From e47b7fe28b5afc6c0c19473ef9cb14aacd205304 Mon Sep 17 00:00:00 2001
From: tiennm99 <tiennm99@outlook.com>
Date: Sun, 10 May 2026 00:40:47 +0700
Subject: [PATCH] fix(mapillary): always sub-sample small bbox + retry on
 transient errors

---
 src/lib/mapillary.js | 60 +++++++++++++++++++++-----------------------
 1 file changed, 28 insertions(+), 32 deletions(-)

diff --git a/src/lib/mapillary.js b/src/lib/mapillary.js
index 3eb8796..e01e5f3 100644
--- a/src/lib/mapillary.js
+++ b/src/lib/mapillary.js
@@ -1,40 +1,34 @@
 // Mapillary API utilities
 
-// Maximum bbox area allowed by Mapillary API (square degrees).
-// Mapillary tightened limits: keep area small enough to avoid 500 'reduce data' errors.
-const MAX_BBOX_AREA = 0.001;
+// Maximum bbox area allowed per Mapillary query (square degrees).
+// Mapillary returns 500 'reduce data' / 'unknown error' on dense urban bboxes,
+// so we keep each query small (~1km square) and rely on the retry loop to
+// re-roll a new random sub-bbox if one query fails or returns empty.
+const MAX_BBOX_AREA = 0.0001;
 
-// Pick a random sub-bbox within the city bbox that fits Mapillary's area limit
+// Pick a random sub-bbox within the city bbox that fits Mapillary's area limit.
 function getRandomSubBbox(bbox) {
   const [minLng, minLat, maxLng, maxLat] = bbox;
   const width = maxLng - minLng;
   const height = maxLat - minLat;
-  const area = width * height;
 
-  if (area <= MAX_BBOX_AREA) {
-    return bbox;
-  }
-
-  // Calculate sub-bbox side length (square) that fits within the limit
-  const side = Math.sqrt(MAX_BBOX_AREA) * 0.9; // 10% margin for safety
+  // Always sub-sample even if the parent bbox is smaller than the cap — a
+  // smaller window keeps Mapillary happy in dense regions like central Hanoi.
+  const side = Math.sqrt(MAX_BBOX_AREA) * 0.9; // 10% safety margin
   const subWidth = Math.min(side, width);
   const subHeight = Math.min(side, height);
 
-  const startLng = minLng + Math.random() * (width - subWidth);
-  const startLat = minLat + Math.random() * (height - subHeight);
+  const startLng = minLng + Math.random() * Math.max(0, width - subWidth);
+  const startLat = minLat + Math.random() * Math.max(0, height - subHeight);
 
   return [startLng, startLat, startLng + subWidth, startLat + subHeight];
 }
 
-// Fetch images from a single bbox query
+// Fetch images from a single bbox query.
 async function queryMapillary(accessToken, queryBbox) {
   const bboxString = queryBbox.join(',');
   const apiUrl = `https://graph.mapillary.com/images?access_token=${accessToken}&fields=id,thumb_2048_url,geometry,is_pano&limit=5&bbox=${bboxString}&is_pano=true`;
 
-  if (process.env.NODE_ENV === 'development') {
-    console.log('Mapillary query bbox:', bboxString);
-  }
-
   const response = await fetch(apiUrl, {
     headers: { 'Accept': 'application/json' },
     next: { revalidate: 0 }
@@ -54,37 +48,39 @@ async function queryMapillary(accessToken, queryBbox) {
   return data.data || [];
 }
 
-// Fetch images using city bbox, retrying with different sub-bboxes
-const MAX_RETRIES = 5;
+// Fetch panoramic images, retrying with a fresh sub-bbox on failure or empty
+// result. Auth failures still abort early.
+const MAX_RETRIES = 8;
 
 export async function fetchMapillaryImages(bbox) {
   const accessToken = process.env.MAPILLARY_ACCESS_TOKEN;
-
   if (!accessToken) {
     throw new Error('MAPILLARY_ACCESS_TOKEN environment variable is not set');
   }
 
-  for (let attempt = 1; attempt <= MAX_RETRIES; attempt++) {
-    try {
-      const queryBbox = getRandomSubBbox(bbox);
-      const images = await queryMapillary(accessToken, queryBbox);
+  let lastError = null;
 
+  for (let attempt = 1; attempt <= MAX_RETRIES; attempt++) {
+    const queryBbox = getRandomSubBbox(bbox);
+    try {
+      const images = await queryMapillary(accessToken, queryBbox);
       if (images.length > 0) {
         console.log(`Found ${images.length} images on attempt ${attempt}`);
         return { success: true, data: images };
       }
-
-      if (process.env.NODE_ENV === 'development') {
-        console.log(`Attempt ${attempt}/${MAX_RETRIES}: no images found, retrying...`);
-      }
+      console.log(`Attempt ${attempt}/${MAX_RETRIES}: no images, retrying with new sub-bbox`);
     } catch (error) {
-      console.error(`Attempt ${attempt}/${MAX_RETRIES} failed:`, error.message);
-      throw error;
+      // Auth issues are not transient — abort fast.
+      if (error.message === 'Mapillary authentication failed') throw error;
+      lastError = error;
+      console.error(`Attempt ${attempt}/${MAX_RETRIES} failed: ${error.message}; retrying with new sub-bbox`);
     }
   }
 
   return {
     success: false,
-    error: 'No street view images found in city bbox'
+    error: lastError
+      ? `No street view images found after ${MAX_RETRIES} attempts (last: ${lastError.message})`
+      : 'No street view images found in city bbox',
   };
 }