/*
 * Copyright © 2009 Reinier Zwitserloot and Roel Spilker.
 * 
 * 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.handlers.PKG.*;

import lombok.EqualsAndHashCode;
import lombok.core.AnnotationValues;
import lombok.core.AST.Kind;
import lombok.javac.Javac;
import lombok.javac.JavacAnnotationHandler;
import lombok.javac.JavacAST.Node;

import org.mangosdk.spi.ProviderFor;

import com.sun.tools.javac.code.BoundKind;
import com.sun.tools.javac.code.Flags;
import com.sun.tools.javac.code.TypeTags;
import com.sun.tools.javac.tree.JCTree;
import com.sun.tools.javac.tree.TreeMaker;
import com.sun.tools.javac.tree.JCTree.JCAnnotation;
import com.sun.tools.javac.tree.JCTree.JCArrayTypeTree;
import com.sun.tools.javac.tree.JCTree.JCBinary;
import com.sun.tools.javac.tree.JCTree.JCBlock;
import com.sun.tools.javac.tree.JCTree.JCClassDecl;
import com.sun.tools.javac.tree.JCTree.JCExpression;
import com.sun.tools.javac.tree.JCTree.JCMethodDecl;
import com.sun.tools.javac.tree.JCTree.JCMethodInvocation;
import com.sun.tools.javac.tree.JCTree.JCModifiers;
import com.sun.tools.javac.tree.JCTree.JCPrimitiveTypeTree;
import com.sun.tools.javac.tree.JCTree.JCStatement;
import com.sun.tools.javac.tree.JCTree.JCTypeParameter;
import com.sun.tools.javac.tree.JCTree.JCUnary;
import com.sun.tools.javac.tree.JCTree.JCVariableDecl;
import com.sun.tools.javac.util.List;
import com.sun.tools.javac.util.Name;

/**
 * Handles the <code>lombok.EqualsAndHashCode</code> annotation for javac.
 */
@ProviderFor(JavacAnnotationHandler.class)
public class HandleEqualsAndHashCode implements JavacAnnotationHandler<EqualsAndHashCode> {
	private void checkForBogusExcludes(Node type, AnnotationValues<EqualsAndHashCode> annotation) {
		List<String> list = List.from(annotation.getInstance().exclude());
		boolean[] matched = new boolean[list.size()];
		
		for ( Node child : type.down() ) {
			if ( list.isEmpty() ) break;
			if ( child.getKind() != Kind.FIELD ) continue;
			if ( (((JCVariableDecl)child.get()).mods.flags & Flags.STATIC) != 0 ) continue;
			if ( (((JCVariableDecl)child.get()).mods.flags & Flags.TRANSIENT) != 0 ) continue;
			int idx = list.indexOf(child.getName());
			if ( idx > -1 ) matched[idx] = true;
		}
		
		for ( int i = 0 ; i < list.size() ; i++ ) {
			if ( !matched[i] ) {
				annotation.setWarning("exclude", "This field does not exist, or would have been excluded anyway.", i);
			}
		}
	}
	
	@Override public boolean handle(AnnotationValues<EqualsAndHashCode> annotation, JCAnnotation ast, Node annotationNode) {
		EqualsAndHashCode ann = annotation.getInstance();
		List<String> excludes = List.from(ann.exclude());
		Node typeNode = annotationNode.up();
		
		checkForBogusExcludes(typeNode, annotation);
		
		return generateMethods(typeNode, annotationNode, excludes, ann.callSuper(), true);
	}
	
	public void generateEqualsAndHashCodeForType(Node typeNode, Node errorNode) {
		for ( Node child : typeNode.down() ) {
			if ( child.getKind() == Kind.ANNOTATION ) {
				if ( Javac.annotationTypeMatches(EqualsAndHashCode.class, child) ) {
					//The annotation will make it happen, so we can skip it.
					return;
				}
			}
		}
		
		boolean callSuper = false;
		try {
			callSuper = ((Boolean)EqualsAndHashCode.class.getMethod("callSuper").getDefaultValue()).booleanValue();
		} catch ( Exception ignore ) {}
		generateMethods(typeNode, errorNode, List.<String>nil(), callSuper, false);
	}
	
	private boolean generateMethods(Node typeNode, Node errorNode, List<String> excludes, 
			boolean callSuper, boolean whineIfExists) {
		boolean notAClass = true;
		if ( typeNode.get() instanceof JCClassDecl ) {
			long flags = ((JCClassDecl)typeNode.get()).mods.flags;
			notAClass = (flags & (Flags.INTERFACE | Flags.ANNOTATION | Flags.ENUM)) != 0;
		}
		
		if ( notAClass ) {
			errorNode.addError("@EqualsAndHashCode is only supported on a class.");
			return false;
		}
		
		boolean isDirectDescendentOfObject = true;
		
