICE);
            }
            if (sConnectivityManager == null) return java.net.Proxy.NO_PROXY;

            ProxyProperties proxyProperties = sConnectivityManager.getProxy();

            if (proxyProperties != null) {
                if (!proxyProperties.isExcluded(host)) {
                    return proxyProperties.makeProxy();
                }
            }
        }
        return java.net.Proxy.NO_PROXY;
    }


    /**
     * Return the proxy host set by the user.
     * @param ctx A Context used to get the settings for the proxy host.
     * @return String containing the host name. If the user did not set a host
     *         name it returns the default host. A null value means that no
     *         host is to be used.
     * @deprecated Use standard java vm proxy values to find the host, port
     *         and exclusion list.  This call ignores the exclusion list.
     */
    public static final String getHost(Context ctx) {
        java.net.Proxy proxy = getProxy(ctx, null);
        if (proxy == java.net.Proxy.NO_PROXY) return null;
        try {
            return ((InetSocketAddress)(proxy.address())).getHostName();
        } catch (Exception e) {
            return null;
        }
    }

    /**
     * Return the proxy port set by the user.
     * @param ctx A Context used to get the settings for the proxy port.
     * @return The port number to use or -1 if no proxy is to be used.
     * @deprecated Use standard java vm proxy values to find the host, port
     *         and exclusion list.  This call ignores the exclusion list.
     */
    public static final int getPort(Context ctx) {
        java.net.Proxy proxy = getProxy(ctx, null);
        if (proxy == java.net.Proxy.NO_PROXY) return -1;
        try {
            return ((InetSocketAddress)(proxy.address())).getPort();
        } catch (Exception e) {
            return -1;
        }
    }

    /**
     * Return the default proxy host specified by the carrier.
     * @return String containing the host name or null if there is no proxy for
     * this carrier.
     * @deprecated Use standard java vm proxy values to find the host, port and
     *         exclusion list.  This call ignores the exclusion list and no
     *         longer reports only mobile-data apn-based proxy values.
     */
    public static final String getDefaultHost() {
        String host = System.getProperty("http.proxyHost");
        if (TextUtils.isEmpty(host)) return null;
        return host;
    }

    /**
     * Return the default proxy port specified by the carrier.
     * @return The port number to be used with the proxy host or -1 if there is
     * no proxy for this carrier.
     * @deprecated Use standard java vm proxy values to find the host, port and
     *         exclusion list.  This call ignores the exclusion list and no
     *         longer reports only mobile-data apn-based proxy values.
     */
    public static final int getDefaultPort() {
        if (getDefaultHost() == null) return -1;
        try {
            return Integer.parseInt(System.getProperty("http.proxyPort"));
        } catch (NumberFormatException e) {
            return -1;
        }
    }

    /**
     * Returns the preferred proxy to be used by clients. This is a wrapper
     * around {@link android.net.Proxy#getHost()}.
     *
     * @param context the context which will be passed to
     * {@link android.net.Proxy#getHost()}
     * @param url the target URL for the request
     * @note Calling this method requires permission
     * android.permission.ACCESS_NETWORK_STATE
     * @return The preferred proxy to be used by clients, or null if there
     * is no proxy.
     * {@hide}
     */
    public static final HttpHost getPreferredHttpHost(Context context,
            String url) {
        java.net.Proxy prefProxy = getProxy(context, url);
        if (prefProxy.equals(java.net.Proxy.NO_PROXY)) {
            return null;
        } else {
            InetSocketAddress sa = (InetSocketAddress)prefProxy.address();
            return new HttpHost(sa.getHostName(), sa.getPort(), "http");
        }
    }

    private static final boolean isLocalHost(String host) {
        if (host == null) {
            return false;
        }
        try {
            if (host != null) {
                if (host.equalsIgnoreCase("localhost")) {
                    return true;
                }
                if (NetworkUtils.numericToInetAddress(host).isLoopbackAddress()) {
                    return true;
                }
            }
        } catch (IllegalArgumentException iex) {
        }
        return false;
    }

