/*******************************************************************************
 * Copyright (c) 2007 BEA Systems, Inc. 
 * All rights reserved. This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License v1.0
 * which accompanies this distribution, and is available at
 * http://www.eclipse.org/legal/epl-v10.html
 *
 * Contributors:
 *    wharley@bea.com - initial API and implementation
 *    
 *******************************************************************************/

package org.eclipse.jdt.internal.compiler.apt.model;

import java.lang.reflect.Array;
import java.util.ArrayList;
import java.util.Collections;
import java.util.EnumSet;
import java.util.List;
import java.util.Set;

import javax.lang.model.element.AnnotationMirror;
import javax.lang.model.element.Element;
import javax.lang.model.element.ElementKind;
import javax.lang.model.element.Modifier;
import javax.lang.model.element.PackageElement;
import javax.lang.model.element.TypeParameterElement;
import javax.lang.model.type.DeclaredType;
import javax.lang.model.type.ErrorType;
import javax.lang.model.type.NoType;
import javax.lang.model.type.NullType;
import javax.lang.model.type.TypeKind;
import javax.lang.model.type.TypeMirror;

import org.eclipse.jdt.internal.compiler.apt.dispatch.BaseProcessingEnvImpl;
import org.eclipse.jdt.internal.compiler.classfmt.ClassFileConstants;
import org.eclipse.jdt.internal.compiler.lookup.AnnotationBinding;
import org.eclipse.jdt.internal.compiler.lookup.ArrayBinding;
import org.eclipse.jdt.internal.compiler.lookup.BaseTypeBinding;
import org.eclipse.jdt.internal.compiler.lookup.Binding;
import org.eclipse.jdt.internal.compiler.lookup.MethodBinding;
import org.eclipse.jdt.internal.compiler.lookup.PackageBinding;
import org.eclipse.jdt.internal.compiler.lookup.ParameterizedTypeBinding;
import org.eclipse.jdt.internal.compiler.lookup.ReferenceBinding;
import org.eclipse.jdt.internal.compiler.lookup.TypeConstants;
import org.eclipse.jdt.internal.compiler.lookup.TypeIds;
import org.eclipse.jdt.internal.compiler.lookup.TypeVariableBinding;
import org.eclipse.jdt.internal.compiler.lookup.VariableBinding;
import org.eclipse.jdt.internal.compiler.lookup.WildcardBinding;

/**
 * Creates javax.lang.model wrappers around JDT internal compiler bindings.
 */
public class Factory {
	
	// using auto-boxing to take advantage of caching, if any.
	// the dummy value picked here falls within the caching range.
	public static final Byte DUMMY_BYTE = 0; 
	public static final Character DUMMY_CHAR = '0'; 
	public static final Double DUMMY_DOUBLE = 0d;
	public static final Float DUMMY_FLOAT = 0f;
	public static final Integer DUMMY_INTEGER = 0;  
	public static final Long DUMMY_LONG = 0l;
	public static final Short DUMMY_SHORT = 0;

	private final BaseProcessingEnvImpl _env;
	
	/**
	 * This object should only be constructed by the BaseProcessingEnvImpl.
	 */
	public Factory(BaseProcessingEnvImpl env) {
		_env = env;
	}

	/**
	 * Convert an array of compiler annotation bindings into a list of AnnotationMirror
	 * @return a non-null, possibly empty, unmodifiable list.
	 */
	public List<? extends AnnotationMirror> getAnnotationMirrors(AnnotationBinding[] annotations) {
		if (null == annotations || 0 == annotations.length) {
			return Collections.emptyList();
		}
		List<AnnotationMirror> list = new ArrayList<AnnotationMirror>(annotations.length);
		for (AnnotationBinding annotation : annotations) {
			if (annotation == null) continue;
			list.add(newAnnotationMirror(annotation));
		}
		return Collections.unmodifiableList(list);
	}
	
	private static void appendModifier(Set<Modifier> result, int modifiers, int modifierConstant, Modifier modifier) {
		if ((modifiers & modifierConstant) != 0) {
			result.add(modifier);
		}
	}
	
