package services

import (
	"context"
	"errors"
	"time"

	"github.com/rs/zerolog/log"
	"gorm.io/gorm"

	"github.com/treytartt/casera-api/internal/dto/requests"
	"github.com/treytartt/casera-api/internal/dto/responses"
	"github.com/treytartt/casera-api/internal/models"
	"github.com/treytartt/casera-api/internal/repositories"
)

// Task-related errors
var (
	ErrTaskNotFound       = errors.New("task not found")
	ErrTaskAccessDenied   = errors.New("you do not have access to this task")
	ErrTaskAlreadyCancelled = errors.New("task is already cancelled")
	ErrTaskAlreadyArchived  = errors.New("task is already archived")
	ErrCompletionNotFound   = errors.New("task completion not found")
)

// TaskService handles task business logic
type TaskService struct {
	taskRepo            *repositories.TaskRepository
	residenceRepo       *repositories.ResidenceRepository
	residenceService    *ResidenceService
	notificationService *NotificationService
	emailService        *EmailService
}

// NewTaskService creates a new task service
func NewTaskService(taskRepo *repositories.TaskRepository, residenceRepo *repositories.ResidenceRepository) *TaskService {
	return &TaskService{
		taskRepo:      taskRepo,
		residenceRepo: residenceRepo,
	}
}

// SetNotificationService sets the notification service (for breaking circular dependency)
func (s *TaskService) SetNotificationService(ns *NotificationService) {
	s.notificationService = ns
}

// SetEmailService sets the email service
func (s *TaskService) SetEmailService(es *EmailService) {
	s.emailService = es
}

// SetResidenceService sets the residence service (for getting summary in CRUD responses)
func (s *TaskService) SetResidenceService(rs *ResidenceService) {
	s.residenceService = rs
}

// getSummaryForUser returns an empty summary placeholder.
// DEPRECATED: Summary calculation has been removed from CRUD responses for performance.
// Clients should calculate summary from kanban data instead (which already includes all tasks).
// The summary field is kept in responses for backward compatibility but will always be empty.
func (s *TaskService) getSummaryForUser(_ uint) responses.TotalSummary {
	// Return empty summary - clients should calculate from kanban data
	return responses.TotalSummary{}
}

// === Task CRUD ===

// GetTask gets a task by ID with access check
func (s *TaskService) GetTask(taskID, userID uint) (*responses.TaskResponse, error) {
	task, err := s.taskRepo.FindByID(taskID)
	if err != nil {
		if errors.Is(err, gorm.ErrRecordNotFound) {
			return nil, ErrTaskNotFound
		}
		return nil, err
	}

	// Check access via residence
	hasAccess, err := s.residenceRepo.HasAccess(task.ResidenceID, userID)
	if err != nil {
		return nil, err
	}
	if !hasAccess {
		return nil, ErrTaskAccessDenied
	}

	resp := responses.NewTaskResponse(task)
	return &resp, nil
}

// ListTasks lists all tasks accessible to a user as a kanban board.
// The `now` parameter should be the start of day in the user's timezone for accurate overdue detection.
func (s *TaskService) ListTasks(userID uint, now time.Time) (*responses.KanbanBoardResponse, error) {
	// Get all residence IDs accessible to user (lightweight - no preloads)
	residenceIDs, err := s.residenceRepo.FindResidenceIDsByUser(userID)
	if err != nil {
		return nil, err
	}

	if len(residenceIDs) == 0 {
		// Return empty kanban board
		return &responses.KanbanBoardResponse{
			Columns:       []responses.KanbanColumnResponse{},
			DaysThreshold: 30,
			ResidenceID:   "all",
		}, nil
	}

	// Get kanban data aggregated across all residences using user's timezone-aware time
	board, err := s.taskRepo.GetKanbanDataForMultipleResidences(residenceIDs, 30, now)
	if err != nil {
		return nil, err
	}

	resp := responses.NewKanbanBoardResponseForAll(board)
	// Include summary for dashboard stats
	summary := s.getSummaryForUser(userID)
	resp.Summary = &summary
	return &resp, nil
}

