/*
 * MailcapCommandMap.java
 * Copyright (C) 2004 The Free Software Foundation
 * 
 * This file is part of GNU Java Activation Framework (JAF), a library.
 * 
 * GNU JAF is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 * 
 * GNU JAF 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 for more details.
 * 
 * You should have received a copy of the GNU General Public License
 * along with this library; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 *
 * As a special exception, if you link this library with other files to
 * produce an executable, this library does not by itself cause the
 * resulting executable to be covered by the GNU General Public License.
 * This exception does not however invalidate any other reasons why the
 * executable file might be covered by the GNU General Public License.
 */
package javax.activation;

import java.io.BufferedReader;
import java.io.File;
import java.io.FileReader;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.IOException;
import java.io.Reader;
import java.io.StringReader;
import java.net.URL;
import java.util.ArrayList;
import java.util.Enumeration;
import java.util.HashMap;
import java.util.Iterator;
import java.util.List;
import java.util.Map;

/**
 * Implementation of a command map using a <code>mailcap</code> file (RFC
 * 1524). Mailcap files are searched for in the following places:
 * <ol>
 * <li>Programmatically added entries to this interface</li>
 * <li>the file <tt>.mailcap</tt> in the user's home directory</li>
 * <li>the file <i>&lt;java.home&gt;</i><tt>/lib/mailcap</tt></li>
 * <li>the resource <tt>META-INF/mailcap</tt></li>
 * <li>the resource <tt>META-INF/mailcap.default</tt> in the JAF
 * distribution</li>
 * </ol>
 *
 * @author <a href='mailto:dog@gnu.org'>Chris Burdess</a>
 * @version 1.0.2
 */
public class MailcapCommandMap
    extends CommandMap
{

    private static final int PROG = 0;
    private static final int HOME = 1;
    private static final int SYS = 2;
    private static final int JAR = 3;
    private static final int DEF = 4;
    private static boolean debug = false;
    
    static 
    {
        try
        {
            String d = System.getProperty("javax.activation.debug");
            debug = Boolean.valueOf(d).booleanValue();
        }
        catch (SecurityException e)
        {
        }
    }
    
    private Map[] mailcaps;

    /**
     * Default constructor.
     */
    public MailcapCommandMap()
    {
        init(null);
    }

    /**
     * Constructor specifying a filename.
     * @param fileName the name of the file to read mailcap entries from
     */
    public MailcapCommandMap(String fileName)
        throws IOException
    {
        Reader in = null;
        try
        {
            in = new FileReader(fileName);
        }
        catch (IOException e)
        {
        }
        init(in);
        if (in != null)
        {
            try
            {
                in.close();
            }
            catch (IOException e)
            {
            }
        }
    }

    /**
     * Constructor specifying an input stream.
     * @param is the input stream to read mailcap entries from
     */
    public MailcapCommandMap(InputStream is)
    {
        init(new InputStreamReader(is));
    }

    private void init(Reader in)
    {
        mailcaps = new Map[5];
        for (int i = 0; i < mailcaps.length; i++)
            mailcaps[i] = new HashMap();
        if (in != null)
        {
            if (debug)
                System.out.println("MailcapCommandMap: load PROG");
            try
            {
                parse(mailcaps[PROG], in);
            }
            catch (IOException e)
            {
            }
        }
        
        if (debug)
            System.out.println("MailcapCommandMap: load HOME");
        try
        {
            String home = System.getProperty("user.home");
            if (home != null)
            {
                parseFile(mailcaps[HOME], new StringBuffer(home)
                        .append(File.separatorChar)
                        .append(".mailcap")
                        .toString());
            }
        }
        catch (SecurityException e)
        {
        }
        
        if (debug)
            System.out.println("MailcapCommandMap: load SYS");
        try
        {
            parseFile(mailcaps[SYS], 
                    new StringBuffer(System.getProperty("java.home"))
                    .append(File.separatorChar)                                                     .append("lib")
                    .append(File.separatorChar)
                    .append("mailcap")
                    .toString());
        }
        catch (SecurityException e)
        {
        }
        
        if (debug)
            System.out.println("MailcapCommandMap: load JAR");
        List systemResources = getSystemResources("META-INF/mailcap");
        int len = systemResources.size();
        if (len > 0)
        {
            for (int i = 0; i < len ; i++)
            {
                Reader urlIn = null;
                URL url = (URL)systemResources.get(i);
                try
                {
                    if (debug)
                        System.out.println("\t" + url.toString());
                    urlIn = new InputStreamReader(url.openStream());
                    parse(mailcaps[JAR], urlIn);
                }
                catch (IOException e)
                {
                    if (debug)
                        System.out.println(e.getClass().getName() + ": " +
                                           e.getMessage());
                }
                finally
                {
                    if (urlIn != null)
                    {
                        try
                        {
                            urlIn.close();
                        }
                        catch (IOException e)
                        {
                        }
                    }
                }
            }
        }
        else
            parseResource(mailcaps[JAR], "/META-INF/mailcap");
        
        if (debug)
            System.out.println("MailcapCommandMap: load DEF");
        parseResource(mailcaps[DEF], "/META-INF/mailcap.default");
    }

