use std::fs::{File, OpenOptions};
use std::io::{Read, Write, Error};
use std::path::Path;
use rocket::request::FromForm;

#[derive(Serialize,Deserialize)]
pub struct Store {
    pub parts : Vec<Part>
}

#[derive(Serialize,Deserialize,FromForm)]
pub struct Part {
    name : String,
    quantity : usize,
    location : String,
}

fn load_file_or(file : impl AsRef<Path>, def : String) -> String {
    let mut file = match File::open(file) {
        Ok(file) => file,
        Err(_) => return def
    };

    let mut buf = String::new();
    if file.read_to_string(&mut buf).is_err() {
        return def;
    }

    buf
}

impl Store {
    pub fn new() -> Self {
        let mut file = load_file_or("inventory.json", "[]".to_string());

        Store {
            parts: serde_json::from_str(&file).unwrap(),
        }
    }

    pub fn add(&mut self, part : Part) {
        self.parts.push(part);

        self.persist()
    }

    pub fn persist(&self) {
        let mut file = OpenOptions::new().write(true).create(true).truncate(true).open("inventory.json").unwrap();

        file.write(serde_json::to_string(&self.parts).unwrap().as_bytes()).unwrap();
    }
}