// GetTasksByResidence gets tasks for a specific residence (kanban board).
// The `now` parameter should be the start of day in the user's timezone for accurate overdue detection.
func (s *TaskService) GetTasksByResidence(residenceID, userID uint, daysThreshold int, now time.Time) (*responses.KanbanBoardResponse, error) {
	// Check access
	hasAccess, err := s.residenceRepo.HasAccess(residenceID, userID)
	if err != nil {
		return nil, err
	}
	if !hasAccess {
		return nil, ErrResidenceAccessDenied
	}

	if daysThreshold <= 0 {
		daysThreshold = 30 // Default
	}

	// Get kanban data using user's timezone-aware time
	board, err := s.taskRepo.GetKanbanData(residenceID, daysThreshold, now)
	if err != nil {
		return nil, err
	}

	resp := responses.NewKanbanBoardResponse(board, residenceID)
	// Include summary for dashboard stats
	summary := s.getSummaryForUser(userID)
	resp.Summary = &summary
	return &resp, nil
}

// CreateTask creates a new task.
// The `now` parameter should be the start of day in the user's timezone for accurate kanban categorization.
func (s *TaskService) CreateTask(req *requests.CreateTaskRequest, userID uint, now time.Time) (*responses.TaskWithSummaryResponse, error) {
	// Check residence access
	hasAccess, err := s.residenceRepo.HasAccess(req.ResidenceID, userID)
	if err != nil {
		return nil, err
	}
	if !hasAccess {
		return nil, ErrResidenceAccessDenied
	}

	dueDate := req.DueDate.ToTimePtr()
	task := &models.Task{
		ResidenceID:        req.ResidenceID,
		CreatedByID:        userID,
		Title:              req.Title,
		Description:        req.Description,
		CategoryID:         req.CategoryID,
		PriorityID:         req.PriorityID,
		FrequencyID:        req.FrequencyID,
		CustomIntervalDays: req.CustomIntervalDays,
		InProgress:         req.InProgress,
		AssignedToID:       req.AssignedToID,
		DueDate:            dueDate,
		NextDueDate:        dueDate, // Initialize next_due_date to due_date
		EstimatedCost:      req.EstimatedCost,
		ContractorID:       req.ContractorID,
	}

	if err := s.taskRepo.Create(task); err != nil {
		return nil, err
	}

	// Reload with relations
	task, err = s.taskRepo.FindByID(task.ID)
	if err != nil {
		return nil, err
	}

	return &responses.TaskWithSummaryResponse{
		Data:    responses.NewTaskResponseWithTime(task, 30, now),
		Summary: s.getSummaryForUser(userID),
	}, nil
}

// UpdateTask updates a task.
// The `now` parameter should be the start of day in the user's timezone for accurate kanban categorization.
func (s *TaskService) UpdateTask(taskID, userID uint, req *requests.UpdateTaskRequest, now time.Time) (*responses.TaskWithSummaryResponse, error) {
	task, err := s.taskRepo.FindByID(taskID)
	if err != nil {
		if errors.Is(err, gorm.ErrRecordNotFound) {
			return nil, ErrTaskNotFound
		}
		return nil, err
	}

	// Check access
	hasAccess, err := s.residenceRepo.HasAccess(task.ResidenceID, userID)
	if err != nil {
		return nil, err
	}
	if !hasAccess {
		return nil, ErrTaskAccessDenied
	}

	// Apply updates
	if req.Title != nil {
		task.Title = *req.Title
	}
	if req.Description != nil {
		task.Description = *req.Description
	}
	if req.CategoryID != nil {
		task.CategoryID = req.CategoryID
	}
	if req.PriorityID != nil {
		task.PriorityID = req.PriorityID
	}
	if req.FrequencyID != nil {
		task.FrequencyID = req.FrequencyID
	}
	if req.CustomIntervalDays != nil {
		task.CustomIntervalDays = req.CustomIntervalDays
	}
	if req.InProgress != nil {
		task.InProgress = *req.InProgress
	}
	if req.AssignedToID != nil {
		task.AssignedToID = req.AssignedToID
	}
	if req.DueDate != nil {
		newDueDate := req.DueDate.ToTimePtr()
		task.DueDate = newDueDate
		// Also update NextDueDate if the task doesn't have completions yet
		// (if it has completions, NextDueDate should be managed by completion logic)
		if len(task.Completions) == 0 {
			task.NextDueDate = newDueDate
		}
	}
	if req.EstimatedCost != nil {
		task.EstimatedCost = req.EstimatedCost
	}
	if req.ActualCost != nil {
		task.ActualCost = req.ActualCost
	}
	if req.ContractorID != nil {
		task.ContractorID = req.ContractorID
	}

	if err := s.taskRepo.Update(task); err != nil {
		return nil, err
	}

	// Reload
	task, err = s.taskRepo.FindByID(task.ID)
	if err != nil {
		return nil, err
	}

	return &responses.TaskWithSummaryResponse{
		Data:    responses.NewTaskResponseWithTime(task, 30, now),
		Summary: s.getSummaryForUser(userID),
	}, nil
}

