package slangc.model.expressions;

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

public class ConditionalExpression extends ExpressionModel implements ExpressionOwner {
	ExpressionModel leftHandSide;
	ExpressionModel trueBranch;
	ExpressionModel falseBranch;

	public ConditionalExpression(ExpressionOwner owner, Node source) {
		super(owner, source);
		leftHandSide = ExpressionModel.construct(this, ((Branch)source).getSubnode(0));
		trueBranch = ExpressionModel.construct(this, ((Branch)source).getSubnode(2));
		falseBranch = ExpressionModel.construct(this, ((Branch)source).getSubnode(4));
	}

	@Override
	public void dump(Reporter reporter, String indent, String incr) {
		reporter.note("DUMP", indent + "> Conditional expression");
		dumpResolved(reporter, indent + incr, incr);
		leftHandSide.dump(reporter, indent + incr, incr);
		trueBranch.dump(reporter, indent + incr, incr);
		falseBranch.dump(reporter, indent + incr, incr);
	}

	@Override
	public ExpressionModel[] getSubexpressions() {
		return new ExpressionModel[] {leftHandSide, trueBranch, falseBranch};
	}
	
	@Override
	public TypeModel getExpectedResult(ExpressionModel e) {
		// TODO not sure if relevant here
		return null;
	}

	@Override
	public InnerTypeScope getTypeScope() {
		return getOwner().getTypeScope();
	}


	@Override
	public TypeModel resolveType(Node subnode) {
		return getOwner().resolveType(subnode);
	}


	@Override
	public MemberModel getMethodOrField() {
		return getOwner().getMethodOrField();
	}
	
	@Override
	protected ExpressionResult resolveResult() {
		if (trueBranch.getResult().resolvesToValueOrNull() && falseBranch.getResult().resolvesToValueOrNull()) {
			TypeModel lhs = trueBranch.getResult().getValueTypeWithNullType(null);
			TypeModel rhs = falseBranch.getResult().getValueTypeWithNullType(null);
			TypeModel res = null;
			if (lhs == null && rhs == null) { 
				res = getSystem().getDefaultBaseType();
			} else if (lhs == null) {
				res = rhs;
			} else if (rhs == null) {
				res = lhs;
			} else {
				res = BinaryExpression.resultType(lhs, ":", rhs);
			}
			if (res == null) {
				return ExpressionResult.INVALID;
			} else {
				return new ExpressionResult.TypedValue(res);
			}
		}
		return super.resolveResult();
	}
	
	@Override
	public TypeSignature innerGenerate(BytecodeInstructionWriter w) {
		BytecodeInstructionWriter.Label elseLabel = w.newLabel("cond_else");
		BytecodeInstructionWriter.Label endLabel = w.newLabel("cond_end");
		
		TypeSignature xt = leftHandSide.generate(w);
		w.genJump(BytecodeInstructionWriter.JumpOp.IFFALSE, elseLabel);
		trueBranch.generate(w);
		w.genJump(BytecodeInstructionWriter.JumpOp.GOTO, endLabel);
		w.labelHere(elseLabel);
		falseBranch.generate(w);
		w.labelHere(endLabel);
		
		return getResult().getValueType().getTypeSignature();
	}
}