/*******************************************************************************
 * Copyright (c) 2008, 2021 IBM Corporation and others.
 *
 * This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License 2.0
 * which accompanies this distribution, and is available at
 * https://www.eclipse.org/legal/epl-2.0/
 *
 * SPDX-License-Identifier: EPL-2.0
 *
 * Contributors:
 *     IBM Corporation - initial API and implementation
 *******************************************************************************/
package org.eclipse.pde.api.tools.internal.builder;

import java.util.Collections;
import java.util.Iterator;
import java.util.LinkedList;
import java.util.List;
import java.util.Set;
import java.util.StringTokenizer;

import org.eclipse.core.resources.IProject;
import org.eclipse.core.resources.IResource;
import org.eclipse.core.runtime.CoreException;
import org.eclipse.core.runtime.IProgressMonitor;
import org.eclipse.core.runtime.NullProgressMonitor;
import org.eclipse.core.runtime.SubMonitor;
import org.eclipse.jdt.core.Flags;
import org.eclipse.jdt.core.ICompilationUnit;
import org.eclipse.jdt.core.IField;
import org.eclipse.jdt.core.IJavaElement;
import org.eclipse.jdt.core.IJavaProject;
import org.eclipse.jdt.core.IMethod;
import org.eclipse.jdt.core.ISourceRange;
import org.eclipse.jdt.core.IType;
import org.eclipse.jdt.core.JavaModelException;
import org.eclipse.jdt.core.Signature;
import org.eclipse.jdt.core.dom.AST;
import org.eclipse.jdt.core.dom.ASTNode;
import org.eclipse.jdt.core.dom.ASTParser;
import org.eclipse.jdt.core.dom.ASTVisitor;
import org.eclipse.jdt.core.dom.AnonymousClassDeclaration;
import org.eclipse.jdt.core.dom.ITypeBinding;
import org.eclipse.jdt.core.dom.TypeDeclaration;
import org.eclipse.jface.text.BadLocationException;
import org.eclipse.jface.text.IDocument;
import org.eclipse.jface.text.IRegion;
import org.eclipse.jface.text.Position;
import org.eclipse.pde.api.tools.internal.model.ApiType;
import org.eclipse.pde.api.tools.internal.model.ProjectComponent;
import org.eclipse.pde.api.tools.internal.problems.ApiProblemFactory;
import org.eclipse.pde.api.tools.internal.provisional.ApiPlugin;
import org.eclipse.pde.api.tools.internal.provisional.IApiMarkerConstants;
import org.eclipse.pde.api.tools.internal.provisional.builder.IApiProblemDetector;
import org.eclipse.pde.api.tools.internal.provisional.builder.IReference;
import org.eclipse.pde.api.tools.internal.provisional.model.IApiBaseline;
import org.eclipse.pde.api.tools.internal.provisional.model.IApiComponent;
import org.eclipse.pde.api.tools.internal.provisional.model.IApiElement;
import org.eclipse.pde.api.tools.internal.provisional.model.IApiField;
import org.eclipse.pde.api.tools.internal.provisional.model.IApiMember;
import org.eclipse.pde.api.tools.internal.provisional.model.IApiMethod;
import org.eclipse.pde.api.tools.internal.provisional.model.IApiType;
import org.eclipse.pde.api.tools.internal.provisional.problems.IApiProblem;
import org.eclipse.pde.api.tools.internal.util.Signatures;
import org.eclipse.pde.api.tools.internal.util.Util;

/**
 * @since 1.1
 */
public abstract class AbstractProblemDetector implements IApiProblemDetector {

	public static final String METHOD_REFERENCE = "::"; //$NON-NLS-1$
	public static final String CONSTRUCTOR_NEW = "new"; //$NON-NLS-1$

	/**
	 * Class used to look up the name of the enclosing method for an
	 * {@link IApiType} when we do not have any enclosing method infos (pre Java
	 * 1.5 class files
	 */
	static class MethodFinder extends ASTVisitor {
		IMethod method = null;
		private IType jtype = null;
		private ApiType type = null;

		public MethodFinder(ApiType type, IType jtype) {
			this.type = type;
			this.jtype = jtype;
		}

		@Override
		public boolean visit(AnonymousClassDeclaration node) {
			if (method == null) {
				ITypeBinding binding = node.resolveBinding();
				String binaryName = binding.getBinaryName();
				if (type.getName().endsWith(binaryName)) {
					try {
						IJavaElement element = jtype.getCompilationUnit().getElementAt(node.getStartPosition());
						if (element != null) {
							IJavaElement ancestor = element.getAncestor(IJavaElement.METHOD);
							if (ancestor != null) {
								method = (IMethod) ancestor;
							}
						}
					} catch (JavaModelException jme) {
						ApiPlugin.log(jme);
					}
					return false;
				}
			}
			return true;
		}

