use chrono::NaiveDate;
use serde::{Deserialize, Serialize};
use std::string::ToString;

/// A specification to build invoice IDs with
#[derive(Serialize, Deserialize)]
pub enum InvoiceId {
    YearMonthId(u16, u8, usize),
}

impl ToString for InvoiceId {
    fn to_string(&self) -> String {
        match self {
            Self::YearMonthId(yr, mo, id) => format!("#{}-{:02}-{:04}", yr, mo, id),
        }
    }
}

/// An invoice for a specific project
#[derive(Serialize, Deserialize)]
pub struct Invoice {
    id: InvoiceId,
    client: String,
    project: String,
    date: NaiveDate,
    amount: usize,
    currency: String,
    vat: u8,
}

#[test]
fn invoice_id_fmt() {
    let inv_id = InvoiceId::YearMonthId(2020, 06, 0055);
    assert_eq!(inv_id.to_string(), "#2020-06-0055".to_string());
}