From 989594263323da1210f7a0d12721cfc492eb68da Mon Sep 17 00:00:00 2001
From: Sameh Khamis <sameh@halfpixel.ai>
Date: Thu, 1 Oct 2026 12:05:41 -0700
Subject: [PATCH] refactor: move TLE text parsing into a portable source module

The satellites layer parsed catalog text inside its Cesium-backed orbit
owner. Move the parser unchanged to src/sources/tle.js, add a catalog
number helper, and have the layer delegate to it so code outside the
layer can read TLE text without loading rendering.
---
 scripts/package-boundaries.json |  3 +++
 src/layers/satellites/orbits.js | 20 ++------------------
 src/sources/tle.js              | 27 +++++++++++++++++++++++++++
 3 files changed, 32 insertions(+), 18 deletions(-)
 create mode 100644 src/sources/tle.js

diff --git a/scripts/package-boundaries.json b/scripts/package-boundaries.json
index 636004286..2bb2e1121 100644
--- a/scripts/package-boundaries.json
+++ b/scripts/package-boundaries.json
@@ -922,6 +922,7 @@
       "src/data/issPass.js",
       "src/data/satelliteClass.js",
       "src/data/satellitePass.js",
+      "src/sources/tle.js",
       "src/layers/satellites/catalog.js",
       "src/layers/satellites/controls.js",
       "src/layers/satellites/index.js",
@@ -1659,6 +1660,7 @@
       "src/layers/satellites/labels.js",
       "src/layers/satellites/lifecycle.js",
       "src/layers/satellites/orbits.js",
+      "src/sources/tle.js",
       "src/layers/satellites/records.js",
       "src/layers/satellites/policy.js",
       "src/layers/satellites/rendering.js",
@@ -2323,6 +2325,7 @@
       "src/layers/satellites/labels.js",
       "src/layers/satellites/lifecycle.js",
       "src/layers/satellites/orbits.js",
+      "src/sources/tle.js",
       "src/layers/satellites/records.js",
       "src/layers/satellites/policy.js",
       "src/layers/satellites/rendering.js",
diff --git a/src/layers/satellites/orbits.js b/src/layers/satellites/orbits.js
index ed26a8883..32bb57cf9 100644
--- a/src/layers/satellites/orbits.js
+++ b/src/layers/satellites/orbits.js
@@ -8,6 +8,7 @@ import {
   twoline2satrec,
 } from 'satellite.js';
 import { findNextSatellitePass } from '../../data/satellitePass.js';
+import { parseTleText } from '../../sources/tle.js';
 import { ORBIT_PATH_STEPS, ISS_NORAD } from './policy.js';
 
 export function createOrbits({ state: layerState, services, parts, source }) {
@@ -40,24 +41,7 @@ export function createOrbits({ state: layerState, services, parts, source }) {
   /**
    * Parse TLE text into array of { name, line1, line2 } objects.
    */
-
-  function parseTLE(text) {
-    const lines = text
-      .trim()
-      .split('\n')
-      .map((l) => l.trim())
-      .filter((l) => l.length > 0);
-    const result = [];
-    for (let i = 0; i < lines.length - 2; i += 3) {
-      const name = lines[i];
-      const line1 = lines[i + 1];
-      const line2 = lines[i + 2];
-      if (line1.startsWith('1 ') && line2.startsWith('2 ')) {
-        result.push({ name, line1, line2 });
-      }
-    }
-    return result;
-  }
+  const parseTLE = parseTleText;
 
   /**
    * Propagate satellite position at a given JS Date.
diff --git a/src/sources/tle.js b/src/sources/tle.js
new file mode 100644
index 000000000..423651e6b
--- /dev/null
+++ b/src/sources/tle.js
@@ -0,0 +1,27 @@
+/**
+ * Parse three-line TLE catalog text into `{ name, line1, line2 }` entries.
+ * Blocks whose second and third lines are not TLE lines 1 and 2 are skipped.
+ */
+export function parseTleText(text) {
+  const lines = String(text)
+    .trim()
+    .split('\n')
+    .map((line) => line.trim())
+    .filter((line) => line.length > 0);
+  const result = [];
+  for (let i = 0; i < lines.length - 2; i += 3) {
+    const name = lines[i];
+    const line1 = lines[i + 1];
+    const line2 = lines[i + 2];
+    if (line1.startsWith('1 ') && line2.startsWith('2 ')) {
+      result.push({ name, line1, line2 });
+    }
+  }
+  return result;
+}
+
+/** The NORAD catalog number from TLE line 1, or null. */
+export function tleCatalogNumber(line1) {
+  const number = Number.parseInt(String(line1).slice(2, 7), 10);
+  return Number.isInteger(number) ? number : null;
+}