/*
 * Copyright 1999,2004 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.jasper.tagplugins.jstl;

import org.apache.jasper.compiler.tagplugin.*;

public final class ForEach implements TagPlugin {

    private boolean hasVar, hasBegin, hasEnd, hasStep;

    public void doTag(TagPluginContext ctxt) {

	String index = null;

	boolean hasVarStatus = ctxt.isAttributeSpecified("varStatus");
	if (hasVarStatus) {
	    ctxt.dontUseTagPlugin();
	    return;
	}

	hasVar = ctxt.isAttributeSpecified("var");
	hasBegin = ctxt.isAttributeSpecified("begin");
	hasEnd = ctxt.isAttributeSpecified("end");
	hasStep = ctxt.isAttributeSpecified("step");

	boolean hasItems = ctxt.isAttributeSpecified("items");
	if (hasItems) {
	    doCollection(ctxt);
	    return;
	}

	// We must have a begin and end attributes
	index = ctxt.getTemporaryVariableName();
	ctxt.generateJavaSource("for (int " + index + " = ");
	ctxt.generateAttribute("begin");
	ctxt.generateJavaSource("; " + index + " <= ");
	ctxt.generateAttribute("end");
	if (hasStep) {
	    ctxt.generateJavaSource("; " + index + "+=");
	    ctxt.generateAttribute("step");
	    ctxt.generateJavaSource(") {");
	}
	else {
	    ctxt.generateJavaSource("; " + index + "++) {");
	}

	// If var is specified and the body contains an EL, then sycn
	// the var attribute
	if (hasVar /* && ctxt.hasEL() */) {
	    ctxt.generateJavaSource("_jspx_page_context.setAttribute(");
	    ctxt.generateAttribute("var");
	    ctxt.generateJavaSource(", String.valueOf(" + index + "));");
	}
	ctxt.generateBody();
	ctxt.generateJavaSource("}");
    }

    /**
     * Generate codes for Collections
     * The pseudo code is:
     */
    private void doCollection(TagPluginContext ctxt) {

	ctxt.generateImport("java.util.*");
	generateIterators(ctxt);

        String itemsV = ctxt.getTemporaryVariableName();
        ctxt.generateJavaSource("Object " + itemsV + "= ");
        ctxt.generateAttribute("items");
        ctxt.generateJavaSource(";");
	
	String indexV=null, beginV=null, endV=null, stepV=null;
	if (hasBegin) {
	    beginV = ctxt.getTemporaryVariableName();
	    ctxt.generateJavaSource("int " + beginV + " = ");
	    ctxt.generateAttribute("begin");
	    ctxt.generateJavaSource(";");
	}
	if (hasEnd) {
	    indexV = ctxt.getTemporaryVariableName();
	    ctxt.generateJavaSource("int " + indexV + " = 0;");
	    endV = ctxt.getTemporaryVariableName();
	    ctxt.generateJavaSource("int " + endV + " = ");
	    ctxt.generateAttribute("end");
	    ctxt.generateJavaSource(";");
	}
	if (hasStep) {
	    stepV = ctxt.getTemporaryVariableName();
	    ctxt.generateJavaSource("int " + stepV + " = ");
	    ctxt.generateAttribute("step");
	    ctxt.generateJavaSource(";");
	}