    /**
     * Returns the list of preferred commands for a given MIME type.
     * @param mimeType the MIME type
     */
    public synchronized CommandInfo[] getPreferredCommands(String mimeType)
    {
        List cmdList = new ArrayList();
        List verbList = new ArrayList();
        for (int i = 0; i < mailcaps.length; i++)
        {
            Map map = getCommands(mailcaps[i], mimeType);
            if (map != null)
            {
                for (Iterator j = map.keySet().iterator(); j.hasNext(); )
                {
                    String verb = (String)j.next();
                    if (!verbList.contains(verb))
                    {
                        List classNames = (List)map.get(verb);
                        String className = (String)classNames.get(0);
                        CommandInfo cmd = new CommandInfo(verb, className);
                        cmdList.add(cmd);
                        verbList.add(verb);
                    }
                }
            }
        }
        CommandInfo[] cmds = new CommandInfo[cmdList.size()];
        cmdList.toArray(cmds);
        return cmds;
    }

    /**
     * Returns all commands for the given MIME type.
     * @param mimeType the MIME type
     */
    public synchronized CommandInfo[] getAllCommands(String mimeType)
    {
        List cmdList = new ArrayList();
        for (int i = 0; i < mailcaps.length; i++)
        {
            Map map = getCommands(mailcaps[i], mimeType);
            if (map != null)
            {
                for (Iterator j = map.keySet().iterator(); j.hasNext(); )
                {
                    String verb = (String)j.next();
                    List classNames = (List)map.get(verb);
                    int len = classNames.size();
                    for (int k = 0; k < len; k++)
                    {
                        String className = (String)classNames.get(k);
                        CommandInfo cmd = new CommandInfo(verb, className);
                        cmdList.add(cmd);
                    }
                }
            }
        }
        CommandInfo[] cmds = new CommandInfo[cmdList.size()];
        cmdList.toArray(cmds);
        return cmds;
    }

    /**
     * Returns the command with the specified name for the given MIME type.
     * @param mimeType the MIME type
     * @param cmdName the command verb
     */
    public synchronized CommandInfo getCommand(String mimeType,
            String cmdName)
    {
        for (int i = 0; i < mailcaps.length; i++)
        {
            Map map = getCommands(mailcaps[i], mimeType);
            if (map != null)
            {
                List classNames = (List)map.get(cmdName);
                if (classNames == null)
                    classNames = (List)map.get("x-java-" + cmdName);
                if (classNames != null)
                {
                    String className = (String)classNames.get(0);
                    return new CommandInfo(cmdName, className);
                }
            }
        }
        return null;
    }

    /**
     * Adds entries programmatically to the registry.
     * @param mail_cap a mailcap string
     */
    public synchronized void addMailcap(String mail_cap)
    {
        if(debug)
            System.out.println("MailcapCommandMap: add to PROG");
        try
        {
            parse(mailcaps[PROG], new StringReader(mail_cap));
        }
        catch (IOException e)
        {
        }
    }

    /**
     * Returns the DCH for the specified MIME type.
     * @param mimeType the MIME type
     */
    public synchronized DataContentHandler createDataContentHandler(
            String mimeType)
    {
        if (debug)
            System.out.println("MailcapCommandMap: createDataContentHandler for " + mimeType);
        for (int i = 0; i < mailcaps.length; i++)
        {
            if (debug)
                System.out.println("  search DB #" + i);
            Map map = getCommands(mailcaps[i], mimeType);
            if (map != null)
            {
                List classNames = (List)map.get("content-handler");
                if (classNames == null)
                    classNames = (List)map.get("x-java-content-handler");
                if (classNames != null)
                {
                    String className = (String)classNames.get(0);
                    if (debug)
                        System.out.println("  In " + nameOf(i) +
                                ", content-handler=" + className);
                    try
                    {
                        Class clazz = Class.forName(className);
                        return (DataContentHandler)clazz.newInstance();
                    }
                    catch (IllegalAccessException e)
                    {
                        if (debug)
                            e.printStackTrace();
                    }
                    catch (ClassNotFoundException e)
                    {
                        if (debug)
                            e.printStackTrace();
                    }
                    catch (InstantiationException e)
                    {
                        if (debug)
                            e.printStackTrace();
                    }
                }
            }
        }
        return null;
    }

    private static String nameOf(int mailcap)
    {
        switch (mailcap)
        {
          case PROG:
            return "PROG";
          case HOME:
            return "HOME";
          case SYS:
            return "SYS";
          case JAR:
            return "JAR";
          case DEF:
            return "DEF";
          default:
            return "ERR";
        }   
    }