		JCTree extending = ((JCClassDecl)typeNode.get()).extending;
		if ( extending != null ) {
			String p = extending.toString();
			isDirectDescendentOfObject = p.equals("Object") || p.equals("java.lang.Object");
		}
		
		if ( isDirectDescendentOfObject && callSuper ) {
			errorNode.addError("Generating equals/hashCode with a supercall to java.lang.Object is pointless.");
			return true;
		}
		
		if ( !isDirectDescendentOfObject && !callSuper ) {
			errorNode.addWarning("Generating equals/hashCode implementation but without a call to superclass, even though this class does not extend java.lang.Object.");
		}
		
		List<Node> nodesForEquality = List.nil();
		for ( Node child : typeNode.down() ) {
			if ( child.getKind() != Kind.FIELD ) continue;
			JCVariableDecl fieldDecl = (JCVariableDecl) child.get();
			//Skip static fields.
			if ( (fieldDecl.mods.flags & Flags.STATIC) != 0 ) continue;
			//Skip transient fields.
			if ( (fieldDecl.mods.flags & Flags.TRANSIENT) != 0 ) continue;
			//Skip excluded fields.
			if ( excludes.contains(fieldDecl.name.toString()) ) continue;
			nodesForEquality = nodesForEquality.append(child);
		}
		
		switch ( methodExists("hashCode", typeNode) ) {
		case NOT_EXISTS:
			JCMethodDecl method = createHashCode(typeNode, nodesForEquality, callSuper);
			injectMethod(typeNode, method);
			break;
		case EXISTS_BY_LOMBOK:
			break;
		default:
		case EXISTS_BY_USER:
			if ( whineIfExists ) {
				errorNode.addWarning("Not generating hashCode(): A method with that name already exists");
			}
			break;
		}
		
		switch ( methodExists("equals", typeNode) ) {
		case NOT_EXISTS:
			JCMethodDecl method = createEquals(typeNode, nodesForEquality, callSuper);
			injectMethod(typeNode, method);
			break;
		case EXISTS_BY_LOMBOK:
			break;
		default:
		case EXISTS_BY_USER:
			if ( whineIfExists ) {
				errorNode.addWarning("Not generating equals(Object other): A method with that name already exists");
			}
			break;
		}
		
		return true;
	}
	
	private JCMethodDecl createHashCode(Node typeNode, List<Node> fields, boolean callSuper) {
		TreeMaker maker = typeNode.getTreeMaker();
		
		JCAnnotation overrideAnnotation = maker.Annotation(chainDots(maker, typeNode, "java", "lang", "Override"), List.<JCExpression>nil());
		JCModifiers mods = maker.Modifiers(Flags.PUBLIC, List.of(overrideAnnotation));
		JCExpression returnType = maker.TypeIdent(TypeTags.INT);
		List<JCStatement> statements = List.nil();
		
		Name primeName = typeNode.toName("PRIME");
		Name resultName = typeNode.toName("result");
		/* final int PRIME = 31; */ {
			if ( !fields.isEmpty() || callSuper ) {
				statements = statements.append(
						maker.VarDef(maker.Modifiers(Flags.FINAL), primeName, maker.TypeIdent(TypeTags.INT), maker.Literal(31)));
			}
		}
		
		/* int result = 1; */ {
			statements = statements.append(maker.VarDef(maker.Modifiers(0), resultName, maker.TypeIdent(TypeTags.INT), maker.Literal(1)));
		}
		
