/* Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You 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 java.net;

import java.io.BufferedInputStream;
import java.io.File;
import java.io.FileInputStream;
import java.io.InputStream;
import java.io.IOException;
import java.security.AccessController;
import java.util.ArrayList;
import java.util.List;
import java.util.Properties;

import org.apache.harmony.luni.internal.nls.Messages;
import org.apache.harmony.luni.util.PriviAction;

/**
 * Default implementation for {@code ProxySelector}.
 */
@SuppressWarnings("unchecked")
class ProxySelectorImpl extends ProxySelector {

    private static final int HTTP_PROXY_PORT = 80;

    private static final int HTTPS_PROXY_PORT = 443;

    private static final int FTP_PROXY_PORT = 80;

    private static final int SOCKS_PROXY_PORT = 1080;

    // Net properties read from net.properties file.
    private static Properties netProps = null;

    // read net.properties file
    static {
        AccessController.doPrivileged(new java.security.PrivilegedAction() {
            public Object run() {
                File f = new File(System.getProperty("java.home") //$NON-NLS-1$
                        + File.separator + "lib" + File.separator //$NON-NLS-1$
                        + "net.properties"); //$NON-NLS-1$

                if (f.exists()) {
                    try {
                        FileInputStream fis = new FileInputStream(f);
                        InputStream is = new BufferedInputStream(fis);
                        netProps = new Properties();
                        netProps.load(is);
                        is.close();
                    } catch (IOException e) {
                    }
                }
                return null;
            }
        });
    }

    public ProxySelectorImpl() {
        super();
    }

    @Override
    public void connectFailed(URI uri, SocketAddress sa, IOException ioe) {
        if (null == uri || null == sa || null == ioe) {
            // luni.4D=Argument must not be null"
            throw new IllegalArgumentException(Messages.getString("luni.4D")); //$NON-NLS-1$
        }
    }

    @Override
    public List<Proxy> select(URI uri) {
        // argument check
        if (null == uri) {
            // luni.4D=Argument must not be null
            throw new IllegalArgumentException(Messages.getString("luni.4D")); //$NON-NLS-1$
        }
        // check scheme
        String scheme = uri.getScheme();
        if (null == scheme) {
            throw new IllegalArgumentException();
        }

        String host = uri.getHost();
        Proxy proxy = Proxy.NO_PROXY;

        if ("http".equals(scheme)) { //$NON-NLS-1$
            proxy = selectHttpProxy(host);
        } else if ("https".equals(scheme)) { //$NON-NLS-1$
            proxy = selectHttpsProxy();
        } else if ("ftp".equals(scheme)) { //$NON-NLS-1$
            proxy = selectFtpProxy(host);
        } else if ("socket".equals(scheme)) { //$NON-NLS-1$
            proxy = selectSocksProxy();
        }
        List<Proxy> proxyList = new ArrayList<Proxy>(1);
        proxyList.add(proxy);
        return proxyList;
    }

    /*
     * Gets proxy for http request. 1. gets from "http.proxyHost", then gets
     * port from "http.proxyPort", or from "proxyPort" if "http.proxyPort" is
     * unavailable. 2. gets from "proxyHost" if 1 is unavailable,then get port
     * from "proxyPort", or from "http.proxyPort" if "proxyPort" is unavailable.
     * 3. gets from "socksProxyHost" if 2 is unavailable.
     */

    private Proxy selectHttpProxy(String uriHost) {
        String host;
        String port = null;
        Proxy.Type type = Proxy.Type.DIRECT;

        String nonProxyHosts = getSystemProperty("http.nonProxyHosts"); //$NON-NLS-1$
        // if host is in non proxy host list, returns Proxy.NO_PROXY
        if (isNonProxyHost(uriHost, nonProxyHosts)) {
            return Proxy.NO_PROXY;
        }

        host = getSystemProperty("http.proxyHost"); //$NON-NLS-1$
        if (null != host) {
            // case 1: http.proxyHost is set, use exact http proxy
            type = Proxy.Type.HTTP;
            port = getSystemPropertyOrAlternative("http.proxyPort", //$NON-NLS-1$
                    "proxyPort", String.valueOf(HTTP_PROXY_PORT)); //$NON-NLS-1$
        } else if ((host = getSystemProperty("proxyHost", null)) != null) { //$NON-NLS-1$
            // case 2: proxyHost is set, use exact http proxy
            type = Proxy.Type.HTTP;
            port = getSystemPropertyOrAlternative("proxyPort", //$NON-NLS-1$
                    "http.proxyPort", String.valueOf(HTTP_PROXY_PORT)); //$NON-NLS-1$

        } else if ((host = getSystemProperty("socksProxyHost")) != null) { //$NON-NLS-1$
            // case 3: use socks proxy instead
            type = Proxy.Type.SOCKS;
            port = getSystemProperty(
                    "socksProxyPort", String.valueOf(SOCKS_PROXY_PORT)); //$NON-NLS-1$
        }
        int defaultPort = (type == Proxy.Type.SOCKS) ? SOCKS_PROXY_PORT
                : HTTP_PROXY_PORT;
        return createProxy(type, host, port, defaultPort);
    }

