package org.zwobble.couscous.backends.python;

import java.util.List;
import java.util.Map;
import java.util.Optional;

import org.zwobble.couscous.backends.python.ast.PythonExpressionNode;
import org.zwobble.couscous.values.StringValue;
import org.zwobble.couscous.values.TypeReference;

import com.google.common.collect.ImmutableMap;

import static java.util.Arrays.asList;
import static org.zwobble.couscous.backends.python.ast.PythonAttributeAccessNode.pythonAttributeAccess;
import static org.zwobble.couscous.backends.python.ast.PythonCallNode.pythonCall;
import static org.zwobble.couscous.backends.python.ast.PythonVariableReferenceNode.pythonVariableReference;

public class PrimitiveMethods {
    private static final Map<String, PrimitiveMethodGenerator> STRING_METHODS =
        ImmutableMap.<String, PrimitiveMethodGenerator>builder()
        
            .put("length", (receiver, arguments) ->
                pythonCall(
                    pythonVariableReference("len"),
                    asList(receiver)))
            
            .put("substring", (receiver, arguments) ->
                pythonCall(
                    pythonAttributeAccess(
                        receiver,
                        "__getitem__"),
                    asList(pythonCall(
                        pythonVariableReference("slice"),
                    arguments))))
            
            .build();
    
    private static final Map<TypeReference, Map<String, PrimitiveMethodGenerator>> METHODS = 
        ImmutableMap.<TypeReference, Map<String, PrimitiveMethodGenerator>>builder()
            .put(StringValue.REF, STRING_METHODS)
            .build();
    
    public static boolean isPrimitive(TypeReference type) {
        return METHODS.containsKey(type);
    }
    
    public static Optional<PrimitiveMethodGenerator> getPrimitiveMethod(TypeReference type, String methodName) {
        return Optional.ofNullable(METHODS.get(type))
            .flatMap(methodsForType -> Optional.ofNullable(methodsForType.get(methodName)));
    }
    
    @FunctionalInterface
    public interface PrimitiveMethodGenerator {
        PythonExpressionNode generate(PythonExpressionNode receiver, List<PythonExpressionNode> arguments);
    }
}