		List<JCExpression> intoResult = List.nil();
		
		if ( callSuper ) {
			JCMethodInvocation callToSuper = maker.Apply(List.<JCExpression>nil(),
					maker.Select(maker.Ident(typeNode.toName("super")), typeNode.toName("hashCode")),
					List.<JCExpression>nil());
			intoResult = intoResult.append(callToSuper);
		}
		
		int tempCounter = 0;
		for ( Node fieldNode : fields ) {
			JCVariableDecl field = (JCVariableDecl) fieldNode.get();
			JCExpression fType = field.vartype;
			JCExpression thisDotField = maker.Select(maker.Ident(typeNode.toName("this")), field.name);
			JCExpression thisDotFieldClone = maker.Select(maker.Ident(typeNode.toName("this")), field.name);
			if ( fType instanceof JCPrimitiveTypeTree ) {
				switch ( ((JCPrimitiveTypeTree)fType).getPrimitiveTypeKind() ) {
				case BOOLEAN:
					/* this.fieldName ? 1231 : 1237 */
					intoResult = intoResult.append(maker.Conditional(thisDotField, maker.Literal(1231), maker.Literal(1237)));
					break;
				case LONG:
					intoResult = intoResult.append(longToIntForHashCode(maker, thisDotField, thisDotFieldClone));
					break;
				case FLOAT:
					/* Float.floatToIntBits(this.fieldName) */
					intoResult = intoResult.append(maker.Apply(
							List.<JCExpression>nil(),
							chainDots(maker, typeNode, "java", "lang", "Float", "floatToIntBits"),
							List.of(thisDotField)));
					break;
				case DOUBLE:
					/* longToIntForHashCode(Double.doubleToLongBits(this.fieldName)) */
					Name tempVar = typeNode.toName("temp" + (++tempCounter));
					JCExpression init = maker.Apply(
							List.<JCExpression>nil(),
							chainDots(maker, typeNode, "java", "lang", "Double", "doubleToLongBits"),
							List.of(thisDotField));
					statements = statements.append(
							maker.VarDef(maker.Modifiers(Flags.FINAL), tempVar, maker.TypeIdent(TypeTags.LONG), init));
					intoResult = intoResult.append(longToIntForHashCode(maker, maker.Ident(tempVar), maker.Ident(tempVar)));
					break;
				default:
				case BYTE:
				case SHORT:
				case INT:
				case CHAR:
					/* just the field */
					intoResult = intoResult.append(thisDotField);
					break;
				}
			} else if ( fType instanceof JCArrayTypeTree ) {
				/* java.util.Arrays.deepHashCode(this.fieldName) //use just hashCode() for primitive arrays. */
				boolean multiDim = ((JCArrayTypeTree)fType).elemtype instanceof JCArrayTypeTree;
				boolean primitiveArray = ((JCArrayTypeTree)fType).elemtype instanceof JCPrimitiveTypeTree;
				boolean useDeepHC = multiDim || !primitiveArray;
				
				JCExpression hcMethod = chainDots(maker, typeNode, "java", "util", "Arrays", useDeepHC ? "deepHashCode" : "hashCode");
				intoResult = intoResult.append(
						maker.Apply(List.<JCExpression>nil(), hcMethod, List.of(thisDotField)));
			} else /* objects */ {
				/* this.fieldName == null ? 0 : this.fieldName.hashCode() */
				JCExpression hcCall = maker.Apply(List.<JCExpression>nil(), maker.Select(thisDotField, typeNode.toName("hashCode")),
						List.<JCExpression>nil());
				JCExpression thisEqualsNull = maker.Binary(JCTree.EQ, thisDotField, maker.Literal(TypeTags.BOT, null));
				intoResult = intoResult.append(
						maker.Conditional(thisEqualsNull, maker.Literal(0), hcCall));
			}
		}
		
		/* fold each intoResult entry into:
		   result = result * PRIME + (item); */
		for ( JCExpression expr : intoResult ) {
			JCExpression mult = maker.Binary(JCTree.MUL, maker.Ident(resultName), maker.Ident(primeName));
			JCExpression add = maker.Binary(JCTree.PLUS, mult, expr);
			statements = statements.append(maker.Exec(maker.Assign(maker.Ident(resultName), add)));
		}
		
		/* return result; */ {
			statements = statements.append(maker.Return(maker.Ident(resultName)));
		}
		
		JCBlock body = maker.Block(0, statements);
		return maker.MethodDef(mods, typeNode.toName("hashCode"), returnType,
				List.<JCTypeParameter>nil(), List.<JCVariableDecl>nil(), List.<JCExpression>nil(), body, null);
	}
	
