package org.simantics.scl.compiler.internal.codegen.utils;

import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;

import org.simantics.scl.runtime.function.FunctionImpl1;
import org.simantics.scl.runtime.function.FunctionImpl2;
import org.simantics.scl.runtime.function.FunctionImpl3;
import org.simantics.scl.runtime.function.FunctionImpl4;
import org.simantics.scl.runtime.function.FunctionImplN;
import org.simantics.scl.runtime.tuple.Tuple0;

public class ValueFromMethod {

    private static final class Arity1Func extends FunctionImpl1<Object, Object> {
        private final Method method;
        private final boolean returnsVoid;

        private Arity1Func(Method method, boolean returnsVoid) {
            this.method = method;
            this.returnsVoid = returnsVoid;
        }

        @Override
        public Object apply(Object p0) {
            try {
                Object ret = method.invoke(null, p0);
                return returnsVoid ? Tuple0.INSTANCE : ret;
            } catch (ReflectiveOperationException e) {
                if (e instanceof InvocationTargetException)
                    throw new RuntimeException(e.getCause());
                throw new RuntimeException(e);
            }
        }

        @Override
        public int hashCode() {
            return method == null ? 0 : method.hashCode();
        }

        @Override
        public boolean equals(Object obj) {
            if (this == obj)
                return true;
            if (obj == null)
                return false;
            if (getClass() != obj.getClass())
                return false;
            Arity1Func other = (Arity1Func) obj;
            return method.equals(other.method);
        }
    }

    private static final class Arity2Func extends FunctionImpl2<Object, Object, Object> {
        private final Method method;
        private final boolean returnsVoid;

        private Arity2Func(Method method, boolean returnsVoid) {
            this.method = method;
            this.returnsVoid = returnsVoid;
        }

        @Override
        public Object apply(Object p0, Object p1) {
            try {
                Object ret = method.invoke(null, p0, p1);
                return returnsVoid ? Tuple0.INSTANCE : ret;
            } catch (ReflectiveOperationException e) {
                throw new RuntimeException(e);
            }
        }
        
        @Override
        public int hashCode() {
            return method == null ? 0 : method.hashCode();
        }

        @Override
        public boolean equals(Object obj) {
            if (this == obj)
                return true;
            if (obj == null)
                return false;
            if (getClass() != obj.getClass())
                return false;
            Arity2Func other = (Arity2Func) obj;
            return method.equals(other.method);
        }
    }

    private static final class Arity3Func extends FunctionImpl3<Object, Object, Object, Object> {
        private final Method method;
        private final boolean returnsVoid;

        private Arity3Func(Method method, boolean returnsVoid) {
            this.method = method;
            this.returnsVoid = returnsVoid;
        }

        @Override
        public Object apply(Object p0, Object p1, Object p2) {
            try {
                Object ret = method.invoke(null, p0, p1, p2);
                return returnsVoid ? Tuple0.INSTANCE : ret;
            } catch (ReflectiveOperationException e) {
                throw new RuntimeException(e);
            }
        }
        
        @Override
        public int hashCode() {
            return method == null ? 0 : method.hashCode();
        }

        @Override
        public boolean equals(Object obj) {
            if (this == obj)
                return true;
            if (obj == null)
                return false;
            if (getClass() != obj.getClass())
                return false;
            Arity3Func other = (Arity3Func) obj;
            return method.equals(other.method);
        }
    }

    private static final class Arity4Func extends FunctionImpl4<Object, Object, Object, Object, Object> {
        private final Method method;
        private final boolean returnsVoid;

        private Arity4Func(Method method, boolean returnsVoid) {
            this.method = method;
            this.returnsVoid = returnsVoid;
        }

        @Override
        public Object apply(Object p0, Object p1, Object p2, Object p3) {
            try {
                Object ret = method.invoke(null, p0, p1, p2, p3);
                return returnsVoid ? Tuple0.INSTANCE : ret;
            } catch (ReflectiveOperationException e) {
                throw new RuntimeException(e);
            }
        }
        
        @Override
        public int hashCode() {
            return method == null ? 0 : method.hashCode();
        }

        @Override
        public boolean equals(Object obj) {
            if (this == obj)
                return true;
            if (obj == null)
                return false;
            if (getClass() != obj.getClass())
                return false;
            Arity4Func other = (Arity4Func) obj;
            return method.equals(other.method);
        }
    }

    private static final class ArityNFunc extends FunctionImplN {
        private final Method method;
        private final boolean returnsVoid;

        private ArityNFunc(int arity, Method method, boolean returnsVoid) {
            super(arity);
            this.method = method;
            this.returnsVoid = returnsVoid;
        }

        @Override
        public Object doApply(Object... ps) {
            try {
                Object ret =  method.invoke(null, ps);
                return returnsVoid ? Tuple0.INSTANCE : ret;
            } catch (ReflectiveOperationException e) {
                throw new RuntimeException(e);
            }
        }
        
        @Override
        public int hashCode() {
            return method == null ? 0 : method.hashCode();
        }

        @Override
        public boolean equals(Object obj) {
            if (this == obj)
                return true;
            if (obj == null)
                return false;
            if (getClass() != obj.getClass())
                return false;
            ArityNFunc other = (ArityNFunc) obj;
            return method.equals(other.method);
        }
    }

    public static Object getValueFromStaticMethod(final Method method) throws ReflectiveOperationException {
        int arity = method.getParameterTypes().length;
        final boolean returnsVoid = method.getReturnType().equals(void.class);
        switch(arity) {
        case 0: {
            Object ret = method.invoke(null);
            return returnsVoid ? Tuple0.INSTANCE : ret;
        }
        case 1:
            return new Arity1Func(method, returnsVoid);
        case 2:
            return new Arity2Func(method, returnsVoid);
        case 3:
            return new Arity3Func(method, returnsVoid);
        case 4:
            return new Arity4Func(method, returnsVoid);
        default:
            return new ArityNFunc(arity, method, returnsVoid);
        }
    }
    
}