coming along well - electron is pretty nice

app/state/AppState.ts

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+import { action, computed, observable, runInAction } from 'mobx';
+import fs from 'fs';
+
+export interface ExpansionType {
+  name: string;
+  servers: ServerType[];
+  directory?: string;
+}
+
+export interface ServerType {
+  name: string;
+  realmlist: string;
+  website: string;
+}
+
+export class AppState {
+
+  constructor() {
+    this.bootstrap();
+  }
+
+  @action
+  private bootstrap(): void {
+    fs.readFile('./servers.json', (err, data) => {
+      if (!err) {
+        runInAction(() => {
+          this.expansions = JSON.parse(data.toString()) as any;
+        });
+      }
+    });
+  }
+
+  @observable
+  public expansions: { [key: string]: ExpansionType } = {
+    vanilla: {
+      name: 'Vanilla',
+      servers: [],
+      directory: '',
+    },
+    bc: {
+      name: 'Burning Crusade',
+      servers: [],
+      directory: '',
+    },
+    wotlk: {
+      name: 'Wrath of the Lich King',
+      servers: [],
+      directory: '',
+    },
+  };
+
+  @observable
+  public selectedExpKey: string = 'vanilla';
+
+  @computed
+  public get selectedExpansion(): ExpansionType {
+    return this.expansions[this.selectedExpKey];
+  }
+
+  @action
+  public setSelectedExpansion(exp: string): void {
+    this.selectedExpKey = exp;
+  }
+
+  @action
+  public setDirectory(dir: string): void {
+    this.expansions[this.selectedExpKey].directory = dir;
+    this.updateFile(this.expansions);
+  }
+
+  private updateFile(exp: any): Promise<void> {
+    return new Promise((resolve, reject) => {
+      fs.writeFile('./servers.json', JSON.stringify(exp, null, 2), {}, (err) => {
+        err ? reject(err) : resolve();
+      });
+    });
+  }
+  
+}
+
+export default new AppState();