	private static void decodeModifiers(Set<Modifier> result, int modifiers, int[] checkBits) {
		if (checkBits == null) return;
		for (int i = 0, max = checkBits.length; i < max; i++) {
			switch(checkBits[i]) {
				case ClassFileConstants.AccPublic :
					appendModifier(result, modifiers, checkBits[i], Modifier.PUBLIC);
					break;
				case ClassFileConstants.AccProtected:
					appendModifier(result, modifiers, checkBits[i], Modifier.PROTECTED);
					break;
				case ClassFileConstants.AccPrivate :
					appendModifier(result, modifiers, checkBits[i], Modifier.PRIVATE);
					break;
				case ClassFileConstants.AccAbstract :
					appendModifier(result, modifiers, checkBits[i], Modifier.ABSTRACT);
					break;
				case ClassFileConstants.AccStatic :
					appendModifier(result, modifiers, checkBits[i], Modifier.STATIC);
					break;
				case ClassFileConstants.AccFinal :
					appendModifier(result, modifiers, checkBits[i], Modifier.FINAL);
					break;
				case ClassFileConstants.AccSynchronized :
					appendModifier(result, modifiers, checkBits[i], Modifier.SYNCHRONIZED);
					break;
				case ClassFileConstants.AccNative :
					appendModifier(result, modifiers, checkBits[i], Modifier.NATIVE);
					break;
				case ClassFileConstants.AccStrictfp :
					appendModifier(result, modifiers, checkBits[i], Modifier.STRICTFP);
					break;
				case ClassFileConstants.AccTransient :
					appendModifier(result, modifiers, checkBits[i], Modifier.TRANSIENT);
					break;
				case ClassFileConstants.AccVolatile :
					appendModifier(result, modifiers, checkBits[i], Modifier.VOLATILE);
					break;
			}
		}
	}
	
    public static Object getMatchingDummyValue(final Class<?> expectedType){
    	if( expectedType.isPrimitive() ){
    		if(expectedType == boolean.class)
    			return Boolean.FALSE;
    		else if( expectedType == byte.class )
    			return DUMMY_BYTE;
    		else if( expectedType == char.class )
    			return DUMMY_CHAR;
    		else if( expectedType == double.class)
    			return DUMMY_DOUBLE;
    		else if( expectedType == float.class )
    			return DUMMY_FLOAT;
    		else if( expectedType == int.class )
    			return DUMMY_INTEGER;
    		else if( expectedType == long.class )
    			return DUMMY_LONG;
    		else if(expectedType == short.class)
    			return DUMMY_SHORT;
    		else // expectedType == void.class. can this happen?
    			return DUMMY_INTEGER; // anything would work
    	}
    	else
    		return null;
    }
    
	public static Set<Modifier> getModifiers(int modifiers, ElementKind kind) {
		return getModifiers(modifiers, kind, false);
	}
	/**
	 * Convert from the JDT's ClassFileConstants flags to the Modifier enum.
	 */
	public static Set<Modifier> getModifiers(int modifiers, ElementKind kind, boolean isFromBinary)
	{
		EnumSet<Modifier> result = EnumSet.noneOf(Modifier.class);
		switch(kind) {
			case CONSTRUCTOR :
			case METHOD :
				// modifiers for methods
				decodeModifiers(result, modifiers, new int[] {
					ClassFileConstants.AccPublic,
					ClassFileConstants.AccProtected,
					ClassFileConstants.AccPrivate,
					ClassFileConstants.AccAbstract,
					ClassFileConstants.AccStatic,
					ClassFileConstants.AccFinal,
					ClassFileConstants.AccSynchronized,
					ClassFileConstants.AccNative,
					ClassFileConstants.AccStrictfp
				});
				break;
			case FIELD :
			case ENUM_CONSTANT :
				// for fields
				decodeModifiers(result, modifiers, new int[] {
					ClassFileConstants.AccPublic,
					ClassFileConstants.AccProtected,
					ClassFileConstants.AccPrivate,
					ClassFileConstants.AccStatic,
					ClassFileConstants.AccFinal,
					ClassFileConstants.AccTransient,
					ClassFileConstants.AccVolatile
				});
				break;
			case ENUM :
				if (isFromBinary) {
					decodeModifiers(result, modifiers, new int[] {
						ClassFileConstants.AccPublic,
						ClassFileConstants.AccProtected,
						ClassFileConstants.AccFinal,
						ClassFileConstants.AccPrivate,
						ClassFileConstants.AccAbstract,
						ClassFileConstants.AccStatic,
						ClassFileConstants.AccStrictfp
					});
				} else {
					// enum from source cannot be explicitly abstract
					decodeModifiers(result, modifiers, new int[] {
						ClassFileConstants.AccPublic,
						ClassFileConstants.AccProtected,
						ClassFileConstants.AccFinal,
						ClassFileConstants.AccPrivate,
						ClassFileConstants.AccStatic,
						ClassFileConstants.AccStrictfp
					});
				}
				break;
			case ANNOTATION_TYPE :
			case INTERFACE :
			case CLASS :
				// for type
				decodeModifiers(result, modifiers, new int[] {
					ClassFileConstants.AccPublic,
					ClassFileConstants.AccProtected,
					ClassFileConstants.AccAbstract,
					ClassFileConstants.AccFinal,
					ClassFileConstants.AccPrivate,
					ClassFileConstants.AccStatic,
					ClassFileConstants.AccStrictfp
				});
		}
		return Collections.unmodifiableSet(result);
	}