		@Override
		public boolean visit(TypeDeclaration node) {
			if (method == null && node.isLocalTypeDeclaration()) {
				ITypeBinding binding = node.resolveBinding();
				String binaryName = binding.getBinaryName();
				if (type.getName().endsWith(binaryName)) {
					try {
						IJavaElement element = jtype.getCompilationUnit().getElementAt(node.getStartPosition());
						if (element.getElementType() == IJavaElement.TYPE) {
							IType ltype = (IType) element;
							IJavaElement parent = ltype.getParent();
							if (parent.getElementType() == IJavaElement.METHOD) {
								method = (IMethod) parent;
							}
						}
					} catch (JavaModelException jme) {
						ApiPlugin.log(jme);
					}
					return false;
				}
			}
			return true;
		}
	}

	/**
	 * List of potential {@link IReference} problems
	 */
	private List<IReference> fPotentialProblems = new LinkedList<>();

	/**
	 * Retains the reference for further analysis.
	 *
	 * @param reference reference
	 */
	protected void retainReference(IReference reference) {
		fPotentialProblems.add(reference);
	}

	/**
	 * Return the list of retained references.
	 *
	 * @return references
	 */
	protected List<IReference> getRetainedReferences() {
		return fPotentialProblems;
	}

	@Override
	public boolean considerReference(IReference reference) {
		return reference != null && (reference.getReferenceKind() & getReferenceKinds()) > 0;
	}

	/**
	 * Creates a problem for a specific reference in the workspace
	 *
	 * @param reference reference
	 * @param associated java project (with reference source location)
	 * @return problem or <code>null</code> if none
	 * @exception CoreException if something goes wrong
	 */
	protected IApiProblem createProblem(IReference reference, IJavaProject javaProject) {
		IProject project = javaProject.getProject();
		if (ApiPlugin.getDefault().getSeverityLevel(getSeverityKey(), project) == ApiPlugin.SEVERITY_IGNORE) {
			return null;
		}
		try {
			IApiMember member = reference.getMember();
			String lookupName = getTypeName(member).replace('$', '.');
			IType type = javaProject.findType(lookupName, new NullProgressMonitor());
			IType typeInProject = Util.getTypeInSameJavaProject(type, lookupName, javaProject);
			if (typeInProject != null) {
				type =typeInProject;
			}
			if (type == null) {
				return null;
			}
			ICompilationUnit compilationUnit = type.getCompilationUnit();
			if (compilationUnit == null) {
				return null;
			}
			IResource resource = Util.getResource(project, type);
			if (resource == null) {
				return null;
			}
			int charStart = -1;
			int charEnd = -1;
			int lineNumber = reference.getLineNumber();
			IJavaElement element = compilationUnit;
			if (!Util.isManifest(resource.getProjectRelativePath()) && !type.isBinary()) {
				IDocument document = Util.getDocument(compilationUnit);
				if (lineNumber > 0) {
					// reference line number are 1-based, but the API problem
					// line number are 0-based
					// they will be converted to 1-based at marker creation time
					lineNumber--;
				}
				// retrieve line number, char start and char end
				if ((reference.getReferenceKind() & (IReference.REF_OVERRIDE | IReference.REF_EXTENDS | IReference.REF_IMPLEMENTS | IReference.REF_PARAMETER | IReference.REF_RETURNTYPE | IReference.REF_THROWS)) != 0) {
					IApiType enclosingType = member.getEnclosingType();
					if (lineNumber > 0 && enclosingType != null && enclosingType.isAnonymous()) {
						String superclass = enclosingType.getSuperclassName();
						String name = null;
						if ("java.lang.Object".equals(superclass)) { //$NON-NLS-1$
							// check the super_interfaces
							String[] superinterfaces = enclosingType.getSuperInterfaceNames();
							if (superinterfaces != null) {
								String superinterface = superinterfaces[0];
								name = superinterface.substring(superinterface.lastIndexOf('.') + 1);
							} else {
								// this is really an anonymous class of Object
								name = superclass.substring(superclass.lastIndexOf('.') + 1);
							}
						} else if (superclass != null) {
							name = superclass.substring(superclass.lastIndexOf('.') + 1);
						}
						if (name != null) {
							try {
								IRegion lineInformation = document.getLineInformation(lineNumber);
								String lineContents = document.get(lineInformation.getOffset(), lineInformation.getLength());
								charStart = lineInformation.getOffset() + lineContents.indexOf(name);
								charEnd = charStart + name.length();
							} catch (BadLocationException e) {
								ApiPlugin.log(e);
								return null;
							}
						}
					}
				}
				if (charStart == -1) {
					// get the source range for the problem
					try {
						Position pos = getSourceRange(type, document, reference);
						if (pos != null) {
							charStart = pos.getOffset();
							if (charStart != -1) {
								charEnd = charStart + pos.getLength();
								lineNumber = document.getLineOfOffset(charStart);
							}
						}
					} catch (CoreException | BadLocationException e) {
						ApiPlugin.log(e);
						return null;
					}
				}
				if (charStart > -1) {
					element = compilationUnit.getElementAt(charStart);
				}
			}
			return ApiProblemFactory.newApiUsageProblem(resource.getProjectRelativePath().toPortableString(), type.getFullyQualifiedName(), getMessageArgs(reference), new String[] {
					IApiMarkerConstants.MARKER_ATTR_HANDLE_ID,
					IApiMarkerConstants.API_MARKER_ATTR_ID }, new Object[] {
					(element == null ? compilationUnit.getHandleIdentifier() : element.getHandleIdentifier()),
					Integer.valueOf(IApiMarkerConstants.API_USAGE_MARKER_ID) }, lineNumber, // 0-based
					charStart, charEnd, getElementType(reference), getProblemKind(), getProblemFlags(reference));
		} catch (CoreException e) {
			ApiPlugin.log(e);
		}
		return null;
	}

