/*
 * Copyright (C) 2009-2019 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.core;

import static lombok.Lombok.sneakyThrow;

import java.lang.reflect.Array;
import java.lang.reflect.Field;
import java.lang.reflect.Modifier;
import java.lang.reflect.ParameterizedType;
import java.lang.reflect.Type;
import java.net.URI;
import java.util.ArrayList;
import java.util.Collection;
import java.util.IdentityHashMap;
import java.util.List;
import java.util.Map;
import java.util.concurrent.ConcurrentHashMap;
import java.util.concurrent.ConcurrentMap;

import lombok.core.configuration.ConfigurationKey;
import lombok.core.debug.HistogramTracker;
import lombok.permit.Permit;

Lombok wraps the AST produced by a target platform into its own AST system, mostly because both Eclipse and javac
do not allow upward traversal (from a method to its owning type, for example).
Params:
A – Self-type.
L – type of all LombokNodes.
N – The common type of all AST nodes in the internal representation of the target platform.
         For example, JCTree for javac, and ASTNode for Eclipse./**
 * Lombok wraps the AST produced by a target platform into its own AST system, mostly because both Eclipse and javac
 * do not allow upward traversal (from a method to its owning type, for example).
 * 
 * @param A Self-type.
 * @param L type of all LombokNodes.
 * @param N The common type of all AST nodes in the internal representation of the target platform.
 *          For example, JCTree for javac, and ASTNode for Eclipse.
 */
public abstract class AST<A extends AST<A, L, N>, L extends LombokNode<A, L, N>, N> {
	
The kind of node represented by a given AST.Node object. /** The kind of node represented by a given AST.Node object. */
	public enum Kind {
		COMPILATION_UNIT, TYPE, FIELD, INITIALIZER, METHOD, ANNOTATION, ARGUMENT, LOCAL, STATEMENT, TYPE_USE;
	}
	
	private L top;
	private final String fileName;
	private final String packageDeclaration;
	private final ImportList imports;
	private TypeResolver importsAsResolver;
	Map<N, N> identityDetector = new IdentityHashMap<N, N>();
	private Map<N, L> nodeMap = new IdentityHashMap<N, L>();
	private boolean changed = false;
	
	// The supertypes which are considered AST Node children. Usually, the Statement, and the Expression,
	// though some platforms (such as Eclipse) group these under one common supertype.
	private final Collection<Class<? extends N>> statementTypes;
	
	private static final HistogramTracker configTracker = System.getProperty("lombok.timeConfig") == null ? null : new HistogramTracker("lombok.config");
	
	protected AST(String fileName, String packageDeclaration, ImportList imports, Collection<Class<? extends N>> statementTypes) {
		this.fileName = fileName == null ? "(unknown).java" : fileName;
		this.packageDeclaration = packageDeclaration;
		this.imports = imports;
		this.statementTypes = statementTypes;
	}
	
	
Attempts to find the absolute path (in URI form) to the source file represented by this AST. May return null if this cannot be done. We don't yet know under which conditions this will happen. /**
	 * Attempts to find the absolute path (in URI form) to the source file represented by this AST.
	 * 
	 * May return {@code null} if this cannot be done. We don't yet know under which conditions this will happen.
	 */
	public abstract URI getAbsoluteFileLocation();
	
	public void setChanged() {
		this.changed = true;
	}
	
	protected void clearChanged() {
		this.changed = false;
	}
	
	public boolean isChanged() {
		return changed;
	}
	
	
Set the node object that wraps the internal Compilation Unit node. /** Set the node object that wraps the internal Compilation Unit node. */
	protected void setTop(L top) {
		this.top = top;
	}
	
	
Return the content of the package declaration on this AST's top (Compilation Unit) node.
Example: "java.util".
/**
	 * Return the content of the package declaration on this AST's top (Compilation Unit) node.
	 * 
	 * Example: "java.util".
	 */
	public final String getPackageDeclaration() {
		return packageDeclaration;
	}
	
	
Return the contents of each non-static import statement on this AST's top (Compilation Unit) node.
/**
	 * Return the contents of each non-static import statement on this AST's top (Compilation Unit) node.
	 */
	public final ImportList getImportList() {
		return imports;
	}
	
