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use chrono::{Datelike, Duration};
use num_traits::Zero;
use crate::currency;
use crate::types::{Date, Decimal};
#[derive(Clone, Copy)]
pub struct Country {
pub currency: &'static str,
tax_rate: Decimal,
tax_precision: u32,
}
impl Country {
// When we work with taxes in Russia, the following rounding rules are applied:
// 1. Result of all calculations must be with kopecks precision
// 2. If we have income in foreign currency then:
// 2.1. Round it to cents
// 2.2. Convert to rubles using precise currency rate (65.4244 for example)
// 2.3. Round to kopecks
// 3. Taxes are calculated with rouble precision. But we should use double rounding here:
// calculate them with kopecks precision first and then round to roubles.
//
// Декларация program allows to enter income only with kopecks precision - not bigger.
// It calculates tax for $10.64 income with 65.4244 currency rate as following:
// 1. income = round(10.64 * 65.4244, 2) = 696.12 (696.115616 without rounding)
// 2. tax = round(round(696.12 * 0.13, 2), 0) = 91 (90.4956 without rounding)
pub fn round_tax(&self, tax: Decimal) -> Decimal {
currency::round_to(currency::round(tax), self.tax_precision)
}
pub fn tax_to_pay(&self, income: Decimal, paid_tax: Option<Decimal>) -> Decimal {
let income = currency::round(income);
if income.is_sign_negative() || income.is_zero() {
return dec!(0);
}
let tax_to_pay = self.round_tax(income * self.tax_rate);
if let Some(paid_tax) = paid_tax {
assert!(!paid_tax.is_sign_negative());
let tax_deduction = self.round_tax(paid_tax);
if tax_deduction < tax_to_pay {
tax_to_pay - tax_deduction
} else {
dec!(0)
}
} else {
tax_to_pay
}
}
}
pub fn russia() -> Country {
Country {
currency: "RUB",
tax_rate: Decimal::new(13, 2),
tax_precision: 0,
}
}
pub fn get_russian_stock_exchange_min_last_working_day(today: Date) -> Date {
// New Year holidays
if today.month() == 1 && today.day() < 10 {
Date::from_ymd(today.year() - 1, 12, 30)
// 8 march holidays
} else if today.month() == 3 && today.day() == 12 {
today - Duration::days(4)
// May holidays
} else if today.month() == 5 && today.day() >= 3 && today.day() <= 13 {
today - Duration::days(5)
// COVID-19 pandemic
} else if today.year() == 2020 && today.month() == 4 && today.day() <= 6 {
Date::from_ymd(2020, 3, 28)
} else {
today - Duration::days(3)
}
}