/*

 * Copyright (c) 2015, 2019, Oracle and/or its affiliates. All rights reserved.

 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

 *

 * This code is free software; you can redistribute it and/or modify it

 * under the terms of the GNU General Public License version 2 only, as

 * published by the Free Software Foundation.  Oracle designates this

 * particular file as subject to the "Classpath" exception as provided

 * by Oracle in the LICENSE file that accompanied this code.

 *

 * This code is distributed in the hope that it will be useful, but WITHOUT

 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or

 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License

 * version 2 for more details (a copy is included in the LICENSE file that

 * accompanied this code).

 *

 * You should have received a copy of the GNU General Public License version

 * 2 along with this work; if not, write to the Free Software Foundation,

 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.

 *

 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA

 * or visit www.oracle.com if you need additional information or have any

 * questions.

 */

package jdk.internal.net.http.common;

import sun.net.NetProperties;

import sun.net.util.IPAddressUtil;

import sun.net.www.HeaderParser;

import javax.net.ssl.ExtendedSSLSession;

import javax.net.ssl.SSLException;

import javax.net.ssl.SSLHandshakeException;

import javax.net.ssl.SSLParameters;

import javax.net.ssl.SSLSession;

import java.io.ByteArrayOutputStream;

import java.io.Closeable;

import java.io.IOException;

import java.io.PrintStream;

import java.io.UncheckedIOException;

import java.io.UnsupportedEncodingException;

import java.lang.System.Logger.Level;

import java.net.ConnectException;

import java.net.InetSocketAddress;

import java.net.URI;

import java.net.URLPermission;

import java.net.http.HttpClient;

import java.net.http.HttpHeaders;

import java.net.http.HttpTimeoutException;

import java.nio.ByteBuffer;

import java.nio.CharBuffer;

import java.nio.charset.CharacterCodingException;

import java.nio.charset.Charset;

import java.nio.charset.CodingErrorAction;

import java.nio.charset.StandardCharsets;

import java.security.AccessController;

import java.security.PrivilegedAction;

import java.text.Normalizer;

import java.util.Arrays;

import java.util.Collection;

import java.util.Collections;

import java.util.List;

import java.util.Set;

import java.util.TreeSet;

import java.util.concurrent.CompletableFuture;

import java.util.concurrent.CompletionException;

import java.util.concurrent.ExecutionException;

import java.util.function.BiPredicate;

import java.util.function.Function;

import java.util.function.Predicate;

import java.util.function.Supplier;

import java.util.stream.Collectors;

import java.util.stream.Stream;

import static java.lang.String.format;

import static java.util.stream.Collectors.joining;

import jdk.internal.net.http.HttpRequestImpl;

/**

 * Miscellaneous utilities

 */

public final class Utils {

    public static final boolean ASSERTIONSENABLED;

    static {

        boolean enabled = false;

        assert enabled = true;

        ASSERTIONSENABLED = enabled;

    }

//    public static final boolean TESTING;

//    static {

//        if (ASSERTIONSENABLED) {

//            PrivilegedAction<String> action = () -> System.getProperty("test.src");

//            TESTING = AccessController.doPrivileged(action) != null;

//        } else TESTING = false;

//    }

    public static final boolean DEBUG = // Revisit: temporary dev flag.

            getBooleanProperty(DebugLogger.HTTP_NAME, false);

    public static final boolean DEBUG_WS = // Revisit: temporary dev flag.

            getBooleanProperty(DebugLogger.WS_NAME, false);

    public static final boolean DEBUG_HPACK = // Revisit: temporary dev flag.

            getBooleanProperty(DebugLogger.HPACK_NAME, false);

    public static final boolean TESTING = DEBUG;

    public static final boolean isHostnameVerificationDisabled = // enabled by default

            hostnameVerificationDisabledValue();

    private static boolean hostnameVerificationDisabledValue() {

        String prop = getProperty("jdk.internal.httpclient.disableHostnameVerification");

        if (prop == null)

            return false;

        return prop.isEmpty() ? true : Boolean.parseBoolean(prop);

    }

    /**

     * Allocated buffer size. Must never be higher than 16K. But can be lower

     * if smaller allocation units preferred. HTTP/2 mandates that all

     * implementations support frame payloads of at least 16K.

