/*
 * 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 org.apache.commons.vfs2.util;

import java.io.File;
import java.util.ArrayList;
import java.util.HashSet;
import java.util.List;
import java.util.Locale;
import java.util.Set;

/**
 * Class to help determining the OS.
 */
public final class Os {

    /**
     * All Windows based OSes.
     */
    public static final OsFamily OS_FAMILY_WINDOWS = new OsFamily("windows");

    /**
     * All DOS based OSes.
     */
    public static final OsFamily OS_FAMILY_DOS = new OsFamily("dos");

    /**
     * All Windows NT based OSes.
     */
    public static final OsFamily OS_FAMILY_WINNT = new OsFamily("nt", new OsFamily[] { OS_FAMILY_WINDOWS });

    /**
     * All Windows 9x based OSes.
     */
    public static final OsFamily OS_FAMILY_WIN9X = new OsFamily("win9x",
            new OsFamily[] { OS_FAMILY_WINDOWS, OS_FAMILY_DOS });

    /**
     * OS/2.
     */
    public static final OsFamily OS_FAMILY_OS2 = new OsFamily("os/2", new OsFamily[] { OS_FAMILY_DOS });

    /**
     * Netware.
     */
    public static final OsFamily OS_FAMILY_NETWARE = new OsFamily("netware");

    /**
     * All UNIX based OSes.
     */
    public static final OsFamily OS_FAMILY_UNIX = new OsFamily("unix");

    /**
     * All Mac based OSes.
     */
    public static final OsFamily OS_FAMILY_MAC = new OsFamily("mac");

    /**
     * OSX.
     */
    public static final OsFamily OS_FAMILY_OSX = new OsFamily("osx", new OsFamily[] { OS_FAMILY_UNIX, OS_FAMILY_MAC });

    private static final String OS_NAME = System.getProperty("os.name").toLowerCase(Locale.US);
    private static final String OS_ARCH = System.getProperty("os.arch").toLowerCase(Locale.US);
    private static final String OS_VERSION = System.getProperty("os.version").toLowerCase(Locale.US);
    private static final String PATH_SEP = File.pathSeparator;
    private static final OsFamily OS_FAMILY;
    private static final OsFamily[] OS_ALL_FAMILIES;

    private static final OsFamily[] ALL_FAMILIES = new OsFamily[] { OS_FAMILY_DOS, OS_FAMILY_MAC, OS_FAMILY_NETWARE,
            OS_FAMILY_OS2, OS_FAMILY_OSX, OS_FAMILY_UNIX, OS_FAMILY_WINDOWS, OS_FAMILY_WINNT, OS_FAMILY_WIN9X };

    static {
        OS_FAMILY = determineOsFamily();
        OS_ALL_FAMILIES = determineAllFamilies();
    }

    /**
     * Private constructor to block instantiation.
     */
    private Os() {
    }

    /**
     * Determines if the OS on which Ant is executing matches the given OS version.
     *
     * @param version The version to check.
     * @return true if the version matches.
     */
    public static boolean isVersion(final String version) {
        return isOs((OsFamily) null, null, null, version);
    }

    /**
     * Determines if the OS on which Ant is executing matches the given OS architecture.
     *
     * @param arch The architecture to check.
     * @return true if the architecture mataches.
     */
    public static boolean isArch(final String arch) {
        return isOs((OsFamily) null, null, arch, null);
    }

    /**
     * Determines if the OS on which Ant is executing matches the given OS family.
     *
     * @param family The family to check.
     * @return true if the family matches.
     */
    public static boolean isFamily(final String family) {
        return isOs(family, null, null, null);
    }

    /**
     * Determines if the OS on which Ant is executing matches the given OS family.
     *
     * @param family The family to check.
     * @return true if the family matches.
     */
    public static boolean isFamily(final OsFamily family) {
        return isOs(family, null, null, null);
    }

