/*******************************************************************************
 * Copyright (c) 2000, 2003 IBM Corporation and others.
 * All rights reserved. This program and the accompanying materials 
 * are made available under the terms of the Common Public License v1.0
 * which accompanies this distribution, and is available at
 * http://www.eclipse.org/legal/cpl-v10.html
 * 
 * Contributors:
 *     IBM Corporation - initial API and implementation
 *******************************************************************************/
package net.sourceforge.phpeclipse.internal.compiler.ast;

import net.sourceforge.phpdt.internal.compiler.ASTVisitor;
import net.sourceforge.phpdt.internal.compiler.codegen.Label;
import net.sourceforge.phpdt.internal.compiler.flow.FlowContext;
import net.sourceforge.phpdt.internal.compiler.flow.FlowInfo;
import net.sourceforge.phpdt.internal.compiler.flow.LoopingFlowContext;
import net.sourceforge.phpdt.internal.compiler.impl.Constant;
import net.sourceforge.phpdt.internal.compiler.lookup.BlockScope;
import net.sourceforge.phpdt.internal.compiler.lookup.TypeBinding;


public class WhileStatement extends Statement {
	
	public Expression condition;
	public Statement action;
	private Label breakLabel, continueLabel;
	int preCondInitStateIndex = -1;
	int condIfTrueInitStateIndex = -1;
	int mergedInitStateIndex = -1;

	public WhileStatement(Expression condition, Statement action, int s, int e) {

		this.condition = condition;
		this.action = action;
		sourceStart = s;
		sourceEnd = e;
	}

	public FlowInfo analyseCode(
		BlockScope currentScope,
		FlowContext flowContext,
		FlowInfo flowInfo) {

		breakLabel = new Label();
		continueLabel = new Label(); 

		Constant cst = this.condition.constant;
		boolean isConditionTrue = cst != NotAConstant && cst.booleanValue() == true;
		boolean isConditionFalse = cst != NotAConstant && cst.booleanValue() == false;

		cst = this.condition.optimizedBooleanConstant();
		boolean isConditionOptimizedTrue = cst != NotAConstant && cst.booleanValue() == true;
		boolean isConditionOptimizedFalse = cst != NotAConstant && cst.booleanValue() == false;
		
		preCondInitStateIndex =
			currentScope.methodScope().recordInitializationStates(flowInfo);
		LoopingFlowContext condLoopContext;
		FlowInfo postCondInfo =
			this.condition.analyseCode(
				currentScope,
				(condLoopContext =
					new LoopingFlowContext(flowContext, this, null, null, currentScope)),
				flowInfo);

		LoopingFlowContext loopingContext;
		FlowInfo actionInfo;
//		if (action == null 
//			|| (action.isEmptyBlock() && currentScope.environment().options.complianceLevel <= CompilerOptions.JDK1_3)) {
//			condLoopContext.complainOnFinalAssignmentsInLoop(currentScope, postCondInfo);
//			if (isConditionTrue) {
//				return FlowInfo.DEAD_END;
//			} else {
//				FlowInfo mergedInfo = postCondInfo.initsWhenFalse().unconditionalInits();
//				if (isConditionOptimizedTrue){
//					mergedInfo.setReachMode(FlowInfo.UNREACHABLE);
//				}
//				mergedInitStateIndex =
//					currentScope.methodScope().recordInitializationStates(mergedInfo);
//				return mergedInfo;
//			}
//		} else {
			// in case the condition was inlined to false, record the fact that there is no way to reach any 
			// statement inside the looping action
			loopingContext =
				new LoopingFlowContext(
					flowContext,
					this,
					breakLabel,
					continueLabel,
					currentScope);
			if (isConditionFalse) {
				actionInfo = FlowInfo.DEAD_END;
			} else {
				actionInfo = postCondInfo.initsWhenTrue().copy();
				if (isConditionOptimizedFalse){
					actionInfo.setReachMode(FlowInfo.UNREACHABLE);
				}
			}

			// for computing local var attributes
			condIfTrueInitStateIndex =
				currentScope.methodScope().recordInitializationStates(
					postCondInfo.initsWhenTrue());

			if (!actionInfo.complainIfUnreachable(action, currentScope, false)) {
				actionInfo = action.analyseCode(currentScope, loopingContext, actionInfo);
			}

			// code generation can be optimized when no need to continue in the loop
			if (!actionInfo.isReachable() && !loopingContext.initsOnContinue.isReachable()) {
				continueLabel = null;
			} else {
				// TODO: (philippe) should simplify in one Loop context
				condLoopContext.complainOnFinalAssignmentsInLoop(currentScope, postCondInfo);
				loopingContext.complainOnFinalAssignmentsInLoop(currentScope, actionInfo);
			}
//		}