	/** The 2 references must be clones of each other. */
	private JCExpression longToIntForHashCode(TreeMaker maker, JCExpression ref1, JCExpression ref2) {
		/* (int)(ref >>> 32 ^ ref) */
		JCExpression shift = maker.Binary(JCTree.USR, ref1, maker.Literal(32));
		JCExpression xorBits = maker.Binary(JCTree.BITXOR, shift, ref2);
		return maker.TypeCast(maker.TypeIdent(TypeTags.INT), xorBits);
	}
	
	private JCMethodDecl createEquals(Node typeNode, List<Node> fields, boolean callSuper) {
		TreeMaker maker = typeNode.getTreeMaker();
		JCClassDecl type = (JCClassDecl) typeNode.get();
		
		Name oName = typeNode.toName("o");
		Name otherName = typeNode.toName("other");
		Name thisName = typeNode.toName("this");
		
		JCAnnotation overrideAnnotation = maker.Annotation(chainDots(maker, typeNode, "java", "lang", "Override"), List.<JCExpression>nil());
		JCModifiers mods = maker.Modifiers(Flags.PUBLIC, List.of(overrideAnnotation));
		JCExpression objectType = maker.Type(typeNode.getSymbolTable().objectType);
		JCExpression returnType = maker.TypeIdent(TypeTags.BOOLEAN);
		
		List<JCStatement> statements = List.nil();
		List<JCVariableDecl> params = List.of(maker.VarDef(maker.Modifiers(0), oName, objectType, null));
		
		/* if ( o == this ) return true; */ {
			statements = statements.append(
					maker.If(maker.Binary(JCTree.EQ, maker.Ident(oName), maker.Ident(thisName)), returnBool(maker, true), null));
		}
		
		/* if ( o == null ) return false; */ {
			statements = statements.append(
					maker.If(maker.Binary(JCTree.EQ, maker.Ident(oName), maker.Literal(TypeTags.BOT, null)), returnBool(maker, false), null));
		}
		
		/* if ( o.getClass() != this.getClass() ) return false; */ {
			Name getClass = typeNode.toName("getClass");
			List<JCExpression> exprNil = List.nil();
			JCExpression oGetClass = maker.Apply(exprNil, maker.Select(maker.Ident(oName), getClass), exprNil);
			JCExpression thisGetClass = maker.Apply(exprNil, maker.Select(maker.Ident(thisName), getClass), exprNil);
			statements = statements.append(
					maker.If(maker.Binary(JCTree.NE, oGetClass, thisGetClass), returnBool(maker, false), null));
		}
		
		/* if ( !super.equals(o) ) return false; */
		if ( callSuper ) {
			JCMethodInvocation callToSuper = maker.Apply(List.<JCExpression>nil(),
					maker.Select(maker.Ident(typeNode.toName("super")), typeNode.toName("equals")),
					List.<JCExpression>of(maker.Ident(oName)));
			JCUnary superNotEqual = maker.Unary(JCTree.NOT, callToSuper);
			statements = statements.append(maker.If(superNotEqual, returnBool(maker, false), null));
		}
		
		/* MyType<?> other = (MyType<?>) o; */ {
			final JCExpression selfType1, selfType2;
			List<JCExpression> wildcards1 = List.nil();
			List<JCExpression> wildcards2 = List.nil();
			for ( int i = 0 ; i < type.typarams.length() ; i++ ) {
				wildcards1 = wildcards1.append(maker.Wildcard(maker.TypeBoundKind(BoundKind.UNBOUND), null));
				wildcards2 = wildcards2.append(maker.Wildcard(maker.TypeBoundKind(BoundKind.UNBOUND), null));
			}
			
			if ( type.typarams.isEmpty() ) {
				selfType1 = maker.Ident(type.name);
				selfType2 = maker.Ident(type.name);
			} else {
				selfType1 = maker.TypeApply(maker.Ident(type.name), wildcards1);
				selfType2 = maker.TypeApply(maker.Ident(type.name), wildcards2);
			}
			
			statements = statements.append(
					maker.VarDef(maker.Modifiers(Flags.FINAL), otherName, selfType1, maker.TypeCast(selfType2, maker.Ident(oName))));
		}
		
