From dc7345fb1ddbb45e05d2f5b75b6f578b3fa9355b Mon Sep 17 00:00:00 2001
From: Tanner Collin <git@tannercollin.com>
Date: Sat, 14 Feb 2026 18:09:47 -0700
Subject: [PATCH] feat: Use file line number as stable METAR ID in URL

Co-authored-by: aider (gemini/gemini-2.5-pro) <aider@aider.chat>
---
 metar.html | 45 ++++++++++++++++++++++++---------------------
 1 file changed, 24 insertions(+), 21 deletions(-)

diff --git a/metar.html b/metar.html
index 9d14c1a..a276588 100644
--- a/metar.html
+++ b/metar.html
@@ -819,16 +819,19 @@
             return sections;
         }
 
-        function displayMetar(index) {
+        function displayMetar(id) {
             if (metars.length === 0) {
                 metarDisplay.textContent = 'No METARs loaded.';
                 return;
             }
 
-            let metarIndex;
-            if (index !== undefined && index >= 0 && index < metars.length) {
-                metarIndex = index;
-            } else {
+            let metarIndex = -1;
+
+            if (id !== undefined) {
+                metarIndex = metars.findIndex(m => m.line === id);
+            }
+
+            if (metarIndex === -1) {
                 // Bias random selection towards the more interesting (higher-scored) METARs.
                 // Math.random() * Math.random() skews distribution towards 0.
                 const randomSortedIndex = Math.floor(Math.random() * Math.random() * sortedMetars.length);
@@ -841,10 +844,10 @@
             }
             currentMetarIndex = metarIndex;
 
-            const metarString = metars[metarIndex].metar;
-            history.replaceState(null, '', '#' + metarIndex);
+            const metarData = metars[metarIndex];
+            history.replaceState(null, '', '#' + metarData.line);
 
-            currentMetarSections = generateMetarSections(metarString);
+            currentMetarSections = generateMetarSections(metarData.metar);
             currentSectionIndex = 0;
             updateDisplay();
         }
@@ -854,11 +857,11 @@
             .then(data => {
                 const lines = data.split('\n');
                 const rawMetars = [];
-                lines.forEach(line => {
+                lines.forEach((line, index) => {
                     if (line.includes('METAR')) {
                         const metarString = line.substring(line.indexOf('METAR') + 6).replace('=', '').trim();
                         if (metarString) {
-                            rawMetars.push(metarString);
+                            rawMetars.push({ metar: metarString, line: index + 1 });
                         }
                     }
                 });
@@ -867,17 +870,17 @@
                 
                 // 1. Calculate component frequencies for rarity scoring
                 const componentFrequencies = {};
-                rawMetars.forEach(metarString => {
-                    const parts = getMetarParts(metarString);
+                rawMetars.forEach(metarObj => {
+                    const parts = getMetarParts(metarObj.metar);
                     parts.forEach(part => {
                         componentFrequencies[part] = (componentFrequencies[part] || 0) + 1;
                     });
                 });
 
                 // 2. Score and store each METAR
-                rawMetars.forEach(metarString => {
-                    const score = calculateMetarScore(metarString, componentFrequencies, rawMetars.length);
-                    metars.push({ metar: metarString, score: score });
+                rawMetars.forEach(metarObj => {
+                    const score = calculateMetarScore(metarObj.metar, componentFrequencies, rawMetars.length);
+                    metars.push({ metar: metarObj.metar, score: score, line: metarObj.line });
                 });
 
                 // 3. Create a sorted copy for biased random selection, but don't sort the main array
@@ -891,10 +894,10 @@
                 }
 
                 const hash = window.location.hash.substring(1);
-                const initialIndex = parseInt(hash, 10);
+                const initialId = parseInt(hash, 10);
 
-                if (!isNaN(initialIndex) && initialIndex >= 0 && initialIndex < metars.length) {
-                    displayMetar(initialIndex);
+                if (!isNaN(initialId)) {
+                    displayMetar(initialId);
                 } else {
                     displayMetar(); // Display initial random METAR
                 }
@@ -908,9 +911,9 @@
         decodeAllCheckbox.addEventListener('change', updateDisplay);
         window.addEventListener('hashchange', () => {
             const hash = window.location.hash.substring(1);
-            const index = parseInt(hash, 10);
-            if (!isNaN(index) && index >= 0 && index < metars.length) {
-                displayMetar(index);
+            const id = parseInt(hash, 10);
+            if (!isNaN(id)) {
+                displayMetar(id);
             }
         });