/* ImportHandler Copyright (C) 1998-2002 Jochen Hoenicke.
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU Lesser General Public License as published by
 * the Free Software Foundation; either version 2, or (at your option)
 * any later version.
 *
 * This program 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 Lesser General Public License
 * along with this program; see the file COPYING.LESSER.  If not, write to
 * the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA.
 *
 * $Id$
 */

package net.sf.jode.decompiler;
import net.sf.jode.GlobalOptions;
import net.sf.jode.bytecode.ClassInfo;
import net.sf.jode.bytecode.ClassPath;
import net.sf.jode.type.Type;
import net.sf.jode.type.ArrayType;
import net.sf.jode.type.ClassInfoType;
import net.sf.jode.type.ClassType;
import net.sf.jode.type.NullType;

///#def COLLECTIONS java.util
import java.util.SortedMap;
import java.util.TreeMap;
import java.util.List;
import java.util.LinkedList;
import java.util.Comparator;
import java.util.Iterator;
///#enddef

import java.io.IOException;
import java.util.Hashtable;

public class ImportHandler {
    /**
     * The default package limit.  MAX_VALUE means, do not import
     * packages at all.
     */
    public final static int DEFAULT_PACKAGE_LIMIT = Integer.MAX_VALUE;
    /**
     * The default class limit.  1 means, import every class used here.
     */
    public final static int DEFAULT_CLASS_LIMIT = 1;

    SortedMap imports;
    /* Classes that doesn't need to be qualified. */
    Hashtable cachedClassNames = null;
    ClassAnalyzer main;
    ClassPath classPath;
    String className;
    String pkg;

    int importPackageLimit;
    int importClassLimit;

    /**
     * A comparator to sort the imports.  We want java.* and javax.*
     * imports first.  java.lang.* should precede java.lang.ref.*, but
     * that is already guaranteed by ascii ordering.  
     */
    static Comparator comparator = new Comparator() {
	public int compare(Object o1, Object o2) {
	    String s1 = (String) o1;
	    String s2 = (String) o2;
	    boolean java1 = s1.startsWith("java");
	    boolean java2 = s2.startsWith("java");

	    if (java1 != java2)
		return java1 ? -1 : 1;
	    return s1.compareTo(s2);
	}
    };

    public ImportHandler(ClassPath classPath) {
	this(classPath, DEFAULT_PACKAGE_LIMIT, DEFAULT_CLASS_LIMIT);
    }
    
    public ImportHandler(ClassPath classPath,
			 int packageLimit, int classLimit) {
	this.classPath = classPath;
	importPackageLimit = packageLimit;
	importClassLimit = classLimit;
    }

    /**
     * Checks if the className conflicts with a class imported from
     * another package and must be fully qualified therefore.
     * The imports must should have been cleaned up before.
     * <p>
     * Known Bug: If a class, local, field or method with the same
     * name as the package of className exists, using the fully
     * qualified name is no solution.  This sometimes can't be fixed
     * at all (except by renaming the package).  It happens only in
     * ambigous contexts, namely static field/method access.
     * @param name The full qualified class name.
     * @return true if this className must be printed fully qualified.  
     */
    private boolean conflictsImport(String name) {
        int pkgdelim = name.lastIndexOf('.');
        if (pkgdelim != -1) {
            String pkgName = name.substring(0, pkgdelim);
            /* All classes in this package doesn't conflict */
            if (pkgName.equals(pkg))
                return false;

            // name without package, but _including_ leading dot.
            name = name.substring(pkgdelim); 

            if (pkg.length() != 0) {
		/* Does this conflict with a class in this package? */
                if (classPath.existsClass(pkg+name))
                    return true;
            } else {
		/* Does this conflict with a class in this unnamed
                 * package? */
		if (classPath.existsClass(name.substring(1)))
		    return true;
	    }

