Add new method for cycling through every login (#142)

* Add new method for cycling through every login

To be used from browser extension when autofilling.
Related PR: https://github.com/bitwarden/browser/pull/956

* Cache sorted ciphers by URL and invalidate them after a period of 5 seconds

* Move file to models

src/models/domain/sortedCiphersCache.ts

@@ -0,0 +1,60 @@
+import { CipherView } from '../view';
+
+const CacheTTL = 5000;
+
+export class SortedCiphersCache {
+    private readonly sortedCiphersByUrl: Map<string, Ciphers> = new Map<string, Ciphers>();
+    private readonly timeouts: Map<string, any> = new Map<string, any>();
+
+    constructor(private readonly comparator: (a: CipherView, b: CipherView) => number) { }
+
+    isCached(url: string) {
+        return this.sortedCiphersByUrl.has(url);
+    }
+
+    addCiphers(url: string, ciphers: CipherView[]) {
+        ciphers.sort(this.comparator);
+        this.sortedCiphersByUrl.set(url, new Ciphers(ciphers));
+        this.resetTimer(url);
+    }
+
+    getLastUsed(url: string) {
+        this.resetTimer(url);
+        return this.isCached(url) ? this.sortedCiphersByUrl.get(url).getLastUsed() : null;
+    }
+
+    getNext(url: string) {
+        this.resetTimer(url);
+        return this.isCached(url) ? this.sortedCiphersByUrl.get(url).getNext() : null;
+    }
+
+    clear() {
+        this.sortedCiphersByUrl.clear();
+        this.timeouts.clear();
+    }
+
+    private resetTimer(url: string) {
+        clearTimeout(this.timeouts.get(url));
+        this.timeouts.set(url, setTimeout(() => {
+            this.sortedCiphersByUrl.delete(url);
+            this.timeouts.delete(url);
+        }, CacheTTL));
+    }
+}
+
+class Ciphers {
+    lastUsedIndex = -1;
+
+    constructor(private readonly ciphers: CipherView[]) { }
+
+    getLastUsed() {
+        this.lastUsedIndex = Math.max(this.lastUsedIndex, 0);
+        return this.ciphers[this.lastUsedIndex];
+    }
+
+    getNext() {
+        const nextIndex = (this.lastUsedIndex + 1) % this.ciphers.length;
+        this.lastUsedIndex = nextIndex;
+        return this.ciphers[nextIndex];
+    }
+}