package main

import (
	"encoding/json"
	"os"
)

type Book struct {
	ID     int    `json:"id"`
	Title  string `json:"title"`
	Author string `json:"author"`
	Read   bool   `json:"read"`
}

type Library struct {
	Books []Book `json:"books"`
}

func (lib *Library) Add(title, author string) {
	id := len(lib.Books) + 1
	lib.Books = append(lib.Books, Book{ID: id, Title: title, Author: author, Read: false})
}

func (lib *Library) MarkRead(id int) {
	for i := range lib.Books {
		if lib.Books[i].ID == id {
			lib.Books[i].Read = true
		}
	}
}

func (lib *Library) Save(filename string) error {
	data, err := json.MarshalIndent(lib, "", "  ")
	if err != nil {
		return err
	}
	return os.WriteFile(filename, data, 0644)
}

func LoadLibrary(filename string) (*Library, error) {
	data, err := os.ReadFile(filename)
	if err != nil {
		return &Library{}, nil
	}
	var lib Library
	err = json.Unmarshal(data, &lib)
	return &lib, err
}