package repositories

import (
	"fmt"
	"time"

	"gorm.io/gorm"

	"github.com/treytartt/casera-api/internal/models"
	"github.com/treytartt/casera-api/internal/task"
	"github.com/treytartt/casera-api/internal/task/categorization"
)

// TaskRepository handles database operations for tasks
type TaskRepository struct {
	db *gorm.DB
}

// NewTaskRepository creates a new task repository
func NewTaskRepository(db *gorm.DB) *TaskRepository {
	return &TaskRepository{db: db}
}

// === Task Filter Options ===

// TaskFilterOptions provides flexible filtering for task queries.
// Use exactly one of ResidenceID, ResidenceIDs, or UserIDs to specify the filter scope.
type TaskFilterOptions struct {
	// Filter by single residence (kanban single-residence view)
	ResidenceID uint

	// Filter by multiple residences (kanban all-residences view)
	ResidenceIDs []uint

	// Filter by users - matches tasks where assigned_to IN userIDs
	// OR residence owner IN userIDs (for notifications)
	UserIDs []uint

	// Include archived tasks (default: false, excludes archived)
	IncludeArchived bool

	// IncludeInProgress controls whether in-progress tasks are included in
	// overdue/due-soon/upcoming queries. Default is false (excludes in-progress)
	// for kanban column consistency. Set to true for notifications where
	// users should still be notified about in-progress tasks that are overdue.
	IncludeInProgress bool

	// Preload options
	PreloadCreatedBy   bool
	PreloadAssignedTo  bool
	PreloadResidence   bool
	PreloadCompletions bool // Minimal: just id, task_id, completed_at
}

// applyFilterOptions applies the filter options to a query.
// Returns a new query with filters and preloads applied.
func (r *TaskRepository) applyFilterOptions(query *gorm.DB, opts TaskFilterOptions) *gorm.DB {
	// Apply residence/user filters
	if opts.ResidenceID != 0 {
		query = query.Where("task_task.residence_id = ?", opts.ResidenceID)
	} else if len(opts.ResidenceIDs) > 0 {
		query = query.Where("task_task.residence_id IN ?", opts.ResidenceIDs)
	} else if len(opts.UserIDs) > 0 {
		// For notifications: tasks assigned to users OR owned by users
		query = query.Where(
			"(task_task.assigned_to_id IN ? OR task_task.residence_id IN (SELECT id FROM residence_residence WHERE owner_id IN ?))",
			opts.UserIDs, opts.UserIDs,
		)
	}

	// Apply archived filter (default excludes archived)
	if !opts.IncludeArchived {
		query = query.Where("task_task.is_archived = ?", false)
	}

	// Apply preloads
	if opts.PreloadCreatedBy {
		query = query.Preload("CreatedBy")
	}
	if opts.PreloadAssignedTo {
		query = query.Preload("AssignedTo")
	}
	if opts.PreloadResidence {
		query = query.Preload("Residence")
	}
	if opts.PreloadCompletions {
		query = query.Preload("Completions", func(db *gorm.DB) *gorm.DB {
			return db.Select("id", "task_id", "completed_at")
		})
	}

	return query
}

// === Single-Purpose Task Query Functions ===
// These functions use the scopes from internal/task/scopes for consistent filtering.
// They are the single source of truth for task categorization queries, used by both
// kanban and notification handlers.

// GetOverdueTasks returns active, non-completed tasks past their effective due date.
// Uses task.ScopeOverdue for consistent filtering logic.
// The `now` parameter should be in the user's timezone for accurate overdue detection.
//
// By default, excludes in-progress tasks for kanban column consistency.
// Set opts.IncludeInProgress=true for notifications where in-progress tasks should still appear.
func (r *TaskRepository) GetOverdueTasks(now time.Time, opts TaskFilterOptions) ([]models.Task, error) {
	var tasks []models.Task
	query := r.db.Model(&models.Task{})

