package database

import (
	"database/sql"
	"log"

	_ "modernc.org/sqlite"
)

type DB struct {
	db *sql.DB
}

func New() *DB {
	d := &DB{}
	con, err := sql.Open("sqlite", "./todogo.db")
	if err != nil {
		log.Fatal(err)
	}
	d.db = con

	err = d.init()
	if err != nil {
		log.Fatal(err)
	}

	return d
}

func (d *DB) init() error {
	d.migrate()

	return nil
}

func (d *DB) InsertTodo(title string) error {
	_, err := d.db.Exec("INSERT INTO todos(title, completed) VALUES(?, ?)", title, 0)
	return err
}

func (d *DB) ToggleTodo(id int) error {
	_, err := d.db.Exec(`
    UPDATE todos
    SET completed = (CASE WHEN completed = 0 THEN 1 ELSE 0 END)
    WHERE id = ?
  `, id)
	return err
}

func (d *DB) DeleteTodo(id int) error {
	_, err := d.db.Exec("DELETE FROM todos WHERE id = ?", id)
	return err
}

func (d *DB) GetAllTodos() ([]*Todo, error) {
	rows, err := d.db.Query("SELECT id, title, completed FROM todos")
	if err != nil {
		return nil, err
	}
	defer rows.Close()
	todos := scanTodos(rows)

	return todos, nil
}

func (d *DB) GetTodosByCompleted(completed bool) ([]*Todo, error) {
	completedInt := 0
	if completed {
		completedInt = 1
	}
	rows, err := d.db.Query("SELECT id, title, completed FROM todos WHERE completed = ?", completedInt)
	if err != nil {
		return nil, err
	}
	defer rows.Close()

	todos := scanTodos(rows)

	return todos, nil
}

func (d *DB) GetIncompleteTodosCount() int {
	row := d.db.QueryRow("SELECT COUNT(*) FROM todos WHERE completed = 0")
	var count int
	err := row.Scan(&count)
	if err != nil {
		log.Printf("failed to get incomplete count")
		return 0
	}

	return count
}

func (d *DB) DeleteCompletedTodos() error {
	_, err := d.db.Exec("DELETE FROM todos WHERE completed = 1")
	return err
}

func scanTodos(rows *sql.Rows) []*Todo {
	var todos []*Todo
	for rows.Next() {
		t := scanTodo(rows)
		if t != nil {
			todos = append(todos, t)
		}
	}

	return todos
}

func scanTodo(row *sql.Rows) *Todo {
	t := new(Todo)
	err := row.Scan(&t.Id, &t.Title, &t.Completed)
	if err != nil {
		log.Printf("Failed to read row %s", err)
		return nil
	}

	return t
}

type Todo struct {
	Id        int
	Title     string
	Completed bool
}