     */

    private static final int DEFAULT_BUFSIZE = 16 * 1024;

    public static final int BUFSIZE = getIntegerNetProperty(

            "jdk.httpclient.bufsize", DEFAULT_BUFSIZE

    );

    public static final BiPredicate<String,String> ACCEPT_ALL = (x,y) -> true;

    private static final Set<String> DISALLOWED_HEADERS_SET = getDisallowedHeaders();

    private static Set<String> getDisallowedHeaders() {

        Set<String> headers = new TreeSet<>(String.CASE_INSENSITIVE_ORDER);

        headers.addAll(Set.of("connection", "content-length", "expect", "host", "upgrade"));

        String v = getNetProperty("jdk.httpclient.allowRestrictedHeaders");

        if (v != null) {

            // any headers found are removed from set.

            String[] tokens = v.trim().split(",");

            for (String token : tokens) {

                headers.remove(token);

            }

            return Collections.unmodifiableSet(headers);

        } else {

            return Collections.unmodifiableSet(headers);

        }

    }

    public static final BiPredicate<String, String>

            ALLOWED_HEADERS = (header, unused) -> !DISALLOWED_HEADERS_SET.contains(header);

    public static final BiPredicate<String, String> VALIDATE_USER_HEADER =

            (name, value) -> {

                assert name != null : "null header name";

                assert value != null : "null header value";

                if (!isValidName(name)) {

                    throw newIAE("invalid header name: \"%s\"", name);

                }

                if (!Utils.ALLOWED_HEADERS.test(name, null)) {

                    throw newIAE("restricted header name: \"%s\"", name);

                }

                if (!isValidValue(value)) {

                    throw newIAE("invalid header value for %s: \"%s\"", name, value);

                }

                return true;

            };

    // Headers that are not generally restricted, and can therefore be set by users,

    // but can in some contexts be overridden by the implementation.

    // Currently, only contains "Authorization" which will

    // be overridden, when an Authenticator is set on the HttpClient.

    // Needs to be BiPred<String,String> to fit with general form of predicates

    // used by caller.

    public static final BiPredicate<String, String> CONTEXT_RESTRICTED(HttpClient client) {

        return (k, v) -> client.authenticator() == null ||

                ! (k.equalsIgnoreCase("Authorization")

                        && k.equalsIgnoreCase("Proxy-Authorization"));

    }

    private static final BiPredicate<String, String> HOST_RESTRICTED = (k,v) -> !"host".equalsIgnoreCase(k);

    public static final BiPredicate<String, String> PROXY_TUNNEL_RESTRICTED(HttpClient client)  {

        return CONTEXT_RESTRICTED(client).and(HOST_RESTRICTED);

    }

    private static final Predicate<String> IS_HOST = "host"::equalsIgnoreCase;

    private static final Predicate<String> IS_PROXY_HEADER = (k) ->

            k != null && k.length() > 6 && "proxy-".equalsIgnoreCase(k.substring(0,6));

    private static final Predicate<String> NO_PROXY_HEADER =

            IS_PROXY_HEADER.negate();

    private static final Predicate<String> ALL_HEADERS = (s) -> true;

    private static final Set<String> PROXY_AUTH_DISABLED_SCHEMES;

    private static final Set<String> PROXY_AUTH_TUNNEL_DISABLED_SCHEMES;

    static {

        String proxyAuthDisabled =

                getNetProperty("jdk.http.auth.proxying.disabledSchemes");

        String proxyAuthTunnelDisabled =

                getNetProperty("jdk.http.auth.tunneling.disabledSchemes");

        PROXY_AUTH_DISABLED_SCHEMES =

                proxyAuthDisabled == null ? Set.of() :

                        Stream.of(proxyAuthDisabled.split(","))

                                .map(String::trim)

                                .filter((s) -> !s.isEmpty())

                                .collect(Collectors.toUnmodifiableSet());

        PROXY_AUTH_TUNNEL_DISABLED_SCHEMES =

                proxyAuthTunnelDisabled == null ? Set.of() :

                        Stream.of(proxyAuthTunnelDisabled.split(","))

                                .map(String::trim)

                                .filter((s) -> !s.isEmpty())

                                .collect(Collectors.toUnmodifiableSet());

    }

    public static <T> CompletableFuture<T> wrapForDebug(Logger logger, String name, CompletableFuture<T> cf) {

        if (logger.on()) {

            return cf.handle((r,t) -> {

                logger.log("%s completed %s", name, t == null ? "successfully" : t );

                return cf;

