From fc6d6ada0c0b67e41ebaf61a0f28b2e26bac8a7a Mon Sep 17 00:00:00 2001
From: Peter Williams <peter@newton.cx>
Date: Sat, 18 Nov 2023 08:23:15 -0500
Subject: [PATCH] stores/constellations.ts: fix history navigation past the
 first page!

Oops, we made it so that the timeline never actually refilled itself
as we navigated forward! So we'd get to the end of page 1 and run out
of scenes.

Also fix a bug with managing the pagination.
---
 stores/constellations.ts | 14 +++++++++++---
 1 file changed, 11 insertions(+), 3 deletions(-)

diff --git a/stores/constellations.ts b/stores/constellations.ts
index a62f7da..1a476ff 100644
--- a/stores/constellations.ts
+++ b/stores/constellations.ts
@@ -132,14 +132,16 @@ export const useConstellationsStore = defineStore("wwt-constellations", () => {
       const page = nextNeededPage;
       const result = await getNextScenes($backendCall, page);
 
+      // Once again, we must make sure that the navigation situation hasn't
+      // change on us while we were waiting for getNextScenes() to resolve.
       if (nextNeededPage === page && !needToChangeSceneSource(navigationMode.value)) {
         for (const scene of result.results) {
           knownScenes.value.set(scene.id, scene);
           futureScenes.value.push(scene);
         }
-      }
 
-      nextNeededPage += 1;
+        nextNeededPage += 1;
+      }
     }
   }
 
@@ -202,6 +204,10 @@ export const useConstellationsStore = defineStore("wwt-constellations", () => {
       return;
     }
 
+    // Make sure that we always have forward coverage past the target, so that
+    // the "next" button remains available if it should!
+    await ensureForwardCoverage(count + 1);
+
     // These two variables are just containers so that we don't need to update ref values more than once
     let scene: GetSceneResponseT | undefined = undefined;
     let node: Yallist.Node<GetSceneResponseT> | undefined = undefined;
@@ -215,7 +221,9 @@ export const useConstellationsStore = defineStore("wwt-constellations", () => {
         node = next;
       } else {
         if (futureScenes.value.length === 0) {
-          await ensureForwardCoverage(count);  // Should this be larger?
+          // Just in case ... once again, ensure that we go past the target to
+          // be able to properly make the "next" button clickable or not.
+          await ensureForwardCoverage(count + 1);
         }
 
         scene = futureScenes.value.shift();