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

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

    @Override
    public MathProblem generate() {
        int operandCount = random.nextInt(3) + 3; // 3-5 个操作数
        double[] operandsVal = new double[operandCount];
        String[] displayOperands = new String[operandCount];
        String[] selectedOperators = new String[operandCount - 1];

        // 生成基本操作数
        for (int i = 0; i < operandCount; i++) {
            int v = random.nextInt(100) + 1;
            operandsVal[i] = v;
            displayOperands[i] = String.valueOf(v);
        }
        // 运算符选择（更均衡，避免连乘/连除）
        String previousOperator = null;
        double pPlus = 0.35, pMinus = 0.25, pTimes = 0.25, pDivide = 0.15;
        for (int i = 0; i < operandCount - 1; i++) {
            String operator;
            if ("*".equals(previousOperator) || "/".equals(previousOperator)) {
                double randValue = random.nextDouble();
                double total = pPlus + pMinus;
                operator = randValue < (pPlus / total) ? "+" : "-";
            } else {
                double randValue = random.nextDouble();
                if (randValue < pPlus) operator = "+";
                else if (randValue < pPlus + pMinus) operator = "-";
                else if (randValue < pPlus + pMinus + pTimes) operator = "*";
                else operator = "/";
            }
            selectedOperators[i] = operator;
            previousOperator = operator;
        }

        // 三角函数
        int trigIndex = random.nextInt(operandCount);
        String[] functions = {"sin", "cos", "tan"};
        String function = functions[random.nextInt(functions.length)];
        int[] angles = {0, 30, 45, 60, 90};
        int angle = angles[random.nextInt(angles.length)];
        if ("tan".equals(function) && angle == 90) angle = 60; // 避免 tan(90°)
        double trigVal = calculateTrigFunction(function, angle);
        operandsVal[trigIndex] = trigVal;
        displayOperands[trigIndex] = function + angle;

        // 括号选择（显示用 displayOperands，计算用 operandsVal）
        boolean addedBracket = false;
        int startPos = findBracketStart(operandsVal, selectedOperators, 0.3);
        StringBuilder expBuilder = new StringBuilder();
        for (int i = 0; i < operandCount; i++) {
            if (startPos != -1 && i == startPos) expBuilder.append("(");
            expBuilder.append(displayOperands[i]);
            if (startPos != -1 && i == startPos + 1) expBuilder.append(")");
            if (i < operandCount - 1) expBuilder.append(" ").append(selectedOperators[i]).append(" ");
        }
        String expression = expBuilder.toString();

        // 计算结果（double）
        double result;
        if (startPos != -1) {
            double bracketResult = applyOperatorDouble(operandsVal[startPos], operandsVal[startPos + 1], selectedOperators[startPos]);
            int newCount = operandCount - 1;
            double[] newVals = new double[newCount];
            String[] newOps = new String[newCount - 1];
            for (int i = 0; i < startPos; i++) newVals[i] = operandsVal[i];
            newVals[startPos] = bracketResult;
            for (int i = startPos + 1; i < newCount; i++) newVals[i] = operandsVal[i + 1];
            for (int i = 0; i < newCount - 1; i++) newOps[i] = (i < startPos) ? selectedOperators[i] : selectedOperators[i + 1];
            result = newVals[0];
            for (int i = 0; i < newCount - 1; i++) result = applyOperatorDouble(result, newVals[i + 1], newOps[i]);
        } else {
            result = operandsVal[0];
            for (int i = 0; i < operandCount - 1; i++) result = applyOperatorDouble(result, operandsVal[i + 1], selectedOperators[i]);
        }

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