/*******************************************************************************
 * Copyright (c) 2005, 2017 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.jdt.internal.debug.core;

import java.io.File;
import java.util.ArrayList;
import java.util.List;

import org.eclipse.core.resources.IResource;
import org.eclipse.core.runtime.CoreException;
import org.eclipse.core.runtime.IAdaptable;
import org.eclipse.core.runtime.IPath;
import org.eclipse.core.runtime.Path;
import org.eclipse.debug.core.DebugException;
import org.eclipse.debug.core.ILaunch;
import org.eclipse.debug.core.model.IDebugElement;
import org.eclipse.debug.core.model.IDebugTarget;
import org.eclipse.debug.core.model.ISourceLocator;
import org.eclipse.debug.core.sourcelookup.ISourceLookupDirector;
import org.eclipse.jdt.core.ICompilationUnit;
import org.eclipse.jdt.core.IJavaElement;
import org.eclipse.jdt.core.IJavaProject;
import org.eclipse.jdt.core.IOrdinaryClassFile;
import org.eclipse.jdt.core.IType;
import org.eclipse.jdt.core.JavaCore;
import org.eclipse.jdt.core.dom.AST;
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.CompilationUnit;
import org.eclipse.jdt.core.dom.ITypeBinding;
import org.eclipse.jdt.core.dom.TypeDeclaration;
import org.eclipse.jdt.debug.core.IJavaDebugTarget;
import org.eclipse.jdt.debug.core.IJavaReferenceType;
import org.eclipse.jdt.debug.core.IJavaStackFrame;
import org.eclipse.jdt.debug.core.IJavaThread;
import org.eclipse.jdt.debug.core.IJavaType;
import org.eclipse.jdt.debug.core.IJavaValue;

import com.sun.jdi.VMDisconnectedException;

/**
 * A Utilities class.
 *
 * @since 3.2
 */
public class JavaDebugUtils {

	// The value must match org.eclipse.jdi.internal.VirtualMachineImpl#JAVA_STRATUM_NAME}
	public static final String JAVA_STRATUM = "Java"; //$NON-NLS-1$

	/**
	 * Resolves and returns a type from the Java model that corresponds to the
	 * declaring type of the given stack frame, or <code>null</code> if none.
	 *
	 * @param frame
	 *            frame to resolve declaring type for
	 * @return corresponding Java model type or <code>null</code>
	 * @exception CoreException
	 *                if an exception occurs during the resolution
	 * @since 3.2
	 */
	public static IType resolveDeclaringType(IJavaStackFrame frame)
			throws CoreException {
		IJavaElement javaElement = resolveJavaElement(frame, frame.getLaunch());
		if (javaElement != null) {
			return resolveType(frame.getDeclaringTypeName(), javaElement);
		}
		return null;
	}

	/**
	 * Resolves and returns a type from the Java model that corresponds to the
	 * type of the given value, or <code>null</code> if none.
	 *
	 * @param value
	 *            value to resolve type for
	 * @return corresponding Java model type or <code>null</code>
	 * @exception CoreException
	 *                if an exception occurs during the resolution
	 */
	public static IType resolveType(IJavaValue value) throws CoreException {
		IJavaElement javaElement = resolveJavaElement(value, value.getLaunch());
		if (javaElement != null) {
			return resolveType(value.getJavaType().getName(), javaElement);
		}
		return null;
	}

	/**
	 * Resolves and returns the Java model type associated with the given Java
	 * debug type, or <code>null</code> if none.
	 *
	 * @param type
	 *            Java debug model type
	 * @return Java model type or <code>null</code>
	 * @throws CoreException if resolving the type fails
	 */
	public static IType resolveType(IJavaType type) throws CoreException {
		IJavaElement element = resolveJavaElement(type, type.getLaunch());
		if (element != null) {
			return resolveType(type.getName(), element);
		}
		return null;
	}

