import java.text.DecimalFormat;
import java.util.Random;

public class MiddleSchoolProblemGenerator extends AbstractProblemGenerator {
    public MiddleSchoolProblemGenerator(Random random, DecimalFormat df) {
        super(random, df);
    }

    @Override
    public MathProblem generate() {
        int operandCount = random.nextInt(3) + 3; // 3-5 个操作数
        int[] operands = new int[operandCount];
        String[] selectedOperators = new String[operandCount - 1];
        String[] displayOperands = new String[operandCount];
        String[] operatorPool = {"+", "-", "*", "/"};

        for (int i = 0; i < operandCount; i++) {
            operands[i] = random.nextInt(100) + 1;
            displayOperands[i] = String.valueOf(operands[i]);
        }
        for (int i = 0; i < operandCount - 1; i++) {
            selectedOperators[i] = operatorPool[random.nextInt(operatorPool.length)];
        }

        // 平方或根号
        int specialOperandIndex = random.nextInt(operandCount);
        boolean useSquareRoot = random.nextBoolean();
        if (useSquareRoot) {
            int base = random.nextInt(24) + 2; //2-25
            int perfectSquare = base * base;
            operands[specialOperandIndex] = base; // √(base^2) = base
            displayOperands[specialOperandIndex] = "√" + perfectSquare;
        } else {
            int base = random.nextInt(9) + 2; // 2-10
            int square = base * base;
            operands[specialOperandIndex] = square;
            displayOperands[specialOperandIndex] = base + "²";
        }

        // 括号选择
        boolean addedBracket = false;
        int bracketStartIndex = findBracketStart(toDoubleArray(operands), selectedOperators, 0.3);
        String expression;
        double result;
        if (bracketStartIndex != -1) {
            // 构建带括号（显示用 displayOperands）
            StringBuilder expressionBuilder = new StringBuilder();
            for (int i = 0; i < operandCount; i++) {
                if (i == bracketStartIndex) expressionBuilder.append("(");
                expressionBuilder.append(displayOperands[i]);
                if (i == bracketStartIndex + 1) expressionBuilder.append(")");
                if (i < operandCount - 1) expressionBuilder.append(" ").append(selectedOperators[i]).append(" ");
            }
            expression = expressionBuilder.toString();
            result = evaluateExpressionWithBrackets(operands, selectedOperators, bracketStartIndex);
        } else {
            StringBuilder expressionBuilder = new StringBuilder();
            expressionBuilder.append(displayOperands[0]);
            result = operands[0];
            for (int i = 0; i < operandCount - 1; i++) {
                expressionBuilder.append(" ").append(selectedOperators[i]).append(" ").append(displayOperands[i + 1]);
                result = applyOperator(result, operands[i + 1], selectedOperators[i]);
            }
            expression = expressionBuilder.toString();
        }

        return new MathProblem(expression, df.format(result), "初中");
    }
}