From 489290b8b16bede6ddfb773adad55dee6471ccfd Mon Sep 17 00:00:00 2001
From: Chocobozzz <me@florianbigard.com>
Date: Thu, 21 Mar 2019 16:49:46 +0100
Subject: Restore videos list components

---
 .../src/app/core/routing/custom-reuse-strategy.ts  | 81 ++++++++++++++++++++++
 .../src/app/core/routing/disable-for-reuse-hook.ts |  7 ++
 2 files changed, 88 insertions(+)
 create mode 100644 client/src/app/core/routing/custom-reuse-strategy.ts
 create mode 100644 client/src/app/core/routing/disable-for-reuse-hook.ts

(limited to 'client/src/app/core')

diff --git a/client/src/app/core/routing/custom-reuse-strategy.ts b/client/src/app/core/routing/custom-reuse-strategy.ts
new file mode 100644
index 000000000..a9f61acec
--- /dev/null
+++ b/client/src/app/core/routing/custom-reuse-strategy.ts
@@ -0,0 +1,81 @@
+import { ActivatedRouteSnapshot, DetachedRouteHandle, RouteReuseStrategy } from '@angular/router'
+
+export class CustomReuseStrategy implements RouteReuseStrategy {
+  storedRouteHandles = new Map<string, DetachedRouteHandle>()
+  recentlyUsed: string
+
+  private readonly MAX_SIZE = 2
+
+  // Decides if the route should be stored
+  shouldDetach (route: ActivatedRouteSnapshot): boolean {
+    return this.isReuseEnabled(route)
+  }
+
+  // Store the information for the route we're destructing
+  store (route: ActivatedRouteSnapshot, handle: DetachedRouteHandle): void {
+    if (!handle) return
+
+    const key = this.generateKey(route)
+    this.recentlyUsed = key
+
+    console.log('Storing component %s to reuse later.', key);
+
+    (handle as any).componentRef.instance.disableForReuse()
+
+    this.storedRouteHandles.set(key, handle)
+
+    this.gb()
+  }
+
+  // Return true if we have a stored route object for the next route
+  shouldAttach (route: ActivatedRouteSnapshot): boolean {
+    const key = this.generateKey(route)
+    return this.isReuseEnabled(route) && this.storedRouteHandles.has(key)
+  }
+
+  // If we returned true in shouldAttach(), now return the actual route data for restoration
+  retrieve (route: ActivatedRouteSnapshot): DetachedRouteHandle {
+    if (!this.isReuseEnabled(route)) return undefined
+
+    const key = this.generateKey(route)
+    this.recentlyUsed = key
+
+    console.log('Reusing component %s.', key)
+
+    const handle = this.storedRouteHandles.get(key)
+    if (!handle) return handle;
+
+    (handle as any).componentRef.instance.enabledForReuse()
+
+    return handle
+  }
+
+  // Reuse the route if we're going to and from the same route
+  shouldReuseRoute (future: ActivatedRouteSnapshot, curr: ActivatedRouteSnapshot): boolean {
+    return future.routeConfig === curr.routeConfig
+  }
+
+  private gb () {
+    if (this.storedRouteHandles.size >= this.MAX_SIZE) {
+      this.storedRouteHandles.forEach((r, key) => {
+        if (key === this.recentlyUsed) return
+
+        console.log('Removing stored component %s.', key);
+
+        (r as any).componentRef.destroy()
+        this.storedRouteHandles.delete(key)
+      })
+    }
+  }
+
+  private generateKey (route: ActivatedRouteSnapshot) {
+    const reuse = route.data.reuse
+    if (!reuse) return undefined
+
+    return reuse.key + JSON.stringify(route.queryParams)
+  }
+
+  private isReuseEnabled (route: ActivatedRouteSnapshot) {
+    return route.data.reuse && route.data.reuse.enabled && route.queryParams['a-state']
+  }
+}
diff --git a/client/src/app/core/routing/disable-for-reuse-hook.ts b/client/src/app/core/routing/disable-for-reuse-hook.ts
new file mode 100644
index 000000000..c5eb5c578
--- /dev/null
+++ b/client/src/app/core/routing/disable-for-reuse-hook.ts
@@ -0,0 +1,7 @@
+export interface DisableForReuseHook {
+
+  disableForReuse (): void
+
+  enabledForReuse (): void
+
+}
-- 
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