	/**
	 * Returns the source name associated with the given object, or
	 * <code>null</code> if none.
	 *
	 * @param object
	 *            an object with an <code>IJavaStackFrame</code> adapter, an
	 *            IJavaValue or an IJavaType
	 * @return the source name associated with the given object, or
	 *         <code>null</code> if none
	 * @exception CoreException
	 *                if unable to retrieve the source name
	 */
	public static String getSourceName(Object object) throws CoreException {
		if (object instanceof String) {
			// assume it's a file name
			return (String) object;
		}
		IJavaStackFrame frame = null;
		if (object instanceof IAdaptable) {
			frame = ((IAdaptable) object)
					.getAdapter(IJavaStackFrame.class);
		}
		String typeName = null;
		try {
			if (frame != null) {
				if (frame.isObsolete()) {
					return null;
				}
				String sourceName = frame.getSourcePath();
				// TODO: this may break fix to bug 21518
				if (sourceName == null) {
					// no debug attributes, guess at source name
					typeName = frame.getDeclaringTypeName();
				} else {
					return sourceName;
				}
			} else {
				if (object instanceof IJavaValue) {
					// look at its type
					object = ((IJavaValue) object).getJavaType();
				}
				if (object instanceof IJavaReferenceType) {
					IJavaReferenceType refType = (IJavaReferenceType) object;
					IJavaDebugTarget target = ((IJavaDebugTarget) refType.getDebugTarget());
					String[] sourcePaths = refType.getSourcePaths(target.getDefaultStratum());
					if (sourcePaths != null && sourcePaths.length > 0) {
						return sourcePaths[0];
					}
				}
				if (object instanceof IJavaType) {
					typeName = ((IJavaType) object).getName();
				}
			}
		} catch (DebugException e) {
			int code = e.getStatus().getCode();
			if (code == IJavaThread.ERR_THREAD_NOT_SUSPENDED
					|| code == IJavaStackFrame.ERR_INVALID_STACK_FRAME
					|| e.getStatus().getException() instanceof VMDisconnectedException) {
				return null;
			}
			throw e;
		}
		if (typeName != null) {
			return generateSourceName(typeName);
		}
		return null;
	}

	/**
	 * Generates and returns a source file path based on a qualified type name.
	 * For example, when <code>java.lang.String</code> is provided, the returned
	 * source name is <code>java/lang/String.java</code>.
	 *
	 * @param qualifiedTypeName
	 *            fully qualified type name that may contain inner types denoted
	 *            with <code>$</code> character
	 * @return a source file path corresponding to the type name
	 */
	public static String generateSourceName(String qualifiedTypeName) {
		int index = qualifiedTypeName.lastIndexOf('.');
		if (index < 0) {
			index = 0;
		}
		qualifiedTypeName = qualifiedTypeName.replace('.', File.separatorChar);
		index = qualifiedTypeName.indexOf('$');
		if (index >= 0) {
			qualifiedTypeName = qualifiedTypeName.substring(0, index);
		}
		if (qualifiedTypeName.length() == 0) {
			// likely a proxy class (see bug 40815)
			qualifiedTypeName = null;
		} else {
			qualifiedTypeName = qualifiedTypeName + ".java"; //$NON-NLS-1$
		}
		return qualifiedTypeName;
	}

	/**
	 * Resolves the type corresponding to the given name contained in the given
	 * top-level Java element (class file, compilation unit, or type).
	 *
	 * @param qualifiedName
	 *            fully qualified type name
	 * @param javaElement
	 *            java element containing the type
	 * @return type
	 */
	private static IType resolveType(final String qualifiedName,
			IJavaElement javaElement) {
		IType type = null;
		String[] typeNames = getNestedTypeNames(qualifiedName);
		if (javaElement instanceof IOrdinaryClassFile) {
			type = ((IOrdinaryClassFile) javaElement).getType();
		} else if (javaElement instanceof ICompilationUnit) {
			type = ((ICompilationUnit) javaElement).getType(typeNames[0]);
		} else if (javaElement instanceof IType) {
			type = (IType) javaElement;
		}
		if (type != null) {
			for (int i = 1; i < typeNames.length; i++) {
				String innerTypeName = typeNames[i];

				class ResultException extends RuntimeException {
					private static final long serialVersionUID = 1L;
					private final IType fResult;

					public ResultException(IType result) {
						fResult = result;
					}
				}
				if (innerTypeName.length() > 0) {
					try {
						Integer.parseInt(innerTypeName.substring(0, 1)); // throws NFE if not an integer
						// perform expensive lookup for anonymous types:
						ASTParser parser = ASTParser.newParser(AST.JLS4);
						parser.setResolveBindings(true);
						parser.setSource(type.getTypeRoot());
						CompilationUnit cu = (CompilationUnit) parser.createAST(null);
						cu.accept(new ASTVisitor(false) {
							@Override
							public boolean visit(AnonymousClassDeclaration node) {
								ITypeBinding binding = node.resolveBinding();
								if (binding == null) {
									return false;
								}
								if (qualifiedName.equals(binding.getBinaryName())) {
									throw new ResultException((IType) binding.getJavaElement());
								}
								return true;
							}