            }).thenCompose(Function.identity());

        } else {

            return cf;

        }

    }

    private static final String WSPACES = " \t\r\n";

    private static final boolean isAllowedForProxy(String name,

                                                   String value,

                                                   Set<String> disabledSchemes,

                                                   Predicate<String> allowedKeys) {

        if (!allowedKeys.test(name)) return false;

        if (disabledSchemes.isEmpty()) return true;

        if (name.equalsIgnoreCase("proxy-authorization")) {

            if (value.isEmpty()) return false;

            for (String scheme : disabledSchemes) {

                int slen = scheme.length();

                int vlen = value.length();

                if (vlen == slen) {

                    if (value.equalsIgnoreCase(scheme)) {

                        return false;

                    }

                } else if (vlen > slen) {

                    if (value.substring(0,slen).equalsIgnoreCase(scheme)) {

                        int c = value.codePointAt(slen);

                        if (WSPACES.indexOf(c) > -1

                                || Character.isSpaceChar(c)

                                || Character.isWhitespace(c)) {

                            return false;

                        }

                    }

                }

            }

        }

        return true;

    }

    public static final BiPredicate<String, String> PROXY_TUNNEL_FILTER =

            (s,v) -> isAllowedForProxy(s, v, PROXY_AUTH_TUNNEL_DISABLED_SCHEMES,

                    // Allows Proxy-* and Host headers when establishing the tunnel.

                    IS_PROXY_HEADER.or(IS_HOST));

    public static final BiPredicate<String, String> PROXY_FILTER =

            (s,v) -> isAllowedForProxy(s, v, PROXY_AUTH_DISABLED_SCHEMES,

                    ALL_HEADERS);

    public static final BiPredicate<String, String> NO_PROXY_HEADERS_FILTER =

            (n,v) -> Utils.NO_PROXY_HEADER.test(n);

    public static boolean proxyHasDisabledSchemes(boolean tunnel) {

        return tunnel ? ! PROXY_AUTH_TUNNEL_DISABLED_SCHEMES.isEmpty()

                      : ! PROXY_AUTH_DISABLED_SCHEMES.isEmpty();

    }

    // WebSocket connection Upgrade headers

    private static final String HEADER_CONNECTION = "Connection";

    private static final String HEADER_UPGRADE    = "Upgrade";

    public static final void setWebSocketUpgradeHeaders(HttpRequestImpl request) {

        request.setSystemHeader(HEADER_UPGRADE, "websocket");

        request.setSystemHeader(HEADER_CONNECTION, "Upgrade");

    }

    public static IllegalArgumentException newIAE(String message, Object... args) {

        return new IllegalArgumentException(format(message, args));

    }

    public static ByteBuffer getBuffer() {

        return ByteBuffer.allocate(BUFSIZE);

    }

    public static Throwable getCompletionCause(Throwable x) {

        if (!(x instanceof CompletionException)

                && !(x instanceof ExecutionException)) return x;

        final Throwable cause = x.getCause();

        if (cause == null) {

            throw new InternalError("Unexpected null cause", x);

        }

        return cause;

    }

    public static IOException getIOException(Throwable t) {

        if (t instanceof IOException) {

            return (IOException) t;

        }

        Throwable cause = t.getCause();

        if (cause != null) {

            return getIOException(cause);

        }

        return new IOException(t);

    }

    /**

     * Adds a more specific exception detail message, based on the given

     * exception type and the message supplier. This is primarily to present

     * more descriptive messages in IOExceptions that may be visible to calling

     * code.

     *

     * @return a possibly new exception that has as its detail message, the

     *         message from the messageSupplier, and the given throwable as its

     *         cause. Otherwise returns the given throwable

     */

    public static Throwable wrapWithExtraDetail(Throwable t,

                                                Supplier<String> messageSupplier) {

        if (!(t instanceof IOException))

            return t;

        if (t instanceof SSLHandshakeException)

            return t;  // no need to decorate

        String msg = messageSupplier.get();

        if (msg == null)

            return t;

        if (t instanceof ConnectionExpiredException) {

            if (t.getCause() instanceof SSLHandshakeException)

                return t;  // no need to decorate

            IOException ioe = new IOException(msg, t.getCause());

            t = new ConnectionExpiredException(ioe);

        } else {

            IOException ioe = new IOException(msg, t);

            t = ioe;

        }

        return t;

    }

    private Utils() { }

    /**

     * Returns the security permissions required to connect to the proxy, or

     * {@code null} if none is required or applicable.