	public AnnotationMirror newAnnotationMirror(AnnotationBinding binding)
	{
		return new AnnotationMirrorImpl(_env, binding);
	}
	
	public Element newElement(Binding binding) {
		if (binding == null) {
			return new ErrorTypeElement(this._env);
		}
		switch (binding.kind()) {
		case Binding.FIELD:
		case Binding.LOCAL:
		case Binding.VARIABLE:
			return new VariableElementImpl(_env, (VariableBinding) binding);
		case Binding.TYPE:
		case Binding.GENERIC_TYPE:
			ReferenceBinding referenceBinding = (ReferenceBinding)binding;
			if (referenceBinding.sourceName == TypeConstants.PACKAGE_INFO_NAME) {
				return new PackageElementImpl(_env, referenceBinding.fPackage);
			}
			return new TypeElementImpl(_env, referenceBinding);
		case Binding.METHOD:
			return new ExecutableElementImpl(_env, (MethodBinding)binding);
		case Binding.RAW_TYPE:
		case Binding.PARAMETERIZED_TYPE:
			return new TypeElementImpl(_env, ((ParameterizedTypeBinding)binding).genericType());
		case Binding.PACKAGE:
			return new PackageElementImpl(_env, (PackageBinding)binding);
		case Binding.TYPE_PARAMETER:
			return new TypeParameterElementImpl(_env, (TypeVariableBinding)binding);
		// TODO: fill in the rest of these
		case Binding.IMPORT:
		case Binding.ARRAY_TYPE:
		case Binding.BASE_TYPE:
		case Binding.WILDCARD_TYPE:
			throw new UnsupportedOperationException("NYI: binding type " + binding.kind()); //$NON-NLS-1$
		}
		return null;
	}
	
	public DeclaredType newDeclaredType(ReferenceBinding binding) {
		if (binding.kind() == Binding.WILDCARD_TYPE) {
			// JDT wildcard binding is a subclass of reference binding, but in JSR269 they're siblings
			throw new IllegalArgumentException("A wildcard binding can't be turned into a DeclaredType"); //$NON-NLS-1$
		}
		return new DeclaredTypeImpl(_env, binding);
	}

	/**
	 * Convenience method - equivalent to {@code (PackageElement)Factory.newElement(binding)}
	 */
	public PackageElement newPackageElement(PackageBinding binding)
	{
		return new PackageElementImpl(_env, binding);
	}
	
	public NullType getNullType() {
		return NoTypeImpl.NULL_TYPE;
	}

	public NoType getNoType(TypeKind kind)
	{
		switch (kind) {
		case NONE:
			return NoTypeImpl.NO_TYPE_NONE;
		case VOID:
			return NoTypeImpl.NO_TYPE_VOID;
		case PACKAGE:
			return NoTypeImpl.NO_TYPE_PACKAGE;
		default:
			throw new IllegalArgumentException();
		}
	}