							@Override
							public boolean visit(TypeDeclaration node) {
								ITypeBinding binding = node.resolveBinding();
								if (binding == null) {
									return false;
								}
								if (qualifiedName.equals(binding.getBinaryName())) {
									throw new ResultException((IType) binding.getJavaElement());
								}
								return true;
							}
						});
						return type; // return enclosing type if exact type not
										// found
					} catch (NumberFormatException e) {
						// normal nested type, continue
					} catch (IllegalStateException e) {
						return type; // binary class without source
					} catch (ResultException e) {
						return e.fResult;
					}
				}
				type = type.getType(innerTypeName);
			}
		}
		return type;
	}

	/**
	 * Returns the Java element corresponding to the given object or
	 * <code>null</code> if none, in the context of the given launch.
	 *
	 * @param launch
	 *            provides source locator
	 * @param object
	 *            object to resolve Java model element for
	 * @return corresponding Java element or <code>null</code>
	 * @throws CoreException if an exception occurs
	 */
	public static IJavaElement resolveJavaElement(Object object, ILaunch launch) throws CoreException {
		Object sourceElement = resolveSourceElement(object, launch);
		IJavaElement javaElement = getJavaElement(sourceElement);
		if (javaElement == null) {
			// fallback if default stratum does not provide a Java element
			sourceElement = resolveSourceElement(object, JAVA_STRATUM, launch);
			javaElement = getJavaElement(sourceElement);
		}
		return javaElement;
	}

	/**
	 * Returns the {@link IJavaElement} associated with the given source element
	 * or <code>null</code> if none.
	 *
	 * @param sourceElement
	 *            a java element, object that adapts to a java element, or a
	 *            resource
	 * @return corresponding {@link IJavaElement} or <code>null</code>
	 * @since 3.4.0
	 */
	public static IJavaElement getJavaElement(Object sourceElement) {
		IJavaElement javaElement = null;
		if (sourceElement instanceof IJavaElement) {
			javaElement = (IJavaElement) sourceElement;
		} else if (sourceElement instanceof IAdaptable) {
			javaElement = ((IAdaptable) sourceElement).getAdapter(IJavaElement.class);
		}
		if (javaElement == null && sourceElement instanceof IResource) {
			javaElement = JavaCore.create((IResource) sourceElement);
		}
		if (javaElement == null) {
			return null;
		}
		if (!javaElement.exists()) {
			return null;
		}
		return javaElement;
	}

	/**
	 * Returns the source element corresponding to the given object or <code>null</code> if none, in the context of the given launch.
	 *
	 * @param launch
	 *            provides source locator
	 * @param object
	 *            object to resolve source element for
	 * @return corresponding source element or <code>null</code>
	 * @throws CoreException
	 *             if an exception occurs
	 */
	public static Object resolveSourceElement(Object object, ILaunch launch) throws CoreException {
		return resolveSourceElement(object, null, launch);
	}

	/**
	 * Returns the source element corresponding to the given object in the given stratum or <code>null</code> if none, in the context of the given
	 * launch.
	 *
	 * @param launch
	 *            provides source locator
	 * @param object
	 *            object to resolve source element for
	 * @param stratum
	 *            the stratum to use
	 * @return corresponding source element or <code>null</code>
	 * @throws CoreException
	 *             if an exception occurs
	 */
	public static Object resolveSourceElement(Object object, String stratum, ILaunch launch) throws CoreException {
		ISourceLocator sourceLocator = launch.getSourceLocator();
		if (stratum != null && object instanceof IDebugElement) {
			IDebugTarget debugTarget = ((IDebugElement) object).getDebugTarget();
			if (debugTarget instanceof IJavaDebugTarget) {
				IJavaDebugTarget javaDebugTarget = (IJavaDebugTarget) debugTarget;
				String def = javaDebugTarget.getDefaultStratum();
				try {
					javaDebugTarget.setDefaultStratum(stratum);
					return doSourceLookup(object, sourceLocator);
				}
				finally {
					javaDebugTarget.setDefaultStratum(def);
				}
			}
		}
		return doSourceLookup(object, sourceLocator);
	}

