package slangc.model.expressions;

import slangc.api.BytecodeInstructionWriter;
import slangc.api.Reporter;
import slangc.bytecode.TypeSignature;
import slangc.model.ArrayTypeModel;
import slangc.model.ExpressionModel;
import slangc.model.ExpressionOwner;
import slangc.model.ExpressionResult;
import slangc.model.TypeModel;
import slangc.parser.Branch;
import slangc.parser.ErrorType;
import slangc.parser.Node;

public class ArrayIndexExpression extends ExpressionModel implements ExpressionOwner {
	private ExpressionModel leftHandSide;
	private ExpressionModel indexExpression;

	public ArrayIndexExpression(ExpressionOwner owner, Node source) {
		super(owner, source);
		leftHandSide = ExpressionModel.construct(this, ((Branch)source).getSubnode(0));
		indexExpression = ExpressionModel.construct(this, ((Branch)source).getSubnode(2));
	}

	@Override
	public void dump(Reporter reporter, String indent, String incr) {
		reporter.note("DUMP", indent + "> Array index expression:");
		dumpResolved(reporter, indent + incr, incr);
		leftHandSide.dump(reporter, indent + incr, incr);
		indexExpression.dump(reporter, indent + incr, incr);
	}

	@Override
	public TypeModel getExpectedResult(ExpressionModel e) {
		// TODO Auto-generated method stub
		return null;
	}
	
	public ExpressionModel getLeftHandSide() {
		return leftHandSide;
	}
	
	public ExpressionModel getIndexExpression() {
		return indexExpression;
	}

	@Override
	public ExpressionModel[] getSubexpressions() {
		return new ExpressionModel[] {leftHandSide, indexExpression};
	}
	
	@Override
	protected ExpressionResult resolveResult() {
		if (leftHandSide.getResult().resolvesToValueOrNull() && leftHandSide.getResult().getKind() != ExpressionResult.Kind.NULL) {
			TypeModel lhsType = leftHandSide.getResult().getValueType();
			if (lhsType instanceof ArrayTypeModel) {
				ArrayTypeModel arrayType = (ArrayTypeModel)lhsType;
				return new ExpressionResult.PointsToStorageSlot(arrayType);
			} else {
				getSource().annotate(ErrorType.INTERNAL_ERROR, "Left hand side of an array index expression should be an array type, got " + lhsType + " instead");
				return ExpressionResult.INVALID;
			}
		} else {
			getSource().annotate(ErrorType.INTERNAL_ERROR, "Couldn't make sense of left-hand-side of array index expression expecting a typeName but got " + leftHandSide.getResult());
			return ExpressionResult.INVALID;
		}
	}
	
	@Override
	public TypeSignature innerGenerate(BytecodeInstructionWriter w) {
		getLeftHandSide().generate(w);
		getIndexExpression().generate(w);
		w.genArrayLoad(getResult().getValueType().getTypeSignature());
		return getResult().getValueType().getTypeSignature();
	}
	
	@Override
	public void generateStore(BytecodeInstructionWriter w, TypeSignature storing) {
		getLeftHandSide().generate(w);
		getIndexExpression().generate(w);
		w.genArrayStore(getResult().getValueType().getTypeSignature());
	}

	public TypeModel resolveType(Node n) {
		return super.resolveType(n); // TODO: Better support for interfaces
	}
}