/*
 * Copyright (C) 2012 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.handlers;

import static lombok.javac.Javac.getCtcInt;
import static lombok.javac.handlers.JavacHandlerUtil.*;

import java.util.Collection;

import lombok.AccessLevel;
import lombok.core.AST.Kind;
import lombok.core.AnnotationValues;
import lombok.core.TransformationsUtil;
import lombok.experimental.Wither;
import lombok.javac.JavacAnnotationHandler;
import lombok.javac.JavacNode;
import lombok.javac.handlers.JavacHandlerUtil.FieldAccess;

import org.mangosdk.spi.ProviderFor;

import com.sun.tools.javac.code.Flags;
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.JCClassDecl;
import com.sun.tools.javac.tree.JCTree.JCConditional;
import com.sun.tools.javac.tree.JCTree.JCExpression;
import com.sun.tools.javac.tree.JCTree.JCMethodDecl;
import com.sun.tools.javac.tree.JCTree.JCNewClass;
import com.sun.tools.javac.tree.JCTree.JCReturn;
import com.sun.tools.javac.tree.JCTree.JCStatement;
import com.sun.tools.javac.tree.JCTree.JCTypeParameter;
import com.sun.tools.javac.tree.JCTree.JCVariableDecl;
import com.sun.tools.javac.tree.TreeMaker;
import com.sun.tools.javac.util.JCDiagnostic.DiagnosticPosition;
import com.sun.tools.javac.util.List;
import com.sun.tools.javac.util.ListBuffer;
import com.sun.tools.javac.util.Name;

/**
 * Handles the {@code lombok.experimental.Wither} annotation for javac.
 */
@ProviderFor(JavacAnnotationHandler.class)
public class HandleWither extends JavacAnnotationHandler<Wither> {
	public void generateWitherForType(JavacNode typeNode, JavacNode errorNode, AccessLevel level, boolean checkForTypeLevelWither) {
		if (checkForTypeLevelWither) {
			if (hasAnnotation(Wither.class, typeNode)) {
				//The annotation will make it happen, so we can skip it.
				return;
			}
		}
		
		JCClassDecl typeDecl = null;
		if (typeNode.get() instanceof JCClassDecl) typeDecl = (JCClassDecl) typeNode.get();
		long modifiers = typeDecl == null ? 0 : typeDecl.mods.flags;
		boolean notAClass = (modifiers & (Flags.INTERFACE | Flags.ANNOTATION | Flags.ENUM)) != 0;
		
		if (typeDecl == null || notAClass) {
			errorNode.addError("@Wither is only supported on a class or a field.");
			return;
		}
		
		for (JavacNode field : typeNode.down()) {
			if (field.getKind() != Kind.FIELD) continue;
			JCVariableDecl fieldDecl = (JCVariableDecl) field.get();
			//Skip fields that start with $
			if (fieldDecl.name.toString().startsWith("$")) continue;
			//Skip static fields.
			if ((fieldDecl.mods.flags & Flags.STATIC) != 0) continue;
			//Skip final initialized fields.
			if ((fieldDecl.mods.flags & Flags.FINAL) != 0 && fieldDecl.init != null) continue;
			
			generateWitherForField(field, errorNode.get(), level);
		}
	}
	
	/**
	 * Generates a wither on the stated field.
	 * 
	 * Used by {@link HandleValue}.
	 * 
	 * The difference between this call and the handle method is as follows:
	 * 
	 * If there is a {@code lombok.experimental.Wither} annotation on the field, it is used and the
	 * same rules apply (e.g. warning if the method already exists, stated access level applies).
	 * If not, the wither is still generated if it isn't already there, though there will not
	 * be a warning if its already there. The default access level is used.
	 * 
	 * @param fieldNode The node representing the field you want a wither for.
	 * @param pos The node responsible for generating the wither (the {@code @Value} or {@code @Wither} annotation).
	 */
	public void generateWitherForField(JavacNode fieldNode, DiagnosticPosition pos, AccessLevel level) {
		for (JavacNode child : fieldNode.down()) {
			if (child.getKind() == Kind.ANNOTATION) {
				if (annotationTypeMatches(Wither.class, child)) {
					//The annotation will make it happen, so we can skip it.
					return;
				}
			}
		}
		
		createWitherForField(level, fieldNode, fieldNode, false);
	}
	
	@Override public void handle(AnnotationValues<Wither> annotation, JCAnnotation ast, JavacNode annotationNode) {
		Collection<JavacNode> fields = annotationNode.upFromAnnotationToFields();
		deleteAnnotationIfNeccessary(annotationNode, Wither.class);
		deleteImportFromCompilationUnit(annotationNode, "lombok.AccessLevel");
		JavacNode node = annotationNode.up();
		AccessLevel level = annotation.getInstance().value();
		
		if (level == AccessLevel.NONE || node == null) return;
		
		switch (node.getKind()) {
		case FIELD:
			createWitherForFields(level, fields, annotationNode, true);
			break;
		case TYPE:
			generateWitherForType(node, annotationNode, level, false);
			break;
		}
	}
	
	private void createWitherForFields(AccessLevel level, Collection<JavacNode> fieldNodes, JavacNode errorNode, boolean whineIfExists) {
		for (JavacNode fieldNode : fieldNodes) {
			createWitherForField(level, fieldNode, errorNode, whineIfExists);
		}
	}
	
	private void createWitherForField(AccessLevel level,
			JavacNode fieldNode, JavacNode source, boolean whineIfExists) {
		
		if (fieldNode.getKind() != Kind.FIELD) {
			fieldNode.addError("@Wither is only supported on a class or a field.");
			return;
		}
		