	private static Object doSourceLookup(Object object, ISourceLocator sourceLocator) {
		if (sourceLocator instanceof ISourceLookupDirector) {
			ISourceLookupDirector director = (ISourceLookupDirector) sourceLocator;
			return director.getSourceElement(object);
		}
		return null;
	}

	/**
	 * Resolves the {@link IJavaProject} within the context of the given {@link IJavaStackFrame}
	 *
	 * @param frame
	 * @return the {@link IJavaProject} or <code>null</code>
	 * @since 3.8.0
	 */
	public static IJavaProject resolveJavaProject(IJavaStackFrame frame) {
		ILaunch launch = frame.getLaunch();
		if(launch != null) {
			try {
				Object sourceElement = resolveSourceElement(frame, launch);
				IJavaElement element = getJavaElement(sourceElement);
				if (element == null) {
					Object sourceElement1 = resolveSourceElement(frame, JAVA_STRATUM, launch);
					if (sourceElement1 != null){
						sourceElement = sourceElement1;
						element = getJavaElement(sourceElement);
					}
				}
				if(element != null) {
					return element.getJavaProject();
				}
				// If Source element is not a Java element
				if (sourceElement instanceof IResource) {
					IJavaProject project = JavaCore.create(((IResource) sourceElement).getProject());
					if (project.exists()) {
						return project;
					}
				}
			}
			catch(CoreException ce) {
				//do nothing, return null
			}
		}
		return null;
	}

	/**
	 * Returns an array of simple type names that are part of the given type's
	 * qualified name. For example, if the given name is <code>x.y.A$B</code>,
	 * an array with <code>["A", "B"]</code> is returned.
	 *
	 * @param typeName
	 *            fully qualified type name
	 * @return array of nested type names
	 */
	private static String[] getNestedTypeNames(String typeName) {
		int index = typeName.lastIndexOf('.');
		if (index >= 0) {
			typeName = typeName.substring(index + 1);
		}
		index = typeName.indexOf('$');
		List<String> list = new ArrayList<>(1);
		while (index >= 0) {
			list.add(typeName.substring(0, index));
			typeName = typeName.substring(index + 1);
			index = typeName.indexOf('$');
		}
		list.add(typeName);
		return list.toArray(new String[list.size()]);
	}

	/**
	 * Returns the class file or compilation unit containing the given fully
	 * qualified name in the specified project. All registered java like file
	 * extensions are considered.
	 *
	 * @param qualifiedTypeName
	 *            fully qualified type name
	 * @param project
	 *            project to search in
	 * @return class file or compilation unit or <code>null</code>
	 * @throws CoreException if an exception occurs
	 */
	public static IJavaElement findElement(String qualifiedTypeName, IJavaProject project) throws CoreException {
		String[] javaLikeExtensions = JavaCore.getJavaLikeExtensions();
		String path = qualifiedTypeName;
		int pos = path.indexOf('$');
		if (pos != -1) {
			path = path.substring(0, pos);
		}
		path = path.replace('.', IPath.SEPARATOR);
		path += "."; //$NON-NLS-1$
		for (String ext : javaLikeExtensions) {
			IJavaElement element = project.findElement(new Path(path + ext));
			if (element != null) {
				return element;
			}
		}
		return null;
	}

	/**
	 * Returns if the type names are equal, where being equals means:
	 * <ul>
	 * <li>The names are non-null and equal</li>
	 * <li>The names are both null</li>
	 * </ul>
	 *
	 * @param name1
	 *            The first name
	 * @param name2
	 *            The second name
	 * @return If the type names are equal
	 * @since 3.8.100
	 */
	public static boolean typeNamesEqual(String name1, String name2) {
		if (name1 == null) {
			return name2 == null;
		}
		return name1.equals(name2);
	}
}