		for ( Node fieldNode : fields ) {
			JCVariableDecl field = (JCVariableDecl) fieldNode.get();
			JCExpression fType = field.vartype;
			JCExpression thisDotField = maker.Select(maker.Ident(thisName), field.name);
			JCExpression otherDotField = maker.Select(maker.Ident(otherName), field.name);
			if ( fType instanceof JCPrimitiveTypeTree ) {
				switch ( ((JCPrimitiveTypeTree)fType).getPrimitiveTypeKind() ) {
				case FLOAT:
					/* if ( Float.compare(this.fieldName, other.fieldName) != 0 ) return false; */
					statements = statements.append(generateCompareFloatOrDouble(thisDotField, otherDotField, maker, typeNode, false));
					break;
				case DOUBLE:
					/* if ( Double(this.fieldName, other.fieldName) != 0 ) return false; */
					statements = statements.append(generateCompareFloatOrDouble(thisDotField, otherDotField, maker, typeNode, true));
					break;
				default:
					/* if ( this.fieldName != other.fieldName ) return false; */
					statements = statements.append(
							maker.If(maker.Binary(JCTree.NE, thisDotField, otherDotField), returnBool(maker, false), null));
					break;
				}
			} else if ( fType instanceof JCArrayTypeTree ) {
				/* if ( !java.util.Arrays.deepEquals(this.fieldName, other.fieldName) ) return false; //use equals for primitive arrays. */
				boolean multiDim = ((JCArrayTypeTree)fType).elemtype instanceof JCArrayTypeTree;
				boolean primitiveArray = ((JCArrayTypeTree)fType).elemtype instanceof JCPrimitiveTypeTree;
				boolean useDeepEquals = multiDim || !primitiveArray;
				
				JCExpression eqMethod = chainDots(maker, typeNode, "java", "util", "Arrays", useDeepEquals ? "deepEquals" : "equals");
				List<JCExpression> args = List.of(thisDotField, otherDotField);
				statements = statements.append(maker.If(maker.Unary(JCTree.NOT,
						maker.Apply(List.<JCExpression>nil(), eqMethod, args)), returnBool(maker, false), null));
			} else /* objects */ {
				/* if ( this.fieldName == null ? other.fieldName != null : !this.fieldName.equals(other.fieldName) ) return false; */
				JCExpression thisEqualsNull = maker.Binary(JCTree.EQ, thisDotField, maker.Literal(TypeTags.BOT, null));
				JCExpression otherNotEqualsNull = maker.Binary(JCTree.NE, otherDotField, maker.Literal(TypeTags.BOT, null));
				JCExpression thisEqualsThat = maker.Apply(
						List.<JCExpression>nil(), maker.Select(thisDotField, typeNode.toName("equals")), List.of(otherDotField));
				JCExpression fieldsAreNotEqual = maker.Conditional(thisEqualsNull, otherNotEqualsNull, maker.Unary(JCTree.NOT, thisEqualsThat));
				statements = statements.append(maker.If(fieldsAreNotEqual, returnBool(maker, false), null));
			}
		}
		
		/* return true; */ {
			statements = statements.append(returnBool(maker, true));
		}
		
		JCBlock body = maker.Block(0, statements);
		return maker.MethodDef(mods, typeNode.toName("equals"), returnType, List.<JCTypeParameter>nil(), params, List.<JCExpression>nil(), body, null);
	}
	
	private JCStatement generateCompareFloatOrDouble(JCExpression thisDotField, JCExpression otherDotField, TreeMaker maker, Node node, boolean isDouble) {
		/* if ( Float.compare(fieldName, other.fieldName) != 0 ) return false; */
		JCExpression clazz = chainDots(maker, node, "java", "lang", isDouble ? "Double" : "Float");
		List<JCExpression> args = List.of(thisDotField, otherDotField);
		JCBinary compareCallEquals0 = maker.Binary(JCTree.NE, maker.Apply(
				List.<JCExpression>nil(), maker.Select(clazz, node.toName("compare")), args), maker.Literal(0));
		return maker.If(compareCallEquals0, returnBool(maker, false), null);
	}
	
	private JCStatement returnBool(TreeMaker maker, boolean bool) {
		return maker.Return(maker.Literal(TypeTags.BOOLEAN, bool ? 1 : 0));
	}
	
}