	/**
	 * Get a type mirror object representing the specified primitive type kind.
	 * @throw IllegalArgumentException if a non-primitive TypeKind is requested
	 */
	public PrimitiveTypeImpl getPrimitiveType(TypeKind kind)
	{
		switch (kind) {
		case BOOLEAN:
			return PrimitiveTypeImpl.BOOLEAN;
		case BYTE:
			return PrimitiveTypeImpl.BYTE;
		case CHAR:
			return PrimitiveTypeImpl.CHAR;
		case DOUBLE:
			return PrimitiveTypeImpl.DOUBLE;
		case FLOAT:
			return PrimitiveTypeImpl.FLOAT;
		case INT:
			return PrimitiveTypeImpl.INT;
		case LONG:
			return PrimitiveTypeImpl.LONG;
		case SHORT:
			return PrimitiveTypeImpl.SHORT;
		default:
			throw new IllegalStateException();
		}
	}
	
	/**
	 * Convenience method to get the PrimitiveTypeImpl corresponding to a particular BaseTypeBinding.
	 */
	public PrimitiveTypeImpl getPrimitiveType(BaseTypeBinding binding) {
		return getPrimitiveType(PrimitiveTypeImpl.getKind(binding));
	}

	/**
	 * Given a binding of uncertain type, try to create the right sort of TypeMirror for it.
	 */
	public TypeMirror newTypeMirror(Binding binding) {
		switch (binding.kind()) {
		case Binding.FIELD:
		case Binding.LOCAL:
		case Binding.VARIABLE:
			// For variables, return the type of the variable
			return newTypeMirror(((VariableBinding)binding).type);
			
		case Binding.PACKAGE:
			return getNoType(TypeKind.PACKAGE);
			
		case Binding.IMPORT:
			throw new UnsupportedOperationException("NYI: import type " + binding.kind()); //$NON-NLS-1$

		case Binding.METHOD:
			return new ExecutableTypeImpl(_env, (MethodBinding) binding);
			
		case Binding.TYPE:
		case Binding.RAW_TYPE:
		case Binding.GENERIC_TYPE:
		case Binding.PARAMETERIZED_TYPE:
			return new DeclaredTypeImpl(_env, (ReferenceBinding)binding);
			
		case Binding.ARRAY_TYPE:
			return new ArrayTypeImpl(_env, (ArrayBinding)binding);
			
		case Binding.BASE_TYPE:
			BaseTypeBinding btb = (BaseTypeBinding)binding;
			switch (btb.id) {
			case TypeIds.T_void:
				return getNoType(TypeKind.VOID);
			case TypeIds.T_null:
				return getNullType();
			default:
				return getPrimitiveType(PrimitiveTypeImpl.getKind((BaseTypeBinding)binding));
			}

		case Binding.WILDCARD_TYPE:
			return new WildcardTypeImpl(_env, (WildcardBinding) binding);

		case Binding.TYPE_PARAMETER:
			return new TypeVariableImpl(_env, (TypeVariableBinding) binding);
		}
		return null;
	}

	/**
	 * @param declaringElement the class, method, etc. that is parameterized by this parameter.
	 */
	public TypeParameterElement newTypeParameterElement(TypeVariableBinding variable, Element declaringElement)
	{
		return new TypeParameterElementImpl(_env, variable, declaringElement);
	}

