/*
 * Copyright (C) 2009-2016 The Project Lombok Authors.
 * 
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 * 
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 * 
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
 * THE SOFTWARE.
 */
package lombok.javac;

import java.lang.reflect.Field;
import java.lang.reflect.Method;
import java.net.URI;
import java.util.ArrayList;
import java.util.Collection;
import java.util.Collections;
import java.util.List;
import java.util.concurrent.ConcurrentHashMap;
import java.util.concurrent.ConcurrentMap;

import javax.annotation.processing.Messager;
import javax.tools.Diagnostic;
import javax.tools.JavaFileObject;

import lombok.core.AST;

import com.sun.tools.javac.code.Source;
import com.sun.tools.javac.code.Symtab;
import com.sun.tools.javac.model.JavacElements;
import com.sun.tools.javac.model.JavacTypes;
import com.sun.tools.javac.tree.JCTree;
import com.sun.tools.javac.tree.JCTree.JCAnnotation;
import com.sun.tools.javac.tree.JCTree.JCBlock;
import com.sun.tools.javac.tree.JCTree.JCCatch;
import com.sun.tools.javac.tree.JCTree.JCClassDecl;
import com.sun.tools.javac.tree.JCTree.JCCompilationUnit;
import com.sun.tools.javac.tree.JCTree.JCExpression;
import com.sun.tools.javac.tree.JCTree.JCFieldAccess;
import com.sun.tools.javac.tree.JCTree.JCIdent;
import com.sun.tools.javac.tree.JCTree.JCMethodDecl;
import com.sun.tools.javac.tree.JCTree.JCStatement;
import com.sun.tools.javac.tree.JCTree.JCTry;
import com.sun.tools.javac.tree.JCTree.JCVariableDecl;
import com.sun.tools.javac.tree.TreeMaker;
import com.sun.tools.javac.util.Context;
import com.sun.tools.javac.util.JCDiagnostic.DiagnosticPosition;
import com.sun.tools.javac.util.Log;
import com.sun.tools.javac.util.Name;

/**
 * Wraps around javac's internal AST view to add useful features as well as the ability to visit parents from children,
 * something javac's own AST system does not offer.
 */
public class JavacAST extends AST<JavacAST, JavacNode, JCTree> {
	private final Messager messager;
	private final JavacElements elements;
	private final JavacTreeMaker treeMaker;
	private final Symtab symtab;
	private final JavacTypes javacTypes;
	private final Log log;
	private final Context context;
	
	/**
	 * Creates a new JavacAST of the provided Compilation Unit.
	 * 
	 * @param messager A Messager for warning and error reporting.
	 * @param context A Context object for interfacing with the compiler.
	 * @param top The compilation unit, which serves as the top level node in the tree to be built.
	 */
	public JavacAST(Messager messager, Context context, JCCompilationUnit top) {
		super(sourceName(top), PackageName.getPackageName(top), new JavacImportList(top), statementTypes());
		setTop(buildCompilationUnit(top));
		this.context = context;
		this.messager = messager;
		this.log = Log.instance(context);
		this.elements = JavacElements.instance(context);
		this.treeMaker = new JavacTreeMaker(TreeMaker.instance(context));
		this.symtab = Symtab.instance(context);
		this.javacTypes = JavacTypes.instance(context);
		clearChanged();
	}
	
	@Override public URI getAbsoluteFileLocation() {
		try {
			JCCompilationUnit cu = (JCCompilationUnit) top().get();
			return cu.sourcefile.toUri();
		} catch (Exception e) {
			return null;
		}
	}
	
	private static String sourceName(JCCompilationUnit cu) {
		return cu.sourcefile == null ? null : cu.sourcefile.toString();
	}
	