	if opts.IncludeArchived {
		// When including archived, build the query manually to skip the archived check
		// but still apply cancelled check, not-completed check, and date check
		startOfDay := time.Date(now.Year(), now.Month(), now.Day(), 0, 0, 0, 0, now.Location())
		query = query.Where("is_cancelled = ?", false).
			Scopes(task.ScopeNotCompleted).
			Where("COALESCE(next_due_date, due_date) < ?", startOfDay)
	} else {
		// Use the combined scope which includes is_archived = false
		query = query.Scopes(task.ScopeOverdue(now))
	}

	query = query.Scopes(task.ScopeKanbanOrder)
	if !opts.IncludeInProgress {
		query = query.Scopes(task.ScopeNotInProgress)
	}
	query = r.applyFilterOptions(query, opts)
	err := query.Find(&tasks).Error
	return tasks, err
}

// GetDueSoonTasks returns active, non-completed tasks due within the threshold.
// Uses task.ScopeDueSoon for consistent filtering logic.
// The `now` parameter should be in the user's timezone for accurate detection.
//
// By default, excludes in-progress tasks for kanban column consistency.
// Set opts.IncludeInProgress=true for notifications where in-progress tasks should still appear.
func (r *TaskRepository) GetDueSoonTasks(now time.Time, daysThreshold int, opts TaskFilterOptions) ([]models.Task, error) {
	var tasks []models.Task
	query := r.db.Model(&models.Task{}).
		Scopes(task.ScopeDueSoon(now, daysThreshold), task.ScopeKanbanOrder)
	if !opts.IncludeInProgress {
		query = query.Scopes(task.ScopeNotInProgress)
	}
	query = r.applyFilterOptions(query, opts)
	err := query.Find(&tasks).Error
	return tasks, err
}

// GetInProgressTasks returns active, non-completed tasks marked as in-progress.
// Uses task.ScopeInProgress for consistent filtering logic.
//
// Note: Excludes completed tasks to match kanban column behavior (completed has higher priority).
func (r *TaskRepository) GetInProgressTasks(opts TaskFilterOptions) ([]models.Task, error) {
	var tasks []models.Task
	query := r.db.Model(&models.Task{}).
		Scopes(task.ScopeActive, task.ScopeNotCompleted, task.ScopeInProgress, task.ScopeKanbanOrder)
	query = r.applyFilterOptions(query, opts)
	err := query.Find(&tasks).Error
	return tasks, err
}

// GetUpcomingTasks returns active, non-completed tasks due after the threshold or with no due date.
// Uses task.ScopeUpcoming for consistent filtering logic.
//
// By default, excludes in-progress tasks for kanban column consistency.
// Set opts.IncludeInProgress=true for notifications where in-progress tasks should still appear.
func (r *TaskRepository) GetUpcomingTasks(now time.Time, daysThreshold int, opts TaskFilterOptions) ([]models.Task, error) {
	var tasks []models.Task
	query := r.db.Model(&models.Task{}).
		Scopes(task.ScopeUpcoming(now, daysThreshold), task.ScopeKanbanOrder)
	if !opts.IncludeInProgress {
		query = query.Scopes(task.ScopeNotInProgress)
	}
	query = r.applyFilterOptions(query, opts)
	err := query.Find(&tasks).Error
	return tasks, err
}

// GetCompletedTasks returns completed tasks (NextDueDate nil with at least one completion).
// Uses task.ScopeCompleted for consistent filtering logic.
func (r *TaskRepository) GetCompletedTasks(opts TaskFilterOptions) ([]models.Task, error) {
	var tasks []models.Task
	// Completed tasks: not cancelled, has completion, no next due date
	// Note: We don't apply ScopeActive because completed tasks may not be "active" in that sense
	query := r.db.Model(&models.Task{}).
		Where("is_cancelled = ?", false).
		Scopes(task.ScopeCompleted, task.ScopeKanbanOrder)
	query = r.applyFilterOptions(query, opts)
	err := query.Find(&tasks).Error
	return tasks, err
}

