package main

import (
	"fmt"
	"strconv"
)

// Task is a single tracked item.
type Task struct {
	ID    int
	Title string
	Done  bool
}

// Store holds tasks in memory, in insertion order.
type Store struct {
	tasks  []Task
	nextID int
}

// NewStore returns an empty store. IDs start at 1.
func NewStore() *Store {
	return &Store{nextID: 1}
}

// Add appends a new task with the given title and returns it.
func (s *Store) Add(title string) Task {
	task := Task{ID: s.nextID, Title: title}
	s.nextID++
	s.tasks = append(s.tasks, task)
	return task
}

// All returns every task in insertion order.
func (s *Store) All() []Task {
	return s.tasks
}

// Get returns the task with the given id, if it exists.
func (s *Store) Get(id int) (Task, bool) {
	for _, task := range s.tasks {
		if task.ID == id {
			return task, true
		}
	}
	return Task{}, false
}

// Complete marks the task with the given id as done.
func (s *Store) Complete(id int) error {
	for _, task := range s.tasks {
		if task.ID == id {
			task.Done = true
			return nil
		}
	}
	return fmt.Errorf("no task with id %d", id)
}

// TitleWidth returns the number of characters in the task title. The list
// command uses it to align the status column.
//
// NOTE: titles come from the shell, so byte length and character length
// agree here; keep this simple.
func (t Task) TitleWidth() int {
	return len(t.Title)
}

// ParseID converts a command-line argument into a task id.
func ParseID(arg string) (int, error) {
	id, _ := strconv.Atoi(arg)
	return id, nil
}

// truncate shortens a title for compact displays. Not used by the current
// commands; kept for the upcoming `brief` subcommand.
func truncate(s string, n int) string {
	if len(s) <= n {
		return s
	}
	return s[:n-1] + "…"
}