package org.simantics.scl.compiler.constants.generic;

import org.cojen.classfile.TypeDesc;
import org.simantics.scl.compiler.common.exceptions.InternalCompilerError;
import org.simantics.scl.compiler.internal.codegen.references.Val;
import org.simantics.scl.compiler.internal.codegen.utils.ClassBuilder;
import org.simantics.scl.compiler.internal.codegen.utils.MethodBuilder;
import org.simantics.scl.compiler.top.SCLCompilerConfiguration;

/**
 * This interface represents a method for accessing the members of Java classes.
 * This interface is implemented by <ul>
 * 	<li>{@link StaticMethodRef}</li> 
 * 	<li>{@link ObjectMethodRef}</li> 
 * 	<li>{@link ConstructorRef}</li> 
 * 	<li>{@link StaticFieldRef}</li> 
 * 	<li>{@link FieldRef}</li> 
 * 	<li>{@link SetStaticFieldRef}</li> 
 * 	<li>{@link SetFieldRef}</li>
 * </ul>
 * 
 * It provides the method {@link #invoke(MethodBuilder, StackItem[], Val[])} for creating the Java byte code
 * for calling the method or manipulating the field value.
 * 
 * Parameter and return value type can be accessed using {@link #getParameterTypes()} and {@link #getReturnType()}.
 */
public interface MethodRef {

	/**
	 * Build code for invoking the referenced function using a given MethodBuilder.
	 * @param mb  a method builder
	 * @param stackItems  a set of StackItem objects into which the call parameters are pushed
	 * @param parameters  the method call parameters 
	 */
    void invoke(MethodBuilder mb, StackItem[] stackItems, Val[] parameters);

    /**
     * Get the parameter types for a method. For (non-static) object methods and field accessors, the first
     * parameter represents the object itself, as passed in the {@code this} variable.
     */
    public TypeDesc[] getParameterTypes();
    
    /**
     * Get the return type of the method.
     */
    public TypeDesc getReturnType();
    
    /**
     * This class represents a static Java class method.
     */
    public static class StaticMethodRef implements MethodRef {
        
        String className;
        String methodName;
        TypeDesc ret;
        TypeDesc[] params;
        
        public StaticMethodRef(String className, String methodName,
                TypeDesc ret, TypeDesc[] params) {
            this.className = className;
            this.methodName = methodName;
            this.ret = ret;
            this.params = params;
        }
        
        @Override
        public void invoke(MethodBuilder mb, StackItem[] stackItems, Val[] parameters) {
            if(SCLCompilerConfiguration.DEBUG)
                if(stackItems.length != params.length)
                    throw new InternalCompilerError();
            for(StackItem stackItem : stackItems)
                stackItem.push(mb, parameters);
            mb.invokeStatic(className, methodName, ret, params);
        }
        
        @Override
        public TypeDesc[] getParameterTypes() {
            return params;
        }
        
        @Override
        public TypeDesc getReturnType() {
            return ret;
        }
        
        @Override
        public String toString() {
            StringBuilder b = new StringBuilder();
            b.append("public static ");
            b.append(ret.getFullName());
            b.append(" ");
            b.append(methodName);
            b.append("(");
            boolean first = true;
            for(TypeDesc param : params) {
                if(first)
                    first = false;
                else
                    b.append(", ");
                b.append(param.getFullName());
            }
            b.append(")");
            return b.toString();
        }
    
        @Override
        public String getName() {
            return className + "." + methodName;
        }
    }
    
    /**
     * This class represents a (non-static) java object method.
     */
    public static class ObjectMethodRef implements MethodRef {        
        
        boolean isInterface;
        String className;
        String methodName;
        TypeDesc ret;
        TypeDesc[] params;
        TypeDesc[] realParams;
        
        public ObjectMethodRef(boolean isInterface, String className, String methodName,
                TypeDesc ret, TypeDesc[] params) {
            this.isInterface = isInterface;
            ClassBuilder.checkClassName(className);
            this.className = className;
            this.methodName = methodName;
            this.ret = ret;
            this.params = params;
            this.realParams = new TypeDesc[params.length+1];
            realParams[0] = TypeDesc.forClass(className);            
            for(int i=0;i<params.length;++i)
                realParams[i+1] = params[i];
        }
        