    /**
     * Validate syntax of hostname, port and exclusion list entries
     * {@hide}
     */
    public static void validate(String hostname, String port, String exclList) {
        Matcher match = HOSTNAME_PATTERN.matcher(hostname);
        Matcher listMatch = EXCLLIST_PATTERN.matcher(exclList);

        if (!match.matches()) {
            throw new IllegalArgumentException();
        }

        if (!listMatch.matches()) {
            throw new IllegalArgumentException();
        }

        if (hostname.length() > 0 && port.length() == 0) {
            throw new IllegalArgumentException();
        }

        if (port.length() > 0) {
            if (hostname.length() == 0) {
                throw new IllegalArgumentException();
            }
            int portVal = -1;
            try {
                portVal = Integer.parseInt(port);
            } catch (NumberFormatException ex) {
                throw new IllegalArgumentException();
            }
            if (portVal <= 0 || portVal > 0xFFFF) {
                throw new IllegalArgumentException();
            }
        }
    }

    static class AndroidProxySelectorRoutePlanner
            extends org.apache.http.impl.conn.ProxySelectorRoutePlanner {

        private Context mContext;

        public AndroidProxySelectorRoutePlanner(SchemeRegistry schreg, ProxySelector prosel,
                Context context) {
            super(schreg, prosel);
            mContext = context;
        }

        @Override
        protected java.net.Proxy chooseProxy(List<java.net.Proxy> proxies, HttpHost target,
                HttpRequest request, HttpContext context) {
            return getProxy(mContext, target.getHostName());
        }

        @Override
        protected HttpHost determineProxy(HttpHost target, HttpRequest request,
                HttpContext context) {
            return getPreferredHttpHost(mContext, target.getHostName());
        }

        @Override
        public HttpRoute determineRoute(HttpHost target, HttpRequest request,
                HttpContext context) {
            HttpHost proxy = getPreferredHttpHost(mContext, target.getHostName());
            if (proxy == null) {
                return new HttpRoute(target);
            } else {
                return new HttpRoute(target, null, proxy, false);
            }
        }
    }

    /** @hide */
    public static final HttpRoutePlanner getAndroidProxySelectorRoutePlanner(Context context) {
        AndroidProxySelectorRoutePlanner ret = new AndroidProxySelectorRoutePlanner(
                new SchemeRegistry(), ProxySelector.getDefault(), context);
        return ret;
    }

    /** @hide */
    public static final void setHttpProxySystemProperty(ProxyProperties p) {
        String host = null;
        String port = null;
        String exclList = null;
        if (p != null) {
            host = p.getHost();
            port = Integer.toString(p.getPort());
            exclList = p.getExclusionList();
        }
        setHttpProxySystemProperty(host, port, exclList);
    }

    /** @hide */
    public static final void setHttpProxySystemProperty(String host, String port, String exclList) {
        if (exclList != null) exclList = exclList.replace(",", "|");
        if (false) Log.d(TAG, "setHttpProxySystemProperty :"+host+":"+port+" - "+exclList);
        if (host != null) {
            System.setProperty("http.proxyHost", host);
            System.setProperty("https.proxyHost", host);
        } else {
            System.clearProperty("http.proxyHost");
            System.clearProperty("https.proxyHost");
        }
        if (port != null) {
            System.setProperty("http.proxyPort", port);
            System.setProperty("https.proxyPort", port);
        } else {
            System.clearProperty("http.proxyPort");
            System.clearProperty("https.proxyPort");
        }
        if (exclList != null) {
            System.setProperty("http.nonProxyHosts", exclList);
            System.setProperty("https.nonProxyHosts", exclList);
        } else {
            System.clearProperty("http.nonProxyHosts");
            System.clearProperty("https.nonProxyHosts");
        }
    }
}