// DeleteTask deletes a task
func (s *TaskService) DeleteTask(taskID, userID uint) (*responses.DeleteWithSummaryResponse, error) {
	task, err := s.taskRepo.FindByID(taskID)
	if err != nil {
		if errors.Is(err, gorm.ErrRecordNotFound) {
			return nil, ErrTaskNotFound
		}
		return nil, err
	}

	// Check access
	hasAccess, err := s.residenceRepo.HasAccess(task.ResidenceID, userID)
	if err != nil {
		return nil, err
	}
	if !hasAccess {
		return nil, ErrTaskAccessDenied
	}

	if err := s.taskRepo.Delete(taskID); err != nil {
		return nil, err
	}

	return &responses.DeleteWithSummaryResponse{
		Data:    "task deleted",
		Summary: s.getSummaryForUser(userID),
	}, nil
}

// === Task Actions ===

// MarkInProgress marks a task as in progress.
// The `now` parameter should be the start of day in the user's timezone for accurate kanban categorization.
func (s *TaskService) MarkInProgress(taskID, userID uint, now time.Time) (*responses.TaskWithSummaryResponse, error) {
	task, err := s.taskRepo.FindByID(taskID)
	if err != nil {
		if errors.Is(err, gorm.ErrRecordNotFound) {
			return nil, ErrTaskNotFound
		}
		return nil, err
	}

	// Check access
	hasAccess, err := s.residenceRepo.HasAccess(task.ResidenceID, userID)
	if err != nil {
		return nil, err
	}
	if !hasAccess {
		return nil, ErrTaskAccessDenied
	}

	if err := s.taskRepo.MarkInProgress(taskID); err != nil {
		return nil, err
	}

	// Reload
	task, err = s.taskRepo.FindByID(taskID)
	if err != nil {
		return nil, err
	}

	return &responses.TaskWithSummaryResponse{
		Data:    responses.NewTaskResponseWithTime(task, 30, now),
		Summary: s.getSummaryForUser(userID),
	}, nil
}

// CancelTask cancels a task.
// The `now` parameter should be the start of day in the user's timezone for accurate kanban categorization.
func (s *TaskService) CancelTask(taskID, userID uint, now time.Time) (*responses.TaskWithSummaryResponse, error) {
	task, err := s.taskRepo.FindByID(taskID)
	if err != nil {
		if errors.Is(err, gorm.ErrRecordNotFound) {
			return nil, ErrTaskNotFound
		}
		return nil, err
	}

	// Check access
	hasAccess, err := s.residenceRepo.HasAccess(task.ResidenceID, userID)
	if err != nil {
		return nil, err
	}
	if !hasAccess {
		return nil, ErrTaskAccessDenied
	}

	if task.IsCancelled {
		return nil, ErrTaskAlreadyCancelled
	}

	if err := s.taskRepo.Cancel(taskID); err != nil {
		return nil, err
	}

	// Reload
	task, err = s.taskRepo.FindByID(taskID)
	if err != nil {
		return nil, err
	}

	return &responses.TaskWithSummaryResponse{
		Data:    responses.NewTaskResponseWithTime(task, 30, now),
		Summary: s.getSummaryForUser(userID),
	}, nil
}

// UncancelTask uncancels a task.
// The `now` parameter should be the start of day in the user's timezone for accurate kanban categorization.
func (s *TaskService) UncancelTask(taskID, userID uint, now time.Time) (*responses.TaskWithSummaryResponse, error) {
	task, err := s.taskRepo.FindByID(taskID)
	if err != nil {
		if errors.Is(err, gorm.ErrRecordNotFound) {
			return nil, ErrTaskNotFound
		}
		return nil, err
	}

