From ca4f8875370e7d76c770830138c0673325992f86 Mon Sep 17 00:00:00 2001
From: Peter Stone <thepeterstone@gmail.com>
Date: Tue, 5 May 2026 12:13:19 -1000
Subject: fix: throttle wind/weather fetches to reduce 429s
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Camera idle: debounce 1.5s so rapid panning/zooming collapses into one fetch

loadWindGrid: skip if center moved < 10 nm AND last fetch < 15 min ago
  (was unbounded — fired on every camera-idle with no gate at all)

loadConditions already had a 5 min + 2 nm gate; unchanged

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
---
 .../src/main/kotlin/org/terst/nav/MainActivity.kt  | 37 ++++++++++++----------
 .../main/kotlin/org/terst/nav/ui/MainViewModel.kt  | 15 +++++++++
 2 files changed, 36 insertions(+), 16 deletions(-)

(limited to 'android-app/app/src')

diff --git a/android-app/app/src/main/kotlin/org/terst/nav/MainActivity.kt b/android-app/app/src/main/kotlin/org/terst/nav/MainActivity.kt
index 5e7ce82..1752fe8 100644
--- a/android-app/app/src/main/kotlin/org/terst/nav/MainActivity.kt
+++ b/android-app/app/src/main/kotlin/org/terst/nav/MainActivity.kt
@@ -60,6 +60,7 @@ class MainActivity : AppCompatActivity(), SafetyFragment.SafetyListener {
     private lateinit var layerManager: MapLayerManager
     private var particleWindView: ParticleWindView? = null
     private var weatherLoaded = false
+    private var cameraIdleJob: kotlinx.coroutines.Job? = null
 
     private lateinit var bottomSheetBehavior: BottomSheetBehavior<View>
     private lateinit var fragmentContainer: FrameLayout
@@ -492,23 +493,27 @@ class MainActivity : AppCompatActivity(), SafetyFragment.SafetyListener {
             }
 
             maplibreMap.addOnCameraIdleListener {
-                val corners = listOfNotNull(
-                    maplibreMap.projection.visibleRegion.nearLeft,
-                    maplibreMap.projection.visibleRegion.nearRight,
-                    maplibreMap.projection.visibleRegion.farLeft,
-                    maplibreMap.projection.visibleRegion.farRight
-                )
-                if (corners.size == 4) {
-                    viewModel.loadWindGrid(
-                        corners.minOf { it.latitude }, corners.maxOf { it.latitude },
-                        corners.minOf { it.longitude }, corners.maxOf { it.longitude }
+                cameraIdleJob?.cancel()
+                cameraIdleJob = lifecycleScope.launch {
+                    kotlinx.coroutines.delay(1_500)
+                    val corners = listOfNotNull(
+                        maplibreMap.projection.visibleRegion.nearLeft,
+                        maplibreMap.projection.visibleRegion.nearRight,
+                        maplibreMap.projection.visibleRegion.farLeft,
+                        maplibreMap.projection.visibleRegion.farRight
                     )
-                }
-                maplibreMap.cameraPosition.target?.let { center ->
-                    // Only refresh conditions when the user has manually panned —
-                    // in following mode the GPS handler already triggers the load.
-                    if (mapHandler?.isFollowing?.value == false) {
-                        viewModel.loadConditions(center.latitude, center.longitude)
+                    if (corners.size == 4) {
+                        viewModel.loadWindGrid(
+                            corners.minOf { it.latitude }, corners.maxOf { it.latitude },
+                            corners.minOf { it.longitude }, corners.maxOf { it.longitude }
+                        )
+                    }
+                    maplibreMap.cameraPosition.target?.let { center ->
+                        // Only refresh conditions when the user has manually panned —
+                        // in following mode the GPS handler already triggers the load.
+                        if (mapHandler?.isFollowing?.value == false) {
+                            viewModel.loadConditions(center.latitude, center.longitude)
+                        }
                     }
                 }
             }
diff --git a/android-app/app/src/main/kotlin/org/terst/nav/ui/MainViewModel.kt b/android-app/app/src/main/kotlin/org/terst/nav/ui/MainViewModel.kt
index 88689e0..530af39 100644
--- a/android-app/app/src/main/kotlin/org/terst/nav/ui/MainViewModel.kt
+++ b/android-app/app/src/main/kotlin/org/terst/nav/ui/MainViewModel.kt
@@ -236,6 +236,10 @@ class MainViewModel(
     private var lastConditionsLon = Double.NaN
     private var lastConditionsMs  = 0L
 
+    private var lastWindGridLat = Double.NaN
+    private var lastWindGridLon = Double.NaN
+    private var lastWindGridMs  = 0L
+
     /**
      * Fetches current conditions snapshot for [lat]/[lon] and exposes it via [marineConditions].
      * Throttled: skips if conditions loaded < 5 min ago and position < 2 nm from last load.
@@ -312,9 +316,20 @@ class MainViewModel(
 
     /**
      * Fetch wind arrows for a 4×5 grid covering the visible map bounds.
+     * Throttled: skips if grid center < 10 nm from last fetch and < 15 min old.
      * Fires-and-forgets; silently ignores network failures (grid is decorative).
      */
     fun loadWindGrid(latMin: Double, latMax: Double, lonMin: Double, lonMax: Double) {
+        val centerLat = (latMin + latMax) / 2.0
+        val centerLon = (lonMin + lonMax) / 2.0
+        val nowMs  = System.currentTimeMillis()
+        val ageMs  = nowMs - lastWindGridMs
+        val distNm = if (lastWindGridLat.isNaN()) Double.MAX_VALUE
+                     else distanceNm(lastWindGridLat, lastWindGridLon, centerLat, centerLon)
+        if (ageMs < 15 * 60_000L && distNm < 10.0) return
+        lastWindGridLat = centerLat
+        lastWindGridLon = centerLon
+        lastWindGridMs  = nowMs
         viewModelScope.launch {
             val points = buildGrid(latMin, latMax, lonMin, lonMax, cols = 4, rows = 5)
             repository.fetchWindGrid(points).getOrNull()?.let { _windGrid.value = it }
-- 
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