	// jdk9 support, types have changed, names stay the same
	static class PackageName {
		private static final Method packageNameMethod;
		
		static {
			Method m = null;
			try {
				m = JCCompilationUnit.class.getDeclaredMethod("getPackageName");
			} catch (Exception e) {}
			packageNameMethod = m;
		}
		
		static String getPackageName(JCCompilationUnit cu) {
			try {
				Object pkg = packageNameMethod.invoke(cu);
				return (pkg instanceof JCFieldAccess || pkg instanceof JCIdent) ? pkg.toString() : null;
			} catch (Exception e) {}
			return null;
		}
	}
	
	public Context getContext() {
		return context;
	}
	
	/**
	 * Runs through the entire AST, starting at the compilation unit, calling the provided visitor's visit methods
	 * for each node, depth first.
	 */
	public void traverse(JavacASTVisitor visitor) {
		top().traverse(visitor);
	}
	
	void traverseChildren(JavacASTVisitor visitor, JavacNode node) {
		for (JavacNode child : node.down()) child.traverse(visitor);
	}
	
	@Override public int getSourceVersion() {
		try {
			String nm = Source.instance(context).name();
			int underscoreIdx = nm.indexOf('_');
			if (underscoreIdx > -1) return Integer.parseInt(nm.substring(underscoreIdx + 1));
		} catch (Exception ignore) {}
		return 6;
	}
	
	@Override public int getLatestJavaSpecSupported() {
		return Javac.getJavaCompilerVersion();
	}
	
	/** @return A Name object generated for the proper name table belonging to this AST. */
	public Name toName(String name) {
		return elements.getName(name);
	}
	
	/** @return A TreeMaker instance that you can use to create new AST nodes. */
	public JavacTreeMaker getTreeMaker() {
		treeMaker.at(-1);
		return treeMaker;
	}
	
	/** @return The symbol table used by this AST for symbols. */
	public Symtab getSymbolTable() {
		return symtab;
	}
	
	/**
	 * @return The implementation of {@link javax.lang.model.util.Types} of javac. Contains a few extra methods beyond
	 * the ones listed in the official annotation API interface. */
	public JavacTypes getTypesUtil() {
		return javacTypes;
	}
	
	/** {@inheritDoc} */
	@Override protected JavacNode buildTree(JCTree node, Kind kind) {
		switch (kind) {
		case COMPILATION_UNIT:
			return buildCompilationUnit((JCCompilationUnit) node);
		case TYPE:
			return buildType((JCClassDecl) node);
		case FIELD:
			return buildField((JCVariableDecl) node);
		case INITIALIZER:
			return buildInitializer((JCBlock) node);
		case METHOD:
			return buildMethod((JCMethodDecl) node);
		case ARGUMENT:
			return buildLocalVar((JCVariableDecl) node, kind);
		case LOCAL:
			return buildLocalVar((JCVariableDecl) node, kind);
		case STATEMENT:
			return buildStatementOrExpression(node);
		case ANNOTATION:
			return buildAnnotation((JCAnnotation) node, false);
		default:
			throw new AssertionError("Did not expect: " + kind);
		}
	}
	
	private JavacNode buildCompilationUnit(JCCompilationUnit top) {
		List<JavacNode> childNodes = new ArrayList<JavacNode>();
		for (JCTree s : top.defs) {
			if (s instanceof JCClassDecl) {
				addIfNotNull(childNodes, buildType((JCClassDecl)s));
			} // else they are import statements, which we don't care about. Or Skip objects, whatever those are.
		}
		
		return new JavacNode(this, top, childNodes, Kind.COMPILATION_UNIT);
	}
	
	private JavacNode buildType(JCClassDecl type) {
		if (setAndGetAsHandled(type)) return null;
		List<JavacNode> childNodes = new ArrayList<JavacNode>();
		
		for (JCAnnotation annotation : type.mods.annotations) addIfNotNull(childNodes, buildAnnotation(annotation, false));
		for (JCTree def : type.defs) {
			/* A def can be:
			 *   JCClassDecl for inner types
			 *   JCMethodDecl for constructors and methods
			 *   JCVariableDecl for fields
			 *   JCBlock for (static) initializers
			 */
			if (def instanceof JCMethodDecl) addIfNotNull(childNodes, buildMethod((JCMethodDecl)def));
			else if (def instanceof JCClassDecl) addIfNotNull(childNodes, buildType((JCClassDecl)def));
			else if (def instanceof JCVariableDecl) addIfNotNull(childNodes, buildField((JCVariableDecl)def));
			else if (def instanceof JCBlock) addIfNotNull(childNodes, buildInitializer((JCBlock)def));
		}
		