            Iterator iter = imports.keySet().iterator();
            while (iter.hasNext()) {
                String importName = (String) iter.next();
                if (importName.endsWith(".*")) {
                    /* strip the "*" */
                    importName = importName.substring
                        (0, importName.length()-2);
                    if (!importName.equals(pkgName)) {
                        if (classPath.existsClass(importName+name))
                            return true;
                    }
                } else {
		    /* Is this a class import with same name? */
		    if (importName.endsWith(name)
			|| importName.equals(name.substring(1)))
			return true;
		}
            }
        }
        return false;
    }

    private void cleanUpImports() {
        Integer dummyVote = new Integer(Integer.MAX_VALUE);
        SortedMap newImports = new TreeMap(comparator);
        List classImports = new LinkedList();
        Iterator iter = imports.keySet().iterator();
        while (iter.hasNext()) {
            String importName = (String) iter.next();
            Integer vote = (Integer) imports.get(importName);
            if (!importName.endsWith(".*")) {
                if (vote.intValue() < importClassLimit)
                    continue;
                int delim = importName.lastIndexOf(".");

		if (delim != -1) {
		    /* Since the imports are sorted, newImports already
		     * contains the package if it should be imported.
		     */
		    if (newImports.containsKey
			(importName.substring(0, delim)+".*"))
			continue;
		    
		    /* This is a single Class import, that is not
		     * superseeded by a package import.  Mark it for
		     * importation, but don't put it in newImports, yet.  
		     */
		    classImports.add(importName);
		} else if (pkg.length() != 0) {
		    /* This is a Class import from the unnamed
		     * package.  It must always be imported.
		     */
		    newImports.put(importName, dummyVote);
		}
            } else {
                if (vote.intValue() < importPackageLimit)
                    continue;
                newImports.put(importName, dummyVote);
            }
        }

        imports = newImports;
        cachedClassNames = new Hashtable();
        /* Now check if the class import conflict with any of the
         * package imports.
         */
        iter = classImports.iterator();
        while (iter.hasNext()) {
            /* If there are more than one single class imports with
             * the same name, exactly the first (in sorted order) will
             * be imported. 
	     */
            String classFQName = (String) iter.next();
            if (!conflictsImport(classFQName)) {
                imports.put(classFQName, dummyVote);
                String name = 
                    classFQName.substring(classFQName.lastIndexOf('.')+1);
                cachedClassNames.put(classFQName, name);
            }
        }
    }

    public void dumpHeader(TabbedPrintWriter writer) 
         throws java.io.IOException
    {
        writer.println("/* "+ className 
		       + " - Decompiled by JODE");
	writer.println(" * Visit "+GlobalOptions.URL);
	writer.println(" */");
        if (pkg.length() != 0)
            writer.println("package "+pkg+";");

        cleanUpImports();
        Iterator iter = imports.keySet().iterator();
	String lastFirstPart = null;
        while (iter.hasNext()) {
            String pkgName = (String)iter.next();
            if (!pkgName.equals("java.lang.*")) {
		int firstDot = pkgName.indexOf('.');
		if (firstDot != -1) {
		    String firstPart = pkgName.substring(0, firstDot);
		    if (lastFirstPart != null
			&& !lastFirstPart.equals(firstPart)) {
			writer.println("");
		    }
		    lastFirstPart = firstPart;
		}
                writer.println("import "+pkgName+";");
	    }
        }
        writer.println("");
    }

    public void error(String message) {
        GlobalOptions.err.println(message);
    }

    public void init(String className) {
        imports = new TreeMap(comparator);
        /* java.lang is always imported */
        imports.put("java.lang.*", new Integer(Integer.MAX_VALUE));

        int pkgdelim = className.lastIndexOf('.');
        pkg = (pkgdelim == -1)? "" : className.substring(0, pkgdelim);
        this.className = (pkgdelim == -1) ? className
            : className.substring(pkgdelim+1);
    }

    /* Marks the clazz as used, so that it will be imported if used often
     * enough.
     */
    public void useClass(ClassInfo clazz) {
	for (;;) {
	    try {
		/* First handle inner classes:  For class scoped classes 
		 * import outer class instead;  for method scoped classes
		 * we don't import anything.
		 */
		clazz.load(ClassInfo.OUTERCLASS);
	    } catch (IOException ex) {
		/* If we can't load outer class information, assume
		 * the clazz is not method or class scoped in this 
		 * class.  There is a big error otherwise anyways.
		 */
		break;
	    }
	    if (clazz.isMethodScoped())
		return;
	    ClassInfo outer = clazz.getOuterClass();
	    if (outer == null)
		break;
	    clazz = outer;
	}
		
	useClass(clazz.getName());
    }

    /* Marks the clazz as used, so that it will be imported if used often
     * enough.
     */
    public void useClass(String name) {
	
