/*

 * Copyright (c) 2016, 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.

 *

 * 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 org.graalvm.compiler.hotspot;

import java.util.Formatter;

import java.util.HashMap;

import java.util.Map;

import java.util.Properties;

/**

 * Mechanism for checking that the current Java runtime environment supports the minimum JVMCI API

 * required by Graal. The {@code JVMCI_VERSION_CHECK} environment variable can be used to ignore a

 * failed check ({@code JVMCI_VERSION_CHECK=ignore}) or print a warning (

 * {@code JVMCI_VERSION_CHECK=warn}) and continue. Otherwise, a failed check results in an

 * {@link InternalError} being raised or, if called from {@link #main(String[])}, the VM exiting

 * with a result code of {@code -1}

 *

 * This class only depends on the JDK so that it can be used without building Graal.

 */

public final class JVMCIVersionCheck {

    private static void failVersionCheck(Map<String, String> props, boolean exit, String reason, Object... args) {

        Formatter errorMessage = new Formatter().format(reason, args);

        String javaHome = props.get("java.home");

        String vmName = props.get("java.vm.name");

        errorMessage.format("Set the JVMCI_VERSION_CHECK environment variable to \"ignore\" to suppress ");

        errorMessage.format("this error or to \"warn\" to emit a warning and continue execution.%n");

        errorMessage.format("Currently used Java home directory is %s.%n", javaHome);

        errorMessage.format("Currently used VM configuration is: %s%n", vmName);

        if (props.get("java.specification.version").compareTo("1.9") < 0) {

            errorMessage.format("Download the latest JVMCI JDK 8 from " +

                            "https://github.com/graalvm/openjdk8-jvmci-builder/releases");

        } else {

            errorMessage.format("Download JDK 11 or later.");

        }

        String value = System.getenv("JVMCI_VERSION_CHECK");

        if ("warn".equals(value)) {

            System.err.println(errorMessage.toString());

        } else if ("ignore".equals(value)) {

            return;

        } else if (exit) {

            System.err.println(errorMessage.toString());

            System.exit(-1);

        } else {

            throw new InternalError(errorMessage.toString());

        }

    }

    private final String javaSpecVersion;

    private final String vmVersion;

    private int cursor;

    private final Map<String, String> props;

    private JVMCIVersionCheck(Map<String, String> props, String javaSpecVersion, String vmVersion) {

        this.props = props;

        this.javaSpecVersion = javaSpecVersion;

        this.vmVersion = vmVersion;

    }

    static void check(Map<String, String> props, boolean exitOnFailure) {

        JVMCIVersionCheck checker = new JVMCIVersionCheck(props, props.get("java.specification.version"), props.get("java.vm.version"));

        checker.run(exitOnFailure, JVMCI8_MIN_MAJOR_VERSION, JVMCI8_MIN_MINOR_VERSION);

    }

    /**

     * Entry point for testing.

     */

    public static void check(Map<String, String> props,

                    int jvmci8MinMajorVersion,

                    int jvmci8MinMinorVersion,

                    String javaSpecVersion,

                    String javaVmVersion,

                    boolean exitOnFailure) {

        JVMCIVersionCheck checker = new JVMCIVersionCheck(props, javaSpecVersion, javaVmVersion);

        checker.run(exitOnFailure, jvmci8MinMajorVersion, jvmci8MinMinorVersion);

    }

    /**

     * Parses a positive decimal number at {@link #cursor}.

     *

     * @return -1 if there is no positive decimal number at {@link #cursor}

     */

    private int parseNumber() {

        int result = -1;

        while (cursor < vmVersion.length()) {

            int digit = vmVersion.charAt(cursor) - '0';

            if (digit >= 0 && digit <= 9) {

                if (result == -1) {

                    result = digit;

                } else {

                    long r = (long) result * (long) 10;

                    if ((int) r != r) {

                        // Overflow

                        return -1;

                    }

                    result = (int) r + digit;

                }

                cursor++;

            } else {

                break;

            }

        }

        return result;

    }

    /**

     * Parse {@code "."} or {@code "-b"} at {@link #cursor}.

     *

     * @return {@code true} iff there was an expected separator at {@link #cursor}

     */

    private boolean parseSeparator() {

        if (cursor < vmVersion.length()) {

            char ch = vmVersion.charAt(cursor);

            if (ch == '.') {

                cursor++;

                return true;

            }

            if (ch == '-') {

                cursor++;

                if (cursor < vmVersion.length()) {

                    if (vmVersion.charAt(cursor) == 'b') {

                        cursor++;

                        return true;

                    }

                }

                return false;

            }

        }

        return false;

    }

    private void run(boolean exitOnFailure, int jvmci8MinMajorVersion, int jvmci8MinMinorVersion) {

        // Don't use regular expressions to minimize Graal startup time

        if (javaSpecVersion.compareTo("1.9") < 0) {

            cursor = vmVersion.indexOf("-jvmci-");

            if (cursor >= 0) {

                cursor += "-jvmci-".length();

                int major = parseNumber();

                if (major == -1) {

                    failVersionCheck(props, exitOnFailure, "The VM does not support the minimum JVMCI API version required by Graal.%n" +

                                    "Cannot read JVMCI major version from java.vm.version property: %s.%n", vmVersion);

                    return;

                }

                if (parseSeparator()) {

                    int minor = parseNumber();

                    if (minor == -1) {

                        failVersionCheck(props, exitOnFailure, "The VM does not support the minimum JVMCI API version required by Graal.%n" +

                                        "Cannot read JVMCI minor version from java.vm.version property: %s.%n", vmVersion);

                        return;

                    }

                    if (major > jvmci8MinMajorVersion || (major >= jvmci8MinMajorVersion && minor >= jvmci8MinMinorVersion)) {

                        return;

                    }

                    return;

                }

            }

            failVersionCheck(props, exitOnFailure, "The VM does not support the minimum JVMCI API version required by Graal.%n" +

                            "Cannot read JVMCI version from java.vm.version property: %s.%n", vmVersion);

        } else if (javaSpecVersion.compareTo("11") < 0) {

            failVersionCheck(props, exitOnFailure, "Graal is not compatible with the JVMCI API in JDK 9 and 10.%n");

        } else {

            if (vmVersion.contains("SNAPSHOT")) {

                return;

            }

            if (vmVersion.contains("internal")) {

                // Allow local builds

                return;

            }

            if (vmVersion.startsWith("11-ea+")) {

                String buildString = vmVersion.substring("11-ea+".length());

                try {

                    int build = Integer.parseInt(buildString);

                    if (build < 20) {

                        failVersionCheck(props, exitOnFailure, "Graal requires build 20 or later of JDK 11 early access binary, got build %d.%n", build);

                        return;

                    }

                } catch (NumberFormatException e) {

                    failVersionCheck(props, exitOnFailure, "Could not parse the JDK 11 early access build number from java.vm.version property: %s.%n", vmVersion);

                    return;

                }

            } else {

                // Graal is compatible with all JDK versions as of 11 GA.

            }

        }

    }

    /**

     * Command line interface for performing the check.

     */

    public static void main(String[] args) {

        Properties sprops = System.getProperties();

        Map<String, String> props = new HashMap<>(sprops.size());

        for (String name : sprops.stringPropertyNames()) {

            props.put(name, sprops.getProperty(name));

        }

        check(props, true);

    }

}