	/**
	 * Returns the source range to include in the associated problem or
	 * <code>null</code> if a valid source range could not be computed.
	 *
	 * @param type resolved type where the reference occurs
	 * @param doc source document of the type
	 * @param reference associated reference
	 * @return source range as a position
	 */
	protected abstract Position getSourceRange(IType type, IDocument doc, IReference reference) throws CoreException, BadLocationException;

	/**
	 * Returns the element type the problem is reported on.
	 *
	 * @return
	 */
	protected abstract int getElementType(IReference reference);

	/**
	 * Returns problem flags, if any.
	 *
	 * @param reference
	 * @return problem flags
	 */
	protected abstract int getProblemFlags(IReference reference);

	/**
	 * Returns problem message arguments
	 *
	 * @return message arguments
	 */
	protected abstract String[] getMessageArgs(IReference reference) throws CoreException;

	/**
	 * Returns problem message arguments to be used in headless build
	 *
	 * @return message arguments
	 */
	protected abstract String[] getQualifiedMessageArgs(IReference reference) throws CoreException;

	/**
	 * Returns the kind of problem to create
	 *
	 * @return problem kind
	 */
	protected abstract int getProblemKind();

	/**
	 * Returns the key used to lookup problem severity.
	 *
	 * @return problem severity key
	 */
	protected abstract String getSeverityKey();

	/**
	 * Returns the fully qualified type name associated with the given member.
	 *
	 * @param member
	 * @return fully qualified type name
	 */
	protected String getTypeName(IApiMember member) throws CoreException {
		switch (member.getType()) {
			case IApiElement.TYPE: {
				IApiType type = (IApiType) member;
				if (type.isAnonymous()) {
					return getTypeName(member.getEnclosingType());
				} else if (type.isLocal()) {
					return getTypeName(member.getEnclosingType());
				}
				return member.getName();
			}
			default: {
				return getTypeName(member.getEnclosingType());
			}
		}
	}

	/**
	 * Returns the qualified type name to display. This method delegates to the
	 * {@link Signatures} class to build the display signatures
	 *
	 * @param member
	 * @return fully qualified display signature for the given {@link IApiType}
	 *         or enclosing type if the member is not a type itself
	 * @throws CoreException
	 */
	protected String getQualifiedTypeName(IApiMember member) throws CoreException {
		switch (member.getType()) {
			case IApiElement.TYPE: {
				IApiType type = (IApiType) member;
				if (type.isAnonymous()) {
					return getQualifiedTypeName(member.getEnclosingType());
				} else if (type.isLocal()) {
					String name = getTypeName(member.getEnclosingType());
					int idx = name.indexOf('$');
					if (idx > -1) {
						return name.substring(0, idx);
					}
					return name;
				}
				return Signatures.getQualifiedTypeSignature((IApiType) member);
			}
			default: {
				return getQualifiedTypeName(member.getEnclosingType());
			}
		}
	}

