refact store again

src/components/App.svelte

@@ -21,11 +21,65 @@
 
 
 <script>
+    import { onMount, onDestroy } from 'svelte'
+    import { get } from 'svelte/store'
+
     import Controls from '/components/Controls.svelte'
     import Queue from '/components/Queue.svelte'
     import Viewer from '/components/Viewer.svelte'
+    import { hashtagIterator } from '/services/mastodon.js'
+    import { mkTracksIterator } from '/services/misc.js'
 
-    import { current } from '/store.js'
+    import { domain, hashtags, queue, next, current, enqueueing, select } from '/store.js'
+
+    let nextUnsubcribe = null
+    let currentUnsubcribe = null
+
+    onMount(async () => {
+        const iterator = mkTracksIterator(hashtagIterator(get(domain), get(hashtags)[0]))
+
+        const { value: first } = await iterator.next()
+
+        queue.set([first])
+        select(first)
+
+        nextUnsubcribe = next.subscribe(async nextValue => {
+            if (nextValue === null) {
+                if (!get(enqueueing)) {
+                    enqueueing.set(true)
+
+                    const { value: newTrack } = await iterator.next()
+
+                    if (newTrack) {
+                        queue.update(queueValue => [...queueValue, newTrack])
+                        next.set(newTrack)
+                    }
+
+                    enqueueing.set(false)
+                }
+            }
+        })
+
+        currentUnsubcribe = current.subscribe(currentValue => {
+            if (currentValue !== null) {
+                next.update(nextValue => {
+                    if (nextValue === currentValue) {
+                        return null
+                    } else {
+                        return nextValue
+                    }
+                })
+            }
+        })
+    })
+
+    onDestroy(() => {
+        for (const unsubcribe of [nextUnsubcribe, currentUnsubcribe]) {
+            if (unsubcribe) {
+                unsubcribe()
+            }
+        }
+    })
 </script>
 
 <style>