		return putInMap(new JavacNode(this, type, childNodes, Kind.TYPE));
	}
	
	private JavacNode buildField(JCVariableDecl field) {
		if (setAndGetAsHandled(field)) return null;
		List<JavacNode> childNodes = new ArrayList<JavacNode>();
		for (JCAnnotation annotation : field.mods.annotations) addIfNotNull(childNodes, buildAnnotation(annotation, true));
		addIfNotNull(childNodes, buildExpression(field.init));
		return putInMap(new JavacNode(this, field, childNodes, Kind.FIELD));
	}
	
	private JavacNode buildLocalVar(JCVariableDecl local, Kind kind) {
		if (setAndGetAsHandled(local)) return null;
		List<JavacNode> childNodes = new ArrayList<JavacNode>();
		for (JCAnnotation annotation : local.mods.annotations) addIfNotNull(childNodes, buildAnnotation(annotation, true));
		addIfNotNull(childNodes, buildExpression(local.init));
		return putInMap(new JavacNode(this, local, childNodes, kind));
	}
	
	private static boolean JCTRY_RESOURCES_FIELD_INITIALIZED;
	private static Field JCTRY_RESOURCES_FIELD;
	
	@SuppressWarnings("unchecked")
	private static List<JCTree> getResourcesForTryNode(JCTry tryNode) {
		if (!JCTRY_RESOURCES_FIELD_INITIALIZED) {
			try {
				JCTRY_RESOURCES_FIELD = JCTry.class.getField("resources");
			} catch (NoSuchFieldException ignore) {
				// Java 1.6 or lower won't have this at all.
			} catch (Exception ignore) {
				// Shouldn't happen. Best thing we can do is just carry on and break on try/catch.
			}
			JCTRY_RESOURCES_FIELD_INITIALIZED = true;
		}
		
		if (JCTRY_RESOURCES_FIELD == null) return Collections.emptyList();
		Object rv = null;
		try {
			rv = JCTRY_RESOURCES_FIELD.get(tryNode);
		} catch (Exception ignore) {}
		
		if (rv instanceof List) return (List<JCTree>) rv;
		return Collections.emptyList();
	}
	
	private JavacNode buildTry(JCTry tryNode) {
		if (setAndGetAsHandled(tryNode)) return null;
		List<JavacNode> childNodes = new ArrayList<JavacNode>();
		for (JCTree varDecl : getResourcesForTryNode(tryNode)) {
			if (varDecl instanceof JCVariableDecl) {
				addIfNotNull(childNodes, buildLocalVar((JCVariableDecl) varDecl, Kind.LOCAL));
			}
		}
		addIfNotNull(childNodes, buildStatement(tryNode.body));
		for (JCCatch jcc : tryNode.catchers) addIfNotNull(childNodes, buildTree(jcc, Kind.STATEMENT));
		addIfNotNull(childNodes, buildStatement(tryNode.finalizer));
		return putInMap(new JavacNode(this, tryNode, childNodes, Kind.STATEMENT));
	}
	
	private JavacNode buildInitializer(JCBlock initializer) {
		if (setAndGetAsHandled(initializer)) return null;
		List<JavacNode> childNodes = new ArrayList<JavacNode>();
		for (JCStatement statement: initializer.stats) addIfNotNull(childNodes, buildStatement(statement));
		return putInMap(new JavacNode(this, initializer, childNodes, Kind.INITIALIZER));
	}
	
