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

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

type ExamSyncService interface {
	SyncUserExams(ctx context.Context, userID string, req *SyncExamsRequest) (*SyncExamsResult, error)
	ListExams(userID, semester string) ([]*model.Exam, error)
}

type examSyncService struct {
	taskManager *runner.TaskManager
	examRepo    repository.ExamRepository
	logger      *zap.Logger
}

func NewExamSyncService(
	taskManager *runner.TaskManager,
	examRepo repository.ExamRepository,
	logger *zap.Logger,
) ExamSyncService {
	return &examSyncService{
		taskManager: taskManager,
		examRepo:    examRepo,
		logger:      logger,
	}
}

func (s *examSyncService) SyncUserExams(ctx context.Context, userID string, req *SyncExamsRequest) (*SyncExamsResult, error) {
	payload := &pb.GetExamsPayload{
		Username: req.Username,
		Password: req.Password,
		Semester: req.Semester,
	}

	taskResult, err := s.taskManager.SubmitTaskSync(ctx, pb.TaskType_TASK_TYPE_GET_EXAMS, payload)
	if err != nil {
		s.logger.Error("failed to submit exams 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 &SyncExamsResult{
			Success:      false,
			Message:      "考试安排获取失败",
			ErrorMessage: taskResult.ErrorMessage,
		}, nil
	}

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

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

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

	return &SyncExamsResult{
		Success:     true,
		Message:     "考试安排同步成功",
		SyncedCount: len(exams),
	}, nil
}

func (s *examSyncService) convertExams(userID string, data *pb.ExamsResultData) []*model.Exam {
	exams := make([]*model.Exam, 0, len(data.Exams))
	for _, e := range data.Exams {
		exams = append(exams, &model.Exam{
			ID:         uuid.New().String(),
			UserID:     userID,
			Semester:   data.Semester,
			CourseName: e.CourseName,
			ExamType:   e.ExamType,
			Date:       e.Date,
			Time:       e.Time,
			Week:       e.Week,
			Weekday:    e.Weekday,
		})
	}
	return exams
}

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

// ListExams 查询用户某学期的考试安排。
func (s *examSyncService) ListExams(userID, semester string) ([]*model.Exam, error) {
	return s.examRepo.ListByUserAndSemester(userID, semester)
}