/*
 * Copyright 2002-2005 The Apache Software Foundation.
 * 
 * Licensed 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.vfs.util;

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.
 *
 * @author <a href="mailto:stefan.bodewig@epost.de">Stefan Bodewig</a>
 * @author <a href="mailto:umagesh@apache.org">Magesh Umasankar</a>
 * @author <a href="mailto:peter@apache.org">Peter Donald</a>
 */
public final class Os
{
    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 =
        System.getProperty("path.separator");
    private static final OsFamily OS_FAMILY;
    private static final OsFamily[] OS_ALL_FAMILIES;

    /**
     * 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 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.
     */
    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.
     */
    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.
     */
    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.
     */
    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;
        }
        else
        {
            return false;
        }
    }

    /**
     * Locates an OsFamily by name (case-insensitive).
     *
     * @return the OS family, or null if not found.
     */
    public static OsFamily getFamily(final String name)
    {
        for (int i = 0; i < ALL_FAMILIES.length; i++)
        {
            final OsFamily osFamily = ALL_FAMILIES[i];
            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 (int i = 0; i < OS_ALL_FAMILIES.length; i++)
        {
            final OsFamily osFamily = OS_ALL_FAMILIES[i];
            if (family == osFamily)
            {
                return true;
            }
        }
        return false;
    }

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