	private JavacNode buildMethod(JCMethodDecl method) {
		if (setAndGetAsHandled(method)) return null;
		List<JavacNode> childNodes = new ArrayList<JavacNode>();
		for (JCAnnotation annotation : method.mods.annotations) addIfNotNull(childNodes, buildAnnotation(annotation, false));
		for (JCVariableDecl param : method.params) addIfNotNull(childNodes, buildLocalVar(param, Kind.ARGUMENT));
		if (method.body != null && method.body.stats != null) {
			for (JCStatement statement : method.body.stats) addIfNotNull(childNodes, buildStatement(statement));
		}
		return putInMap(new JavacNode(this, method, childNodes, Kind.METHOD));
	}
	
	private JavacNode buildAnnotation(JCAnnotation annotation, boolean varDecl) {
		boolean handled = setAndGetAsHandled(annotation);
		if (!varDecl && handled) {
			// @Foo int x, y; is handled in javac by putting the same annotation node on 2 JCVariableDecls.
			return null;
		}
		return putInMap(new JavacNode(this, annotation, null, Kind.ANNOTATION));
	}
	
	private JavacNode buildExpression(JCExpression expression) {
		return buildStatementOrExpression(expression);
	}
	
	private JavacNode buildStatement(JCStatement statement) {
		return buildStatementOrExpression(statement);
	}
	
	private JavacNode buildStatementOrExpression(JCTree statement) {
		if (statement == null) return null;
		if (statement instanceof JCAnnotation) return null;
		if (statement instanceof JCClassDecl) return buildType((JCClassDecl)statement);
		if (statement instanceof JCVariableDecl) return buildLocalVar((JCVariableDecl)statement, Kind.LOCAL);
		if (statement instanceof JCTry) return buildTry((JCTry) statement);
		if (statement.getClass().getSimpleName().equals("JCLambda")) return buildLambda(statement);
		if (setAndGetAsHandled(statement)) return null;
		
		return drill(statement);
	}
	
	private JavacNode buildLambda(JCTree jcTree) {
		return buildStatementOrExpression(getBody(jcTree));
	}
	
	private JCTree getBody(JCTree jcTree) {
		try {
			return (JCTree) getBodyMethod(jcTree.getClass()).invoke(jcTree);
		} catch (Exception e) {
			throw Javac.sneakyThrow(e);
		}
	}
	
	private final static ConcurrentMap<Class<?>, Method> getBodyMethods = new ConcurrentHashMap<Class<?>, Method>();
	
	private Method getBodyMethod(Class<?> c) {
		Method m = getBodyMethods.get(c);
		if (m != null) {
			return m;
		}
		try {
			m = c.getMethod("getBody");
		} catch (NoSuchMethodException e) {
			throw Javac.sneakyThrow(e);
		}
		getBodyMethods.putIfAbsent(c, m);
		return getBodyMethods.get(c);
	}
	
	private JavacNode drill(JCTree statement) {
		try {
			List<JavacNode> childNodes = new ArrayList<JavacNode>();
			for (FieldAccess fa : fieldsOf(statement.getClass())) childNodes.addAll(buildWithField(JavacNode.class, statement, fa));
			return putInMap(new JavacNode(this, statement, childNodes, Kind.STATEMENT));
		} catch (OutOfMemoryError oome) {
			String msg = oome.getMessage();
			if (msg == null) msg = "(no original message)";
			OutOfMemoryError newError = new OutOfMemoryError(getFileName() + "@pos" + statement.getPreferredPosition() + ": " + msg);
			// We could try to set the stack trace of the new exception to the same one as the old exception, but this costs memory,
			// and we're already in an extremely fragile situation in regards to remaining heap space, so let's not do that.
			throw newError;
		}
	}
	
	/* For javac, both JCExpression and JCStatement are considered as valid children types. */
	private static Collection<Class<? extends JCTree>> statementTypes() {
		Collection<Class<? extends JCTree>> collection = new ArrayList<Class<? extends JCTree>>(3);
		collection.add(JCStatement.class);
		collection.add(JCExpression.class);
		collection.add(JCCatch.class);
		return collection;
	}
	
	private static void addIfNotNull(Collection<JavacNode> nodes, JavacNode node) {
		if (node != null) nodes.add(node);
	}
	
