Allow downloading savegames

src/js/core/read_write_proxy.js

@@ -79,6 +79,16 @@ export class ReadWriteProxy {
         return this.currentData;
     }
 
+    /**
+     *
+     * @param {object} obj
+     */
+    static serializeObject(obj) {
+        const jsonString = JSON_stringify(compressObject(obj));
+        const checksum = sha1(jsonString + salt);
+        return compressionPrefix + compressX64(checksum + jsonString);
+    }
+
     /**
      * Writes the data asychronously, fails if verify() fails
      * @returns {Promise<string>}

src/js/core/utils.js

@@ -859,3 +859,20 @@ export function formatSecondsToTimeAgo(secs) {
         return days + " days ago";
     }
 }
+
+/**
+ * Generates a file download
+ * @param {string} filename
+ * @param {string} text
+ */
+export function generateFileDownload(filename, text) {
+    var element = document.createElement("a");
+    element.setAttribute("href", "data:text/plain;charset=utf-8," + encodeURIComponent(text));
+    element.setAttribute("download", filename);
+
+    element.style.display = "none";
+    document.body.appendChild(element);
+
+    element.click();
+    document.body.removeChild(element);
+}

src/js/states/main_menu.js

@@ -1,7 +1,8 @@
 import { GameState } from "../core/game_state";
 import { cachebust } from "../core/cachebust";
 import { globalConfig } from "../core/config";
-import { makeDiv, formatSecondsToTimeAgo } from "../core/utils";
+import { makeDiv, formatSecondsToTimeAgo, generateFileDownload } from "../core/utils";
+import { ReadWriteProxy } from "../core/read_write_proxy";
 
 export class MainMenuState extends GameState {
     constructor() {
@@ -90,10 +91,15 @@ export class MainMenuState extends GameState {
                     formatSecondsToTimeAgo((new Date().getTime() - games[i].lastUpdate) / 1000.0)
                 );
 
+                const downloadButton = document.createElement("button");
+                downloadButton.classList.add("styledButton", "downloadGame");
+                elem.appendChild(downloadButton);
+
                 const resumeBtn = document.createElement("button");
                 resumeBtn.classList.add("styledButton", "resumeGame");
                 elem.appendChild(resumeBtn);
 
+                this.trackClicks(downloadButton, () => this.downloadGame(games[i]));
                 this.trackClicks(resumeBtn, () => this.resumeGame(games[i]));
             }
         }
@@ -111,6 +117,17 @@ export class MainMenuState extends GameState {
         });
     }
 
+    /**
+     * @param {object} game
+     */
+    downloadGame(game) {
+        const savegame = this.app.savegameMgr.getSavegameById(game.internalId);
+        savegame.readAsync().then(() => {
+            const data = ReadWriteProxy.serializeObject(savegame.currentData);
+            generateFileDownload(savegame.filename, data);
+        });
+    }
+
     onPlayButtonClicked() {
         const savegame = this.app.savegameMgr.createNewSavegame();