// GetCancelledTasks returns cancelled OR archived tasks.
// Archived tasks are grouped with cancelled for kanban purposes - they both represent
// tasks that are no longer active/actionable.
func (r *TaskRepository) GetCancelledTasks(opts TaskFilterOptions) ([]models.Task, error) {
	var tasks []models.Task
	// Include both cancelled and archived tasks in this column
	// Archived tasks should ONLY appear here, not in any other column
	query := r.db.Model(&models.Task{}).
		Where("is_cancelled = ? OR is_archived = ?", true, true).
		Scopes(task.ScopeKanbanOrder)

	// Override IncludeArchived to true since this function specifically handles archived tasks
	opts.IncludeArchived = true
	query = r.applyFilterOptions(query, opts)
	err := query.Find(&tasks).Error
	return tasks, err
}

// === Task CRUD ===

// FindByID finds a task by ID with preloaded relations
// Note: Category, Priority, Frequency are NOT preloaded - client resolves from cache using IDs
func (r *TaskRepository) FindByID(id uint) (*models.Task, error) {
	var task models.Task
	err := r.db.Preload("Residence").
		Preload("CreatedBy").
		Preload("AssignedTo").
		Preload("Completions").
		Preload("Completions.Images").
		Preload("Completions.CompletedBy").
		First(&task, id).Error
	if err != nil {
		return nil, err
	}
	return &task, nil
}

// FindByResidence finds all tasks for a residence
// Note: Category, Priority, Frequency are NOT preloaded - client resolves from cache using IDs
func (r *TaskRepository) FindByResidence(residenceID uint) ([]models.Task, error) {
	var tasks []models.Task
	err := r.db.Preload("CreatedBy").
		Preload("AssignedTo").
		Preload("Completions").
		Preload("Completions.Images").
		Preload("Completions.CompletedBy").
		Where("residence_id = ?", residenceID).
		Order("due_date ASC NULLS LAST, created_at DESC").
		Find(&tasks).Error
	return tasks, err
}

// FindByUser finds all tasks accessible to a user (across all their residences)
// Note: Category, Priority, Frequency are NOT preloaded - client resolves from cache using IDs
func (r *TaskRepository) FindByUser(userID uint, residenceIDs []uint) ([]models.Task, error) {
	var tasks []models.Task
	err := r.db.Preload("Residence").
		Preload("CreatedBy").
		Preload("AssignedTo").
		Preload("Completions").
		Preload("Completions.Images").
		Preload("Completions.CompletedBy").
		Where("residence_id IN ?", residenceIDs).
		Order("due_date ASC NULLS LAST, created_at DESC").
		Find(&tasks).Error
	return tasks, err
}

// Create creates a new task
func (r *TaskRepository) Create(task *models.Task) error {
	return r.db.Create(task).Error
}

// Update updates a task
// Uses Omit to exclude associations that shouldn't be updated via Save
func (r *TaskRepository) Update(task *models.Task) error {
	return r.db.Omit("Residence", "CreatedBy", "AssignedTo", "Category", "Priority", "Frequency", "ParentTask", "Completions").Save(task).Error
}

// Delete hard-deletes a task
func (r *TaskRepository) Delete(id uint) error {
	return r.db.Delete(&models.Task{}, id).Error
}

// === Task State Operations ===

// MarkInProgress marks a task as in progress
func (r *TaskRepository) MarkInProgress(id uint) error {
	return r.db.Model(&models.Task{}).
		Where("id = ?", id).
		Update("in_progress", true).Error
}

// Cancel cancels a task
func (r *TaskRepository) Cancel(id uint) error {
	return r.db.Model(&models.Task{}).
		Where("id = ?", id).
		Update("is_cancelled", true).Error
}

// Uncancel uncancels a task
func (r *TaskRepository) Uncancel(id uint) error {
	return r.db.Model(&models.Task{}).
		Where("id = ?", id).
		Update("is_cancelled", false).Error
}

// Archive archives a task
func (r *TaskRepository) Archive(id uint) error {
	return r.db.Model(&models.Task{}).
		Where("id = ?", id).
		Update("is_archived", true).Error
}