	/**
	 * Attempts to remove any compiler errors generated by java whose reporting position is located anywhere between the start and end of the supplied node.
	 */
	void removeDeferredErrors(JavacNode node) {
		DiagnosticPosition pos = node.get().pos();
		JCCompilationUnit top = (JCCompilationUnit) top().get();
		removeFromDeferredDiagnostics(pos.getStartPosition(), Javac.getEndPosition(pos, top));
	}
	
	/** Supply either a position or a node (in that case, position of the node is used) */
	void printMessage(Diagnostic.Kind kind, String message, JavacNode node, DiagnosticPosition pos, boolean attemptToRemoveErrorsInRange) {
		JavaFileObject oldSource = null;
		JavaFileObject newSource = null;
		JCTree astObject = node == null ? null : node.get();
		JCCompilationUnit top = (JCCompilationUnit) top().get();
		newSource = top.sourcefile;
		if (newSource != null) {
			oldSource = log.useSource(newSource);
			if (pos == null) pos = astObject.pos();
		}
		if (pos != null && attemptToRemoveErrorsInRange) {
			removeFromDeferredDiagnostics(pos.getStartPosition(), node.getEndPosition(pos));
		}
		try {
			switch (kind) {
			case ERROR:
				increaseErrorCount(messager);
				boolean prev = log.multipleErrors;
				log.multipleErrors = true;
				try {
					log.error(pos, "proc.messager", message);
				} finally {
					log.multipleErrors = prev;
				}
				break;
			default:
			case WARNING:
				log.warning(pos, "proc.messager", message);
				break;
			}
		} finally {
			if (oldSource != null) log.useSource(oldSource);
		}
	}

	public void removeFromDeferredDiagnostics(int startPos, int endPos) {
		JCCompilationUnit self = (JCCompilationUnit) top().get();
		new CompilerMessageSuppressor(getContext()).removeAllBetween(self.sourcefile, startPos, endPos);
	}
	
	/** {@inheritDoc} */
	@Override protected void setElementInASTCollection(Field field, Object refField, List<Collection<?>> chain, Collection<?> collection, int idx, JCTree newN) throws IllegalAccessException {
		com.sun.tools.javac.util.List<?> list = setElementInConsList(chain, collection, ((List<?>)collection).get(idx), newN);
		field.set(refField, list);
	}
	
	private com.sun.tools.javac.util.List<?> setElementInConsList(List<Collection<?>> chain, Collection<?> current, Object oldO, Object newO) {
		com.sun.tools.javac.util.List<?> oldL = (com.sun.tools.javac.util.List<?>) current;
		com.sun.tools.javac.util.List<?> newL = replaceInConsList(oldL, oldO, newO);
		if (chain.isEmpty()) return newL;
		List<Collection<?>> reducedChain = new ArrayList<Collection<?>>(chain);
		Collection<?> newCurrent = reducedChain.remove(reducedChain.size() -1);
		return setElementInConsList(reducedChain, newCurrent, oldL, newL);
	}
	
	private com.sun.tools.javac.util.List<?> replaceInConsList(com.sun.tools.javac.util.List<?> oldL, Object oldO, Object newO) {
		boolean repl = false;
		Object[] a = oldL.toArray();
		for (int i = 0; i < a.length; i++) {
			if (a[i] == oldO) {
				a[i] = newO;
				repl = true;
			}
		}
		
		if (repl) return com.sun.tools.javac.util.List.<Object>from(a);
		return oldL;
	}
	
	private void increaseErrorCount(Messager m) {
		try {
			Field f = m.getClass().getDeclaredField("errorCount");
			f.setAccessible(true);
			if (f.getType() == int.class) {
				int val = ((Number)f.get(m)).intValue();
				f.set(m, val +1);
			}
		} catch (Throwable t) {
			//Very unfortunate, but in most cases it still works fine, so we'll silently swallow it.
		}
	}
}