		JCVariableDecl fieldDecl = (JCVariableDecl)fieldNode.get();
		String methodName = toWitherName(fieldNode);
		
		if (methodName == null) {
			source.addWarning("Not generating wither for this field: It does not fit your @Accessors prefix list.");
			return;
		}
		
		if ((fieldDecl.mods.flags & Flags.STATIC) != 0) {
			source.addWarning("Not generating wither for this field: Withers cannot be generated for static fields.");
			return;
		}
		
		if ((fieldDecl.mods.flags & Flags.FINAL) != 0 && fieldDecl.init != null) {
			source.addWarning("Not generating wither for this field: Withers cannot be generated for final, initialized fields.");
			return;
		}
		
		if (fieldDecl.name.toString().startsWith("$")) {
			source.addWarning("Not generating wither for this field: Withers cannot be generated for fields starting with $.");
			return;
		}
		
		for (String altName : toAllWitherNames(fieldNode)) {
			switch (methodExists(altName, fieldNode, false, 1)) {
			case EXISTS_BY_LOMBOK:
				return;
			case EXISTS_BY_USER:
				if (whineIfExists) {
					String altNameExpl = "";
					if (!altName.equals(methodName)) altNameExpl = String.format(" (%s)", altName);
					source.addWarning(
						String.format("Not generating %s(): A method with that name already exists%s", methodName, altNameExpl));
				}
				return;
			default:
			case NOT_EXISTS:
				//continue scanning the other alt names.
			}
		}
		
		long access = toJavacModifier(level);
		
		JCMethodDecl createdWither = createWither(access, fieldNode, fieldNode.getTreeMaker(), source.get());
		injectMethod(fieldNode.up(), createdWither);
	}
	
	private JCMethodDecl createWither(long access, JavacNode field, TreeMaker treeMaker, JCTree source) {
		String witherName = toWitherName(field);
		if (witherName == null) return null;
		
		JCVariableDecl fieldDecl = (JCVariableDecl) field.get();
		
		ListBuffer<JCStatement> statements = ListBuffer.lb();
		List<JCAnnotation> nonNulls = findAnnotations(field, TransformationsUtil.NON_NULL_PATTERN);
		List<JCAnnotation> nullables = findAnnotations(field, TransformationsUtil.NULLABLE_PATTERN);
		
		Name methodName = field.toName(witherName);
		List<JCAnnotation> annsOnParam = nonNulls.appendList(nullables);
		
		JCVariableDecl param = treeMaker.VarDef(treeMaker.Modifiers(Flags.FINAL, annsOnParam), fieldDecl.name, fieldDecl.vartype, null);
		
		JCExpression selfType = cloneSelfType(field);
		if (selfType == null) return null;
		
		TreeMaker maker = field.getTreeMaker();
		
		ListBuffer<JCExpression> args = ListBuffer.lb();
		for (JavacNode child : field.up().down()) {
			if (child.getKind() != Kind.FIELD) continue;
			JCVariableDecl childDecl = (JCVariableDecl) child.get();
			// Skip fields that start with $
			if (childDecl.name.toString().startsWith("$")) continue;
			long fieldFlags = childDecl.mods.flags;
			// Skip static fields.
			if ((fieldFlags & Flags.STATIC) != 0) continue;
			// Skip initialized final fields.
			if (((fieldFlags & Flags.FINAL) != 0) && childDecl.init != null) continue;
			if (child.get() == field.get()) {
				args.append(maker.Ident(fieldDecl.name));
			} else {
				args.append(createFieldAccessor(maker, child, FieldAccess.ALWAYS_FIELD));
			}
		}
		
		JCNewClass newClass = maker.NewClass(null, List.<JCExpression>nil(), selfType, args.toList(), null);
		JCExpression identityCheck = maker.Binary(getCtcInt(JCTree.class, "EQ"), createFieldAccessor(maker, field, FieldAccess.ALWAYS_FIELD), maker.Ident(fieldDecl.name));
		JCConditional conditional = maker.Conditional(identityCheck, maker.Ident(field.toName("this")), newClass);
		JCReturn returnStatement = maker.Return(conditional);
		
		if (nonNulls.isEmpty()) {
			statements.append(returnStatement);
		} else {
			JCStatement nullCheck = generateNullCheck(treeMaker, field);
			if (nullCheck != null) statements.append(nullCheck);
			statements.append(returnStatement);
		}
		
		JCExpression returnType = cloneSelfType(field);
		
		JCBlock methodBody = treeMaker.Block(0, statements.toList());
		List<JCTypeParameter> methodGenericParams = List.nil();
		List<JCVariableDecl> parameters = List.of(param);
		List<JCExpression> throwsClauses = List.nil();
		JCExpression annotationMethodDefaultValue = null;
		
		List<JCAnnotation> annsOnMethod = List.nil();
		if (isFieldDeprecated(field)) {
			annsOnMethod = annsOnMethod.prepend(treeMaker.Annotation(chainDots(field, "java", "lang", "Deprecated"), List.<JCExpression>nil()));
		}
		return recursiveSetGeneratedBy(treeMaker.MethodDef(treeMaker.Modifiers(access, annsOnMethod), methodName, returnType,
				methodGenericParams, parameters, throwsClauses, methodBody, annotationMethodDefaultValue), source);
	}
}