        String iterV = ctxt.getTemporaryVariableName();
        ctxt.generateJavaSource("Iterator " + iterV + " = null;");
	// Object[]
	ctxt.generateJavaSource("if (" + itemsV + " instanceof Object[])");
	ctxt.generateJavaSource(iterV + "=toIterator((Object[])" + itemsV + ");");
	// boolean[]
	ctxt.generateJavaSource("else if (" + itemsV + " instanceof boolean[])");
	ctxt.generateJavaSource(iterV + "=toIterator((boolean[])" + itemsV + ");");
	// byte[]
	ctxt.generateJavaSource("else if (" + itemsV + " instanceof byte[])");
	ctxt.generateJavaSource(iterV + "=toIterator((byte[])" + itemsV + ");");
	// char[]
	ctxt.generateJavaSource("else if (" + itemsV + " instanceof char[])");
	ctxt.generateJavaSource(iterV + "=toIterator((char[])" + itemsV + ");");
	// short[]
	ctxt.generateJavaSource("else if (" + itemsV + " instanceof short[])");
	ctxt.generateJavaSource(iterV + "=toIterator((short[])" + itemsV + ");");
	// int[]
	ctxt.generateJavaSource("else if (" + itemsV + " instanceof int[])");
	ctxt.generateJavaSource(iterV + "=toIterator((int[])" + itemsV + ");");
	// long[]
	ctxt.generateJavaSource("else if (" + itemsV + " instanceof long[])");
	ctxt.generateJavaSource(iterV + "=toIterator((long[])" + itemsV + ");");
	// float[]
	ctxt.generateJavaSource("else if (" + itemsV + " instanceof float[])");
	ctxt.generateJavaSource(iterV + "=toIterator((float[])" + itemsV + ");");
	// double[]
	ctxt.generateJavaSource("else if (" + itemsV + " instanceof double[])");
	ctxt.generateJavaSource(iterV + "=toIterator((double[])" + itemsV + ");");

        // Collection
        ctxt.generateJavaSource("else if (" + itemsV + " instanceof Collection)");
        ctxt.generateJavaSource(iterV + "=((Collection)" + itemsV + ").iterator();");

        // Iterator
        ctxt.generateJavaSource("else if (" + itemsV + " instanceof Iterator)");
        ctxt.generateJavaSource(iterV + "=(Iterator)" + itemsV + ";");

	// Enumeration
	ctxt.generateJavaSource("else if (" + itemsV + " instanceof Enumeration)");
	ctxt.generateJavaSource(iterV + "=toIterator((Enumeration)" + itemsV + ");");

        // Map
        ctxt.generateJavaSource("else if (" + itemsV + " instanceof Map)");
        ctxt.generateJavaSource(iterV + "=((Map)" + itemsV + ").entrySet().iterator();");

	if (hasBegin) {
            String tV = ctxt.getTemporaryVariableName();
	    ctxt.generateJavaSource("for (int " + tV + "=" + beginV + ";" +
			tV + ">0 && " + iterV + ".hasNext(); " +
			tV + "--)");
	    ctxt.generateJavaSource(iterV + ".next();");
	}

	ctxt.generateJavaSource("while (" + iterV + ".hasNext()){");
	if (hasVar) {
	    ctxt.generateJavaSource("_jspx_page_context.setAttribute(");
	    ctxt.generateAttribute("var");
	    ctxt.generateJavaSource(", " + iterV + ".next());");
	}

	ctxt.generateBody();

	if (hasStep) {
	    String tV = ctxt.getTemporaryVariableName();
	    ctxt.generateJavaSource("for (int " + tV + "=" + stepV + "-1;" +
			tV + ">0 && " + iterV + ".hasNext(); " +
			tV + "--)");
	    ctxt.generateJavaSource(iterV + ".next();");
	}
	if (hasEnd) {
	    if (hasStep) {
		ctxt.generateJavaSource(indexV + "+=" + stepV + ";");
	    }
	    else {
		ctxt.generateJavaSource(indexV + "++;");
	    }
	    if (hasBegin) {
		ctxt.generateJavaSource("if(" + beginV + "+" + indexV +
			">"+ endV + ")");
	    }
	    else {
		ctxt.generateJavaSource("if(" + indexV + ">" + endV + ")");
	    }
	    ctxt.generateJavaSource("break;");
	}
	ctxt.generateJavaSource("}");	// while
    }

    /**
     * Generate iterators for data types supported in items
     */
    private void generateIterators(TagPluginContext ctxt) {

	// Object[]
	ctxt.generateDeclaration("ObjectArrayIterator", 
	    "private Iterator toIterator(final Object[] a){\n" +
	    "  return (new Iterator() {\n" +
	    "    int index=0;\n" +
	    "    public boolean hasNext() {\n" +
	    "      return index < a.length;}\n" +
	    "    public Object next() {\n" +
	    "      return a[index++];}\n" +
	    "    public void remove() {}\n" +
	    "  });\n" +
	    "}"
	);