	// Check access
	hasAccess, err := s.residenceRepo.HasAccess(task.ResidenceID, userID)
	if err != nil {
		return nil, err
	}
	if !hasAccess {
		return nil, ErrTaskAccessDenied
	}

	if err := s.taskRepo.Uncancel(taskID); err != nil {
		return nil, err
	}

	// Reload
	task, err = s.taskRepo.FindByID(taskID)
	if err != nil {
		return nil, err
	}

	return &responses.TaskWithSummaryResponse{
		Data:    responses.NewTaskResponseWithTime(task, 30, now),
		Summary: s.getSummaryForUser(userID),
	}, nil
}

// ArchiveTask archives a task.
// The `now` parameter should be the start of day in the user's timezone for accurate kanban categorization.
func (s *TaskService) ArchiveTask(taskID, userID uint, now time.Time) (*responses.TaskWithSummaryResponse, error) {
	task, err := s.taskRepo.FindByID(taskID)
	if err != nil {
		if errors.Is(err, gorm.ErrRecordNotFound) {
			return nil, ErrTaskNotFound
		}
		return nil, err
	}

	// Check access
	hasAccess, err := s.residenceRepo.HasAccess(task.ResidenceID, userID)
	if err != nil {
		return nil, err
	}
	if !hasAccess {
		return nil, ErrTaskAccessDenied
	}

	if task.IsArchived {
		return nil, ErrTaskAlreadyArchived
	}

	if err := s.taskRepo.Archive(taskID); err != nil {
		return nil, err
	}

	// Reload
	task, err = s.taskRepo.FindByID(taskID)
	if err != nil {
		return nil, err
	}

	return &responses.TaskWithSummaryResponse{
		Data:    responses.NewTaskResponseWithTime(task, 30, now),
		Summary: s.getSummaryForUser(userID),
	}, nil
}

// UnarchiveTask unarchives a task.
// The `now` parameter should be the start of day in the user's timezone for accurate kanban categorization.
func (s *TaskService) UnarchiveTask(taskID, userID uint, now time.Time) (*responses.TaskWithSummaryResponse, error) {
	task, err := s.taskRepo.FindByID(taskID)
	if err != nil {
		if errors.Is(err, gorm.ErrRecordNotFound) {
			return nil, ErrTaskNotFound
		}
		return nil, err
	}

	// Check access
	hasAccess, err := s.residenceRepo.HasAccess(task.ResidenceID, userID)
	if err != nil {
		return nil, err
	}
	if !hasAccess {
		return nil, ErrTaskAccessDenied
	}

	if err := s.taskRepo.Unarchive(taskID); err != nil {
		return nil, err
	}

	// Reload
	task, err = s.taskRepo.FindByID(taskID)
	if err != nil {
		return nil, err
	}

	return &responses.TaskWithSummaryResponse{
		Data:    responses.NewTaskResponseWithTime(task, 30, now),
		Summary: s.getSummaryForUser(userID),
	}, nil
}

// === Task Completions ===

// CreateCompletion creates a task completion.
// The `now` parameter should be the start of day in the user's timezone for accurate kanban categorization.
func (s *TaskService) CreateCompletion(req *requests.CreateTaskCompletionRequest, userID uint, now time.Time) (*responses.TaskCompletionWithSummaryResponse, error) {
	// Get the task
	task, err := s.taskRepo.FindByID(req.TaskID)
	if err != nil {
		if errors.Is(err, gorm.ErrRecordNotFound) {
			return nil, ErrTaskNotFound
		}
		return nil, err
	}

	// Check access
	hasAccess, err := s.residenceRepo.HasAccess(task.ResidenceID, userID)
	if err != nil {
		return nil, err
	}
	if !hasAccess {
		return nil, ErrTaskAccessDenied
	}

	completedAt := time.Now().UTC()
	if req.CompletedAt != nil {
		completedAt = *req.CompletedAt
	}

	completion := &models.TaskCompletion{
		TaskID:        req.TaskID,
		CompletedByID: userID,
		CompletedAt:   completedAt,
		Notes:         req.Notes,
		ActualCost:    req.ActualCost,
		Rating:        req.Rating,
	}

	if err := s.taskRepo.CreateCompletion(completion); err != nil {
		return nil, err
	}