	
Return the contents of each non-static import statement on this AST's top (Compilation Unit) node, packed into a (cached) TypeResolver.
/**
	 * Return the contents of each non-static import statement on this AST's top (Compilation Unit) node, packed into a (cached) TypeResolver.
	 */
	public final TypeResolver getImportListAsTypeResolver() {
		if (importsAsResolver != null) return importsAsResolver;
		return importsAsResolver = new TypeResolver(getImportList());
	}
	
	
Puts the given node in the map so that javac/Eclipse's own internal AST object can be translated to
an AST.Node object. Also registers the object as visited to avoid endless loops.
/**
	 * Puts the given node in the map so that javac/Eclipse's own internal AST object can be translated to
	 * an AST.Node object. Also registers the object as visited to avoid endless loops.
	 */
	protected L putInMap(L node) {
		nodeMap.put(node.get(), node);
		identityDetector.put(node.get(), node.get());
		return node;
	}
	
	
Returns the node map, that can map javac/Eclipse internal AST objects to AST.Node objects. /** Returns the node map, that can map javac/Eclipse internal AST objects to AST.Node objects. */
	protected Map<N, L> getNodeMap() {
		return nodeMap;
	}
	
	
Clears the registry that avoids endless loops, and empties the node map. The existing node map
object is left untouched, and instead a new map is created. /** Clears the registry that avoids endless loops, and empties the node map. The existing node map
	 * object is left untouched, and instead a new map is created. */
	protected void clearState() {
		identityDetector = new IdentityHashMap<N, N>();
		nodeMap = new IdentityHashMap<N, L>();
	}
	
	
Marks the stated node as handled (to avoid endless loops if 2 nodes refer to each other, or a node
refers to itself). Will then return true if it was already set as handled before this call - in which
case you should do nothing lest the AST build process loops endlessly.
/**
	 * Marks the stated node as handled (to avoid endless loops if 2 nodes refer to each other, or a node
	 * refers to itself). Will then return true if it was already set as handled before this call - in which
	 * case you should do nothing lest the AST build process loops endlessly.
	 */
	protected boolean setAndGetAsHandled(N node) {
		return identityDetector.put(node, node) != null;
	}
	
	public String getFileName() {
		return fileName;
	}
	
	
The AST.Node object representing the Compilation Unit. /** The AST.Node object representing the Compilation Unit. */
	public L top() {
		return top;
	}
	
	
Maps a javac/Eclipse internal AST Node to the appropriate AST.Node object. /** Maps a javac/Eclipse internal AST Node to the appropriate AST.Node object. */
	public L get(N node) {
		return nodeMap.get(node);
	}
	
	
Returns the JLS spec version that the compiler uses to parse and compile this AST. For example, if -source 1.6 is on the command line, this will return 6. /**
	 * Returns the JLS spec version that the compiler uses to parse and compile this AST.
	 * For example, if -source 1.6 is on the command line, this will return {@code 6}.
	 */
	public int getSourceVersion() {
		return 6;
	}
	
	
Returns the latest version of the java language specification supported by the host compiler. For example, if compiling with javac v1.7, this returns 7. NB: Even if -source (lower than maximum) is specified, this method still returns the maximum supported number. /**
	 * Returns the latest version of the java language specification supported by the host compiler.
	 * For example, if compiling with javac v1.7, this returns {@code 7}.
	 * 
	 * NB: Even if -source (lower than maximum) is specified, this method still returns the maximum supported number.
	 */
	public int getLatestJavaSpecSupported() {
		return 6;
	}
	
	@SuppressWarnings({"unchecked", "rawtypes"})
	L replaceNewWithExistingOld(Map<N, L> oldNodes, L newNode) {
		L oldNode = oldNodes.get(newNode.get());
		L targetNode = oldNode == null ? newNode : oldNode;
		
		List children = new ArrayList();
		for (L child : newNode.children) {
			L oldChild = replaceNewWithExistingOld(oldNodes, child);
			children.add(oldChild);
			oldChild.parent = targetNode;
		}
		
		targetNode.children = LombokImmutableList.copyOf(children);
		
		return targetNode;
	}
	
	
Build an AST.Node object for the stated internal (javac/Eclipse) AST Node object. /** Build an AST.Node object for the stated internal (javac/Eclipse) AST Node object. */
	protected abstract L buildTree(N item, Kind kind);
	
	
Represents a field that contains AST children.
/**
	 * Represents a field that contains AST children.
	 */
	protected static class FieldAccess {
		
The actual field. /** The actual field. */
		public final Field field;
		
