/*
 * Copyright (c) 2016, 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;

/**
 * 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.
 */
class JVMCIVersionCheck {

    private static final int JVMCI8_MIN_MAJOR_VERSION = 0;
    private static final int JVMCI8_MIN_MINOR_VERSION = 23;

    // Will be updated once an ea build with the required JVMCI API is available.
    private static final int JVMCI9_MIN_EA_BUILD = 143;

    private static void failVersionCheck(boolean exit, String reason, Object... args) {
        Formatter errorMessage = new Formatter().format(reason, args);
        String javaHome = System.getProperty("java.home");
        String vmName = System.getProperty("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 (System.getProperty("java.specification.version").compareTo("1.9") < 0) {
            errorMessage.format("Download the latest JVMCI JDK 8 from http://www.oracle.com/technetwork/oracle-labs/program-languages/downloads/index.html");
        } else {
            errorMessage.format("Download the latest JDK 9 EA from https://jdk9.java.net/download/");
        }
        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());
        }
    }

    static void check(boolean exitOnFailure) {
        // Don't use regular expressions to minimize Graal startup time
        String vmVersion = System.getProperty("java.vm.version");
        if (System.getProperty("java.specification.version").compareTo("1.9") < 0) {
            int start = vmVersion.indexOf("-jvmci-");
            if (start >= 0) {
                start += "-jvmci-".length();
                int end = vmVersion.indexOf('.', start);
                if (end > 0) {
                    int major = Integer.parseInt(vmVersion.substring(start, end));
                    start = end + 1;
                    end = start;
                    while (end < vmVersion.length() && Character.isDigit(vmVersion.charAt(end))) {
                        end++;
                    }
                    int minor = Integer.parseInt(vmVersion.substring(start, end));
                    if (major >= JVMCI8_MIN_MAJOR_VERSION && minor >= JVMCI8_MIN_MINOR_VERSION) {
                        return;
                    }
                    failVersionCheck(exitOnFailure, "The VM does not support the minimum JVMCI API version required by Graal: %d.%d < %d.%d.%n",
                                    major, minor, JVMCI8_MIN_MAJOR_VERSION, JVMCI8_MIN_MINOR_VERSION);
                    return;
                }
            }
            failVersionCheck(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 (vmVersion.contains("SNAPSHOT")) {
                // The snapshot of http://hg.openjdk.java.net/jdk9/hs tip is expected to work
                return;
            }
            if (vmVersion.contains("internal")) {
                // Allow local builds
                return;
            }
            // http://openjdk.java.net/jeps/223
            // Only support EA builds until GA is available
            if (vmVersion.startsWith("9-ea+")) {
                int start = "9-ea+".length();
                int end = start;
                end = start;
                while (end < vmVersion.length() && Character.isDigit(vmVersion.charAt(end))) {
                    end++;
                }
                int build = Integer.parseInt(vmVersion.substring(start, end));
                if (build >= JVMCI9_MIN_EA_BUILD) {
                    return;
                }
                failVersionCheck(exitOnFailure, "The VM is an insufficiently recent EA JDK9 build for Graal: %d < %d.%n", build, JVMCI9_MIN_EA_BUILD);
                return;
            }
            failVersionCheck(exitOnFailure, "The VM does not support the minimum JVMCI API version required by Graal.%n" +
                            "Cannot read JDK9 EA build number from java.vm.version property: %s.%n", vmVersion);
        }
    }

    /**
     * Command line interface for performing the check.
     */
    public static void main(String[] args) {
        check(true);
    }
}