	// Update next_due_date and in_progress based on frequency
	// - If frequency is "Once" (days = nil or 0), set next_due_date to nil (marks as completed)
	// - If frequency is "Custom", use task.CustomIntervalDays for recurrence
	// - If frequency is recurring, calculate next_due_date = completion_date + frequency_days
	//   and reset in_progress to false so task shows in correct kanban column
	//
	// Note: Frequency is no longer preloaded for performance, so we load it separately if needed
	var intervalDays *int
	if task.FrequencyID != nil {
		frequency, err := s.taskRepo.GetFrequencyByID(*task.FrequencyID)
		if err == nil && frequency != nil {
			if frequency.Name == "Custom" {
				// Custom frequency - use task's custom_interval_days
				intervalDays = task.CustomIntervalDays
			} else {
				// Standard frequency - use frequency's days
				intervalDays = frequency.Days
			}
		}
	}

	if intervalDays == nil || *intervalDays == 0 {
		// One-time task - clear next_due_date (completion is determined by NextDueDate == nil + has completions)
		task.NextDueDate = nil
		task.InProgress = false
	} else {
		// Recurring task - calculate next due date from completion date + interval
		nextDue := completedAt.AddDate(0, 0, *intervalDays)
		task.NextDueDate = &nextDue

		// Reset in_progress to false so task appears in upcoming/due_soon
		// instead of staying in "In Progress" column
		task.InProgress = false
	}
	if err := s.taskRepo.Update(task); err != nil {
		log.Error().Err(err).Uint("task_id", task.ID).Msg("Failed to update task after completion")
	}

	// Create images if provided
	for _, imageURL := range req.ImageURLs {
		if imageURL != "" {
			img := &models.TaskCompletionImage{
				CompletionID: completion.ID,
				ImageURL:     imageURL,
			}
			if err := s.taskRepo.CreateCompletionImage(img); err != nil {
				log.Error().Err(err).Uint("completion_id", completion.ID).Msg("Failed to create completion image")
			}
		}
	}

	// Reload completion with user info and images
	completion, err = s.taskRepo.FindCompletionByID(completion.ID)
	if err != nil {
		return nil, err
	}

	// Reload task with updated completions (so client can update kanban column)
	task, err = s.taskRepo.FindByID(req.TaskID)
	if err != nil {
		// Non-fatal - still return the completion, just without the task
		log.Warn().Err(err).Uint("task_id", req.TaskID).Msg("Failed to reload task after completion")
		resp := responses.NewTaskCompletionResponse(completion)
		return &responses.TaskCompletionWithSummaryResponse{
			Data:    resp,
			Summary: s.getSummaryForUser(userID),
		}, nil
	}

	// Send notification to residence owner and other users
	s.sendTaskCompletedNotification(task, completion)

	// Return completion with updated task (includes kanban_column for UI update)
	resp := responses.NewTaskCompletionWithTaskResponseWithTime(completion, task, 30, now)
	return &responses.TaskCompletionWithSummaryResponse{
		Data:    resp,
		Summary: s.getSummaryForUser(userID),
	}, nil
}

// QuickComplete creates a minimal task completion (for widget use)
// Returns only success/error, no response body
func (s *TaskService) QuickComplete(taskID uint, userID uint) error {
	// Get the task
	task, err := s.taskRepo.FindByID(taskID)
	if err != nil {
		if errors.Is(err, gorm.ErrRecordNotFound) {
			return ErrTaskNotFound
		}
		return err
	}

	// Check access
	hasAccess, err := s.residenceRepo.HasAccess(task.ResidenceID, userID)
	if err != nil {
		return err
	}
	if !hasAccess {
		return ErrTaskAccessDenied
	}

	completedAt := time.Now().UTC()

	completion := &models.TaskCompletion{
		TaskID:        taskID,
		CompletedByID: userID,
		CompletedAt:   completedAt,
		Notes:         "Completed from widget",
	}

	if err := s.taskRepo.CreateCompletion(completion); err != nil {
		return err
	}

	// Update next_due_date and in_progress based on frequency
	// Determine interval days: Custom frequency uses task.CustomIntervalDays, otherwise use frequency.Days
	// Note: Frequency is no longer preloaded for performance, so we load it separately if needed
	var quickIntervalDays *int
	var frequencyName = "unknown"
	if task.FrequencyID != nil {
		frequency, err := s.taskRepo.GetFrequencyByID(*task.FrequencyID)
		if err == nil && frequency != nil {
			frequencyName = frequency.Name
			if frequency.Name == "Custom" {
				quickIntervalDays = task.CustomIntervalDays
			} else {
				quickIntervalDays = frequency.Days
			}
		}
	}