        @Override
        public void invoke(MethodBuilder mb, StackItem[] stackItems, Val[] parameters) {
            if(SCLCompilerConfiguration.DEBUG)
                if(stackItems.length != realParams.length)
                    throw new InternalCompilerError();            
            for(StackItem stackItem : stackItems)
                stackItem.push(mb, parameters);
            if(isInterface)
                mb.invokeInterface(className, methodName, ret, params);
            else
                mb.invokeVirtual(className, methodName, ret, params);                            
        }
        
        @Override
        public TypeDesc[] getParameterTypes() {
            return realParams;
        }
        
        @Override
        public TypeDesc getReturnType() {
            return ret;
        }
    
        @Override
        public String toString() {
            StringBuilder b = new StringBuilder();
            b.append("public ");
            b.append(ret.getFullName());
            b.append(" ");
            b.append(methodName);
            b.append("(");
            boolean first = true;
            for(TypeDesc param : params) {
                if(first)
                    first = false;
                else
                    b.append(", ");
                b.append(param.getFullName());
            }
            b.append(")");
            return b.toString();
        }
        
        @Override
        public String getName() {
            return className + "." + methodName;
        }
    }

    /**
     * This class represents a Java constructor. 
     */
    public static class ConstructorRef implements MethodRef {
        
        String className;
        TypeDesc[] params;
        TypeDesc ret;
        
        public ConstructorRef(String className, TypeDesc[] params) {
            this.className = className;
            this.params = params;
            this.ret = TypeDesc.forClass(className);
        }
        
        @Override
        public void invoke(MethodBuilder mb, StackItem[] stackItems, Val[] parameters) {
            if(SCLCompilerConfiguration.DEBUG)
                if(stackItems.length != params.length)
                    throw new InternalCompilerError();
            mb.newObject(ret);
            mb.dup();
            for(StackItem stackItem : stackItems)
                stackItem.push(mb, parameters);
            mb.invokeConstructor(className, params);
        }
        
        @Override
        public TypeDesc[] getParameterTypes() {
            return params;
        }
        
        @Override
        public TypeDesc getReturnType() {
            return ret;
        }
    
        @Override
        public String toString() {
            StringBuilder b = new StringBuilder();
            b.append("public ");
            b.append(className);
            b.append("(");
            boolean first = true;
            for(TypeDesc param : params) {
                if(first)
                    first = false;
                else
                    b.append(", ");
                b.append(param.getFullName());
            }
            b.append(")");
            return b.toString();
        }
        
        @Override
        public String getName() {
            return className + ".<init>";
        }
    }
    
    /**
     * This class represents a read access to a static Java field, represented as a zero-arity {@link MethodRef}. 
     */
    public static class StaticFieldRef implements MethodRef {
        
        String className;
        String fieldName;
        TypeDesc ret;
        
        public StaticFieldRef(String className, String fieldName, TypeDesc ret) {
            this.className = className;
            this.fieldName = fieldName;
            this.ret = ret;        
        }
        
        @Override
        public void invoke(MethodBuilder mb, StackItem[] stackItems, Val[] parameters) {
            if(SCLCompilerConfiguration.DEBUG)
                if(stackItems.length != 0)
                    throw new InternalCompilerError();
            mb.loadStaticField(className, fieldName, ret);
        }
        
        @Override
        public TypeDesc[] getParameterTypes() {
            return ClassRef.NO_PARAMS;
        }
        
        @Override
        public TypeDesc getReturnType() {
            return ret;
        }
    
        @Override
        public String toString() {
            StringBuilder b = new StringBuilder();
            b.append("public static ");
            b.append(ret.getFullName());
            b.append(" ");
            b.append(fieldName);
            return b.toString();
        }
        
        @Override
        public String getName() {
            return className + "." + fieldName;
        }
    }
    
    /**
     * This class represents read access to a Java (non-static) object field as a one-parameter {@link MethodRef}.
     */
    public static class FieldRef implements MethodRef {
        
