From 1d9a5c490af1ea6c3b588756c16c644d1151603a Mon Sep 17 00:00:00 2001
From: Bruno Windels <brunow@matrix.org>
Date: Mon, 23 Dec 2019 14:28:42 +0100
Subject: [PATCH] add record/replay network layer

---
 src/matrix/net/replay.js | 108 +++++++++++++++++++++++++++++++++++++++
 1 file changed, 108 insertions(+)
 create mode 100644 src/matrix/net/replay.js

diff --git a/src/matrix/net/replay.js b/src/matrix/net/replay.js
new file mode 100644
index 00000000..b6ddcb74
--- /dev/null
+++ b/src/matrix/net/replay.js
@@ -0,0 +1,108 @@
+import {
+    RequestAbortError,
+    NetworkError
+} from "../error.js";
+
+class RequestLogItem {
+    constructor(url, options) {
+        this.url = url;
+        this.options = options;
+        this.error = null;
+        this.body = null;
+        this.status = status;
+        this.start = performance.now();
+        this.end = 0;
+    }
+
+    async handleResponse(response) {
+        this.end = performance.now();
+        this.status = response.status;
+        this.body = response.body;
+    }
+
+    handleError(err) {
+        this.end = performance.now();
+        this.error = {
+            aborted: err instanceof RequestAbortError,
+            network: err instanceof NetworkError,
+            message: err.message,
+        };
+    }
+}
+
+export class RecordRequester {
+    constructor(request) {
+        this._origRequest = request;
+        this._requestLog = [];
+        this.request = this.request.bind(this);
+    }
+
+    request(url, options) {
+        const requestItem = new RequestLogItem(url, options);
+        this._requestLog.push(requestItem);
+        try {
+            const requestResult = this._origRequest(url, options);
+            requestResult.response().then(response => {
+                requestItem.handleResponse(response);
+            });
+            return requestResult;
+        } catch (err) {
+            requestItem.handleError(err);
+            throw err;
+        }
+    }
+
+    log() {
+        return this._requestLog;
+    }
+}
+
+export class ReplayRequester {
+    constructor(log, options) {
+        this._log = log.slice();
+        this._options = options;
+        this.request = this.request.bind(this);
+    }
+
+    request(url, options) {
+        const idx = this._log.findIndex(item => {
+            return item.url === url && options.method === item.options.method;
+        });
+        if (idx === -1) {
+            return new ReplayRequestResult({status: 404}, options);
+        } else {
+            const [item] = this._log.splice(idx, 1);
+            return new ReplayRequestResult(item, options);
+        }
+    }
+}
+
+class ReplayRequestResult {
+    constructor(item, options) {
+        this._item = item;
+        this._options = options;
+        this._aborted = false;
+    }
+
+    abort() {
+        this._aborted = true;
+    }
+
+    async response() {
+        if (this._options.delay) {
+            const delay = this._item.end - this._item.start;
+            await new Promise(resolve => setTimeout(resolve, delay));
+        }
+        if (this._item.error || this._aborted) {
+            const error = this._item.error;
+            if (error.aborted || this._aborted) {
+                throw new RequestAbortError(error.message);
+            } else if (error.network) {
+                throw new NetworkError(error.message);
+            } else {
+                throw new Error(error.message);
+            }
+        }
+        return this._item;
+    }
+}