Refactor settings migration code in functional style

src/settings/index.ts

@@ -1 +1 @@
-export type SettingsMigrator = (settings: object) => object;
+export type SettingsMigrator<From, To> = (settings: From) => To;

src/settings/migrators/1.1.0-1.2.0.ts

@@ -2,28 +2,38 @@ import { SettingsMigrator } from '..';
 import { MarkpilotSettings1_1_0 } from '../versions/1.1.0';
 import { MarkpilotSettings1_2_0 } from '../versions/1.2.0';
 
-export const migrateVersion1_1_0_toVersion1_2_0: SettingsMigrator = (
-  settings: MarkpilotSettings1_1_0,
-) => {
-  const apiKey = settings.apiKey as string;
-  delete settings.apiKey;
-  // eslint-disable-next-line @typescript-eslint/no-explicit-any
-  const newSettings: MarkpilotSettings1_2_0 = structuredClone(settings) as any;
-  newSettings.providers = {
-    openai: {
-      apiKey,
+export const migrateVersion1_1_0_toVersion1_2_0: SettingsMigrator<
+  MarkpilotSettings1_1_0,
+  MarkpilotSettings1_2_0
+> = (settings) => {
+  const newSettings: MarkpilotSettings1_2_0 = {
+    version: '1.2.0',
+    providers: {
+      openai: {
+        apiKey: settings.apiKey,
+      },
+      openrouter: {
+        apiKey: undefined,
+      },
+      ollama: {
+        apiUrl: undefined,
+      },
     },
-    openrouter: {
-      apiKey: undefined,
+    completions: {
+      ...settings.completions,
+      provider: 'openai',
+      ignoredFiles: [],
+      ignoredTags: [],
     },
-    ollama: {
-      apiUrl: undefined,
+    chat: {
+      ...settings.chat,
+      provider: 'openai',
     },
+    cache: {
+      enabled: true, // Enable cache by default.
+    },
+    usage: settings.usage,
   };
-  newSettings.completions.provider = 'openai';
-  newSettings.completions.ignoredFiles = [];
-  newSettings.completions.ignoredTags = [];
-  newSettings.chat.provider = 'openai';
   // Update if default models are still selected.
   if (settings.completions.model === 'gpt-3.5-turbo-instruct') {
     newSettings.completions.model = 'gpt-3.5-turbo';

src/settings/runner.ts

@@ -3,12 +3,9 @@ import Markpilot from '../main';
 import { migrateVersion1_1_0_toVersion1_2_0 } from './migrators/1.1.0-1.2.0';
 
 export class SettingsMigrationsRunner {
-  nextMigrators: Record<string, SettingsMigrator> = {
+  migrators: Record<string, SettingsMigrator<object, object>> = {
     '1.1.0': migrateVersion1_1_0_toVersion1_2_0,
   };
-  nextVersions: Record<string, string> = {
-    '1.1.0': '1.2.0',
-  };
 
   constructor(private plugin: Markpilot) {}
 
@@ -19,16 +16,15 @@ export class SettingsMigrationsRunner {
     // NOTE:
     // An infinite loop would also work because of the break statement
     // but we take the safe path here.
-    const maxIterations = Object.keys(this.nextMigrators).length;
+    const maxIterations = Object.keys(this.migrators).length;
     for (let i = 0; i < maxIterations + 1; i++) {
       // Settings versions and migrations were introduced from version 1.1.0.
       const version = settings.version ?? '1.1.0';
-      const migrator = this.nextMigrators[version];
+      const migrator = this.migrators[version];
       if (migrator === undefined) {
         break;
       }
-      settings = migrator(settings);
-      settings.version = this.nextVersions[version];
+      settings = migrator(structuredClone(settings));
     }
 
     this.plugin.settings = settings;