		// infinite loop
		FlowInfo mergedInfo;
		if (isConditionOptimizedTrue) {
			mergedInitStateIndex =
				currentScope.methodScope().recordInitializationStates(
					mergedInfo = loopingContext.initsOnBreak);
			return mergedInfo;
		}

		// end of loop: either condition false or break
		mergedInfo =
			postCondInfo.initsWhenFalse().unconditionalInits().mergedWith(
				loopingContext.initsOnBreak);
		if (isConditionOptimizedTrue && continueLabel == null){
			mergedInfo.setReachMode(FlowInfo.UNREACHABLE);
		}
		mergedInitStateIndex =
			currentScope.methodScope().recordInitializationStates(mergedInfo);
		return mergedInfo;
	}

	/**
	 * While code generation
	 *
	 * @param currentScope net.sourceforge.phpdt.internal.compiler.lookup.BlockScope
	 * @param codeStream net.sourceforge.phpdt.internal.compiler.codegen.CodeStream
	 */
//	public void generateCode(BlockScope currentScope, CodeStream codeStream) {
//
//		if ((bits & IsReachableMASK) == 0) {
//			return;
//		}
//		int pc = codeStream.position;
//		breakLabel.codeStream = codeStream;
//
//		// generate condition
//		if (continueLabel == null) {
//			// no need to reverse condition
//			if (condition.constant == NotAConstant) {
//				condition.generateOptimizedBoolean(
//					currentScope,
//					codeStream,
//					null,
//					breakLabel,
//					true);
//			}
//		} else {
//			continueLabel.codeStream = codeStream;
//			if (!(((condition.constant != NotAConstant)
//				&& (condition.constant.booleanValue() == true))
//				|| (action == null)
//				|| action.isEmptyBlock())) {
//				int jumpPC = codeStream.position;
//				codeStream.goto_(continueLabel);
//				codeStream.recordPositionsFrom(jumpPC, condition.sourceStart);
//			}
//		}
//		// generate the action
//		Label actionLabel;
//		(actionLabel = new Label(codeStream)).place();
//		if (action != null) {
//			// Required to fix 1PR0XVS: LFRE:WINNT - Compiler: variable table for method appears incorrect
//			if (condIfTrueInitStateIndex != -1) {
//				// insert all locals initialized inside the condition into the action generated prior to the condition
//				codeStream.addDefinitelyAssignedVariables(
//					currentScope,
//					condIfTrueInitStateIndex);
//			}
//			action.generateCode(currentScope, codeStream);
//			// May loose some local variable initializations : affecting the local variable attributes
//			if (preCondInitStateIndex != -1) {
//				codeStream.removeNotDefinitelyAssignedVariables(
//					currentScope,
//					preCondInitStateIndex);
//			}
//
//		}
//		// output condition and branch back to the beginning of the repeated action
//		if (continueLabel != null) {
//			continueLabel.place();
//			condition.generateOptimizedBoolean(
//				currentScope,
//				codeStream,
//				actionLabel,
//				null,
//				true);
//		}
//		breakLabel.place();
//
//		// May loose some local variable initializations : affecting the local variable attributes
//		if (mergedInitStateIndex != -1) {
//			codeStream.removeNotDefinitelyAssignedVariables(
//				currentScope,
//				mergedInitStateIndex);
//		}
//		codeStream.recordPositionsFrom(pc, this.sourceStart);
//	}

	public void resetStateForCodeGeneration() {
		if (this.breakLabel != null) {
			this.breakLabel.resetStateForCodeGeneration();
		}
		if (this.continueLabel != null) {
			this.continueLabel.resetStateForCodeGeneration();
		}
	}
	public StringBuffer printStatement(int tab, StringBuffer output) {

		printIndent(tab, output).append("while ("); //$NON-NLS-1$
		condition.printExpression(0, output).append(')');
		if (action == null)
			output.append(';');
		else
			action.printStatement(tab + 1, output); 
		return output;
	}
	public void resolve(BlockScope scope) {

		TypeBinding type = condition.resolveTypeExpecting(scope, BooleanBinding);
		condition.implicitWidening(type, type);
		if (action != null)
			action.resolve(scope);
	}

	public String toString(int tab) {

		String s = tabString(tab);
		s = s + "while (" + condition.toStringExpression() + ")"; 	//$NON-NLS-1$ //$NON-NLS-2$
		if (action == null)
			s = s + " {} ;"; //$NON-NLS-1$ 
		else if (action instanceof Block)
			s = s + "\n" + action.toString(tab + 1); //$NON-NLS-1$
		else
			s = s + " {\n" + action.toString(tab + 1) + "}"; //$NON-NLS-2$ //$NON-NLS-1$
		return s;
	}

	public void traverse(
	    ASTVisitor visitor,
		BlockScope blockScope) {

		if (visitor.visit(this, blockScope)) {
			condition.traverse(visitor, blockScope);
			if (action != null)
				action.traverse(visitor, blockScope);
		}
		visitor.endVisit(this, blockScope);
	}
}