	/**
	 * Returns the unqualified type name associated with the given member.
	 *
	 * @param member
	 * @return unqualified type name
	 */
	protected String getSimpleTypeName(IApiMember member) throws CoreException {
		switch (member.getType()) {
			case IApiElement.TYPE: {
				IApiType type = (IApiType) member;
				if (type.isAnonymous()) {
					return getSimpleTypeName(type.getEnclosingType());
				} else if (type.isLocal()) {
					String name = getSimpleTypeName(member.getEnclosingType());
					int idx = name.indexOf('$');
					if (idx > -1) {
						return name.substring(0, idx);
					}
					return name;
				}
				return Signatures.getTypeName(Signatures.getTypeSignature(type));
			}
			default:
				return getSimpleTypeName(member.getEnclosingType());
		}
	}

	/**
	 * Default strategy for when no source position can be computed: creates a
	 * {@link Position} for the name of the given {@link IType}. Returns
	 * <code>null</code> in the event the given {@link IType} is
	 * <code>null</code> or the name range cannot be computed for the type.
	 *
	 * @param type the type
	 * @param reference the reference
	 * @throws CoreException
	 * @return returns a default {@link Position} for the name range of the
	 *         given {@link IType}
	 */
	protected Position defaultSourcePosition(IType type, IReference reference) throws CoreException {
		if (type != null) {
			ISourceRange range = type.getNameRange();
			if (range != null) {
				return new Position(range.getOffset(), range.getLength());
			}
		}
		return null;
	}

	/**
	 * Finds the method name to select on the given line of code starting from
	 * the given index. This method will recurse to find a method name in the
	 * even there is a name clash with the type. For example:
	 *
	 * <pre>
	 * MyType type = new MyType();
	 * </pre>
	 *
	 * If we are trying to find the constructor method call we have a name
	 * collision (and the first occurrence of MyType would be selected). <br>
	 * A name is determined to be a method name if it is followed by a '('
	 * character (excluding spaces)
	 *
	 * @param namepart
	 * @param line
	 * @param index
	 * @return the index of the method name on the given line or -1 if not found
	 */
	protected int findMethodNameStart(String namepart, String line, int index) {
		if (namepart.startsWith(METHOD_REFERENCE)) {
			// a method ref, walk back to find the token
			int offset = index;
			char c = line.charAt(offset);
			while (!Character.isJavaIdentifierPart((int) c)) {
				offset--;
				c = line.charAt(offset);
			}
			while (Character.isJavaIdentifierPart((int) c)) {
				offset--;
				c = line.charAt(offset);
				if (c == '<') {
					// might encounter the opening bound, skip it
					c = line.charAt(--offset);
				}
			}
			offset++;
			return offset;
		} else {
			int start = line.indexOf(namepart, index);
			if (start < 0) {
				return -1;
			}
			int offset = start + namepart.length();
			char c = line.charAt(offset);
			while (c == ' ') {
				offset++;
				c = line.charAt(offset);
			}

			if (c == '(' || c == '<') {
				return start;
			}

			// assumes that "::" & method name/"new" in same line
			if (line.contains(METHOD_REFERENCE)) {
				if ((c == ';') || (c == '\r') || (c == ')')) {
					return start;
				}
				// method reference constructor
				if ((c == ':') && line.charAt(offset + 1) == ':' && line.contains(CONSTRUCTOR_NEW)) {
					return start;
				}

			}
			return findMethodNameStart(namepart, line, offset);
		}
	}

	@Override
	public List<IApiProblem> createProblems(IProgressMonitor monitor) {
		List<IReference> references = getRetainedReferences();
		if (references.isEmpty()) {
			return Collections.emptyList();
		}
		List<IApiProblem> problems = new LinkedList<>();
		Iterator<IReference> iterator = references.iterator();
		SubMonitor loopMonitor = SubMonitor.convert(monitor, references.size());
		while (iterator.hasNext() && !monitor.isCanceled()) {
			loopMonitor.split(1);
			IReference reference = iterator.next();
			if (reference.getResolvedReference() == null) {
				// unresolved reference ignore it
			} else {
				if (isProblem(reference, monitor)) {
					IApiComponent component = reference.getMember().getApiComponent();
					try {
						IApiProblem problem = null;
						if (component instanceof ProjectComponent) {
							ProjectComponent ppac = (ProjectComponent) component;
							IJavaProject project = ppac.getJavaProject();
							problem = createProblem(reference, project);
						} else {
							problem = createProblem(reference);
						}
						if (problem != null) {
							problems.add(problem);
						}
					} catch (CoreException e) {
						ApiPlugin.log(e.getStatus());
						checkIfDisposed(component, monitor);
					}
				}
			}
		}
		return problems;
	}

