QoL and metric value inverter

src/physcom_web/app.py

@@ -2,6 +2,7 @@
 
 from __future__ import annotations
 
+import math
 import os
 import secrets
 from pathlib import Path
@@ -53,10 +54,54 @@ def close_db(exc: BaseException | None = None) -> None:
         repo.conn.close()
 
 
+_SI_PREFIXES = [
+    (1e12, "T"),
+    (1e9, "G"),
+    (1e6, "M"),
+    (1e3, "k"),
+]
+
+
+def _si_format(value: object) -> str:
+    """Format a number with SI prefixes for readability.
+
+    Handles string inputs (like dep.value) by trying float conversion first.
+    Non-numeric values are returned as-is.
+    """
+    if isinstance(value, str):
+        try:
+            num = float(value)
+        except (ValueError, TypeError):
+            return value
+    elif isinstance(value, (int, float)):
+        num = float(value)
+    else:
+        return str(value)
+
+    if math.isnan(num) or math.isinf(num):
+        return str(value)
+
+    abs_num = abs(num)
+    if abs_num < 1000:
+        # Small numbers: drop trailing zeros, cap at 4 significant figures
+        if num == int(num) and abs_num < 100:
+            return str(int(num))
+        return f"{num:.4g}"
+
+    for threshold, prefix in _SI_PREFIXES:
+        if abs_num >= threshold:
+            scaled = num / threshold
+            return f"{scaled:.4g}{prefix}"
+
+    return f"{num:.4g}"
+
+
 def create_app() -> Flask:
     app = Flask(__name__)
     app.secret_key = _load_or_generate_secret_key()
 
+    app.jinja_env.filters["si"] = _si_format
+
     app.teardown_appcontext(close_db)
 
     # Register blueprints