package db

import (
	"database/sql"
	"errors"
)

// GetAllTasks retrieves all tasks from the database
func GetAllTasks() ([]Task, error) {
	var tasks []Task
	query := `SELECT "TaskID", "TaskName", "TaskDescription", "GroupID", "IsDone", "CreatedAt" 
			  FROM "Tasks" ORDER BY "CreatedAt" DESC`

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

	for rows.Next() {
		var task Task
		err := rows.Scan(&task.TaskID, &task.TaskName, &task.TaskDescription,
			&task.GroupID, &task.IsDone, &task.CreatedAt)
		if err != nil {
			return nil, err
		}
		tasks = append(tasks, task)
	}

	return tasks, nil
}

// GetTasksByGroupID retrieves all tasks for a specific group
func GetTasksByGroupID(groupID int) ([]Task, error) {
	var tasks []Task
	query := `SELECT "TaskID", "TaskName", "TaskDescription", "GroupID", "IsDone", "CreatedAt" 
			  FROM "Tasks" WHERE "GroupID" = $1 ORDER BY "CreatedAt" DESC`

	rows, err := DB.Query(query, groupID)
	if err != nil {
		return nil, err
	}
	defer rows.Close()

	for rows.Next() {
		var task Task
		err := rows.Scan(&task.TaskID, &task.TaskName, &task.TaskDescription,
			&task.GroupID, &task.IsDone, &task.CreatedAt)
		if err != nil {
			return nil, err
		}
		tasks = append(tasks, task)
	}

	return tasks, nil
}

// GetTaskByID retrieves a single task by ID
func GetTaskByID(taskID int) (*Task, error) {
	var task Task
	query := `SELECT "TaskID", "TaskName", "TaskDescription", "GroupID", "IsDone", "CreatedAt" 
			  FROM "Tasks" WHERE "TaskID" = $1`

	err := DB.QueryRow(query, taskID).Scan(&task.TaskID, &task.TaskName,
		&task.TaskDescription, &task.GroupID,
		&task.IsDone, &task.CreatedAt)
	if err != nil {
		if err == sql.ErrNoRows {
			return nil, errors.New("task not found")
		}
		return nil, err
	}

	return &task, nil
}

// CreateTask creates a new task in the database
func CreateTask(taskName string, taskDescription *string, groupID int) (*Task, error) {
	var task Task
	query := `INSERT INTO "Tasks" ("TaskName", "TaskDescription", "GroupID") 
			  VALUES ($1, $2, $3) RETURNING "TaskID", "TaskName", "TaskDescription", "GroupID", "IsDone", "CreatedAt"`

	err := DB.QueryRow(query, taskName, taskDescription, groupID).
		Scan(&task.TaskID, &task.TaskName, &task.TaskDescription,
			&task.GroupID, &task.IsDone, &task.CreatedAt)
	if err != nil {
		return nil, err
	}

	return &task, nil
}

// UpdateTask updates an existing task
func UpdateTask(taskID int, taskName string, taskDescription *string) error {
	query := `UPDATE "Tasks" SET "TaskName" = $1, "TaskDescription" = $2 
			  WHERE "TaskID" = $3`

	result, err := DB.Exec(query, taskName, taskDescription, taskID)
	if err != nil {
		return err
	}

	rowsAffected, err := result.RowsAffected()
	if err != nil {
		return err
	}

	if rowsAffected == 0 {
		return errors.New("task not found")
	}

	return nil
}

// MarkTaskDone marks a task as completed
func MarkTaskDone(taskID int) error {
	query := `UPDATE "Tasks" SET "IsDone" = true WHERE "TaskID" = $1`

	result, err := DB.Exec(query, taskID)
	if err != nil {
		return err
	}

	rowsAffected, err := result.RowsAffected()
	if err != nil {
		return err
	}

	if rowsAffected == 0 {
		return errors.New("task not found")
	}

	return nil
}

// DeleteTask deletes a task from the database
func DeleteTask(taskID int) error {
	query := `DELETE FROM "Tasks" WHERE "TaskID" = $1`

	result, err := DB.Exec(query, taskID)
	if err != nil {
		return err
	}

	rowsAffected, err := result.RowsAffected()
	if err != nil {
		return err
	}

	if rowsAffected == 0 {
		return errors.New("task not found")
	}

	return nil
}