/*******************************************************************************
 * Copyright (c) 2000, 2015 IBM Corporation and others.
 * All rights reserved. This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License v1.0
 * which accompanies this distribution, and is available at
 * http://www.eclipse.org/legal/epl-v10.html
 *
 * Contributors:
 *     IBM Corporation - initial API and implementation
 *     Stephan Herrmann - Contribution for Bug 463360 - [override method][null] generating method override should not create redundant null annotations
 *******************************************************************************/
package org.eclipse.jdt.internal.ui.text.java;

import org.eclipse.core.runtime.Assert;
import org.eclipse.core.runtime.CoreException;
import org.eclipse.core.runtime.NullProgressMonitor;

import org.eclipse.text.edits.MalformedTreeException;

import org.eclipse.jface.viewers.StyledString;

import org.eclipse.jface.text.BadLocationException;
import org.eclipse.jface.text.Document;
import org.eclipse.jface.text.IDocument;
import org.eclipse.jface.text.IRegion;
import org.eclipse.jface.text.TextUtilities;
import org.eclipse.jface.text.contentassist.ICompletionProposalExtension4;

import org.eclipse.jdt.core.ICompilationUnit;
import org.eclipse.jdt.core.IJavaProject;
import org.eclipse.jdt.core.dom.ASTNode;
import org.eclipse.jdt.core.dom.ASTParser;
import org.eclipse.jdt.core.dom.AbstractTypeDeclaration;
import org.eclipse.jdt.core.dom.AnonymousClassDeclaration;
import org.eclipse.jdt.core.dom.ChildListPropertyDescriptor;
import org.eclipse.jdt.core.dom.CompilationUnit;
import org.eclipse.jdt.core.dom.IMethodBinding;
import org.eclipse.jdt.core.dom.ITypeBinding;
import org.eclipse.jdt.core.dom.MethodDeclaration;
import org.eclipse.jdt.core.dom.NodeFinder;
import org.eclipse.jdt.core.dom.rewrite.ASTRewrite;
import org.eclipse.jdt.core.dom.rewrite.ITrackedNodePosition;
import org.eclipse.jdt.core.dom.rewrite.ImportRewrite;
import org.eclipse.jdt.core.dom.rewrite.ImportRewrite.ImportRewriteContext;
import org.eclipse.jdt.core.dom.rewrite.ListRewrite;
import org.eclipse.jdt.core.formatter.IndentManipulation;

import org.eclipse.jdt.internal.corext.codemanipulation.CodeGenerationSettings;
import org.eclipse.jdt.internal.corext.codemanipulation.ContextSensitiveImportRewriteContext;
import org.eclipse.jdt.internal.corext.codemanipulation.StubUtility;
import org.eclipse.jdt.internal.corext.codemanipulation.StubUtility2;
import org.eclipse.jdt.internal.corext.dom.Bindings;

import org.eclipse.jdt.ui.SharedASTProvider;

import org.eclipse.jdt.internal.ui.JavaPlugin;
import org.eclipse.jdt.internal.ui.javaeditor.ASTProvider;
import org.eclipse.jdt.internal.ui.preferences.JavaPreferencesSettings;

public class OverrideCompletionProposal extends JavaTypeCompletionProposal implements ICompletionProposalExtension4 {

	private IJavaProject fJavaProject;
	private String fMethodName;
	private String[] fParamTypes;

	public OverrideCompletionProposal(IJavaProject jproject, ICompilationUnit cu, String methodName, String[] paramTypes, int start, int length, StyledString displayName, String completionProposal) {
		super(completionProposal, cu, start, length, null, displayName, 0);
		Assert.isNotNull(jproject);
		Assert.isNotNull(methodName);
		Assert.isNotNull(paramTypes);
		Assert.isNotNull(cu);

		fParamTypes= paramTypes;
		fMethodName= methodName;

		fJavaProject= jproject;

		StringBuffer buffer= new StringBuffer();
		buffer.append(completionProposal);
		buffer.append(" {};"); //$NON-NLS-1$

		setReplacementString(buffer.toString());
	}

	/*
	 * @see org.eclipse.jface.text.contentassist.ICompletionProposalExtension3#getPrefixCompletionText(org.eclipse.jface.text.IDocument,int)
	 */
	@Override
	public CharSequence getPrefixCompletionText(IDocument document, int completionOffset) {
		return fMethodName;
	}

	private CompilationUnit getRecoveredAST(IDocument document, int offset, Document recoveredDocument) {
		CompilationUnit ast= SharedASTProvider.getAST(fCompilationUnit, SharedASTProvider.WAIT_ACTIVE_ONLY, null);
		if (ast != null) {
			recoveredDocument.set(document.get());
			return ast;
		}

		char[] content= document.get().toCharArray();

