Reset application on updates

Fixes #16.

package.json

@@ -1,6 +1,6 @@
 {
     "name": "fwdekker.com",
-    "version": "0.24.4",
+    "version": "0.25.0",
     "description": "The source code of [my personal website](https://fwdekker.com/).",
     "author": "Felix W. Dekker",
     "repository": {
@@ -16,13 +16,15 @@
         "coverage": "nyc npm run test"
     },
     "dependencies": {
-        "js-cookie": "^2.2.1"
+        "js-cookie": "^2.2.1",
+        "semver": "^6.3.0"
     },
     "devDependencies": {
         "@istanbuljs/nyc-config-typescript": "^0.1.3",
         "@types/chai": "^4.2.5",
         "@types/js-cookie": "^2.2.4",
         "@types/mocha": "^5.2.7",
+        "@types/semver": "^6.2.0",
         "chai": "^4.2.0",
         "grunt": "^1.0.4",
         "grunt-cli": "^1.3.2",
@@ -33,7 +35,7 @@
         "mocha": "^6.2.2",
         "nyc": "^14.1.1",
         "ts-loader": "^6.2.1",
-        "ts-node": "^8.5.2",
+        "ts-node": "^8.5.4",
         "typescript": "^3.7.2",
         "webpack": "^4.41.2",
         "webpack-cli": "^3.3.10"

src/main/js/Commands.ts

@@ -4,7 +4,7 @@ import {Directory, File, FileSystem, Path} from "./FileSystem"
 import {InputArgs} from "./InputArgs";
 import {InputParser} from "./InputParser";
 import {Persistence} from "./Persistence";
-import {escapeHtml, IllegalArgumentError, IllegalStateError, isStandalone} from "./Shared";
+import {escapeHtml, ExpectedGoodbyeError, IllegalArgumentError, IllegalStateError, isStandalone} from "./Shared";
 import {EscapeCharacters} from "./Terminal";
 import {UserList} from "./UserList";
 import {StreamSet} from "./Stream";
@@ -60,7 +60,7 @@ export class Commands {
                 `concatenate and print files`,
                 `cat [<b>-e</b> | <b>--escape-html</b>] <u>file</u> <u>...</u>`,
                 `Reads files sequentially, writing them to the standard output.
-                
+
                 If the file contains valid HTML, it will be displayed as such by default. If the <b>--html</b> \\\
                 option is given, special HTML characters are escaped and the raw text contents can be inspected.\\\
                 `.trimMultiLines(),
@@ -270,7 +270,7 @@ export class Commands {
         if (input.command === "factory-reset") {
             Persistence.reset();
             location.reload();
-            throw new Error("Goodbye");
+            throw new ExpectedGoodbyeError("Goodbye");
         }
 
         if (input.command === "")

src/main/js/Main.ts

@@ -1,6 +1,7 @@
 import {Persistence} from "./Persistence";
-import {addOnLoad, q} from "./Shared";
+import {addOnLoad, ExpectedGoodbyeError, q} from "./Shared";
 import {Terminal} from "./Terminal";
+import * as semver from "semver";
 
 
 declare global {
@@ -19,13 +20,45 @@ declare global {
 }
 
 
+/**
+ * Compares version numbers to ensure no compatibility errors ensure.
+ */
+addOnLoad(() => {
+    const userVersion = Persistence.getVersion();
+    const latestVersion = "%%VERSION_NUMBER%%";
+
+    if (semver.lt(userVersion, latestVersion)) {
+        Persistence.reset();
+        Persistence.setWasUpdated(true); // Message is displayed after reload
+        location.reload();
+        throw new ExpectedGoodbyeError("Goodbye");
+    }
+
+    if (Persistence.getWasUpdated()) {
+        q("#terminalOutput").innerHTML = "" +
+            "<span style=\"color:red\">This website has been updated. To prevent unexpected errors, all previous " +
+            "user changes have been reset.</span>\n\n";
+        Persistence.setWasUpdated(false);
+    }
+
+    Persistence.setVersion(latestVersion);
+});
+
+/**
+ * Exist the application if the server is "shut down".
+ */
 addOnLoad(() => {
     if (Persistence.getPoweroff()) {
         q("#terminalOutput").innerText = "Could not connect to fwdekker.com. Retrying in 10 seconds.";
         setTimeout(() => location.reload(), 10000);
-        return;
+        throw new ExpectedGoodbyeError("Goodbye");
     }
+});
 
+/**
+ * Initializes the application.
+ */
+addOnLoad(() => {
     window.terminal = new Terminal(
         q("#terminal"),
         q("#terminalCurrentFocusInput"),

src/main/js/Persistence.ts

@@ -10,51 +10,19 @@ import {UserList} from "./UserList";
  */
 export class Persistence {
     /**
-     * Deserializes an environment from persistent storage, or returns the default environment if the deserialization
-     * failed.
-     *
-     * @param userList the list of users used to validate the `user` environment variable
+     * Removes all persistent storage.
      */
-    static getEnvironment(userList: UserList): Environment {
-        const environmentString = Cookies.get("env") ?? "{}";
-
-        let environment: Environment;
-        try {
-            environment = new Environment(["cwd", "home", "user", "status"], JSON.parse(environmentString));
-        } catch (error) {
-            console.warn("Failed to set environment from cookie.");
-            environment = new Environment(["cwd", "home", "user", "status"]);
-        }
-
-        // Check user in environment
-        if (!environment.has("user")) {
-            environment.set("user", "felix");
-        } else if (environment.get("user") !== "" && !userList.has(environment.get("user"))) {
-            console.warn(`Invalid user '${environment.get("user")}' in environment.`);
-            environment.set("user", "felix");
-        }
-
-        // Set home directory
-        environment.set("home", userList.get(environment.get("user"))?.home ?? "/");
-
-        // Check cwd in environment
-        if (!environment.has("cwd"))
-            environment.set("cwd", environment.get("home"));
-
-        // Set status
-        environment.set("status", "0");
-
-        return environment;
+    static reset(): void {
+        sessionStorage.clear();
+        localStorage.clear();
+        Cookies.remove("env");
+        Cookies.remove("poweroff");
     }
 