	// boolean[]
	ctxt.generateDeclaration("booleanArrayIterator", 
	    "private Iterator toIterator(final boolean[] a){\n" +
	    "  return (new Iterator() {\n" +
	    "    int index=0;\n" +
	    "    public boolean hasNext() {\n" +
	    "      return index < a.length;}\n" +
	    "    public Object next() {\n" +
	    "      return new Boolean(a[index++]);}\n" +
	    "    public void remove() {}\n" +
	    "  });\n" +
	    "}"
	);

	// byte[]
	ctxt.generateDeclaration("byteArrayIterator", 
	    "private Iterator toIterator(final byte[] a){\n" +
	    "  return (new Iterator() {\n" +
	    "    int index=0;\n" +
	    "    public boolean hasNext() {\n" +
	    "      return index < a.length;}\n" +
	    "    public Object next() {\n" +
	    "      return new Byte(a[index++]);}\n" +
	    "    public void remove() {}\n" +
	    "  });\n" +
	    "}"
	);

	// char[]
	ctxt.generateDeclaration("charArrayIterator", 
	    "private Iterator toIterator(final char[] a){\n" +
	    "  return (new Iterator() {\n" +
	    "    int index=0;\n" +
	    "    public boolean hasNext() {\n" +
	    "      return index < a.length;}\n" +
	    "    public Object next() {\n" +
	    "      return new Character(a[index++]);}\n" +
	    "    public void remove() {}\n" +
	    "  });\n" +
	    "}"
	);

	// short[]
	ctxt.generateDeclaration("shortArrayIterator", 
	    "private Iterator toIterator(final short[] a){\n" +
	    "  return (new Iterator() {\n" +
	    "    int index=0;\n" +
	    "    public boolean hasNext() {\n" +
	    "      return index < a.length;}\n" +
	    "    public Object next() {\n" +
	    "      return new Short(a[index++]);}\n" +
	    "    public void remove() {}\n" +
	    "  });\n" +
	    "}"
	);

	// int[]
	ctxt.generateDeclaration("intArrayIterator", 
	    "private Iterator toIterator(final int[] a){\n" +
	    "  return (new Iterator() {\n" +
	    "    int index=0;\n" +
	    "    public boolean hasNext() {\n" +
	    "      return index < a.length;}\n" +
	    "    public Object next() {\n" +
	    "      return new Integer(a[index++]);}\n" +
	    "    public void remove() {}\n" +
	    "  });\n" +
	    "}"
	);

	// long[]
	ctxt.generateDeclaration("longArrayIterator", 
	    "private Iterator toIterator(final long[] a){\n" +
	    "  return (new Iterator() {\n" +
	    "    int index=0;\n" +
	    "    public boolean hasNext() {\n" +
	    "      return index < a.length;}\n" +
	    "    public Object next() {\n" +
	    "      return new Long(a[index++]);}\n" +
	    "    public void remove() {}\n" +
	    "  });\n" +
	    "}"
	);

	// float[]
	ctxt.generateDeclaration("floatArrayIterator",
	    "private Iterator toIterator(final float[] a){\n" +
	    "  return (new Iterator() {\n" +
	    "    int index=0;\n" +
	    "    public boolean hasNext() {\n" +
	    "      return index < a.length;}\n" +
	    "    public Object next() {\n" +
	    "      return new Float(a[index++]);}\n" +
	    "    public void remove() {}\n" +
	    "  });\n" +
	    "}"
	);

	// double[]
	ctxt.generateDeclaration("doubleArrayIterator",
	    "private Iterator toIterator(final double[] a){\n" +
	    "  return (new Iterator() {\n" +
	    "    int index=0;\n" +
	    "    public boolean hasNext() {\n" +
	    "      return index < a.length;}\n" +
	    "    public Object next() {\n" +
	    "      return new Double(a[index++]);}\n" +
	    "    public void remove() {}\n" +
	    "  });\n" +
	    "}"
	);

	// Enumeration
	ctxt.generateDeclaration("enumIterator",
	    "private Iterator toIterator(final Enumeration e){\n" +
	    "  return (new Iterator() {\n" +
	    "    public boolean hasNext() {\n" +
	    "      return e.hasMoreElements();}\n" +
	    "    public Object next() {\n" +
	    "      return e.nextElement();}\n" +
	    "    public void remove() {}\n" +
	    "  });\n" +
	    "}"
	);

    }
}