// Unarchive unarchives a task
func (r *TaskRepository) Unarchive(id uint) error {
	return r.db.Model(&models.Task{}).
		Where("id = ?", id).
		Update("is_archived", false).Error
}

// === Kanban Board ===

// buildKanbanColumns builds the kanban column array from categorized task slices.
// This is a helper function to reduce duplication between GetKanbanData and GetKanbanDataForMultipleResidences.
func buildKanbanColumns(
	overdue, inProgress, dueSoon, upcoming, completed, cancelled []models.Task,
) []models.KanbanColumn {
	return []models.KanbanColumn{
		{
			Name:        string(categorization.ColumnOverdue),
			DisplayName: "Overdue",
			ButtonTypes: []string{"edit", "complete", "cancel", "mark_in_progress"},
			Icons:       map[string]string{"ios": "exclamationmark.triangle", "android": "Warning"},
			Color:       "#FF3B30",
			Tasks:       overdue,
			Count:       len(overdue),
		},
		{
			Name:        string(categorization.ColumnInProgress),
			DisplayName: "In Progress",
			ButtonTypes: []string{"edit", "complete", "cancel"},
			Icons:       map[string]string{"ios": "hammer", "android": "Build"},
			Color:       "#5856D6",
			Tasks:       inProgress,
			Count:       len(inProgress),
		},
		{
			Name:        string(categorization.ColumnDueSoon),
			DisplayName: "Due Soon",
			ButtonTypes: []string{"edit", "complete", "cancel", "mark_in_progress"},
			Icons:       map[string]string{"ios": "clock", "android": "Schedule"},
			Color:       "#FF9500",
			Tasks:       dueSoon,
			Count:       len(dueSoon),
		},
		{
			Name:        string(categorization.ColumnUpcoming),
			DisplayName: "Upcoming",
			ButtonTypes: []string{"edit", "complete", "cancel", "mark_in_progress"},
			Icons:       map[string]string{"ios": "calendar", "android": "Event"},
			Color:       "#007AFF",
			Tasks:       upcoming,
			Count:       len(upcoming),
		},
		{
			Name:        string(categorization.ColumnCompleted),
			DisplayName: "Completed",
			ButtonTypes: []string{},
			Icons:       map[string]string{"ios": "checkmark.circle", "android": "CheckCircle"},
			Color:       "#34C759",
			Tasks:       completed,
			Count:       len(completed),
		},
		{
			Name:        string(categorization.ColumnCancelled),
			DisplayName: "Cancelled",
			ButtonTypes: []string{"uncancel", "delete"},
			Icons:       map[string]string{"ios": "xmark.circle", "android": "Cancel"},
			Color:       "#8E8E93",
			Tasks:       cancelled,
			Count:       len(cancelled),
		},
	}
}

// GetKanbanData retrieves tasks organized for kanban display.
// Uses single-purpose query functions for each column type, ensuring consistency
// with notification handlers that use the same functions.
// The `now` parameter should be the start of day in the user's timezone for accurate overdue detection.
//
// Optimization: Preloads only minimal completion data (id, task_id, completed_at) for count/detection.
// Images and CompletedBy are NOT preloaded - fetch separately when viewing completion details.
func (r *TaskRepository) GetKanbanData(residenceID uint, daysThreshold int, now time.Time) (*models.KanbanBoard, error) {
	opts := TaskFilterOptions{
		ResidenceID:        residenceID,
		PreloadCreatedBy:   true,
		PreloadAssignedTo:  true,
		PreloadCompletions: true,
	}

