package abstractSyntaxTree.Expression;

import TypeCheck.TypeCheckResult;
import TypeCheck.TypeCheckHelper;
import TypeCheck.AbstractType;
import org.objectweb.asm.*;

import java.beans.Expression;
import java.util.Objects;

public class BinaryExpression extends AbstractType implements IExpression{

    public String operator;
    public IExpression left;
    public IExpression right;

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

        TypeCheckResult leftType = left.typeCheck();
        TypeCheckResult rightType = right.typeCheck();

        switch (operator) {

            case "&&":
            case "||" :{
                if (Objects.equals(helper.upperBound(leftType.type, rightType.type), "bool")){
                    result.type = "bool";
                }
                break;
            }
            case "==":
            case "<":
            case ">":
            case "<=":
            case ">=":
            case "!=":
                    result.type = helper.upperBound(leftType.type, rightType.type);
                break;

            case "-":
            case "+":
            case "*":
            case "/":
                if (Objects.equals(helper.upperBound(leftType.type, rightType.type), "int")){
                    result.type = "int";
                }
                break;

            //case "&" ist für logisches und auf bit level
            //case "|" ist für logisches oder auf bit level
        }

        setTypeCheckResult(result);
        return result;
    }


    @Override
    public void CodeGen(MethodVisitor mv) throws Exception {
        // Label for the jump instruction
        Label operationFalse = new Label();   //Operation is false
        Label operationTrue = new Label();    //Operation is true
        // Labels are placed at the end of this method
        Label expressionEnd = new Label();     //End of the whole expression

        // Bytecode for the binary operation
        switch (operator) {
            case "&&":
                left.CodeGen(mv);
                mv.visitJumpInsn(Opcodes.IFEQ, operationFalse); // IFEQ --> "if equals to zero" (false) --> if left exp is false

                right.CodeGen(mv);
                mv.visitJumpInsn(Opcodes.IFEQ, operationFalse); // If right exp is false, jump to the end of the whole expression

                mv.visitJumpInsn(Opcodes.GOTO, operationTrue); // If it reaches this point, the right exp is true
                break;

            case "||":
                left.CodeGen(mv);
                mv.visitJumpInsn(Opcodes.IFNE, operationTrue); // IFNE --> "if not equals to zero" (true) --> if left exp is true

                right.CodeGen(mv);
                mv.visitJumpInsn(Opcodes.IFNE, operationTrue);
                break;

           case "==":
               // Keep in mind that only primitive types are allowed in this case (at this time)

               left.CodeGen(mv);
               right.CodeGen(mv);

                mv.visitJumpInsn(Opcodes.IF_ICMPEQ, operationTrue); // If the two values are equal, jump to the end of the expression
                break;

            case "<":
                left.CodeGen(mv);
                right.CodeGen(mv);

                mv.visitJumpInsn(Opcodes.IF_ICMPLT, operationTrue); // Checks only on less than, not equal
                break;

            case ">":
                left.CodeGen(mv);
                right.CodeGen(mv);

                mv.visitJumpInsn(Opcodes.IF_ICMPGT, operationTrue); // Checks only on greater than, not equal
                break;

            case "<=":
                left.CodeGen(mv);
                right.CodeGen(mv);

                mv.visitJumpInsn(Opcodes.IF_ICMPLE, operationTrue); // Checks on less than OR equal
                break;

            case ">=":
                left.CodeGen(mv);
                right.CodeGen(mv);

                mv.visitJumpInsn(Opcodes.IF_ICMPGE, operationTrue); // Checks on greater than OR equal
                break;

            case "!=":
                left.CodeGen(mv);
                right.CodeGen(mv);

                mv.visitJumpInsn(Opcodes.IF_ICMPNE, operationTrue); // Checks on not equal
                break;

            case "+":
                left.CodeGen(mv);
                right.CodeGen(mv);
                mv.visitInsn(Opcodes.IADD);
                break;

            case "-":
                left.CodeGen(mv);
                right.CodeGen(mv);
                mv.visitInsn(Opcodes.ISUB);
                break;

            case "*":
                left.CodeGen(mv);
                right.CodeGen(mv);
                mv.visitInsn(Opcodes.IMUL);
                break;

            case "/":
                left.CodeGen(mv);
                right.CodeGen(mv);
                mv.visitInsn(Opcodes.IDIV);
                break;

            default:
                throw new Exception("Unknown operator: " + operator);
        }

        mv.visitLabel(operationFalse);
        mv.visitInsn(Opcodes.ICONST_0); // Push false on the stack
        mv.visitJumpInsn(Opcodes.GOTO, expressionEnd); // Jump to the end of the expression (skip the true push)

        mv.visitLabel(operationTrue);
        mv.visitInsn(Opcodes.ICONST_1); // Push true on the stack

        mv.visitLabel(expressionEnd);
    }
}