package service

import (
	"time"

	"gorm.io/gorm"

	"github.com/sundynix/pets-be/internal/model"
)

func dayStart(t time.Time) time.Time {
	return time.Date(t.Year(), t.Month(), t.Day(), 0, 0, 0, 0, t.Location())
}

// ensureDayTasks 惰性生成某天的任务：今天/未来若为空，则从「最近一次有任务的那天」顺延复制，
// 无历史则用养护模板。过去的日子不补（保留历史真实）。
func (s *Service) ensureDayTasks(pet *model.Pet, day time.Time) {
	start := dayStart(day)
	if start.Before(dayStart(time.Now())) {
		return
	}
	end := start.AddDate(0, 0, 1)
	var cnt int64
	s.db.Model(&model.DailyTask{}).Where("pet_id = ? AND task_date >= ? AND task_date < ?", pet.ID, start, end).Count(&cnt)
	if cnt > 0 {
		return
	}

	var defs []model.DailyTask
	var latest model.DailyTask
	if err := s.db.Where("pet_id = ? AND task_date < ?", pet.ID, start).Order("task_date desc, id desc").First(&latest).Error; err == nil {
		ls := dayStart(latest.TaskDate)
		var prev []model.DailyTask
		s.db.Where("pet_id = ? AND task_date >= ? AND task_date < ?", pet.ID, ls, ls.AddDate(0, 0, 1)).Order("id asc").Find(&prev)
		for _, t := range prev {
			defs = append(defs, model.DailyTask{
				PetID: pet.ID, UserID: pet.UserID, TaskDate: start,
				Title: t.Title, Description: t.Description, Priority: t.Priority, SheetType: t.SheetType,
			})
		}
	} else {
		for _, it := range s.careTemplateItems(SpeciesOf(pet.Type), pet.Stage) {
			if it.Kind == model.CareKindTask {
				defs = append(defs, model.DailyTask{
					PetID: pet.ID, UserID: pet.UserID, TaskDate: start,
					Title: it.Title, Description: it.Description, Priority: it.Priority, SheetType: it.SheetType,
				})
			}
		}
	}
	if len(defs) > 0 {
		s.db.Create(&defs)
	}
}

// ListTasks 列出宠物某天任务（date 为空则取今天）；今天/未来为空会惰性生成
func (s *Service) ListTasks(userID, petID string, date *time.Time) ([]model.DailyTask, error) {
	pet, err := s.ownedPet(userID, petID)
	if err != nil {
		return nil, err
	}
	target := time.Now()
	if date != nil {
		target = *date
	}
	s.ensureDayTasks(pet, target)

	start := dayStart(target)
	end := start.AddDate(0, 0, 1)
	var tasks []model.DailyTask
	err = s.db.Where("pet_id = ? AND task_date >= ? AND task_date < ?", petID, start, end).
		Order("id asc").Find(&tasks).Error
	return tasks, err
}

// TaskInput 增/改任务入参
type TaskInput struct {
	Title       string
	Description string
	Priority    string
	SheetType   string
	Date        *time.Time // 仅新增用，默认今天
}

// CreateTask 为某天新增一条任务（默认今天）
func (s *Service) CreateTask(userID, petID string, in TaskInput) (*model.DailyTask, error) {
	if _, err := s.ownedPet(userID, petID); err != nil {
		return nil, err
	}
	day := time.Now()
	if in.Date != nil {
		day = *in.Date
	}
	t := model.DailyTask{
		PetID: petID, UserID: userID, TaskDate: dayStart(day),
		Title: in.Title, Description: in.Description, Priority: in.Priority, SheetType: in.SheetType,
	}
	if err := s.db.Create(&t).Error; err != nil {
		return nil, err
	}
	return &t, nil
}

// UpdateTask 修改任务文案/优先级/关联弹层
func (s *Service) UpdateTask(userID, taskID string, in TaskInput) (*model.DailyTask, error) {
	var t model.DailyTask
	if err := s.db.Where("id = ? AND user_id = ?", taskID, userID).First(&t).Error; err != nil {
		return nil, ErrNotFound
	}
	if err := s.db.Model(&model.DailyTask{}).Where("id = ?", taskID).Updates(map[string]any{
		"title": in.Title, "description": in.Description, "priority": in.Priority, "sheet_type": in.SheetType,
	}).Error; err != nil {
		return nil, err
	}
	return s.UpdateTaskReload(taskID)
}

// UpdateTaskReload 重新读取任务
func (s *Service) UpdateTaskReload(taskID string) (*model.DailyTask, error) {
	var t model.DailyTask
	if err := s.db.First(&t, "id = ?", taskID).Error; err != nil {
		return nil, ErrNotFound
	}
	return &t, nil
}

// DeleteTask 删除任务
func (s *Service) DeleteTask(userID, taskID string) error {
	res := s.db.Where("id = ? AND user_id = ?", taskID, userID).Delete(&model.DailyTask{})
	if res.Error != nil {
		return res.Error
	}
	if res.RowsAffected == 0 {
		return ErrNotFound
	}
	return nil
}

// ToggleTask 切换任务完成状态
func (s *Service) ToggleTask(userID, taskID string) (*model.DailyTask, error) {
	var task model.DailyTask
	if err := s.db.Where("id = ? AND user_id = ?", taskID, userID).First(&task).Error; err != nil {
		if err == gorm.ErrRecordNotFound {
			return nil, ErrNotFound
		}
		return nil, err
	}
	task.Done = !task.Done
	if task.Done {
		now := time.Now()
		task.CompletedAt = &now
	} else {
		task.CompletedAt = nil
	}
	if err := s.db.Save(&task).Error; err != nil {
		return nil, err
	}
	return &task, nil
}

// CompleteAllTasks 完成宠物今日全部任务
func (s *Service) CompleteAllTasks(userID, petID string) ([]model.DailyTask, error) {
	if _, err := s.ownedPet(userID, petID); err != nil {
		return nil, err
	}
	now := time.Now()
	start := time.Date(now.Year(), now.Month(), now.Day(), 0, 0, 0, 0, now.Location())
	end := start.AddDate(0, 0, 1)
	if err := s.db.Model(&model.DailyTask{}).
		Where("pet_id = ? AND task_date >= ? AND task_date < ?", petID, start, end).
		Updates(map[string]any{"done": true, "completed_at": now}).Error; err != nil {
		return nil, err
	}
	return s.ListTasks(userID, petID, &now)
}