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use std::collections::HashMap;
use std::fs;
use std::io::ErrorKind;
use chrono::NaiveDate;
use serde::{Deserialize, Deserializer};
use toml::de::Error as DeserializerError;
#[derive(Deserialize, PartialEq, Debug)]
pub struct Account {
#[serde(deserialize_with = "deserialize_date")]
pub start_date: NaiveDate,
#[serde(deserialize_with = "deserialize_date")]
pub end_date: NaiveDate,
pub budget: f64,
#[serde(default)]
pub essential_categories: Vec<String>,
pub days: Vec<Day>,
}
#[derive(Deserialize, PartialEq, Debug)]
pub struct Day {
#[serde(deserialize_with = "deserialize_date")]
pub date: NaiveDate,
#[serde(default)]
pub expenses: Vec<Expense>,
}
#[derive(Deserialize, PartialEq, Debug)]
pub struct Expense {
pub name: String,
pub price: f64,
#[serde(default)]
/// Whom this expense is shared with (if anybody).
pub shared: Vec<String>,
#[serde(default)]
/// Whether this was something we paid for somebody else, and thus is owed
/// to us. If true, then shared is the list of person(s) that owe us this
/// expense, and should therefore contain at least one name.
pub owed: bool,
#[serde(default)]
pub category: Option<String>,
}
#[derive(PartialEq, Debug)]
pub struct Calculated {
pub all_day_average: f64,
pub essential_day_average: f64,
pub categories_day_average: HashMap<String, f64>,
pub essential_subtotal: f64,
pub categories_subtotal: HashMap<String, f64>,
pub total: f64,
pub balance: f64,
pub owed: HashMap<String, f64>,
pub total_owed: f64,
pub days_left: f64,
pub days_left_essential: f64,
pub last_day: NaiveDate,
}
#[derive(PartialEq, Eq, Debug)]
pub enum ParseError {
IOError(ErrorKind),
DeserializerError(DeserializerError),
}
// Parse the dates from toml's Datetime to Chrono's NaiveDate
fn deserialize_date<'de, D>(deserializer: D) -> Result<NaiveDate, D::Error>
where
D: Deserializer<'de>,
{
toml::value::Datetime::deserialize(deserializer)
.map(|v| {
let s = v.to_string();
NaiveDate::parse_from_str(&s, "%Y-%m-%d")
})?
.map_err(serde::de::Error::custom)
}
pub fn parse_account(path: &str) -> Result<Account, ParseError> {
let contents = match fs::read_to_string(path) {
Ok(data) => data,
Err(error) => {
return Err(ParseError::IOError(error.kind()));
}
};
match toml::from_str::<Account>(&contents) {
Ok(budget) => Ok(budget),
Err(error) => Err(ParseError::DeserializerError(error)),
}
}
pub fn calculate(account: &Account, consider_owed: bool) -> Option<Calculated> {
if account.days.is_empty() {
return None;
}
let mut calculated = Calculated {
all_day_average: 0.0,
essential_day_average: 0.0,
categories_day_average: HashMap::<String, f64>::new(),
essential_subtotal: 0.0,
categories_subtotal: HashMap::<String, f64>::new(),
total: 0.0,
balance: 0.0,
owed: HashMap::<String, f64>::new(),
total_owed: 0.0,
days_left: 0.0,
days_left_essential: 0.0,
last_day: account.days.last().unwrap().date,
};
for day in account.days.iter() {
if day.date > calculated.last_day {
calculated.last_day = day.date;
}
for expense in day.expenses.iter() {
let mut actual_expense: f64 = 0.0;
if expense.shared.len() > 0 {
let owed_share = if expense.owed {
expense.price / expense.shared.len() as f64
} else {
actual_expense =
expense.price / (expense.shared.len() as f64 + 1.0);
actual_expense
};
for person in expense.shared.iter() {
calculated.total_owed += owed_share;
if let Some(owed_by_person) =
calculated.owed.get_mut(person)
{
*owed_by_person += owed_share;
} else {
calculated.owed.insert(person.clone(), owed_share);
}
}
}
if expense.shared.len() == 0 || consider_owed {
actual_expense = expense.price;
} else if expense.owed {
continue;
}
calculated.total += actual_expense;
if let Some(category) = &expense.category {
if let Some(category_subtotal) =
calculated.categories_subtotal.get_mut(category)
{
*category_subtotal += actual_expense;
} else {
calculated
.categories_subtotal
.insert(category.to_string(), actual_expense);
}
if account.essential_categories.contains(category) {
calculated.essential_subtotal += actual_expense;
}
}
}
}
let days_elapsed =
(calculated.last_day - account.start_date).num_days() + 1;
calculated.all_day_average = calculated.total / days_elapsed as f64;
calculated.essential_day_average =
calculated.essential_subtotal / days_elapsed as f64;
for (category, subtotal) in calculated.categories_subtotal.iter() {
calculated
.categories_day_average
.insert(category.clone(), subtotal / days_elapsed as f64);
}
calculated.balance = account.budget - calculated.total;
calculated.days_left = calculated.balance / calculated.all_day_average;
calculated.days_left_essential =
calculated.balance / calculated.essential_day_average;
Some(calculated)
}
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