Make Client remember its token, add ID form checks

Refactor MattermostClient, deduplicating code and making it remember its token.

Make functions that ask for a Mattermost ID check that they get
something of the correct form.

index.html

@@ -64,7 +64,7 @@
 
 		<script type="text/javascript" src="/js/ajax.js"></script>
 		<script type="text/javascript" src="/js/util.js"></script>
-		<script type="text/javascript" src="/js/model/credentials.js"></script>
+		<script type="text/javascript" src="/js/model/localstorage_credentials.js"></script>
 		<script type="text/javascript" src="/js/model/mm_client.js"></script>
 		<script type="text/javascript" src="/js/view/view.js"></script>
 		<script type="text/javascript" src="/js/controller/controller.js"></script>

js/controller/controller.js

@@ -2,7 +2,7 @@
 
 function createClient(endpoint) {
 	const api = new mm_client.MattermostApi(normalizedEndpoint(endpoint));
-	return new mm_client.MattermostClient(api);
+	return new mm_client.MattermostClient(api, localstorage_credentials);
 }
 
 function buttonDisable(element, text) {

js/model/localstorage_credentials.js

@@ -1,4 +1,4 @@
-const credentials = (function() { "use strict";
+const localstorage_credentials = (function() { "use strict";
 
 const LOCALSTORAGE_KEY_SERVER = "mattermostServer";
 const RE_SERVER_ITEM = new RegExp(`^${LOCALSTORAGE_KEY_SERVER}_(.*)\$`, "");

js/model/mm_client.js

@@ -31,74 +31,84 @@ class MattermostApi {
 
 
 class MattermostClient {
-	constructor (api) {
+	constructor (api, credentials_provider) {
 		this.api = api;
+		this.credentials = credentials_provider;
+		const creds = this.credentials.get(this.api.id);
+		this.token = creds ? creds.token : null;
+		console.info(`Created MattermostClient for ${this.api.id}, ${this.token ? "found token" : "did not find token"}`);
+	}
+
+	async authenticatedGet(url, queryParams) {
+		assert(this.token, "logged in");
+		const response = await this.api.get(url, this.token, queryParams);
+		return response.responseJson;
+	}
+
+	async loggedIn() {
+		if (!this.token) {
+			return false;
+		}
+		try {
+			const meResponse = await this.userMe();
+			return true;
+		} catch (e) {
+			if (e instanceof ajax.NotOkError && e.xhr.status == 401) {
+				return false;
+			} else {
+				throw e;
+			}
+		}
 	}
 
 	async logIn(login_id, password) {
+		if (this.token && await this.tokenWorks()) {
+			throw Error("Already logged in on this server");
+		}
+
 		const response = await this.api.post("/users/login", undefined, {login_id, password});
 		const token = response.getResponseHeader("Token");
 		if (!token) {
 			throw Error("No Token header in response to log in request");
 		}
-		credentials.store(this.api.id, login_id, token);
+		this.credentials.store(this.api.id, login_id, token);
+		this.token = token;
 		return response.responseJson;
 	}
 
 	async logOut() {
-		const stored = credentials.get(this.api.id);
-		if (!stored || !stored.token) {
-			throw Error("No token stored");
-		}
-		const response = await this.api.post("/users/logout", stored.token);
+		assert(this.token, "logged in");
+		const response = await this.api.post("/users/logout", this.token);
 
 		// Verify that the token is now invalidated
-		let tokenWorks;
-		try {
-			const meResponse = await this.usersMe();
-			tokenWorks = true;
-		} catch (e) {
-			if (e instanceof ajax.NotOkError && e.xhr.status == 401) {
-				tokenWorks = false;
-			} else {
-				throw e;
-			}
-		}
-		if (tokenWorks) {
+		if (await loggedIn()) {
 			throw new Error("Failed to log out: token still works after trying to log out");
 		}
 
-		credentials.clear(this.api.id);
+		this.credentials.clear(this.api.id);
+		this.token = null;
 		return response.responseJson;
 	}
 
-	async usersMe() {
-		const stored = credentials.get(this.api.id);
-		if (!stored || !stored.token) {
-			throw Error("No token stored");
+	user(user_id) {
+		assertIsMattermostId(user_id);
+		return this.authenticatedGet(`/users/${user_id}`);
 	}
-		const response = await this.api.get("/users/me", stored.token);
-		return response.responseJson;
+	userMe()            { return this.authenticatedGet("/users/me"); }
+	myTeams()           { return this.authenticatedGet("/users/me/teams"); }
+
+	myChannels(team_id) {
+		assertIsMattermostId(team_id);
+		return this.authenticatedGet(`/users/me/teams/${team_id}/channels`);
 	}
 
-	async myTeams() {
-		const stored = credentials.get(this.api.id);
-		const response = await this.api.get("/users/me/teams", stored.token);
-		return response.responseJson;
-	}
-
-	async myChannels(team_id) {
-		const stored = credentials.get(this.api.id);
-		const response = await this.api.get(`/users/me/teams/${team_id}/channels`, stored.token);
-		return response.responseJson;
-	}
-
-	async channelPosts(channel_id, beforePost=null, afterPost=null, since=null) {
-		const stored = credentials.get(this.api.id);
-		const response = await this.api.get(`/channels/${channel_id}/posts`, stored.token, {
+	channelPosts(channel_id, beforePost=null, afterPost=null, since=null) {
+		assertIsMattermostId(channel_id);
+		assertIsNullOrMattermostId(beforePost);
+		assertIsNullOrMattermostId(afterPost);
+		return this.authenticatedGet(`/channels/${channel_id}/posts`, {
 			before: beforePost, after: afterPost, since
 		});
-		return response.responseJson;
 	}
 }
 

js/util.js

@@ -44,3 +44,25 @@ function thisToArg(f) {
 	}
 }
 
+
+class AssertionError extends Error {}
+/**
+ * Throw an AssertionError if the first argument is not true
+ */
+function assert(condition, message) {
+	if (!condition) {
+		if (message) {
+			throw new AssertionError(`Assertion failed: ${message}`);
+		} else {
+			throw new AssertionError("Assertion failed");
+		}
+	}
+}
+
+const MATTERMOST_ID_REGEXP = /^[a-z0-9]{26}$/;
+function assertIsMattermostId(string, name="") {
+	assert(MATTERMOST_ID_REGEXP.test(string), `${name} has the form of a Mattermost ID`);
+}
+function assertIsNullOrMattermostId(string, name="") {
+	assert(string === null || MATTERMOST_ID_REGEXP.test(string), `${name} is null or has the form of a Mattermost ID`);
+}

js/view/view.js

@@ -1,5 +1,5 @@
 function populateServerSelectionList() {
-	const servers = credentials.getServers();
+	const servers = localstorage_credentials.getServers();
 
 	let nodes = [];
 	for (let server of servers) {
@@ -49,7 +49,7 @@ function populateChannelList() {
 		}
 	}
 
-	const servers = credentials.getServers();
+	const servers = localstorage_credentials.getServers();
 
 	byId("channel_list").innerHTML = "";
 	for (let server of servers) {