From c0613a8d42e0d2db250ea24e7b80a528612cb58f Mon Sep 17 00:00:00 2001
From: Felipe Knorr Kuhn <git@knorrium.info>
Date: Thu, 5 Feb 2026 19:22:02 -0800
Subject: [PATCH] Cap values to max supply

---
 .../calculator/calculator.component.ts        | 39 +++++++++++++++----
 .../app/shared/pipes/bitcoinsatoshis.pipe.ts  |  7 +++-
 .../app/shared/pipes/fiat-currency.pipe.ts    |  6 ++-
 3 files changed, 43 insertions(+), 9 deletions(-)

diff --git a/frontend/src/app/components/calculator/calculator.component.ts b/frontend/src/app/components/calculator/calculator.component.ts
index 94732f86e..148fbe502 100644
--- a/frontend/src/app/components/calculator/calculator.component.ts
+++ b/frontend/src/app/components/calculator/calculator.component.ts
@@ -53,12 +53,15 @@ export class CalculatorComponent implements OnInit {
       this.price$,
       this.form.get('fiat').valueChanges
     ]).subscribe(([price, value]) => {
-      const rate = (value / price).toFixed(8);
-      const satsRate = Math.round(value / price * 100_000_000);
+      let rate = parseFloat((value / price).toFixed(8));
+      if (rate > 21000000) {
+        rate = 21000000;
+      }
+      const satsRate = Math.round(rate * 100_000_000);
       if (isNaN(value)) {
         return;
       }
-      this.form.get('bitcoin').setValue(rate, { emitEvent: false });
+      this.form.get('bitcoin').setValue(rate.toFixed(8), { emitEvent: false });
       this.form.get('satoshis').setValue(satsRate, { emitEvent: false } );
     });
 
@@ -70,7 +73,7 @@ export class CalculatorComponent implements OnInit {
       if (isNaN(value)) {
         return;
       }
-      this.form.get('fiat').setValue(rate, { emitEvent: false } );
+      this.form.get('fiat').setValue(this.formatFiat(rate), { emitEvent: false } );
       this.form.get('satoshis').setValue(Math.round(value * 100_000_000), { emitEvent: false } );
     });
 
@@ -78,12 +81,17 @@ export class CalculatorComponent implements OnInit {
       this.price$,
       this.form.get('satoshis').valueChanges
     ]).subscribe(([price, value]) => {
-      const rate = parseFloat((value / 100_000_000 * price).toFixed(8));
-      const bitcoinRate = (value / 100_000_000).toFixed(8);
+      let bitcoinValue = value / 100_000_000;
+      if (bitcoinValue > 21000000) {
+        bitcoinValue = 21000000;
+        value = 21000000 * 100_000_000;
+      }
+      const rate = parseFloat((bitcoinValue * price).toFixed(8));
+      const bitcoinRate = bitcoinValue.toFixed(8);
       if (isNaN(value)) {
         return;
       }
-      this.form.get('fiat').setValue(rate, { emitEvent: false } );
+      this.form.get('fiat').setValue(this.formatFiat(rate), { emitEvent: false } );
       this.form.get('bitcoin').setValue(bitcoinRate, { emitEvent: false });
     });
 
@@ -110,6 +118,12 @@ export class CalculatorComponent implements OnInit {
     if (name === 'satoshis') {
       sanitizedValue = parseFloat(sanitizedValue).toFixed(0);
     }
+    if (name === 'bitcoin' && parseFloat(sanitizedValue) >= 21000000) {
+      sanitizedValue = '21000000';
+    }
+    if (name === 'satoshis' && parseFloat(sanitizedValue) > 2100000000000000) {
+      sanitizedValue = '2100000000000000';
+    }
     formControl.setValue(sanitizedValue, {emitEvent: true});
   }
 
@@ -137,4 +151,15 @@ export class CalculatorComponent implements OnInit {
   selectAll(event): void {
     event.target.select();
   }
+
+  formatFiat(num: number): string | number {
+    if (Math.abs(num) >= 1000) {
+      // For values >= 1000: show 2 decimals, or 0 if whole number
+      if (num % 1 === 0) {
+        return Math.round(num);
+      }
+      return (Math.round(num * 100) / 100).toFixed(2);
+    }
+    return num;
+  }
 }
diff --git a/frontend/src/app/shared/pipes/bitcoinsatoshis.pipe.ts b/frontend/src/app/shared/pipes/bitcoinsatoshis.pipe.ts
index 5f1f97b40..348319f19 100644
--- a/frontend/src/app/shared/pipes/bitcoinsatoshis.pipe.ts
+++ b/frontend/src/app/shared/pipes/bitcoinsatoshis.pipe.ts
@@ -10,7 +10,12 @@ export class BitcoinsatoshisPipe implements PipeTransform {
   constructor(private sanitizer: DomSanitizer) { }
 
   transform(value: string, firstPartClass?: string): SafeHtml {
-    const newValue = this.insertSpaces(parseFloat(value || '0').toFixed(8));
+    const numValue = parseFloat(value || '0');
+    // Don't show decimals at max supply (21M BTC)
+    if (numValue >= 21000000) {
+      return this.sanitizer.bypassSecurityTrustHtml('21 000 000');
+    }
+    const newValue = this.insertSpaces(numValue.toFixed(8));
     const position = (newValue || '0').search(/[1-9]/);
 
     const firstPart = newValue.slice(0, position);
diff --git a/frontend/src/app/shared/pipes/fiat-currency.pipe.ts b/frontend/src/app/shared/pipes/fiat-currency.pipe.ts
index 0b211d4cf..ffaef26d3 100644
--- a/frontend/src/app/shared/pipes/fiat-currency.pipe.ts
+++ b/frontend/src/app/shared/pipes/fiat-currency.pipe.ts
@@ -25,7 +25,11 @@ export class FiatCurrencyPipe implements PipeTransform {
     const currency = args[1] || this.currency || 'USD';
 
     if (Math.abs(num) >= 1000) {
-      return new Intl.NumberFormat(this.locale, { style: 'currency', currency, maximumFractionDigits: 0 }).format(num);
+      // Check if decimals are exactly 0
+      if (num % 1 === 0) {
+        return new Intl.NumberFormat(this.locale, { style: 'currency', currency, maximumFractionDigits: 0 }).format(num);
+      }
+      return new Intl.NumberFormat(this.locale, { style: 'currency', currency, minimumFractionDigits: 2, maximumFractionDigits: 2 }).format(num);
     } else {
       return new Intl.NumberFormat(this.locale, { style: 'currency', currency }).format(num);
     }