    /*
     * Gets proxy for https request.
     */
    private Proxy selectHttpsProxy() {
        String host;
        String port = null;
        Proxy.Type type = Proxy.Type.DIRECT;

        host = getSystemProperty("https.proxyHost"); //$NON-NLS-1$
        if (null != host) {
            // case 1: use exact https proxy
            type = Proxy.Type.HTTP;
            port = getSystemProperty(
                    "https.proxyPort", String.valueOf(HTTPS_PROXY_PORT)); //$NON-NLS-1$
        } else {
            host = getSystemProperty("socksProxyHost"); //$NON-NLS-1$
            if (null != host) {
                // case 2: use socks proxy instead
                type = Proxy.Type.SOCKS;
                port = getSystemProperty(
                        "socksProxyPort", String.valueOf(SOCKS_PROXY_PORT)); //$NON-NLS-1$
            }
        }
        int defaultPort = (type == Proxy.Type.SOCKS) ? SOCKS_PROXY_PORT
                : HTTPS_PROXY_PORT;
        return createProxy(type, host, port, defaultPort);
    }

    /*
     * Gets proxy for ftp request.
     */
    private Proxy selectFtpProxy(String uriHost) {
        String host;
        String port = null;
        Proxy.Type type = Proxy.Type.DIRECT;
        String nonProxyHosts = getSystemProperty("ftp.nonProxyHosts"); //$NON-NLS-1$
        // if host is in non proxy host list, returns Proxy.NO_PROXY
        if (isNonProxyHost(uriHost, nonProxyHosts)) {
            return Proxy.NO_PROXY;
        }

        host = getSystemProperty("ftp.proxyHost"); //$NON-NLS-1$
        if (null != host) {
            // case 1: use exact ftp proxy
            type = Proxy.Type.HTTP;
            port = getSystemProperty(
                    "ftp.proxyPort", String.valueOf(FTP_PROXY_PORT)); //$NON-NLS-1$
        } else {
            host = getSystemProperty("socksProxyHost"); //$NON-NLS-1$
            if (null != host) {
                // case 2: use socks proxy instead
                type = Proxy.Type.SOCKS;
                port = getSystemProperty(
                        "socksProxyPort", String.valueOf(SOCKS_PROXY_PORT)); //$NON-NLS-1$
            }
        }
        int defaultPort = (type == Proxy.Type.SOCKS) ? SOCKS_PROXY_PORT
                : FTP_PROXY_PORT;
        return createProxy(type, host, port, defaultPort);
    }

    /*
     * Gets proxy for socks request.
     */
    private Proxy selectSocksProxy() {
        String host;
        String port = null;
        Proxy.Type type = Proxy.Type.DIRECT;

        host = getSystemProperty("socksProxyHost"); //$NON-NLS-1$
        if (null != host) {
            type = Proxy.Type.SOCKS;
            port = getSystemProperty(
                    "socksProxyPort", String.valueOf(SOCKS_PROXY_PORT)); //$NON-NLS-1$
        }
        return createProxy(type, host, port, SOCKS_PROXY_PORT);
    }

    /*
     * checks whether the host needs proxy. return true if it doesn't need a
     * proxy.
     */
    private boolean isNonProxyHost(String host, String nonProxyHosts) {
        // nonProxyHosts is not set
        if (null == host || null == nonProxyHosts) {
            return false;
        }
        // Construct regex expression of nonProxyHosts
        int length = nonProxyHosts.length();
        char ch;
        StringBuilder buf = new StringBuilder(length);
        for (int i = 0; i < nonProxyHosts.length(); i++) {
            ch = nonProxyHosts.charAt(i);
            switch (ch) {
                case '.':
                    buf.append("\\."); //$NON-NLS-1$
                    break;
                case '*':
                    buf.append(".*"); //$NON-NLS-1$
                    break;
                default:
                    buf.append(ch);
            }
        }
        String nonProxyHostsReg = buf.toString();
        // check whether the host is the nonProxyHosts.
        return host.matches(nonProxyHostsReg);
    }

    /*
     * Create Proxy by "type","host" and "port".
     */
    private Proxy createProxy(Proxy.Type type, String host, String port,
            int defaultPort) {
        Proxy proxy;
        if (type == Proxy.Type.DIRECT) {
            proxy = Proxy.NO_PROXY;
        } else {
            int iPort;
            try {
                iPort = Integer.valueOf(port).intValue();
            } catch (NumberFormatException e) {
                iPort = defaultPort;
            }
            proxy = new Proxy(type, InetSocketAddress.createUnresolved(host,
                    iPort));
        }
        return proxy;
    }

    /*
     * gets system property, privileged operation. If the value of the property
     * is null or empty String, it returns defaultValue.
     */
    private String getSystemProperty(final String property) {
        return getSystemProperty(property, null);
    }

    /*
     * gets system property, privileged operation. If the value of the property
     * is null or empty String, it returns defaultValue.
     */
    private String getSystemProperty(final String property,
            final String defaultValue) {
        String value = AccessController.doPrivileged(new PriviAction<String>(
                property));
        if (null == value || "".equals(value)) { //$NON-NLS-1$
            value = (netProps != null)
                    ? netProps.getProperty(property, defaultValue)
                    : defaultValue;
        }
        return value;
    }

    /*
     * gets system property, privileged operation. If the value of "key"
     * property is null, then retrieve value from "alternative" property.
     * Finally, if the value is null or empty String, it returns defaultValue.
     */
    private String getSystemPropertyOrAlternative(final String key,
            final String alternativeKey, final String defaultValue) {
        String value = getSystemProperty(key);
        if (value == null) {
            value = getSystemProperty(alternativeKey);
            if (null == value) {
                value = defaultValue;
            }
        }
        return value;
    }
}