	// Query each column using single-purpose functions
	// These functions use the same scopes as notification handlers for consistency
	overdue, err := r.GetOverdueTasks(now, opts)
	if err != nil {
		return nil, fmt.Errorf("get overdue tasks: %w", err)
	}

	inProgress, err := r.GetInProgressTasks(opts)
	if err != nil {
		return nil, fmt.Errorf("get in-progress tasks: %w", err)
	}

	dueSoon, err := r.GetDueSoonTasks(now, daysThreshold, opts)
	if err != nil {
		return nil, fmt.Errorf("get due-soon tasks: %w", err)
	}

	upcoming, err := r.GetUpcomingTasks(now, daysThreshold, opts)
	if err != nil {
		return nil, fmt.Errorf("get upcoming tasks: %w", err)
	}

	completed, err := r.GetCompletedTasks(opts)
	if err != nil {
		return nil, fmt.Errorf("get completed tasks: %w", err)
	}

	cancelled, err := r.GetCancelledTasks(opts)
	if err != nil {
		return nil, fmt.Errorf("get cancelled tasks: %w", err)
	}

	columns := buildKanbanColumns(overdue, inProgress, dueSoon, upcoming, completed, cancelled)

	return &models.KanbanBoard{
		Columns:       columns,
		DaysThreshold: daysThreshold,
		ResidenceID:   fmt.Sprintf("%d", residenceID),
	}, nil
}

// GetKanbanDataForMultipleResidences retrieves tasks from multiple residences organized for kanban display.
// Uses single-purpose query functions for each column type, ensuring consistency
// with notification handlers that use the same functions.
// The `now` parameter should be the start of day in the user's timezone for accurate overdue detection.
//
// Optimization: Preloads only minimal completion data (id, task_id, completed_at) for count/detection.
// Images and CompletedBy are NOT preloaded - fetch separately when viewing completion details.
func (r *TaskRepository) GetKanbanDataForMultipleResidences(residenceIDs []uint, daysThreshold int, now time.Time) (*models.KanbanBoard, error) {
	opts := TaskFilterOptions{
		ResidenceIDs:       residenceIDs,
		PreloadCreatedBy:   true,
		PreloadAssignedTo:  true,
		PreloadResidence:   true,
		PreloadCompletions: true,
	}

	// Query each column using single-purpose functions
	// These functions use the same scopes as notification handlers for consistency
	overdue, err := r.GetOverdueTasks(now, opts)
	if err != nil {
		return nil, fmt.Errorf("get overdue tasks: %w", err)
	}

	inProgress, err := r.GetInProgressTasks(opts)
	if err != nil {
		return nil, fmt.Errorf("get in-progress tasks: %w", err)
	}

	dueSoon, err := r.GetDueSoonTasks(now, daysThreshold, opts)
	if err != nil {
		return nil, fmt.Errorf("get due-soon tasks: %w", err)
	}

	upcoming, err := r.GetUpcomingTasks(now, daysThreshold, opts)
	if err != nil {
		return nil, fmt.Errorf("get upcoming tasks: %w", err)
	}

	completed, err := r.GetCompletedTasks(opts)
	if err != nil {
		return nil, fmt.Errorf("get completed tasks: %w", err)
	}

	cancelled, err := r.GetCancelledTasks(opts)
	if err != nil {
		return nil, fmt.Errorf("get cancelled tasks: %w", err)
	}

	columns := buildKanbanColumns(overdue, inProgress, dueSoon, upcoming, completed, cancelled)

	return &models.KanbanBoard{
		Columns:       columns,
		DaysThreshold: daysThreshold,
		ResidenceID:   "all",
	}, nil
}

// === Lookup Operations ===

// GetAllCategories returns all task categories
func (r *TaskRepository) GetAllCategories() ([]models.TaskCategory, error) {
	var categories []models.TaskCategory
	err := r.db.Order("display_order, name").Find(&categories).Error
	return categories, err
}

// GetAllPriorities returns all task priorities
func (r *TaskRepository) GetAllPriorities() ([]models.TaskPriority, error) {
	var priorities []models.TaskPriority
	err := r.db.Order("level").Find(&priorities).Error
	return priorities, err
}

// GetAllFrequencies returns all task frequencies
func (r *TaskRepository) GetAllFrequencies() ([]models.TaskFrequency, error) {
	var frequencies []models.TaskFrequency
	err := r.db.Order("display_order").Find(&frequencies).Error
	return frequencies, err
}

// GetFrequencyByID retrieves a single frequency by ID
func (r *TaskRepository) GetFrequencyByID(id uint) (*models.TaskFrequency, error) {
	var frequency models.TaskFrequency
	err := r.db.First(&frequency, id).Error
	if err != nil {
		return nil, err
	}
	return &frequency, nil
}