-    /**
-     * Persists the given environment.
-     *
-     * @param environment the environment to persist
-     */
-    static setEnvironment(environment: Environment): void {
-        Cookies.set("env", environment.variables, {"path": "/"});
-    }
+
+    ///
+    /// Long-term storage
+    ///
 
     /**
      * Deserializes a file system from persistent storage, or returns the default file system if the deserialization
@@ -108,21 +76,89 @@ export class Persistence {
     }
 
     /**
-     * Returns the persisted "power off" setting.
+     * Deserializes an environment from persistent storage, or returns the default environment if the deserialization
+     * failed.
+     *
+     * @param userList the list of users used to validate the `user` environment variable
+     */
+    static getEnvironment(userList: UserList): Environment {
+        const environmentString = Cookies.get("env") ?? "{}";
+
+        let environment: Environment;
+        try {
+            environment = new Environment(["cwd", "home", "user", "status"], JSON.parse(environmentString));
+        } catch (error) {
+            console.warn("Failed to set environment from cookie.");
+            environment = new Environment(["cwd", "home", "user", "status"]);
+        }
+
+        // Check user in environment
+        if (!environment.has("user")) {
+            environment.set("user", "felix");
+        } else if (environment.get("user") !== "" && !userList.has(environment.get("user"))) {
+            console.warn(`Invalid user '${environment.get("user")}' in environment.`);
+            environment.set("user", "felix");
+        }
+
+        // Set home directory
+        environment.set("home", userList.get(environment.get("user"))?.home ?? "/");
+
+        // Check cwd in environment
+        if (!environment.has("cwd"))
+            environment.set("cwd", environment.get("home"));
+
+        // Set status
+        environment.set("status", "0");
+
+        return environment;
+    }
+
+    /**
+     * Persists the given environment.
+     *
+     * @param environment the environment to persist
+     */
+    static setEnvironment(environment: Environment): void {
+        Cookies.set("env", environment.variables, {"path": "/"});
+    }
+
+    /**
+     * Returns the version of the scripts that were used the last time the user visited the website.
+     */
+    static getVersion(): string {
+        return localStorage.getItem("version") ?? "%%VERSION_NUMBER%%";
+    }
+
+    /**
+     * Sets the version of the scripts that were used the last time the user visited the website.
+     *
+     * @param version the version of the scripts that were used the last time the user visited the website
+     */
+    static setVersion(version: string) {
+        localStorage.setItem("version", version);
+    }
+
+
+    ///
+    /// Short-term storage
+    ///
+
+    /**
+     * Returns `true` if and only if the server is "turned off".
      */
     static getPoweroff(): boolean {
         try {
             return JSON.parse(Cookies.get("poweroff") ?? "false");
-        } catch(error) {
+        } catch (error) {
             console.warn("Failed to deserialize 'poweroff' cookie.", error);
             return false;
         }
     }
 
     /**
-     * Persists the "power off" setting.
+     * Stores whether the server is "turned off".
      *
-     * @param value the value to persist for the "power off" setting
+     * @param value whether the server is "turned off"
      */
     static setPoweroff(value: boolean): void {
         Cookies.set("poweroff", "" + value, {
@@ -132,11 +168,23 @@ export class Persistence {
     }
 
     /**
-     * Removes all persistent storage.
+     * Returns `true` if and only if the terminal was updated in this session.
      */
-    static reset(): void {
-        localStorage.clear();
-        Cookies.remove("env");
-        Cookies.remove("poweroff");
+    static getWasUpdated(): boolean {
+        try {
+            return JSON.parse(sessionStorage.getItem("has-updated") ?? "false");
+        } catch (error) {
+            console.warn("Failed to deserialize 'poweroff' cookie.", error);
+            return false;
+        }
+    }
+
+    /**
+     * Stores whether the terminal was updated in this session.
+     *
+     * @param value whether the terminal was updated in this session
+     */
+    static setWasUpdated(value: boolean): void {
+        sessionStorage.setItem("has-updated", "" + value);
     }
 }

src/main/js/Shared.ts

@@ -129,6 +129,18 @@ export function q(query: string): HTMLElement {
 }
 
 
+/**
+ * Indicates that the application will exit under normal circumstances.
+ *
+ * That is, this is not actually an error. This "error" is thrown when the normal flow of execution should be
+ * interrupted right away so that the application can exit.
+ */
+export class ExpectedGoodbyeError extends Error {
+    constructor(message: string) {
+        super(message);
+    }
+}
+
 /**
  * Indicates that an argument is given to a function that should not have been given.
  *

src/main/js/Terminal.ts

@@ -86,8 +86,8 @@ export class Terminal {
             scrollStartPosition = newPosition;
         }, {passive: true});
 
-        this.outputText = this.shell.generateHeader();
-        this.prefixText = this.shell.generatePrefix();
+        this.outputText += this.shell.generateHeader();
+        this.prefixText += this.shell.generatePrefix();
         this.input.focus();
     }