    public ErrorType getErrorType() {
		return new ErrorTypeImpl(this._env);
	}

	/**
     * This method is derived from code in org.eclipse.jdt.apt.core.
     * 
     * This method is designed to be invoked by the invocation handler and anywhere that requires
     * a AnnotationValue (AnnotationMirror member values and default values from annotation member).
     * 
     * Regardless of the path, there are common primitive type conversion that needs to take place. 
     * The type conversions respect the type widening and narrowing rules from JLS 5.1.2 and 5.1.2.
     * 
     * The only question remains is what is the type of the return value when the type conversion fails?
     * When <code>avoidReflectException</code> is set to <code>true</code> 
     * Return <code>false</code> if the expected type is <code>boolean</code>
     * Return numeric 0 for all numeric primitive types and '0' for <code>char</code>
     * 
     * Otherwise:
     * Return the value unchanged. 
     *  
     * In the invocation handler case: 
     * The value returned by {@link java.lang.reflect.InvocationHandler#invoke} 
     * will be converted into the expected type by the {@link java.lang.reflect.Proxy}. 
     * If the value and the expected type does not agree, and the value is not null, 
     * a ClassCastException will be thrown. A NullPointerException will result if the 
     * expected type is a primitive type and the value is null.
     * This behavior causes annotation processors a lot of pain and the decision is
     * to not throw such unchecked exception. In the case where a ClassCastException or 
     * NullPointerException will be thrown return some dummy value. Otherwise, return 
     * the original value.
     * Chosen dummy values:  
     * Return <code>false</code> if the expected type is <code>boolean</code>
     * Return numeric 0 for all numeric primitive types and '0' for <code>char</code>
     * 
     * This behavior is triggered by setting <code>avoidReflectException</code> to <code>true</code>
     * 
     * Note: the new behavior deviates from what's documented in
     * {@link java.lang.reflect.InvocationHandler#invoke} and also deviates from 
     * Sun's implementation.
     *
     * @param value the current value from the annotation instance.
     * @param expectedType the expected type of the value.
     * 
     */
    public static Object performNecessaryPrimitiveTypeConversion(
    		final Class<?> expectedType,
    		final Object value,
    		final boolean avoidReflectException)
    {
    	assert expectedType.isPrimitive() : "expectedType is not a primitive type: " + expectedType.getName(); //$NON-NLS-1$
    	if( value == null)
    		return avoidReflectException ? getMatchingDummyValue(expectedType) : null;
    	// apply widening conversion based on JLS 5.1.2 and 5.1.3
    	final String typeName = expectedType.getName();
		final char expectedTypeChar = typeName.charAt(0);
		final int nameLen = typeName.length();
		// widening byte -> short, int, long, float or double
		// narrowing byte -> char
		if( value instanceof Byte )
		{
			final byte b = ((Byte)value).byteValue();
			switch( expectedTypeChar )
			{
			case 'b':
				if(nameLen == 4) // byte
					return value; // exact match.
				else 
					return avoidReflectException ? Boolean.FALSE : value;
			case 'c':
				return new Character((char)b); // narrowing.
			case 'd':
				return new Double(b); // widening.
			case 'f':
				return new Float(b); // widening.
			case 'i':
				return new Integer(b); // widening.
			case 'l':
				return new Long(b); // widening.
			case 's':
				return new Short(b); // widening.
			default:  				
				throw new IllegalStateException("unknown type " + expectedTypeChar); //$NON-NLS-1$
			}
		}
		// widening short -> int, long, float, or double 
		// narrowing short -> byte or char
		else if( value instanceof Short )
		{
			final short s = ((Short)value).shortValue();
			switch( expectedTypeChar )
			{
			case 'b':
				if(nameLen == 4) // byte
					return new Byte((byte)s); // narrowing.
				else
					return avoidReflectException ? Boolean.FALSE : value; // completely wrong.
			case 'c':
				return new Character((char)s); // narrowing.
			case 'd':
				return new Double(s); // widening.
			case 'f':
				return new Float(s); // widening.
			case 'i':
				return new Integer(s); // widening.
			case 'l':
				return new Long(s); // widening.
			case 's':
				return value; // exact match
			default:  				
				throw new IllegalStateException("unknown type " + expectedTypeChar); //$NON-NLS-1$
			}
		}
		// widening char -> int, long, float, or double 
		// narrowing char -> byte or short
		else if( value instanceof Character )
		{
			final char c = ((Character)value).charValue();
			switch( expectedTypeChar )
			{
			case 'b':
				if(nameLen == 4) // byte
					return new Byte((byte)c); // narrowing.
				else
					return avoidReflectException ? Boolean.FALSE : value; // completely wrong.
			case 'c':
				return value; // exact match
			case 'd':
				return new Double(c); // widening.
			case 'f':
				return new Float(c); // widening.
			case 'i':
				return new Integer(c); // widening.
			case 'l':
				return new Long(c); // widening.
			case 's':
				return new Short((short)c); // narrowing.
			default:  				
				throw new IllegalStateException("unknown type " + expectedTypeChar); //$NON-NLS-1$
			}
		}
		
