snapshot

src/app.ts

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+import { openDB, type IDBPDatabase } from "idb";
+import type { Readable } from "svelte/motion";
+import { readable, writable } from "svelte/store";
+
+export interface IGalleryImage {
+  id: IDBValidKey;
+  when: Date;
+  dataUrl: string;
+}
+
+export interface IFetchGalleryImagesArgs {
+  constraint?: IDBKeyRange;
+  direction?: IDBCursorDirection;
+  take?: number;
+  skip?: number;
+}
+
+export interface IFetchGalleryImagesPage {
+  count: number;
+  images: Array<IGalleryImage>;
+}
+
+export interface IFetchGalleryImagesQuery {
+  result: Readable<IFetchGalleryImagesPage>;
+
+  refresh() : Promise<void>;
+
+  setArgs(args: IFetchGalleryImagesArgs): void;
+}
+
+export interface IGalleryDb {
+  storeImage (image: Omit<IGalleryImage, 'id'>) : Promise<IDBValidKey>;
+
+  selectImages (index: string): IFetchGalleryImagesQuery;
+}
+
+const storeName = "images";
+
+export async function initGallery() {
+  const updates = Array<CallableFunction>();
+
+  const db = await openDB("image-diary", 1, {
+    upgrade(db) {
+      const images = db.createObjectStore(storeName, { keyPath: "id", autoIncrement: true });
+
+      images.createIndex("ix_when", ["when"]);
+    },
+  });
+
+  const fnStoreImage = async (image: IGalleryImage) => {
+    const tx = db.transaction(storeName, "readwrite");
+    const id = await tx.objectStore(storeName).add(image);
+
+    await tx.done;
+
+    for (const update of updates) {
+      update();
+    }
+
+    return id;
+  }
+
+  const fnSelectImages = (index: string): IFetchGalleryImagesQuery => {
+    var skip = 0;
+    var take = 5;
+    var direction: IDBCursorDirection = 'next';
+    var constraint: IDBKeyRange | null = null;
+
+    const setters = new Array<(v: IFetchGalleryImagesPage) => void>();
+  
+    const fnRefresh = async () => {
+      if (setters.length == 0) {
+        return;
+      }
+
+      // console.log('refresh', 'skip', skip, 'take', take, 'direction', direction, 'constraint', constraint);
+
+      const tx = db.transaction(storeName, "readonly");
+      const store = tx.objectStore(storeName);
+      const index = store.index("ix_when");
+
+      var shouldSkip = skip;
+      var shouldTake = take;
+
+      var result = new Array<IGalleryImage>();
+
+      const count = await index.count();
+
+      for await (const cursor of index.iterate(constraint, direction)) {
+        if (shouldSkip > 0) {
+          cursor.advance(skip);
+
+          shouldSkip = 0;
+          continue;
+        }
+
+        if (shouldTake > 0) {
+          result.push(cursor.value);
+
+          shouldTake--;
+          continue;
+        }
+
+        break;
+      }
+
+      for (const set of setters) {
+        set({
+          count: count,
+          images: result
+        });
+      }
+    
+      await tx.done;
+    };
+  
+    return {
+      result: readable<IFetchGalleryImagesPage>({count: 0, images: []}, (set) => {
+        setters.push(set);
+        updates.push(fnRefresh);
+
+        return () => {
+          setters.splice(setters.indexOf(set), 1);
+          updates.splice(updates.indexOf(fnRefresh), 1);
+        };
+      }),
+      refresh: fnRefresh,
+      setArgs: (args) => {
+        constraint = args.constraint ?? null;
+        direction = args.direction ?? 'next';
+        skip = args.skip ?? 0;
+        take = args.take ?? 5;
+      },
+    }
+  }
+
+  return {
+    storeImage: fnStoreImage,
+    selectImages: fnSelectImages,
+  };
+}