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use std::collections::HashMap;
use std::fmt;
pub struct Simulation {
mortgage: Mortgage,
updates: MortgageUpdates,
history: Vec<Quota>,
topay_total: f64,
topay_interest: f64,
payed_principal: f64,
payed_interest: f64,
payed_amortized: f64,
}
impl Simulation {
pub fn new(principal: f64, i1: f64, years: u32) -> Self {
let pending_quotas = years * 12;
let i12 = i1 / 12.0;
let mortgage = Mortgage {
period: 0,
principal,
i12,
monthly: Mortgage::monthly(principal, i12, pending_quotas),
pending_quotas,
};
let topay_total = mortgage.monthly * pending_quotas as f64;
Simulation {
mortgage,
topay_total,
topay_interest: topay_total - principal,
payed_principal: 0.,
payed_interest: 0.,
payed_amortized: 0.,
history: vec![],
updates: HashMap::new(),
}
}
pub fn run(&mut self, updates: MortgageUpdates) {
self.updates = updates;
let mut mortgage = self.mortgage.clone();
while mortgage.pending_quotas > 0 && mortgage.principal > 0. {
let quota = mortgage.step();
self.payed_principal += quota.principal;
self.payed_interest += quota.interest;
self.history.push(quota);
self.apply_updates(&mut mortgage);
}
}
fn apply_updates(&mut self, mortgage: &mut Mortgage) {
match self.updates.get_mut(&mortgage.period) {
Some(MortgageUpdate::Amortize(principal)) => {
if *principal > mortgage.principal {
*principal = mortgage.principal;
};
mortgage.principal -= *principal;
mortgage.monthly =
Mortgage::monthly(mortgage.principal, mortgage.i12, mortgage.pending_quotas);
self.payed_amortized += *principal;
}
None => (),
}
}
pub fn render_table(&self) {
let mortgage = &self.mortgage;
println!("\n========================================================");
println!(
"=== HIPOTECA: {}€, A {} AÑOS, INTERÉS FIJO {:.2}% ===",
mortgage.principal,
mortgage.pending_quotas / 12,
mortgage.i12 * 12. * 100.,
);
println!("========================================================");
println!("\n\n# SIMULACIÓN CUOTAS\n");
println!("Year | Mon | Quota ( Amrtzd + Intrst) | Pending");
for mortgage in self.history.iter() {
print!("{mortgage}");
if let Some(update) = self.updates.get(&mortgage.period) {
print!(" {update}");
}
println!();
}
let payed_total = self.payed_principal + self.payed_interest + self.payed_amortized;
println!("\n\n# A PRIORI\n");
println!(
"== Total a pagar: {:.2} ({:.2} cap + {:.2} int)",
self.topay_total, mortgage.principal, self.topay_interest
);
println!(
"== Los intereses suponen un {:.2}% del total",
100. * self.topay_interest / self.topay_total
);
println!("\n\n# RESULTADO FINAL\n");
println!(
"== Total pagado: {:.2} ({:.2} cap + {:.2} int + {:.2} amortizado)",
payed_total, self.payed_principal, self.payed_interest, self.payed_amortized
);
println!(
"== Los intereses suponen un {:.2}% del total",
100. * self.payed_interest / payed_total
);
println!();
}
}
#[derive(Clone)]
pub struct Quota {
period: u32,
interest: f64,
principal: f64,
pending_principal: f64,
}
impl fmt::Display for Quota {
fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
write!(
f,
"{:4} | {:3} | {:7.2} ({:7.2} + {:7.2}) | {:10.2}",
if (self.period - 1) % 12 == 0 {
format!("Y{}", (self.period / 12) + 1)
} else {
// return Ok(());
"".to_string()
},
self.period,
self.interest + self.principal,
self.principal,
self.interest,
self.pending_principal
)
}
}
#[derive(Clone)]
pub struct Mortgage {
period: u32,
principal: f64,
i12: f64,
monthly: f64,
pending_quotas: u32,
}
impl Mortgage {
fn monthly(principal: f64, i12: f64, pending_quotas: u32) -> f64 {
principal * i12 / (1.0 - (1.0 + i12).powi(-(pending_quotas as i32)))
}
fn step(&mut self) -> Quota {
let interest = self.quota_interest();
let principal = self.quota_principal();
self.period += 1;
self.pending_quotas -= 1;
self.principal = (1.0 + self.i12) * self.principal - self.monthly;
Quota {
period: self.period,
interest,
principal,
pending_principal: self.principal,
}
}
fn quota_interest(&self) -> f64 {
self.i12 * self.principal
}
fn quota_principal(&self) -> f64 {
self.monthly - self.quota_interest()
}
}
pub type MortgageUpdates = HashMap<u32, MortgageUpdate>;
#[derive(Clone)]
pub enum MortgageUpdate {
Amortize(f64),
}
impl fmt::Display for MortgageUpdate {
fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
write!(f, "[MORTGAGE UPDATE: ")?;
match self {
Self::Amortize(principal) => {
write!(f, "{principal:.2} amortized to reduce pending_quotas]")
}
}
}
}
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