	/**
	 * Checks if given component is disposed or belongs to already disposed baseline
	 * - and if yes, cancels given monitor if the API analysis runs in a job
	 *
	 * @param component
	 * @param monitor
	 */
	public static void checkIfDisposed(IApiComponent component, IProgressMonitor monitor) {
		if (component != null && !monitor.isCanceled() && ApiAnalysisBuilder.isRunningAsJob()) {
			try {
				if (component.isDisposed()) {
					monitor.setCanceled(true);
					return;
				}
				IApiBaseline baseline = component.getBaseline();
				if (baseline != null && baseline.isDisposed()) {
					monitor.setCanceled(true);
				}
			} catch (CoreException e) {
				monitor.setCanceled(true);
			}
		}
	}

	/**
	 * Returns whether the resolved reference is a real problem.
	 *
	 * @param reference
	 * @param monitor
	 * @return whether a problem
	 */
	protected boolean isProblem(IReference reference, IProgressMonitor monitor) {
		// by default fragment -> host references are not problems
		// https://bugs.eclipse.org/bugs/show_bug.cgi?id=255659
		IApiMember member = reference.getResolvedReference();
		if (member != null) {
			IApiMember local = reference.getMember();
			try {
				IApiComponent lcomp = local.getApiComponent();
				if (lcomp != null && lcomp.isFragment()) {
					return !lcomp.getHost().equals(member.getApiComponent());
				}
			} catch (CoreException ce) {
				checkIfDisposed(reference.getMember().getApiComponent(), monitor);
				ApiPlugin.log(ce);
			}
		}
		return true;
	}

	protected boolean isReferenceFromComponent(IReference reference, String componentId) {
		if (componentId != null) {
			final IApiComponent apiComponent = reference.getResolvedReference().getApiComponent();
			// API component is either component id itself or one of its
			// fragment
			if (apiComponent.getSymbolicName().equals(componentId)) {
				return true;
			}
			try {
				// If the exact same reference exist in another component id
				IApiComponent apiComponent2 = apiComponent.getBaseline().getApiComponent(componentId);
				String name = reference.getResolvedReference().getName();
				if (Util.getClassFile(new IApiComponent[] {
						apiComponent2 }, name) != null) {
					IApiComponent[] components = reference.getMember().getApiComponent().getBaseline().getPrerequisiteComponents(new IApiComponent[] {
							reference.getMember().getApiComponent() });
					// and that component resides on prerequisite of component
					// being analyzed - flag as error
					for (IApiComponent iApiComponent : components) {
						if (iApiComponent.getSymbolicName().equals(apiComponent2.getSymbolicName())) {
							return true;
						}
					}
				}
				final IApiComponent host = apiComponent.getHost();
				return host != null && host.getSymbolicName().equals(componentId);
			} catch (CoreException e) {
				ApiPlugin.log(e);
			}
		}
		return false;
	}

	/**
	 * Tries to find the given {@link IApiMethod} in the given {@link IType}. If
	 * a matching method is not found <code>null</code> is returned
	 *
	 * @param type the type top look in for the given {@link IApiMethod}
	 * @param method the {@link IApiMethod} to look for
	 * @return the {@link IMethod} from the given {@link IType} that matches the
	 *         given {@link IApiMethod} or <code>null</code> if no matching
	 *         method is found
	 * @throws JavaModelException
	 * @throws CoreException
	 */
	protected IMethod findMethodInType(IType type, IApiMethod method) throws JavaModelException, CoreException {
		String[] parameterTypes = Signature.getParameterTypes(method.getSignature());
		for (int i = 0; i < parameterTypes.length; i++) {
			parameterTypes[i] = parameterTypes[i].replace('/', '.');
		}
		String methodname = method.getName();
		if (method.isConstructor()) {
			IApiType enclosingType = method.getEnclosingType();
			if (enclosingType.isMemberType() && !Flags.isStatic(enclosingType.getModifiers())) {
				// remove the synthetic argument that corresponds to the
				// enclosing type
				int length = parameterTypes.length - 1;
				System.arraycopy(parameterTypes, 1, (parameterTypes = new String[length]), 0, length);
			}
			methodname = enclosingType.getSimpleName();
		}
		IMethod Qmethod = type.getMethod(methodname, parameterTypes);
		IMethod[] methods = type.getMethods();
		IMethod match = null;
		for (IMethod m : methods) {
			if (m.isSimilar(Qmethod)) {
				match = m;
				break;
			}
		}
		return match;
	}