// CountByResidence counts tasks in a residence
func (r *TaskRepository) CountByResidence(residenceID uint) (int64, error) {
	var count int64
	err := r.db.Model(&models.Task{}).
		Where("residence_id = ? AND is_cancelled = ? AND is_archived = ?", residenceID, false, false).
		Count(&count).Error
	return count, err
}

// === Task Completion Operations ===

// CreateCompletion creates a new task completion
func (r *TaskRepository) CreateCompletion(completion *models.TaskCompletion) error {
	return r.db.Create(completion).Error
}

// FindCompletionByID finds a completion by ID
func (r *TaskRepository) FindCompletionByID(id uint) (*models.TaskCompletion, error) {
	var completion models.TaskCompletion
	err := r.db.Preload("Task").
		Preload("CompletedBy").
		Preload("Images").
		First(&completion, id).Error
	if err != nil {
		return nil, err
	}
	return &completion, nil
}

// FindCompletionsByTask finds all completions for a task
func (r *TaskRepository) FindCompletionsByTask(taskID uint) ([]models.TaskCompletion, error) {
	var completions []models.TaskCompletion
	err := r.db.Preload("CompletedBy").
		Preload("Images").
		Where("task_id = ?", taskID).
		Order("completed_at DESC").
		Find(&completions).Error
	return completions, err
}

// FindCompletionsByUser finds all completions by a user
func (r *TaskRepository) FindCompletionsByUser(userID uint, residenceIDs []uint) ([]models.TaskCompletion, error) {
	var completions []models.TaskCompletion
	err := r.db.Preload("Task").
		Preload("CompletedBy").
		Preload("Images").
		Joins("JOIN task_task ON task_task.id = task_taskcompletion.task_id").
		Where("task_task.residence_id IN ?", residenceIDs).
		Order("completed_at DESC").
		Find(&completions).Error
	return completions, err
}

// DeleteCompletion deletes a task completion
func (r *TaskRepository) DeleteCompletion(id uint) error {
	// Delete images first
	r.db.Where("completion_id = ?", id).Delete(&models.TaskCompletionImage{})
	return r.db.Delete(&models.TaskCompletion{}, id).Error
}

// CreateCompletionImage creates a new completion image
func (r *TaskRepository) CreateCompletionImage(image *models.TaskCompletionImage) error {
	return r.db.Create(image).Error
}

// DeleteCompletionImage deletes a completion image
func (r *TaskRepository) DeleteCompletionImage(id uint) error {
	return r.db.Delete(&models.TaskCompletionImage{}, id).Error
}

// FindCompletionImageByID finds a completion image by ID
func (r *TaskRepository) FindCompletionImageByID(id uint) (*models.TaskCompletionImage, error) {
	var image models.TaskCompletionImage
	err := r.db.First(&image, id).Error
	if err != nil {
		return nil, err
	}
	return &image, nil
}

// GetOverdueCountByResidence returns a map of residence ID to overdue task count.
// Uses the task.scopes package for consistent filtering logic.
// The `now` parameter should be the start of day in the user's timezone for accurate overdue detection.
func (r *TaskRepository) GetOverdueCountByResidence(residenceIDs []uint, now time.Time) (map[uint]int, error) {
	if len(residenceIDs) == 0 {
		return map[uint]int{}, nil
	}

	// Query to get overdue count grouped by residence
	type result struct {
		ResidenceID uint
		Count       int64
	}
	var results []result

	err := r.db.Model(&models.Task{}).
		Select("residence_id, COUNT(*) as count").
		Scopes(task.ScopeForResidences(residenceIDs), task.ScopeOverdue(now)).
		Group("residence_id").
		Scan(&results).Error
	if err != nil {
		return nil, err
	}

	// Convert to map
	countMap := make(map[uint]int)
	for _, r := range results {
		countMap[r.ResidenceID] = int(r.Count)
	}

	return countMap, nil
}