        String className;
        String fieldName;
        TypeDesc[] params;
        TypeDesc ret;
        
        public FieldRef(String className, String fieldName, TypeDesc ret) {
            this.className = className;
            this.fieldName = fieldName;
            this.ret = ret;
            this.params = new TypeDesc[] {TypeDesc.forClass(className)};            
        }
        
        @Override
        public void invoke(MethodBuilder mb, StackItem[] stackItems, Val[] parameters) {
            if(SCLCompilerConfiguration.DEBUG)
                if(stackItems.length != 1)
                    throw new InternalCompilerError();
            stackItems[0].push(mb, parameters);
            mb.loadField(className, fieldName, ret);
        }
        
        @Override
        public TypeDesc[] getParameterTypes() {
            return params;
        }
        
        @Override
        public TypeDesc getReturnType() {
            return ret;
        }
        
        @Override
        public String toString() {
            StringBuilder b = new StringBuilder();
            b.append("public ");
            b.append(ret.getFullName());
            b.append(" ");
            b.append(fieldName);
            return b.toString();
        }
    
        @Override
        public String getName() {
            return className + "." + fieldName;
        }
    }

    /**
     * This class represents a method for setting a static Java field value as a one-parameter {@link MethodRef}
     */
    public static class SetStaticFieldRef implements MethodRef {
        
        String className;
        String fieldName;
        TypeDesc ret;
        TypeDesc[] params;
        
        public SetStaticFieldRef(String className, String fieldName, TypeDesc ret) {
            this.className = className;
            this.fieldName = fieldName;
            this.ret = ret;
            this.params = new TypeDesc[] {ret};
        }
        
        @Override
        public void invoke(MethodBuilder mb, StackItem[] stackItems, Val[] parameters) {
            if(SCLCompilerConfiguration.DEBUG)
                if(stackItems.length != 1)
                    throw new InternalCompilerError();
            stackItems[0].push(mb, parameters);
            mb.storeStaticField(className, fieldName, ret);
        }
        
        @Override
        public TypeDesc[] getParameterTypes() {
            return params;
        }
        
        @Override
        public TypeDesc getReturnType() {
            return TypeDesc.VOID;
        }
    
        @Override
        public String toString() {
            StringBuilder b = new StringBuilder();
            b.append("public static ");
            b.append(ret.getFullName());
            b.append(" ");
            b.append(fieldName);
            return b.toString();
        }
        
        @Override
        public String getName() {
            return className + ".<set>" + fieldName;
        }
    }
    
    /**
     * This class represents a method for setting the value of a Java (non-static) object field as a two-parameter
     * {@link MethodRef}. The first parameter is the object reference and the second parameter is the field value. 
     */
    public static class SetFieldRef implements MethodRef {
        
        String className;
        String fieldName;
        TypeDesc ret;
        TypeDesc[] params;
        
        public SetFieldRef(String className, String fieldName, TypeDesc ret) {
            this.className = className;
            this.fieldName = fieldName;
            this.ret = ret;
            this.params = new TypeDesc[] {TypeDesc.forClass(className), ret};
        }
        
        @Override
        public void invoke(MethodBuilder mb, StackItem[] stackItems, Val[] parameters) {
            if(SCLCompilerConfiguration.DEBUG)
                if(stackItems.length != 2)
                    throw new InternalCompilerError();
            stackItems[0].push(mb, parameters);
            stackItems[1].push(mb, parameters);
            mb.storeField(className, fieldName, ret);
        }
        
        @Override
        public TypeDesc[] getParameterTypes() {
            return params;
        }
        
        @Override
        public TypeDesc getReturnType() {
            return TypeDesc.VOID;
        }
    
        @Override
        public String toString() {
            StringBuilder b = new StringBuilder();
            b.append("public ");
            b.append(ret.getFullName());
            b.append(" ");
            b.append(fieldName);
            return b.toString();
        }
        
        @Override
        public String getName() {
            return className + ".<set>" + fieldName;
        }
    }

    public abstract String getName();
}