	Integer i = (Integer) imports.get(name);
	if (i == null) {
	    /* This class wasn't imported before.  Mark the whole package
	     * as used once more. */
	    
	    int pkgdelim = name.lastIndexOf('.');
	    if (pkgdelim != -1) {
		String pkgName = name.substring(0, pkgdelim);
		if (pkgName.equals(pkg))
		    return;
		
		Integer pkgVote = (Integer) imports.get(pkgName+".*");
		if (pkgVote != null 
		    && pkgVote.intValue() >= importPackageLimit)
		    return;

		pkgVote = (pkgVote == null)
		    ? new Integer(1): new Integer(pkgVote.intValue()+1);
		imports.put(pkgName+".*", pkgVote);
	    }
	    i = new Integer(1);
	} else {
	    if (i.intValue() >= importClassLimit)
		return;
	    i = new Integer(i.intValue()+1);
	}
	imports.put(name, i);
    }

    public final void useType(Type type) {
	if (type instanceof ArrayType)
	    useType(((ArrayType) type).getElementType());
	else if (type instanceof ClassInfoType)
	    useClass(((ClassInfoType) type).getClassInfo());
	else if (type instanceof ClassType)
	    useClass(((ClassType) type).getClassName());
    }

    /**
     * Check if clazz is imported and maybe remove package delimiter from
     * full qualified class name.
     * <p>
     * Known Bug 1: If this is called before the imports are cleaned up,
     * (that is only for debugging messages), the result is unpredictable.
     * <p>
     * Known Bug 2: It is not checked if the class name conflicts with
     * a local variable, field or method name.  This is very unlikely
     * since the java standard has different naming convention for those
     * names. (But maybe an intelligent obfuscator may use this fact.)
     * This can only happen with static fields or static methods.
     * @return a legal string representation of clazz.  
     */
    public String getClassString(ClassInfo clazz) {
	return getClassString(clazz.getName());
    }

    /**
     * Check if clazz is imported and maybe remove package delimiter from
     * full qualified class name.
     * <p>
     * Known Bug 1: If this is called before the imports are cleaned up,
     * (that is only for debugging messages), the result is unpredictable.
     * <p>
     * Known Bug 2: It is not checked if the class name conflicts with
     * a local variable, field or method name.  This is very unlikely
     * since the java standard has different naming convention for those
     * names. (But maybe an intelligent obfuscator may use this fact.)
     * This can only happen with static fields or static methods.
     * @return a legal string representation of clazz.  
     */
    public String getClassString(String name) {
        if (cachedClassNames == null)
            /* We are not yet clean, return the full name */
            return name;

        /* First look in our cache. */
        String cached = (String) cachedClassNames.get(name);
        if (cached != null)
            return cached;

        int pkgdelim = name.lastIndexOf('.');
        if (pkgdelim != -1) {
                
            String pkgName = name.substring(0, pkgdelim);

            if (pkgName.equals(pkg)
                || (imports.get(pkgName+".*") != null
                    && !conflictsImport(name))) {
                String result = name.substring(pkgdelim+1);
                cachedClassNames.put(name, result);
                return result;
            }
        }
        cachedClassNames.put(name, name);
        return name;
    }

    public String getTypeString(Type type) {
	if (type instanceof ArrayType)
	    return getTypeString(((ArrayType) type).getElementType()) + "[]";
	else if (type instanceof ClassInfoType)
	    return getClassString(((ClassInfoType) type).getClassInfo());
	else if (type instanceof ClassType)
	    return getClassString(((ClassType) type).getClassName());
	else if (type instanceof NullType)
	    return "Object";
	else
	    return type.toString();
    }

    protected int loadFileFlags()
    {
        return 1;
    }
}