package com.sztzjy.linkCommerce.service.impl;

import com.sztzjy.linkCommerce.config.exception.handler.ServiceException;
import com.sztzjy.linkCommerce.config.security.JwtUser;
import com.sztzjy.linkCommerce.entity.StudentTrainingAnswer;
import com.sztzjy.linkCommerce.entity.TeachingClassStudent;
import com.sztzjy.linkCommerce.entity.TrainingTask;
import com.sztzjy.linkCommerce.entity.dto.HardwareCostStepFourValidationRequest;
import com.sztzjy.linkCommerce.entity.dto.HardwareCostStepFourValidationResult;
import com.sztzjy.linkCommerce.mapper.StudentTrainingAnswerMapper;
import com.sztzjy.linkCommerce.mapper.TeachingClassStudentMapper;
import com.sztzjy.linkCommerce.mapper.TrainingTaskMapper;
import com.sztzjy.linkCommerce.service.HardwareCostStepFourService;
import org.apache.commons.lang3.StringUtils;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.http.HttpStatus;
import org.springframework.stereotype.Service;

@Service
public class HardwareCostStepFourServiceImpl implements HardwareCostStepFourService {
    private static final String TASK_KEY = "hardware-cost";
    private static final int MAX_OPTIMIZATION_PLAN_LENGTH = 3000;

    @Autowired
    private StudentTrainingAnswerMapper studentTrainingAnswerMapper;
    @Autowired
    private TeachingClassStudentMapper teachingClassStudentMapper;
    @Autowired
    private TrainingTaskMapper trainingTaskMapper;

    @Override
    public HardwareCostStepFourValidationResult validate(HardwareCostStepFourValidationRequest request, JwtUser user) {
        requireStudent(user);
        requirePreviousStepsCompleted(user);

        String smallBatchChartUrl = request == null ? "" : StringUtils.trimToEmpty(request.getSmallBatchChartUrl());
        String largeBatchChartUrl = request == null ? "" : StringUtils.trimToEmpty(request.getLargeBatchChartUrl());
        String optimizationPlan = request == null ? "" : StringUtils.trimToEmpty(request.getOptimizationPlan());
        if (StringUtils.isBlank(smallBatchChartUrl) || StringUtils.isBlank(largeBatchChartUrl)) {
            throw new ServiceException(HttpStatus.BAD_REQUEST,
                    "Please upload both small-batch and mass-production cost structure charts.");
        }
        if (StringUtils.isBlank(optimizationPlan)) {
            throw new ServiceException(HttpStatus.BAD_REQUEST, "Please enter the cost optimisation decision.");
        }
        if (optimizationPlan.length() > MAX_OPTIMIZATION_PLAN_LENGTH) {
            throw new ServiceException(HttpStatus.BAD_REQUEST,
                    "The cost optimisation decision cannot exceed " + MAX_OPTIMIZATION_PLAN_LENGTH + " characters.");
        }

        HardwareCostStepFourValidationResult result = new HardwareCostStepFourValidationResult();
        result.setValid(true);
        result.setMessage("Cost structure charts and optimisation decision have been validated.");
        return result;
    }

    private void requirePreviousStepsCompleted(JwtUser user) {
        TeachingClassStudent membership = teachingClassStudentMapper.selectActiveByStudentUserId(user.getUserId());
        TrainingTask task = trainingTaskMapper.selectByTaskKey(TASK_KEY);
        if (membership == null || task == null) {
            throw new ServiceException(HttpStatus.BAD_REQUEST, "Current training task context was not found.");
        }
        StudentTrainingAnswer answer = studentTrainingAnswerMapper.selectByStudentClassAndTask(
                user.getUserId(), membership.getTeachingClassId(), task.getId());
        if (answer == null || StringUtils.isAnyBlank(answer.getStep1Answer(), answer.getStep2Answer(), answer.getStep3Answer())) {
            throw new ServiceException(HttpStatus.BAD_REQUEST,
                    "Please save the first three cost-estimation steps before completing Step 4.");
        }
    }

    private void requireStudent(JwtUser user) {
        if (user == null || StringUtils.isBlank(user.getUserId())) {
            throw new ServiceException(HttpStatus.UNAUTHORIZED, "Please log in first.");
        }
        if (user.getRoleId() != 4) {
            throw new ServiceException(HttpStatus.FORBIDDEN, "Only students can validate training answers.");
        }
    }
}