Dimensions of the field. Works for arrays, or for java.util.collections. /** Dimensions of the field. Works for arrays, or for java.util.collections. */
		public final int dim;
		
		FieldAccess(Field field, int dim) {
			this.field = field;
			this.dim = dim;
		}
	}
	
	private static final ConcurrentMap<Class<?>, FieldAccess[]> fieldsOfASTClasses = new ConcurrentHashMap<Class<?>, FieldAccess[]>();
	
	
Returns FieldAccess objects for the stated class. Each field that contains objects of the kind returned by getStatementTypes(), either directly or inside of an array or java.util.collection (or array-of-arrays, or collection-of-collections, et cetera), is returned. /** Returns FieldAccess objects for the stated class. Each field that contains objects of the kind returned by
	 * {@link #getStatementTypes()}, either directly or inside of an array or java.util.collection (or array-of-arrays,
	 * or collection-of-collections, et cetera), is returned.
	 */
	protected FieldAccess[] fieldsOf(Class<?> c) {
		FieldAccess[] fields = fieldsOfASTClasses.get(c);
		if (fields != null) return fields;
		
		List<FieldAccess> fieldList = new ArrayList<FieldAccess>();
		getFields(c, fieldList);
		fieldsOfASTClasses.putIfAbsent(c, fieldList.toArray(new FieldAccess[0]));
		return fieldsOfASTClasses.get(c);
	}
	
	private void getFields(Class<?> c, Collection<FieldAccess> fields) {
		if (c == Object.class || c == null) return;
		for (Field f : c.getDeclaredFields()) {
			if (Modifier.isStatic(f.getModifiers())) continue;
			Class<?> t = f.getType();
			int dim = 0;
			
			if (t.isArray()) {
				while (t.isArray()) {
					dim++;
					t = t.getComponentType();
				}
			} else {
				while (Collection.class.isAssignableFrom(t)) {
					dim++;
					t = getComponentType(f.getGenericType());
				}
			}
			
			if (shouldDrill(c, t, f.getName())) {
				Permit.setAccessible(f);
				fields.add(new FieldAccess(f, dim));
			}
		}
		
		getFields(c.getSuperclass(), fields);
	}
	
	private Class<?> getComponentType(Type type) {
		if (type instanceof ParameterizedType) {
			Type component = ((ParameterizedType) type).getActualTypeArguments()[0];
			return component instanceof Class<?> ? (Class<?>) component : Object.class;
		}
		return Object.class;
	}
	
	private boolean shouldDrill(Class<?> parentType, Class<?> childType, String fieldName) {
		for (Class<?> statementType : statementTypes) {
			if (statementType.isAssignableFrom(childType)) return true;
		}
		
		return false;
	}
	
	
buildTree implementation that uses reflection to find all child nodes by way of inspecting
the fields. /**
	 * buildTree implementation that uses reflection to find all child nodes by way of inspecting
	 * the fields. */
	protected Collection<L> buildWithField(Class<L> nodeType, N statement, FieldAccess fa) {
		List<L> list = new ArrayList<L>();
		buildWithField0(nodeType, statement, fa, list);
		return list;
	}
	
	
Uses reflection to find the given direct child on the given statement, and replace it with a new child.
/**
	 * Uses reflection to find the given direct child on the given statement, and replace it with a new child.
	 */
	protected boolean replaceStatementInNode(N statement, N oldN, N newN) {
		for (FieldAccess fa : fieldsOf(statement.getClass())) {
			if (replaceStatementInField(fa, statement, oldN, newN)) return true;
		}
		
		return false;
	}
	
	private boolean replaceStatementInField(FieldAccess fa, N statement, N oldN, N newN) {
		try {
			Object o = fa.field.get(statement);
			if (o == null) return false;
			
			if (o == oldN) {
				fa.field.set(statement, newN);
				return true;
			}
			
			if (fa.dim > 0) {
				if (o.getClass().isArray()) {
					return replaceStatementInArray(o, oldN, newN);
				} else if (Collection.class.isInstance(o)) {
					return replaceStatementInCollection(fa.field, statement, new ArrayList<Collection<?>>(), (Collection<?>)o, oldN, newN);
				}
			}
			
			return false;
		} catch (IllegalAccessException e) {
			throw sneakyThrow(e);
		}
		
