package service

import (
	"context"
	"encoding/json"
	"fmt"

	"with_you/internal/grpc/runner"
	"with_you/internal/model"
	"with_you/internal/repository"
	pb "with_you/proto/runner"

	"github.com/google/uuid"
	"go.uber.org/zap"
)

type SyncGradesRequest struct {
	Username string `json:"username" binding:"required"`
	Password string `json:"password" binding:"required"`
	Semester string `json:"semester"`
}

type SyncGradesResult struct {
	Success      bool   `json:"success"`
	Message      string `json:"message"`
	SyncedCount  int    `json:"synced_count"`
	ErrorMessage string `json:"error_message,omitempty"`
}

type GradeSyncService interface {
	SyncUserGrades(ctx context.Context, userID string, req *SyncGradesRequest) (*SyncGradesResult, error)
}

type gradeSyncService struct {
	taskManager *runner.TaskManager
	gradeRepo   repository.GradeRepository
	logger      *zap.Logger
}

func NewGradeSyncService(
	taskManager *runner.TaskManager,
	gradeRepo repository.GradeRepository,
	logger *zap.Logger,
) GradeSyncService {
	return &gradeSyncService{
		taskManager: taskManager,
		gradeRepo:   gradeRepo,
		logger:      logger,
	}
}

func (s *gradeSyncService) SyncUserGrades(ctx context.Context, userID string, req *SyncGradesRequest) (*SyncGradesResult, error) {
	payload := &pb.GetGradesPayload{
		Username: req.Username,
		Password: req.Password,
		Semester: req.Semester,
	}

	taskResult, err := s.taskManager.SubmitTaskSync(ctx, pb.TaskType_TASK_TYPE_GET_GRADES, payload)
	if err != nil {
		s.logger.Error("failed to submit grades sync task",
			zap.String("user_id", userID),
			zap.Error(err))
		return nil, fmt.Errorf("failed to submit task: %w", err)
	}

	if taskResult.Status != pb.TaskStatus_TASK_STATUS_SUCCESS {
		return &SyncGradesResult{
			Success:      false,
			Message:      "成绩获取失败",
			ErrorMessage: taskResult.ErrorMessage,
		}, nil
	}

	var resultData pb.GradesResultData
	if err := json.Unmarshal(taskResult.Data, &resultData); err != nil {
		s.logger.Error("failed to parse grades result",
			zap.String("user_id", userID),
			zap.Error(err))
		return nil, fmt.Errorf("failed to parse result: %w", err)
	}

	grades := s.convertGrades(userID, &resultData)
	if err := s.saveGrades(ctx, userID, resultData.Semester, grades); err != nil {
		s.logger.Error("failed to save grades",
			zap.String("user_id", userID),
			zap.Error(err))
		return nil, fmt.Errorf("failed to save grades: %w", err)
	}

	if resultData.GpaSummary != nil {
		summary := s.convertGpaSummary(userID, resultData.Semester, resultData.GpaSummary)
		if err := s.gradeRepo.SaveGpaSummary(ctx, summary); err != nil {
			s.logger.Warn("failed to save gpa summary",
				zap.String("user_id", userID),
				zap.Error(err))
		}
	}

	s.logger.Info("grades sync completed",
		zap.String("user_id", userID),
		zap.Int("grade_count", len(grades)))

	return &SyncGradesResult{
		Success:     true,
		Message:     "成绩同步成功",
		SyncedCount: len(grades),
	}, nil
}

func (s *gradeSyncService) convertGrades(userID string, data *pb.GradesResultData) []*model.Grade {
	grades := make([]*model.Grade, 0, len(data.Grades))
	for _, g := range data.Grades {
		grades = append(grades, &model.Grade{
			ID:         uuid.New().String(),
			UserID:     userID,
			Term:       g.Term,
			CourseCode: g.CourseCode,
			CourseName: g.CourseName,
			Nature:     g.Nature,
			Category:   g.Category,
			Credit:     g.Credit,
			Score:      g.Score,
			GradePoint: g.GradePoint,
			IsExam:     g.IsExam,
		})
	}
	return grades
}

func (s *gradeSyncService) convertGpaSummary(userID, semester string, gpa *pb.GpaSummary) *model.GpaSummary {
	return &model.GpaSummary{
		ID:               uuid.New().String(),
		UserID:           userID,
		Semester:         semester,
		AverageGpa:       gpa.AverageGpa,
		Rank:             gpa.Rank,
		ExamTotalGpa:     gpa.ExamTotalGpa,
		ExamTotalCredits: gpa.ExamTotalCredits,
		FailCredits:      gpa.FailCredits,
		Semesters:        gpa.Semesters,
	}
}

func (s *gradeSyncService) saveGrades(ctx context.Context, userID, semester string, grades []*model.Grade) error {
	if err := s.gradeRepo.DeleteByUserAndSemester(ctx, userID, semester); err != nil {
		return fmt.Errorf("failed to delete old grades: %w", err)
	}
	if len(grades) == 0 {
		return nil
	}
	if err := s.gradeRepo.BatchCreate(ctx, grades); err != nil {
		return fmt.Errorf("failed to create grades: %w", err)
	}
	return nil
}