    /**
     * Determines if the OS on which Ant is executing matches the given OS name.
     *
     * @param name Description of Parameter
     * @return The Name value
     * @since 1.7
     */
    public static boolean isName(final String name) {
        return isOs((OsFamily) null, name, null, null);
    }

    /**
     * Determines if the OS on which Ant is executing matches the given OS family, name, architecture and version.
     *
     * @param family The OS family
     * @param name The OS name
     * @param arch The OS architecture
     * @param version The OS version
     * @return The Os value
     */
    public static boolean isOs(final String family, final String name, final String arch, final String version) {
        return isOs(getFamily(family), name, arch, version);
    }

    /**
     * Determines if the OS on which Ant is executing matches the given OS family, name, architecture and version.
     *
     * @param family The OS family
     * @param name The OS name
     * @param arch The OS architecture
     * @param version The OS version
     * @return The Os value
     */
    public static boolean isOs(final OsFamily family, final String name, final String arch, final String version) {
        if (family != null || name != null || arch != null || version != null) {
            final boolean isFamily = familyMatches(family);
            final boolean isName = nameMatches(name);
            final boolean isArch = archMatches(arch);
            final boolean isVersion = versionMatches(version);

            return isFamily && isName && isArch && isVersion;
        }
        return false;
    }

    /**
     * Locates an OsFamily by name (case-insensitive).
     *
     * @param name The family name to lookup.
     * @return the OS family, or null if not found.
     */
    public static OsFamily getFamily(final String name) {
        for (final OsFamily osFamily : ALL_FAMILIES) {
            if (osFamily.getName().equalsIgnoreCase(name)) {
                return osFamily;
            }
        }

        return null;
    }

    private static boolean versionMatches(final String version) {
        boolean isVersion = true;
        if (version != null) {
            isVersion = version.equalsIgnoreCase(OS_VERSION);
        }
        return isVersion;
    }

    private static boolean archMatches(final String arch) {
        boolean isArch = true;
        if (arch != null) {
            isArch = arch.equalsIgnoreCase(OS_ARCH);
        }
        return isArch;
    }

    private static boolean nameMatches(final String name) {
        boolean isName = true;
        if (name != null) {
            isName = name.equalsIgnoreCase(OS_NAME);
        }
        return isName;
    }

    private static boolean familyMatches(final OsFamily family) {
        if (family == null) {
            return false;
        }
        for (final OsFamily osFamily : OS_ALL_FAMILIES) {
            if (family == osFamily) {
                return true;
            }
        }
        return false;
    }

    private static OsFamily[] determineAllFamilies() {
        // Determine all families the current OS belongs to
        final Set<OsFamily> allFamilies = new HashSet<>();
        if (OS_FAMILY != null) {
            final List<OsFamily> queue = new ArrayList<>();
            queue.add(OS_FAMILY);
            while (queue.size() > 0) {
                final OsFamily family = queue.remove(0);
                allFamilies.add(family);
                final OsFamily[] families = family.getFamilies();
                for (final OsFamily parent : families) {
                    queue.add(parent);
                }
            }
        }
        return allFamilies.toArray(new OsFamily[allFamilies.size()]);
    }

    private static OsFamily determineOsFamily() {
        // Determine the most specific OS family
        if (OS_NAME.indexOf("windows") > -1) {
            if (OS_NAME.indexOf("xp") > -1 || OS_NAME.indexOf("2000") > -1 || OS_NAME.indexOf("nt") > -1) {
                return OS_FAMILY_WINNT;
            }
            return OS_FAMILY_WIN9X;
        } else if (OS_NAME.indexOf("os/2") > -1) {
            return OS_FAMILY_OS2;
        } else if (OS_NAME.indexOf("netware") > -1) {
            return OS_FAMILY_NETWARE;
        } else if (OS_NAME.indexOf("mac") > -1) {
            if (OS_NAME.endsWith("x")) {
                return OS_FAMILY_OSX;
            }
            return OS_FAMILY_MAC;
        } else if (PATH_SEP.equals(":")) {
            return OS_FAMILY_UNIX;
        } else {
            return null;
        }
    }
}