     */

    public static URLPermission permissionForProxy(InetSocketAddress proxyAddress) {

        if (proxyAddress == null)

            return null;

        StringBuilder sb = new StringBuilder();

        sb.append("socket://")

          .append(proxyAddress.getHostString()).append(":")

          .append(proxyAddress.getPort());

        String urlString = sb.toString();

        return new URLPermission(urlString, "CONNECT");

    }

    /**

     * Returns the security permission required for the given details.

     */

    public static URLPermission permissionForServer(URI uri,

                                                    String method,

                                                    Stream<String> headers) {

        String urlString = new StringBuilder()

                .append(uri.getScheme()).append("://")

                .append(uri.getRawAuthority())

                .append(uri.getRawPath()).toString();

        StringBuilder actionStringBuilder = new StringBuilder(method);

        String collected = headers.collect(joining(","));

        if (!collected.isEmpty()) {

            actionStringBuilder.append(":").append(collected);

        }

        return new URLPermission(urlString, actionStringBuilder.toString());

    }

    // ABNF primitives defined in RFC 7230

    private static final boolean[] tchar      = new boolean[256];

    private static final boolean[] fieldvchar = new boolean[256];

    static {

        char[] allowedTokenChars =

                ("!#$%&'*+-.^_`|~0123456789" +

                 "abcdefghijklmnopqrstuvwxyz" +

                 "ABCDEFGHIJKLMNOPQRSTUVWXYZ").toCharArray();

        for (char c : allowedTokenChars) {

            tchar[c] = true;

        }

        for (char c = 0x21; c < 0xFF; c++) {

            fieldvchar[c] = true;

        }

        fieldvchar[0x7F] = false; // a little hole (DEL) in the range

    }

    /*

     * Validates a RFC 7230 field-name.

     */

    public static boolean isValidName(String token) {

        for (int i = 0; i < token.length(); i++) {

            char c = token.charAt(i);

            if (c > 255 || !tchar[c]) {

                return false;

            }

        }

        return !token.isEmpty();

    }

    public static class ServerName {

        ServerName(String name, boolean isLiteral) {

            this.name = name;

            this.isLiteral = isLiteral;

        }

        final String name;

        final boolean isLiteral;

        public String getName() {

            return name;

        }

        public boolean isLiteral() {

            return isLiteral;

        }

    }

    /**

     * Analyse the given address and determine if it is literal or not,

     * returning the address in String form.

     */

    public static ServerName getServerName(InetSocketAddress addr) {

        String host = addr.getHostString();

        byte[] literal = IPAddressUtil.textToNumericFormatV4(host);

        if (literal == null) {

            // not IPv4 literal. Check IPv6

            literal = IPAddressUtil.textToNumericFormatV6(host);

            return new ServerName(host, literal != null);

        } else {

            return new ServerName(host, true);

        }

    }

    private static boolean isLoopbackLiteral(byte[] bytes) {

        if (bytes.length == 4) {

            return bytes[0] == 127;

        } else if (bytes.length == 16) {

            for (int i=0; i<14; i++)

                if (bytes[i] != 0)

                    return false;

            if (bytes[15] != 1)

                return false;

            return true;

        } else

            throw new InternalError();

    }

    /*

     * Validates a RFC 7230 field-value.

     *

     * "Obsolete line folding" rule

     *

     *     obs-fold = CRLF 1*( SP / HTAB )

     *

     * is not permitted!

     */

    public static boolean isValidValue(String token) {

        for (int i = 0; i < token.length(); i++) {

            char c = token.charAt(i);

            if (c > 255) {

                return false;

            }

            if (c == ' ' || c == '\t') {

                continue;

            } else if (!fieldvchar[c]) {

                return false; // forbidden byte

            }

        }

        return true;

    }

    public static int getIntegerNetProperty(String name, int defaultValue) {

        return AccessController.doPrivileged((PrivilegedAction<Integer>) () ->

                NetProperties.getInteger(name, defaultValue));

    }

    public static String getNetProperty(String name) {

        return AccessController.doPrivileged((PrivilegedAction<String>) () ->

                NetProperties.get(name));

    }

    public static boolean getBooleanProperty(String name, boolean def) {

        return AccessController.doPrivileged((PrivilegedAction<Boolean>) () ->