	}
	
	private boolean replaceStatementInCollection(Field field, Object fieldRef, List<Collection<?>> chain, Collection<?> collection, N oldN, N newN) throws IllegalAccessException {
		if (collection == null) return false;
		
		int idx = -1;
		for (Object o : collection) {
			idx++;
			if (o == null) continue;
			if (Collection.class.isInstance(o)) {
				Collection<?> newC = (Collection<?>) o;
				List<Collection<?>> newChain = new ArrayList<Collection<?>>(chain);
				newChain.add(newC);
				if (replaceStatementInCollection(field, fieldRef, newChain, newC, oldN, newN)) return true;
			}
			if (o == oldN) {
				setElementInASTCollection(field, fieldRef, chain, collection, idx, newN);
				return true;
			}
		}
		
		return false;
	}
	
	
Override if your AST collection does not support the set method. Javac's for example, does not.
Params:
field – The field that contains the array or list of AST nodes.
fieldRef – The object that you can supply to the field's get method.
chain – If the collection is immutable, you need to update the pointer to the collection in each element in the chain.
Throws:
IllegalAccessException – This exception won't happen, but we allow you to throw it so you can avoid having to catch it./**
	 * Override if your AST collection does not support the set method. Javac's for example, does not.
	 * 
	 * @param field The field that contains the array or list of AST nodes.
	 * @param fieldRef The object that you can supply to the field's {@code get} method.
	 * @param chain If the collection is immutable, you need to update the pointer to the collection in each element in the chain.
	 * 
	 * @throws IllegalAccessException This exception won't happen, but we allow you to throw it so you can avoid having to catch it.
	 */
	@SuppressWarnings({"rawtypes", "unchecked"})
	protected void setElementInASTCollection(Field field, Object fieldRef, List<Collection<?>> chain, Collection<?> collection, int idx, N newN) throws IllegalAccessException {
		if (collection instanceof List<?>) {
			((List) collection).set(idx, newN);
		}
	}
	
	private boolean replaceStatementInArray(Object array, N oldN, N newN) {
		if (array == null) return false;
		
		int len = Array.getLength(array);
		for (int i = 0; i < len; i++) {
			Object o = Array.get(array, i);
			if (o == null) continue;
			if (o.getClass().isArray()) {
				if (replaceStatementInArray(o, oldN, newN)) return true;
			} else if (o == oldN) {
				Array.set(array, i, newN);
				return true;
			}
		}
		
		return false;
	}
	
	@SuppressWarnings("unchecked")
	private void buildWithField0(Class<L> nodeType, N child, FieldAccess fa, Collection<L> list) {
		try {
			Object o = fa.field.get(child);
			if (o == null) return;
			if (fa.dim == 0) {
				L node = buildTree((N) o, Kind.STATEMENT);
				if (node != null) list.add(nodeType.cast(node));
			} else if (o.getClass().isArray()) {
				buildWithArray(nodeType, o, list, fa.dim);
			} else if (Collection.class.isInstance(o)) {
				buildWithCollection(nodeType, o, list, fa.dim);
			}
		} catch (IllegalAccessException e) {
			throw sneakyThrow(e);
		}
	}
	
	@SuppressWarnings("unchecked")
	private void buildWithArray(Class<L> nodeType, Object array, Collection<L> list, int dim) {
		if (dim == 1) {
			for (Object v : (Object[]) array) {
				if (v == null) continue;
				L node = buildTree((N)v, Kind.STATEMENT);
				if (node != null) list.add(nodeType.cast(node));
			}
		} else for (Object v : (Object[]) array) {
			if (v == null) return;
			buildWithArray(nodeType, v, list, dim -1);
		}
	}
	
	@SuppressWarnings("unchecked")
	private void buildWithCollection(Class<L> nodeType, Object collection, Collection<L> list, int dim) {
		if (dim == 1) {
			for (Object v : (Collection<?>) collection) {
				if (v == null) continue;
				L node = buildTree((N) v, Kind.STATEMENT);
				if (node != null) list.add(nodeType.cast(node));
			}
		} else for (Object v : (Collection<?>) collection) {
			buildWithCollection(nodeType, v, list, dim - 1);
		}
	}
	
	public final <T> T readConfiguration(ConfigurationKey<T> key) {
		long start = configTracker == null ? 0L : configTracker.start();
		try {
			return LombokConfiguration.read(key, this);
		} finally {
			if (configTracker != null) configTracker.end(start);
		}
	}
}