		// widening int -> long, float, or double 
		// narrowing int -> byte, short, or char 
		else if( value instanceof Integer )
		{
			final int i = ((Integer)value).intValue();
			switch( expectedTypeChar )
			{    
			case 'b':
				if(nameLen == 4) // byte
					return new Byte((byte)i); // narrowing.
				else
					return avoidReflectException ? Boolean.FALSE : value; // completely wrong.
			case 'c':
				return new Character((char)i); // narrowing
			case 'd':
				return new Double(i); // widening.
			case 'f':
				return new Float(i); // widening.
			case 'i':
				return value; // exact match
			case 'l':
				return new Long(i); // widening.
			case 's':
				return new Short((short)i); // narrowing.
			default:  				
				throw new IllegalStateException("unknown type " + expectedTypeChar); //$NON-NLS-1$
			}
		}
		// widening long -> float or double
		else if( value instanceof Long )
		{
			final long l = ((Long)value).longValue();
			switch( expectedTypeChar )
			{
			case 'b': // both byte and boolean
			case 'c': 
			case 'i':
			case 's':
				// completely wrong.
				return avoidReflectException ? getMatchingDummyValue(expectedType) : value;
			case 'd':
				return new Double(l); // widening.
			case 'f':
				return new Float(l); // widening.			
			case 'l': 
				return value; // exact match.
		
			default:  				
				throw new IllegalStateException("unknown type " + expectedTypeChar); //$NON-NLS-1$
			}
		}
		
		// widening float -> double    		 
		else if( value instanceof Float )
		{
			final float f = ((Float)value).floatValue();
			switch( expectedTypeChar )
			{    		
			case 'b': // both byte and boolean
			case 'c': 
			case 'i':
			case 's':
			case 'l':
				// completely wrong.
				return avoidReflectException ? getMatchingDummyValue(expectedType) : value;
			case 'd':
				return new Double(f); // widening.
			case 'f':
				return value; // exact match.
			default:  				
				throw new IllegalStateException("unknown type " + expectedTypeChar); //$NON-NLS-1$
			}
		}
		else if( value instanceof Double ){
			if(expectedTypeChar == 'd' )
				return value; // exact match
			else{
				return avoidReflectException ? getMatchingDummyValue(expectedType) : value; // completely wrong.
			}
		}
		else if( value instanceof Boolean ){
			if( expectedTypeChar == 'b' && nameLen == 7) // "boolean".length() == 7
				return value;
			else
				return avoidReflectException ? getMatchingDummyValue(expectedType) : value; // completely wrong.
		}
		else // can't convert
			return avoidReflectException ? getMatchingDummyValue(expectedType) : value;
    }

    /**
     * Set an element of an array to the appropriate dummy value type
     * @param array
     * @param i
     * @param expectedLeafType
     */
	public static void setArrayMatchingDummyValue(Object array, int i, Class<?> expectedLeafType)
	{
		if (boolean.class.equals(expectedLeafType)) {
			Array.setBoolean(array, i, false);
		}
		else if (byte.class.equals(expectedLeafType)) {
			Array.setByte(array, i, DUMMY_BYTE);
		}
		else if (char.class.equals(expectedLeafType)) {
			Array.setChar(array, i, DUMMY_CHAR);
		}
		else if (double.class.equals(expectedLeafType)) {
			Array.setDouble(array, i, DUMMY_DOUBLE);
		}
		else if (float.class.equals(expectedLeafType)) {
			Array.setFloat(array, i, DUMMY_FLOAT);
		}
		else if (int.class.equals(expectedLeafType)) {
			Array.setInt(array, i, DUMMY_INTEGER);
		}
		else if (long.class.equals(expectedLeafType)) {
			Array.setLong(array, i, DUMMY_LONG);
		}
		else if (short.class.equals(expectedLeafType)) {
			Array.setShort(array, i, DUMMY_SHORT);
		}
		else {
			Array.set(array, i, null);
		}
	}
    
}