Another big refactor + perfect quota sim

1 files changed, 73 insertions, 56 deletions

diff --git a/src/lib.rs b/src/lib.rs
index aa4ee79..66ebe32 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -2,8 +2,9 @@ use std::collections::HashMap;
 use std::fmt;
 
 pub struct Simulation {
-    history: Vec<Mortgage>,
+    mortgage: Mortgage,
     updates: MortgageUpdates,
+    history: Vec<Quota>,
     topay_total: f64,
     topay_interest: f64,
     payed_principal: f64,
@@ -12,13 +13,41 @@ pub struct Simulation {
 }
 
 impl Simulation {
-    fn run(&mut self, mut mortgage: Mortgage) {
-        while mortgage.quotas > 0 && mortgage.principal > 0. {
-            self.history.push(mortgage.clone());
+    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);
-            self.payed_principal += mortgage.quota_principal();
-            self.payed_interest += mortgage.quota_interest();
-            mortgage.step();
         }
     }
 
@@ -30,7 +59,7 @@ impl Simulation {
                 };
                 mortgage.principal -= *principal;
                 mortgage.monthly =
-                    Mortgage::monthly(mortgage.principal, mortgage.i12, mortgage.quotas);
+                    Mortgage::monthly(mortgage.principal, mortgage.i12, mortgage.pending_quotas);
 
                 self.payed_amortized += *principal;
             }
@@ -39,19 +68,19 @@ impl Simulation {
     }
 
     pub fn render_table(&self) {
-        let mortgage = &self.history[0];
+        let mortgage = &self.mortgage;
 
         println!("\n========================================================");
         println!(
             "=== HIPOTECA: {}€, A {} AÑOS, INTERÉS FIJO {:.2}% ===",
             mortgage.principal,
-            mortgage.quotas / 12,
+            mortgage.pending_quotas / 12,
             mortgage.i12 * 12. * 100.,
         );
         println!("========================================================");
 
         println!("\n\n# SIMULACIÓN CUOTAS\n");
-        println!("Year | Mon |   Quota ( Intrst +  Amrtzd) |  Principal");
+        println!("Year | Mon |   Quota ( Amrtzd +  Intrst) |    Pending");
         for mortgage in self.history.iter() {
             print!("{mortgage}");
             if let Some(update) = self.updates.get(&mortgage.period) {
@@ -64,7 +93,7 @@ impl Simulation {
 
         println!("\n\n# A PRIORI\n");
         println!(
-            "== Total a pagar: {:.2} ({} cap + {:.2} int)",
+            "== Total a pagar: {:.2} ({:.2} cap + {:.2} int)",
             self.topay_total, mortgage.principal, self.topay_interest
         );
         println!(
@@ -86,73 +115,61 @@ impl Simulation {
 }
 
 #[derive(Clone)]
-pub struct Mortgage {
+pub struct Quota {
     period: u32,
+    interest: f64,
     principal: f64,
-    i12: f64,
-    monthly: f64,
-    quotas: u32,
+    pending_principal: f64,
 }
 
-impl fmt::Display for Mortgage {
+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 % 12 == 0 {
+            if (self.period - 1) % 12 == 0 {
                 format!("Y{}", (self.period / 12) + 1)
             } else {
                 // return Ok(());
                 "".to_string()
             },
             self.period,
-            self.monthly,
-            self.quota_interest(),
-            self.quota_principal(),
-            self.principal
+            self.interest + self.principal,
+            self.principal,
+            self.interest,
+            self.pending_principal
         )
     }
 }
 
-impl Mortgage {
-    pub fn new(principal: f64, i1: f64, years: u32) -> Self {
-        let quotas = years * 12;
-        let i12 = i1 / 12.0;
-        Mortgage {
-            period: 0,
-            principal,
-            i12,
-            monthly: Self::monthly(principal, i12, quotas),
-            quotas,
-        }
-    }
-
-    pub fn simulate(&mut self, updates: MortgageUpdates) -> Simulation {
-        let topay_total = self.monthly * self.quotas as f64;
-
-        let mut sim = Simulation {
-            topay_total,
-            topay_interest: topay_total - self.principal,
-            payed_principal: 0.,
-            payed_interest: 0.,
-            payed_amortized: 0.,
-            history: vec![],
-            updates,
-        };
-
-        sim.run(self.clone());
+#[derive(Clone)]
+pub struct Mortgage {
+    period: u32,
+    principal: f64,
+    i12: f64,
+    monthly: f64,
+    pending_quotas: u32,
+}
 
-        sim
+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 monthly(principal: f64, i12: f64, quotas: u32) -> f64 {
-        principal * i12 / (1.0 - (1.0 + i12).powi(-(quotas as i32)))
-    }
+    fn step(&mut self) -> Quota {
+        let interest = self.quota_interest();
+        let principal = self.quota_principal();
 
-    fn step(&mut self) {
         self.period += 1;
-        self.quotas -= 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 {
@@ -176,7 +193,7 @@ impl fmt::Display for MortgageUpdate {
         write!(f, "[MORTGAGE UPDATE: ")?;
         match self {
             Self::Amortize(principal) => {
-                write!(f, "{principal:.2} amortized to reduce quotas]")
+                write!(f, "{principal:.2} amortized to reduce pending_quotas]")
             }
         }
     }