	if quickIntervalDays == nil || *quickIntervalDays == 0 {
		// One-time task - clear next_due_date (completion is determined by NextDueDate == nil + has completions)
		log.Info().
			Uint("task_id", task.ID).
			Bool("has_frequency", task.FrequencyID != nil).
			Msg("QuickComplete: One-time task, clearing next_due_date")
		task.NextDueDate = nil
		task.InProgress = false
	} else {
		// Recurring task - calculate next due date from completion date + interval
		nextDue := completedAt.AddDate(0, 0, *quickIntervalDays)
		// frequencyName was already set when loading frequency above
		log.Info().
			Uint("task_id", task.ID).
			Str("frequency_name", frequencyName).
			Int("interval_days", *quickIntervalDays).
			Time("completed_at", completedAt).
			Time("next_due_date", nextDue).
			Msg("QuickComplete: Recurring task, setting next_due_date")
		task.NextDueDate = &nextDue

		// Reset in_progress to false
		task.InProgress = false
	}
	if err := s.taskRepo.Update(task); err != nil {
		log.Error().Err(err).Uint("task_id", task.ID).Msg("Failed to update task after quick completion")
		return err // Return error so caller knows the update failed
	}
	log.Info().Uint("task_id", task.ID).Msg("QuickComplete: Task updated successfully")

	// Send notification (fire and forget)
	go s.sendTaskCompletedNotification(task, completion)

	return nil
}

// sendTaskCompletedNotification sends notifications when a task is completed
func (s *TaskService) sendTaskCompletedNotification(task *models.Task, completion *models.TaskCompletion) {
	// Get all users with access to this residence
	users, err := s.residenceRepo.GetResidenceUsers(task.ResidenceID)
	if err != nil {
		log.Error().Err(err).Uint("task_id", task.ID).Msg("Failed to get residence users for notification")
		return
	}

	// Get residence name
	residence, err := s.residenceRepo.FindByIDSimple(task.ResidenceID)
	residenceName := "your property"
	if err == nil && residence != nil {
		residenceName = residence.Name
	}

	completedByName := "Someone"
	if completion.CompletedBy.ID > 0 {
		completedByName = completion.CompletedBy.GetFullName()
	}

	// Notify all users
	for _, user := range users {
		isCompleter := user.ID == completion.CompletedByID

		// Send push notification (to everyone EXCEPT the person who completed it)
		if !isCompleter && s.notificationService != nil {
			go func(userID uint) {
				ctx := context.Background()
				if err := s.notificationService.CreateAndSendTaskNotification(
					ctx,
					userID,
					models.NotificationTaskCompleted,
					task,
				); err != nil {
					log.Error().Err(err).Uint("user_id", userID).Uint("task_id", task.ID).Msg("Failed to send task completion push notification")
				}
			}(user.ID)
		}

		// Send email notification (to everyone INCLUDING the person who completed it)
		// Check user's email notification preferences first
		if s.emailService != nil && user.Email != "" && s.notificationService != nil {
			prefs, err := s.notificationService.GetPreferences(user.ID)
			if err != nil || (prefs != nil && prefs.EmailTaskCompleted) {
				// Send email if we couldn't get prefs (fail-open) or if email notifications are enabled
				go func(u models.User) {
					if err := s.emailService.SendTaskCompletedEmail(
						u.Email,
						u.GetFullName(),
						task.Title,
						completedByName,
						residenceName,
					); err != nil {
						log.Error().Err(err).Str("email", u.Email).Uint("task_id", task.ID).Msg("Failed to send task completion email")
					} else {
						log.Info().Str("email", u.Email).Uint("task_id", task.ID).Msg("Task completion email sent")
					}
				}(user)
			}
		}
	}
}

// GetCompletion gets a task completion by ID
func (s *TaskService) GetCompletion(completionID, userID uint) (*responses.TaskCompletionResponse, error) {
	completion, err := s.taskRepo.FindCompletionByID(completionID)
	if err != nil {
		if errors.Is(err, gorm.ErrRecordNotFound) {
			return nil, ErrCompletionNotFound
		}
		return nil, err
	}