	/**
	 * Tries to find the given {@link IApiField} in the given {@link IType}. If
	 * the field cannot be found <code>null</code> is returned
	 *
	 * @param type
	 * @param field
	 * @return the {@link IField} matching the given {@link IApiField} or
	 *         <code>null</code>
	 * @since 1.0.600
	 * @throws JavaModelException
	 */
	protected IField findFieldInType(IType type, IApiField field) throws JavaModelException {
		IField match = null;
		match = type.getField(field.getName());
		if (!match.exists()) {
			IField[] fields = type.getFields();
			// optimistically try to find the first match
			for (IField loopField : fields) {
				if (loopField.getElementName().equals(field.getName())) {
					match = loopField;
					break;
				}
			}
		}
		return match;
	}

	/**
	 * Tries to find the given {@link IApiType} in the given {@link IType}. If
	 * no match is found <code>null</code> is returned.
	 *
	 * @param type
	 * @param apitype
	 * @param reference
	 * @param doc
	 * @return the matching {@link IType} or <code>null</code>
	 * @since 1.0.600
	 * @throws CoreException
	 * @throws JavaModelException
	 */
	protected IType findTypeInType(IType type, IApiType apitype, IReference reference, IDocument doc) throws CoreException, JavaModelException {
		if (apitype.isLocal()) {
			String name = apitype.getSimpleName();
			ICompilationUnit cunit = type.getCompilationUnit();
			if (cunit.isWorkingCopy()) {
				cunit.reconcile(AST.getJLSLatest(), false, null, null);
			}
			IMethod method = getEnclosingMethod(type, reference, doc);
			if (method != null) {
				return method.getType(name, 1);
			}
		}
		String tname = type.getElementName();
		if (tname.equals(apitype.getName()) || tname.equals(apitype.getSimpleName())) {
			return type;
		}
		IType match = null;
		for (IType t : type.getTypes()) {
			if (t.getElementName().equals(apitype.getName())) {
				match = t;
				break;
			}
		}
		return match;
	}

	/**
	 * Returns the enclosing {@link IMethod} for the given type or
	 * <code>null</code> if it cannot be computed
	 *
	 * @param type
	 * @param jtype
	 * @param reference
	 * @param document
	 * @return the {@link IMethod} enclosing the given type or <code>null</code>
	 * @throws CoreException
	 */
	protected IMethod getEnclosingMethod(final IType jtype, IReference reference, IDocument document) throws CoreException {
		IApiMember member = reference.getMember();
		if ((member.getType() == IApiElement.TYPE)) {
			ApiType type = (ApiType) member;
			IApiMethod apimethod = type.getEnclosingMethod();
			if (apimethod != null) {
				String signature = Signatures.processMethodSignature(apimethod);
				String methodname = Signatures.getMethodName(apimethod);
				IMethod method = jtype.getMethod(methodname, Signature.getParameterTypes(signature));
				if (method.exists()) {
					return method;
				}
			} else {
				// try to look it up
				IMethod method = null;
				if (reference.getLineNumber() > -1) {
					try {
						int offset = document.getLineOffset(reference.getLineNumber());
						method = quickLookup(jtype, document, reference, offset);
					} catch (BadLocationException ble) {
						// ignore
					}
				}
				if (method == null) {
					// look it up the hard way
					ISourceRange range = jtype.getCompilationUnit().getSourceRange();
					ASTParser parser = ASTParser.newParser(AST.getJLSLatest());
					parser.setSource(jtype.getCompilationUnit());
					parser.setSourceRange(range.getOffset(), range.getLength());
					parser.setResolveBindings(true);
					ASTNode ptype = parser.createAST(null);
					MethodFinder finder = new MethodFinder(type, jtype);
					ptype.accept(finder);
					method = finder.method;
				}
				if (method != null && method.exists()) {
					ApiType etype = (ApiType) type.getEnclosingType();
					IApiMethod[] methods = etype.getMethods();
					String msig = null;
					for (IApiMethod m : methods) {
						msig = m.getSignature();
						if (Signatures.getMethodName(m).equals(method.getElementName()) && Signatures.matchesSignatures(msig.replace('/', '.'), method.getSignature())) {
							type.setEnclosingMethodInfo(m.getName(), msig);
						}
					}
					return method;
				}
			}
		}
		return null;
	}

	/**
	 * Performs a quick look-up using the offset into the the
	 * {@link ICompilationUnit}
	 *
	 * @param jtype
	 * @param document
	 * @param reference
	 * @param offset
	 * @return
	 * @throws JavaModelException
	 */
	protected IMethod quickLookup(final IType jtype, IDocument document, IReference reference, int offset) throws JavaModelException {
		if (offset > -1) {
			IJavaElement element = jtype.getCompilationUnit().getElementAt(offset);
			if (element != null) {
				IJavaElement ancestor = element.getAncestor(IJavaElement.METHOD);
				if (ancestor != null) {
					return (IMethod) ancestor;
				}
			}
		}
		return null;
	}

