/*
 * IzPack - Copyright 2001-2005 Julien Ponge, All Rights Reserved.
 * 
 * http://www.izforge.com/izpack/
 * http://developer.berlios.de/projects/izpack/
 * 
 * Copyright 2002 Olexij Tkatchenko
 * 
 * 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 com.izforge.izpack.util;

import java.util.ArrayList;
import java.util.Iterator;
import java.util.List;

import net.n3.nanoxml.XMLElement;

/**
 * Encapsulates OS constraints specified on creation time and allows to check them against the
 * current OS.
 * 
 * For example, this is used for <executable>s to check whether the executable is suitable for
 * the current OS.
 * 
 * @author Olexij Tkatchenko <ot@parcs.de>
 */
public class OsConstraint implements java.io.Serializable
{

    /**
     * 
     */
    private static final long serialVersionUID = 3762248660406450488L;

    /** The OS family */
    private String family;

    /** OS name from java system properties */
    private String name;

    /** OS version from java system properties */
    private String version;

    /** OS architecture from java system properties */
    private String arch;

    /**
     * Constructs a new instance. Please remember, MacOSX belongs to Unix family.
     * 
     * @param family The OS family (unix, windows or mac).
     * @param name The exact OS name.
     * @param version The exact OS version (check property <code>os.version</code> for values).
     * @param arch The machine architecture (check property <code>os.arch</code> for values).
     */
    public OsConstraint(String family, String name, String version, String arch)
    {
        this.family = family != null ? family.toLowerCase() : null;
        this.name = name != null ? name.toLowerCase() : null;
        this.version = version != null ? version.toLowerCase() : null;
        this.arch = arch != null ? arch.toLowerCase() : null;
    }

    /**
     * Matches OS specification in this class against current system properties.
     * 
     * @return Description of the Return Value
     */
    public boolean matchCurrentSystem()
    {
        boolean match = true;
        String osName = System.getProperty("os.name").toLowerCase();

        if (arch != null && arch.length() != 0)
        {
            match = System.getProperty("os.arch").toLowerCase().equals(arch);
        }
        if (match && version != null && version.length() != 0)
        {
            match = System.getProperty("os.version").toLowerCase().equals(version);
        }
        if (match && name != null && name.length() != 0)
        {
            match = osName.equals(name);
        }
        if (match && family != null)
        {
            if (family.equals("windows"))
            {
                match = OsVersion.IS_WINDOWS;
            }
            else if (family.equals("mac") || family.equals("osx"))
            {
                match = OsVersion.IS_OSX;
            }
            else if (family.equals("unix"))
            {
                match = OsVersion.IS_UNIX;
            }
        }

        return match && (family != null || name != null || version != null || arch != null);
    }

    /**
     * Extract a list of OS constraints from given element.
     * 
     * @param element parent XMLElement
     * @return List of OsConstraint (or empty List if no constraints found)
     */
    static public List getOsList(XMLElement element)
    {
        // get os info on this executable
        ArrayList osList = new ArrayList();
        Iterator osIterator = element.getChildrenNamed("os").iterator();
        while (osIterator.hasNext())
        {
            XMLElement os = (XMLElement) osIterator.next();
            osList.add(new OsConstraint(os.getAttribute("family", null), os.getAttribute("name",
                    null), os.getAttribute("version", null), os.getAttribute("arch", null)));
        }

        // backward compatibility: still support os attribute
        String osattr = element.getAttribute("os");
        if (osattr != null && osattr.length() > 0)
        {
            // add the "os" attribute as a family constraint
            osList.add(new OsConstraint(osattr, null, null, null));
        }

        return osList;
    }

    /**
     * Helper function: Scan a list of OsConstraints for a match.
     * 
     * @param constraint_list List of OsConstraint to check
     * 
     * @return true if one of the OsConstraints matched the current system or constraint_list is
     * null (no constraints), false if none of the OsConstraints matched
     */
    public static boolean oneMatchesCurrentSystem(List constraint_list)
    {
        if (constraint_list == null) return true;

        Iterator constraint_it = constraint_list.iterator();

        // no constraints at all - matches!
        if (!constraint_it.hasNext()) return true;

        while (constraint_it.hasNext())
        {
            OsConstraint osc = (OsConstraint) constraint_it.next();

            Debug.trace("checking if os constraints " + osc + " match current OS");

            // check for match
            if (osc.matchCurrentSystem())
            {
                Debug.trace("matched current OS.");
                return true; // bail out on first match
            }

        }

        Debug.trace("no match with current OS!");
        // no match found
        return false;
    }

    /**
     * Helper function: Check whether the given XMLElement is "suitable" for the current OS.
     * 
     * @param el The XMLElement to check for OS constraints.
     * 
     * @return true if there were no OS constraints or the constraints matched the current OS.
     * 
     */
    public static boolean oneMatchesCurrentSystem(XMLElement el)
    {
        return oneMatchesCurrentSystem(getOsList(el));
    }

    public void setFamily(String f)
    {
        family = f.toLowerCase();
    }

    public String getFamily()
    {
        return family;
    }

    public void setName(String n)
    {
        name = n.toLowerCase();
    }

    public String getName()
    {
        return name;
    }

    public void setVersion(String v)
    {
        version = v.toLowerCase();
    }

    public String getVersion()
    {
        return version;
    }

    public void setArch(String a)
    {
        arch = a.toLowerCase();
    }

    public String getArch()
    {
        return arch;
    }

    public String toString()
    {
        StringBuffer retval = new StringBuffer();
        retval.append("[Os ");
        retval.append(" family " + family);
        retval.append(" name " + name);
        retval.append(" version " + version);
        retval.append(" arch " + arch);
        retval.append(" ]");
        return retval.toString();
    }

}