		// clear prefix to avoid compile errors
		int index= offset - 1;
		while (index >= 0 && Character.isJavaIdentifierPart(content[index])) {
			content[index]= ' ';
			index--;
		}

		recoveredDocument.set(new String(content));

		final ASTParser parser= ASTParser.newParser(ASTProvider.SHARED_AST_LEVEL);
		parser.setResolveBindings(true);
		parser.setStatementsRecovery(true);
		parser.setSource(content);
		parser.setUnitName(fCompilationUnit.getElementName());
		parser.setProject(fCompilationUnit.getJavaProject());
		return (CompilationUnit) parser.createAST(new NullProgressMonitor());
	}

	/*
	 * @see JavaTypeCompletionProposal#updateReplacementString(IDocument,char,int,ImportRewrite)
	 */
	@Override
	protected boolean updateReplacementString(IDocument document, char trigger, int offset, ImportRewrite importRewrite) throws CoreException, BadLocationException {
		Document recoveredDocument= new Document();
		CompilationUnit unit= getRecoveredAST(document, offset, recoveredDocument);
		ImportRewriteContext context;
		if (importRewrite != null) {
			context= new ContextSensitiveImportRewriteContext(unit, offset, importRewrite);
		} else {
			importRewrite= StubUtility.createImportRewrite(unit, true); // create a dummy import rewriter to have one
			context= new ImportRewriteContext() { // forces that all imports are fully qualified
				@Override
				public int findInContext(String qualifier, String name, int kind) {
					return RES_NAME_CONFLICT;
				}
			};
		}

		ITypeBinding declaringType= null;
		ChildListPropertyDescriptor descriptor= null;
		ASTNode node= NodeFinder.perform(unit, offset, 1);
		if (node instanceof AnonymousClassDeclaration) {
			declaringType= ((AnonymousClassDeclaration) node).resolveBinding();
			descriptor= AnonymousClassDeclaration.BODY_DECLARATIONS_PROPERTY;
		} else if (node instanceof AbstractTypeDeclaration) {
			AbstractTypeDeclaration declaration= (AbstractTypeDeclaration) node;
			descriptor= declaration.getBodyDeclarationsProperty();
			declaringType= declaration.resolveBinding();
		}
		if (declaringType != null) {
			ASTRewrite rewrite= ASTRewrite.create(unit.getAST());
			IMethodBinding methodToOverride= Bindings.findMethodInHierarchy(declaringType, fMethodName, fParamTypes);
			if (methodToOverride == null && declaringType.isInterface()) {
				methodToOverride= Bindings.findMethodInType(node.getAST().resolveWellKnownType("java.lang.Object"), fMethodName, fParamTypes); //$NON-NLS-1$
			}
			if (methodToOverride != null) {
				CodeGenerationSettings settings= JavaPreferencesSettings.getCodeGenerationSettings(fJavaProject);
				MethodDeclaration stub= StubUtility2.createImplementationStub(fCompilationUnit, rewrite, importRewrite, context, methodToOverride, declaringType, settings, declaringType.isInterface(), declaringType);
				ListRewrite rewriter= rewrite.getListRewrite(node, descriptor);
				rewriter.insertFirst(stub, null);

				ITrackedNodePosition position= rewrite.track(stub);
				try {
					rewrite.rewriteAST(recoveredDocument, fJavaProject.getOptions(true)).apply(recoveredDocument);

					String generatedCode= recoveredDocument.get(position.getStartPosition(), position.getLength());
					int generatedIndent= IndentManipulation.measureIndentUnits(getIndentAt(recoveredDocument, position.getStartPosition(), settings), settings.tabWidth, settings.indentWidth);

					String indent= getIndentAt(document, getReplacementOffset(), settings);
					setReplacementString(IndentManipulation.changeIndent(generatedCode, generatedIndent, settings.tabWidth, settings.indentWidth, indent, TextUtilities.getDefaultLineDelimiter(document)));

				} catch (MalformedTreeException exception) {
					JavaPlugin.log(exception);
				} catch (BadLocationException exception) {
					JavaPlugin.log(exception);
				}
			}
		}
		return true;
	}

	private static String getIndentAt(IDocument document, int offset, CodeGenerationSettings settings) {
		try {
			IRegion region= document.getLineInformationOfOffset(offset);
			return IndentManipulation.extractIndentString(document.get(region.getOffset(), region.getLength()), settings.tabWidth, settings.indentWidth);
		} catch (BadLocationException e) {
			return ""; //$NON-NLS-1$
		}
	}

	/*
	 * @see org.eclipse.jface.text.contentassist.ICompletionProposalExtension4#isAutoInsertable()
	 */
	@Override
	public boolean isAutoInsertable() {
		return false;
	}
}