	/**
	 * Returns the source range for the given {@link IApiMethod} within the
	 * given {@link IType}
	 *
	 * @param type the type to look for the method within
	 * @param reference the reference the method comes from
	 * @param method the {@link IApiMethod} to look for the source range for
	 * @return the {@link ISourceRange} in the {@link IType} enclosing the given
	 *         {@link IApiMethod}
	 * @throws CoreException
	 * @throws JavaModelException
	 */
	protected Position getSourceRangeForMethod(IType type, IReference reference, IApiMethod method) throws CoreException, JavaModelException {
		IMethod match = findMethodInType(type, method);
		Position pos = null;
		if (match != null) {
			ISourceRange range = match.getNameRange();
			if (range != null) {
				pos = new Position(range.getOffset(), range.getLength());
			}
		}
		if (pos == null) {
			return defaultSourcePosition(type, reference);
		}
		return pos;
	}

	/**
	 * Returns the source range to use for the given field within the given
	 * {@link IType}
	 *
	 * @param type the type to look in for the given {@link IApiField}
	 * @param reference the reference the field is involved in
	 * @param field the field to find the range for
	 * @return the {@link ISourceRange} in the given {@link IType} that encloses
	 *         the given {@link IApiField}
	 * @throws JavaModelException
	 * @throws CoreException
	 */
	protected Position getSourceRangeForField(IType type, IReference reference, IApiField field) throws JavaModelException, CoreException {
		IField javaField = type.getField(field.getName());
		Position pos = null;
		if (javaField.exists()) {
			ISourceRange range = javaField.getNameRange();
			if (range != null) {
				pos = new Position(range.getOffset(), range.getLength());
			}
		}
		if (pos == null) {
			return defaultSourcePosition(type, reference);
		}
		return pos;
	}

	/**
	 * Returns the range of the name of the given {@link IApiField} to select
	 * when creating {@link IApiProblem}s. Source ranges are computed and tried
	 * in the following order:
	 * <ol>
	 * <li>Try the type-qualified name of the variable</li>
	 * <li>Try looking for 'super.variable'</li>
	 * <li>Try looking for 'this.variable'</li>
	 * <li>Try looking for pattern '*.variable'</li>
	 * <li>Else select the entire line optimistically</li>
	 * </ol>
	 *
	 * @param field the field to find the name range for
	 * @param document the document to look within
	 * @param reference the reference the field is from
	 * @return the range of text to select, or <code>null</code> if one could
	 *         not be computed
	 * @throws BadLocationException
	 * @throws CoreException
	 */
	protected Position getFieldNameRange(IApiField field, IDocument document, IReference reference) throws BadLocationException, CoreException {
		return getFieldNameRange(field.getEnclosingType().getName(), field.getName(), document, reference);
	}

	protected Position getFieldNameRange(String typeName, String fieldName, IDocument document, IReference reference) throws BadLocationException {
		int linenumber = reference.getLineNumber();
		if (linenumber > 0) {
			// line number are 1-based for the reference, but 0-based for the
			// document
			linenumber--;
		}
		if (linenumber > 0) {
			int offset = document.getLineOffset(linenumber);
			String line = document.get(offset, document.getLineLength(linenumber));
			String qname = typeName + "." + fieldName; //$NON-NLS-1$
			int first = line.indexOf(qname);
			if (first < 0) {
				qname = "super." + fieldName; //$NON-NLS-1$
				first = line.indexOf(qname);
			}
			if (first < 0) {
				qname = "this." + fieldName; //$NON-NLS-1$
				first = line.indexOf(qname);
			}
			if (first < 0) {
				// try a pattern [.*field_name]
				// the field might be ref'd via a constant, e.g. enum constant
				int idx = line.indexOf(fieldName);
				while (idx > -1) {
					if (line.charAt(idx - 1) == '.') {
						first = idx;
						qname = fieldName;
						break;
					}
					idx = line.indexOf(fieldName, idx + 1);
				}
			}
			Position pos = null;
			if (first > -1) {
				pos = new Position(offset + first, qname.length());
			} else {
				// optimistically select the whole line since we can't find the
				// correct variable name and we can't just select
				// the first occurrence
				pos = new Position(offset, line.length());
			}
			return pos;
		}
		return null;
	}