    private void parseFile(Map mailcap, String filename)
    {
        Reader in = null;
        try
        {
            if (debug)
                System.out.println("\t" + filename);
            in = new FileReader(filename);
            parse(mailcap, in);
        }
        catch (IOException e)
        {
            if (debug)
                System.out.println(e.getClass().getName() + ": " +
                                   e.getMessage());
        }
        finally
        {
            if (in != null)
            {
                try
                {
                    in.close();
                }
                catch (IOException e)
                {
                }
            }
        }
    }

    private void parseResource(Map mailcap, String name)
    {
        Reader in = null;
        try
        {
            InputStream is = getClass().getResourceAsStream(name);
            if (is != null)
            {
                if (debug)
                    System.out.println("\t" + name);
                in = new InputStreamReader(is);
                parse(mailcap, in);
            }
        }
        catch (IOException e)
        {
            if (debug)
                System.out.println(e.getClass().getName() + ": " +
                                   e.getMessage());
        }
        finally
        {
            if (in != null)
            {
                try
                {
                    in.close();
                }
                catch (IOException e)
                {
                }
            }
        }
    }

    private void parse(Map mailcap, Reader in)
        throws IOException
    {
        BufferedReader br = new BufferedReader(in);
        StringBuffer buf = null;
        for (String line = br.readLine(); line != null; line = br.readLine())
        {
            line = line.trim();
            int len = line.length();
            if (len == 0 || line.charAt(0) == '#')
                continue; // Comment
            if (line.charAt(len - 1) == '\\')
            {
                if (buf == null)
                    buf = new StringBuffer();
                buf.append(line.substring(0, len - 1));
            }
            else if (buf != null)
            {
                buf.append(line);
                parseEntry(mailcap, buf.toString());
                buf = null;
            }
            else
                parseEntry(mailcap, line);
        }
    }

    private void parseEntry(Map mailcap, String line)
    {
        // Tokenize entry into fields
        char[] chars = line.toCharArray();
        int len = chars.length;
        boolean inQuotedString = false;
        StringBuffer buffer = new StringBuffer();
        List fields = new ArrayList();
        for (int i = 0; i < len; i++) {
            char c = chars[i];
            if (c == '\\')
                c = chars[++i];// qchar
            if (c == ';' && !inQuotedString)
            {
                fields.add(buffer.toString().trim());
                buffer.setLength(0);
            }
            else
            {
                if (c == '"')
                    inQuotedString = !inQuotedString;
                buffer.append(c);
            }
        }
        fields.add(buffer.toString().trim());

        len = fields.size();
        if (len < 2)
        {
            if (debug)
                System.err.println("Invalid mailcap entry: " + line);
            return;
        }

        String mimeType = (String)fields.get(0);
        addField(mailcap, mimeType, "view-command", (String)fields.get(1));
        for (int i = 2; i < len; i++)
            addField(mailcap, mimeType, null, (String)fields.get(i));
    }

    private void addField(Map mailcap, String mimeType, String verb,
            String command)
    {
        if (verb == null)
        {
            int ei = command.indexOf('=');
            if (ei != -1)
            {
                verb = command.substring(0, ei);
                command = command.substring(ei + 1);
            }
        }
        if (command.length() == 0 || verb == null || verb.length() == 0)
            return; // Invalid field or flag
        
        Map commands = (Map)mailcap.get(mimeType);
        if (commands == null)
        {
            commands = new HashMap();
            mailcap.put(mimeType, commands);
        }
        List classNames = (List)commands.get(verb);
        if (classNames == null)
        {
            classNames = new ArrayList();
            commands.put(verb, classNames);
        }
        classNames.add(command);
    }

    private Map getCommands(Map mailcap, String mimeType)
    {
        int si = mimeType.indexOf('/');
        String genericMimeType = new StringBuffer(mimeType.substring(0, si))
            .append('/')
            .append('*')
            .toString();
        Map specific = (Map)mailcap.get(mimeType);
        Map generic = (Map)mailcap.get(genericMimeType);
        if (generic == null)
            return specific;
        if (specific == null)
            return generic;
        Map combined = new HashMap();
        combined.putAll(specific);
        for (Iterator i = generic.keySet().iterator(); i.hasNext(); )
        {
            String verb = (String)i.next();
            List genericClassNames = (List)generic.get(verb);
            List classNames = (List)combined.get(verb);
            if (classNames == null)
                combined.put(verb, genericClassNames);
            else
                classNames.addAll(genericClassNames);
        }
        return combined;
    }

    // -- Utility methods --

    private List getSystemResources(String name)
    {
        List acc = new ArrayList();
        try
        {
            for (Enumeration i = ClassLoader.getSystemResources(name);
                    i.hasMoreElements(); )
                acc.add(i.nextElement());
        }
        catch (IOException e)
        {
        }
        return acc;
    }

}