	// Check access via task's residence
	hasAccess, err := s.residenceRepo.HasAccess(completion.Task.ResidenceID, userID)
	if err != nil {
		return nil, err
	}
	if !hasAccess {
		return nil, ErrTaskAccessDenied
	}

	resp := responses.NewTaskCompletionResponse(completion)
	return &resp, nil
}

// ListCompletions lists all task completions for a user
func (s *TaskService) ListCompletions(userID uint) ([]responses.TaskCompletionResponse, error) {
	// Get all residence IDs (lightweight - no preloads)
	residenceIDs, err := s.residenceRepo.FindResidenceIDsByUser(userID)
	if err != nil {
		return nil, err
	}

	if len(residenceIDs) == 0 {
		return []responses.TaskCompletionResponse{}, nil
	}

	completions, err := s.taskRepo.FindCompletionsByUser(userID, residenceIDs)
	if err != nil {
		return nil, err
	}

	return responses.NewTaskCompletionListResponse(completions), nil
}

// DeleteCompletion deletes a task completion
func (s *TaskService) DeleteCompletion(completionID, userID uint) (*responses.DeleteWithSummaryResponse, error) {
	completion, err := s.taskRepo.FindCompletionByID(completionID)
	if err != nil {
		if errors.Is(err, gorm.ErrRecordNotFound) {
			return nil, ErrCompletionNotFound
		}
		return nil, err
	}

	// Check access
	hasAccess, err := s.residenceRepo.HasAccess(completion.Task.ResidenceID, userID)
	if err != nil {
		return nil, err
	}
	if !hasAccess {
		return nil, ErrTaskAccessDenied
	}

	if err := s.taskRepo.DeleteCompletion(completionID); err != nil {
		return nil, err
	}

	return &responses.DeleteWithSummaryResponse{
		Data:    "completion deleted",
		Summary: s.getSummaryForUser(userID),
	}, nil
}

// GetCompletionsByTask gets all completions for a specific task
func (s *TaskService) GetCompletionsByTask(taskID, userID uint) ([]responses.TaskCompletionResponse, error) {
	// Get the task to check access
	task, err := s.taskRepo.FindByID(taskID)
	if err != nil {
		if errors.Is(err, gorm.ErrRecordNotFound) {
			return nil, ErrTaskNotFound
		}
		return nil, err
	}

	// Check access via residence
	hasAccess, err := s.residenceRepo.HasAccess(task.ResidenceID, userID)
	if err != nil {
		return nil, err
	}
	if !hasAccess {
		return nil, ErrTaskAccessDenied
	}

	// Get completions for the task
	completions, err := s.taskRepo.FindCompletionsByTask(taskID)
	if err != nil {
		return nil, err
	}

	return responses.NewTaskCompletionListResponse(completions), nil
}

// === Lookups ===

// GetCategories returns all task categories
func (s *TaskService) GetCategories() ([]responses.TaskCategoryResponse, error) {
	categories, err := s.taskRepo.GetAllCategories()
	if err != nil {
		return nil, err
	}

	result := make([]responses.TaskCategoryResponse, len(categories))
	for i, c := range categories {
		result[i] = *responses.NewTaskCategoryResponse(&c)
	}
	return result, nil
}

// GetPriorities returns all task priorities
func (s *TaskService) GetPriorities() ([]responses.TaskPriorityResponse, error) {
	priorities, err := s.taskRepo.GetAllPriorities()
	if err != nil {
		return nil, err
	}

	result := make([]responses.TaskPriorityResponse, len(priorities))
	for i, p := range priorities {
		result[i] = *responses.NewTaskPriorityResponse(&p)
	}
	return result, nil
}

// GetFrequencies returns all task frequencies
func (s *TaskService) GetFrequencies() ([]responses.TaskFrequencyResponse, error) {
	frequencies, err := s.taskRepo.GetAllFrequencies()
	if err != nil {
		return nil, err
	}

	result := make([]responses.TaskFrequencyResponse, len(frequencies))
	for i, f := range frequencies {
		result[i] = *responses.NewTaskFrequencyResponse(&f)
	}
	return result, nil
}