package abstractSyntaxTree.Statement;

import TypeCheck.TypeCheckResult;
import TypeCheck.AbstractType;
import abstractSyntaxTree.Expression.IExpression;
import org.objectweb.asm.*;

public class WhileStatement extends AbstractType implements IStatement {
    IExpression condition;
    IStatement statement;

    public WhileStatement(IExpression condition, IStatement statement) {
        this.condition = condition;
        this.statement = statement;
    }

    @Override
    public TypeCheckResult typeCheck() throws Exception {
        TypeCheckResult result = new TypeCheckResult();

        TypeCheckResult conditionType = condition.typeCheck();

        if (!conditionType.equals("bool")) {
            throw new IllegalArgumentException("Expected boolean");
        }

        TypeCheckResult statementType = statement.typeCheck();

        result.type = statementType.type;
        return result;
    }

    @Override
    public void codeGen(MethodVisitor mv) throws Exception {
        Label conditionFalse = new Label();
        Label LoopStart = new Label();

        mv.visitLabel(LoopStart);

        condition.codeGen(mv);
        mv.visitJumpInsn(Opcodes.IFEQ, conditionFalse); // Checks if the condition is false (0)

        statement.codeGen(mv);
        //TODO: If the block ends with a return statement, we might have to pop it from the stack
        //      So the next iteration starts with a clean stack
        mv.visitJumpInsn(Opcodes.GOTO, LoopStart); // Jump to the start of the while loop

        mv.visitLabel(conditionFalse);
    }
}