package repository

import (
	"database/sql"
	"errors"
	"time"

	"github.com/daniil/homelab-api/internal/model"
	"github.com/jmoiron/sqlx"
)

var ErrTaskNotFound = errors.New("task not found")

type TaskRepository struct {
	db *sqlx.DB
}

func NewTaskRepository(db *sqlx.DB) *TaskRepository {
	return &TaskRepository{db: db}
}

func (r *TaskRepository) Create(task *model.Task) error {
	query := `
		INSERT INTO tasks (user_id, title, description, icon, color, due_date, priority, reminder_time)
		VALUES ($1, $2, $3, $4, $5, $6, $7, $8)
		RETURNING id, created_at, updated_at`

	return r.db.QueryRow(query,
		task.UserID,
		task.Title,
		task.Description,
		task.Icon,
		task.Color,
		task.DueDate,
		task.Priority,
		task.ReminderTime,
	).Scan(&task.ID, &task.CreatedAt, &task.UpdatedAt)
}

func (r *TaskRepository) GetByID(id, userID int64) (*model.Task, error) {
	var task model.Task

	query := `
		SELECT id, user_id, title, description, icon, color, due_date, priority, reminder_time, completed_at, created_at, updated_at
		FROM tasks WHERE id = $1 AND user_id = $2`

	err := r.db.QueryRow(query, id, userID).Scan(
		&task.ID, &task.UserID, &task.Title, &task.Description,
		&task.Icon, &task.Color, &task.DueDate, &task.Priority,
		&task.ReminderTime, &task.CompletedAt, &task.CreatedAt, &task.UpdatedAt,
	)

	if err != nil {
		if errors.Is(err, sql.ErrNoRows) {
			return nil, ErrTaskNotFound
		}
		return nil, err
	}

	task.ProcessForJSON()
	return &task, nil
}

func (r *TaskRepository) ListByUser(userID int64, completed *bool) ([]model.Task, error) {
	query := `
		SELECT id, user_id, title, description, icon, color, due_date, priority, reminder_time, completed_at, created_at, updated_at
		FROM tasks WHERE user_id = $1`

	if completed != nil {
		if *completed {
			query += " AND completed_at IS NOT NULL"
		} else {
			query += " AND completed_at IS NULL"
		}
	}
	query += " ORDER BY COALESCE(due_date, '9999-12-31'::date), priority DESC, created_at DESC"

	rows, err := r.db.Query(query, userID)
	if err != nil {
		return nil, err
	}
	defer rows.Close()

	var tasks []model.Task
	for rows.Next() {
		var task model.Task

		if err := rows.Scan(
			&task.ID, &task.UserID, &task.Title, &task.Description,
			&task.Icon, &task.Color, &task.DueDate, &task.Priority,
			&task.ReminderTime, &task.CompletedAt, &task.CreatedAt, &task.UpdatedAt,
		); err != nil {
			return nil, err
		}

		task.ProcessForJSON()
		tasks = append(tasks, task)
	}

	return tasks, nil
}

func (r *TaskRepository) GetTodayTasks(userID int64) ([]model.Task, error) {
	today := time.Now().Format("2006-01-02")
	
	query := `
		SELECT id, user_id, title, description, icon, color, due_date, priority, reminder_time, completed_at, created_at, updated_at
		FROM tasks 
		WHERE user_id = $1 AND completed_at IS NULL AND due_date <= $2
		ORDER BY priority DESC, due_date, created_at`

	rows, err := r.db.Query(query, userID, today)
	if err != nil {
		return nil, err
	}
	defer rows.Close()

	var tasks []model.Task
	for rows.Next() {
		var task model.Task

		if err := rows.Scan(
			&task.ID, &task.UserID, &task.Title, &task.Description,
			&task.Icon, &task.Color, &task.DueDate, &task.Priority,
			&task.ReminderTime, &task.CompletedAt, &task.CreatedAt, &task.UpdatedAt,
		); err != nil {
			return nil, err
		}

		task.ProcessForJSON()
		tasks = append(tasks, task)
	}

	return tasks, nil
}

func (r *TaskRepository) GetTasksWithReminder(reminderTime string, date string) ([]model.Task, error) {
	query := `
		SELECT t.id, t.user_id, t.title, t.description, t.icon, t.color, t.due_date, t.priority, t.reminder_time, t.completed_at, t.created_at, t.updated_at
		FROM tasks t
		JOIN users u ON t.user_id = u.id
		WHERE t.reminder_time = $1
		AND t.completed_at IS NULL
		AND (t.due_date IS NULL OR t.due_date >= $2)
		AND u.telegram_chat_id IS NOT NULL
		AND u.notifications_enabled = true`

	rows, err := r.db.Query(query, reminderTime, date)
	if err != nil {
		return nil, err
	}
	defer rows.Close()

	var tasks []model.Task
	for rows.Next() {
		var task model.Task
		if err := rows.Scan(
			&task.ID, &task.UserID, &task.Title, &task.Description,
			&task.Icon, &task.Color, &task.DueDate, &task.Priority,
			&task.ReminderTime, &task.CompletedAt, &task.CreatedAt, &task.UpdatedAt,
		); err != nil {
			return nil, err
		}
		task.ProcessForJSON()
		tasks = append(tasks, task)
	}

	return tasks, nil
}

func (r *TaskRepository) Update(task *model.Task) error {
	query := `
		UPDATE tasks 
		SET title = $2, description = $3, icon = $4, color = $5, due_date = $6, priority = $7, reminder_time = $8, updated_at = CURRENT_TIMESTAMP
		WHERE id = $1 AND user_id = $9
		RETURNING updated_at`

	return r.db.QueryRow(query,
		task.ID,
		task.Title,
		task.Description,
		task.Icon,
		task.Color,
		task.DueDate,
		task.Priority,
		task.ReminderTime,
		task.UserID,
	).Scan(&task.UpdatedAt)
}

func (r *TaskRepository) Delete(id, userID int64) error {
	query := `DELETE FROM tasks WHERE id = $1 AND user_id = $2`
	result, err := r.db.Exec(query, id, userID)
	if err != nil {
		return err
	}

	rows, _ := result.RowsAffected()
	if rows == 0 {
		return ErrTaskNotFound
	}

	return nil
}

func (r *TaskRepository) Complete(id, userID int64) error {
	query := `UPDATE tasks SET completed_at = CURRENT_TIMESTAMP, updated_at = CURRENT_TIMESTAMP WHERE id = $1 AND user_id = $2 AND completed_at IS NULL`
	result, err := r.db.Exec(query, id, userID)
	if err != nil {
		return err
	}

	rows, _ := result.RowsAffected()
	if rows == 0 {
		return ErrTaskNotFound
	}

	return nil
}

func (r *TaskRepository) Uncomplete(id, userID int64) error {
	query := `UPDATE tasks SET completed_at = NULL, updated_at = CURRENT_TIMESTAMP WHERE id = $1 AND user_id = $2 AND completed_at IS NOT NULL`
	result, err := r.db.Exec(query, id, userID)
	if err != nil {
		return err
	}

	rows, _ := result.RowsAffected()
	if rows == 0 {
		return ErrTaskNotFound
	}

	return nil
}