	/**
	 * Searches for the name of a method at the line number specified in the
	 * given reference.
	 *
	 * @param name method name
	 * @param document document to search in
	 * @param reference provides line number
	 * @return method name range
	 * @throws CoreException
	 */
	protected Position getMethodNameRange(boolean isContructor, String name, IDocument document, IReference reference) throws CoreException, BadLocationException {
		int linenumber = reference.getLineNumber();
		if (linenumber > 0) {
			// line number are 1-based for the reference, but 0-based for the
			// document
			linenumber--;
		}
		String methodname = name;
		int idx = methodname.indexOf('$');
		if (idx > -1) {
			methodname = methodname.substring(0, idx);
		}
		idx = methodname.indexOf(Signatures.getLT());
		if (idx > -1) {
			methodname = methodname.substring(0, idx);
		}
		int offset = document.getLineOffset(linenumber);
		String line = document.get(offset, document.getLineLength(linenumber));
		int start = line.indexOf('=');
		if (start < 0) {
			if (isContructor) {
				// new keyword should only be checked if the method is a
				// constructor
				// what if space between the two?
				start = line.indexOf(METHOD_REFERENCE + CONSTRUCTOR_NEW);
				if (start < 0) {
					start = line.indexOf(CONSTRUCTOR_NEW);
					if (start < 0) {
						start = 0;
					}
				} else {
					int first = findMethodNameStart(METHOD_REFERENCE + CONSTRUCTOR_NEW, line, start);
					return new Position(offset + first, (start - first) + 5);
				}
			} else {
				start = 0;
			}
		} else {
			char charat = line.charAt(start - 1);
			// make sure its not '==' | '!=' | '<=' | '>='
			if (line.charAt(start + 1) == '=' || charat == '!' || charat == '<' || charat == '>') {
				start = 0;
			}
		}
		int first = findMethodNameStart(methodname, line, start);

		if (line.contains(METHOD_REFERENCE) && line.contains(CONSTRUCTOR_NEW) && isContructor) {
			String afterReference = line.substring(line.indexOf(METHOD_REFERENCE));
			methodname = afterReference.substring(afterReference.indexOf(METHOD_REFERENCE) + 2, afterReference.indexOf(CONSTRUCTOR_NEW) + 3);
		}
		if (first < 0) {
			methodname = "super"; //$NON-NLS-1$
			first = findMethodNameStart(methodname, line, start);
		}
		if (first > -1) {
			idx = line.indexOf(METHOD_REFERENCE, first);
			if (idx > -1 && isContructor) {
				//a method ref, add the start + :: + method name length
				return new Position(offset + first, (idx - first) + 2 + methodname.length());
			}
			return new Position(offset + first, methodname.length());
		}
		return null;
	}


	/**
	 * Returns if the signature is enclosed by the one of the elements of the
	 * given set of type names.
	 *
	 * @param signature the signature of the element
	 * @param typenames the Set of {@link String}s of type names
	 * @return <code>true</code> if the given set contains a type name that
	 *         encloses the given signature, <code>false</code> otherwise
	 *
	 * @since 1.0.400
	 */
	boolean isEnclosedBy(String signature, Set<String> typenames) {
		if (signature == null || typenames == null) {
			return false;
		}
		if (typenames.contains(signature)) {
			return true;
		}
		StringTokenizer tokenizer = new StringTokenizer(signature, "$"); //$NON-NLS-1$
		while (tokenizer.hasMoreTokens()) {
			if (typenames.contains(tokenizer.nextToken())) {
				return true;
			}
		}
		return false;
	}

	/**
	 * @param reference
	 * @return
	 * @throws CoreException
	 */
	public IApiProblem createProblem(IReference reference) throws CoreException {
		int lineNumber = reference.getLineNumber();
		if (lineNumber > 0) {
			lineNumber--;
		}
		String ltypename = getTypeName(reference.getMember());
		return ApiProblemFactory.newApiUsageProblem(null, ltypename, getQualifiedMessageArgs(reference), new String[] { IApiMarkerConstants.API_MARKER_ATTR_ID }, new Object[] { Integer.valueOf(IApiMarkerConstants.API_USAGE_MARKER_ID) }, lineNumber, IApiProblem.NO_CHARRANGE, IApiProblem.NO_CHARRANGE, getElementType(reference), getProblemKind(), getProblemFlags(reference));
	}

	/**
	 * @param reference
	 * @return the API problem if problem or null
	 * @throws CoreException
	 */
	public IApiProblem checkAndCreateProblem(IReference reference, IProgressMonitor monitor) throws CoreException {
		if (isProblem(reference, monitor) == false) {
			return null;
		}
		return createProblem(reference);
	}

}