1 files changed, 98 insertions, 0 deletions

diff --git a/packages/main/src/reactions/synchronizeConfig.ts b/packages/main/src/reactions/synchronizeConfig.ts
new file mode 100644
index 0000000..480cc1a
--- /dev/null
+++ b/packages/main/src/reactions/synchronizeConfig.ts
@@ -0,0 +1,98 @@
+/*
+ * Copyright (C)  2021-2022 Kristóf Marussy <kristof@marussy.com>
+ *
+ * This file is part of Sophie.
+ *
+ * Sophie is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License as
+ * published by the Free Software Foundation, version 3.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU Affero General Public License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ *
+ * SPDX-License-Identifier: AGPL-3.0-only
+ */
+
+import deepEqual from 'deep-equal';
+import { debounce } from 'lodash-es';
+import { reaction } from 'mobx';
+import ms from 'ms';
+
+import type ConfigRepository from '../infrastructure/config/ConfigRepository';
+import type SharedStore from '../stores/SharedStore';
+import type { Config } from '../stores/SharedStore';
+import type Disposer from '../utils/Disposer';
+import { getLogger } from '../utils/log';
+
+const DEFAULT_CONFIG_DEBOUNCE_TIME = ms('1s');
+
+const log = getLogger('synchronizeConfig');
+
+export default async function synchronizeConfig(
+  sharedStore: SharedStore,
+  repository: ConfigRepository,
+  debounceTime: number = DEFAULT_CONFIG_DEBOUNCE_TIME,
+): Promise<Disposer> {
+  let lastConfigOnDisk: Config | undefined;
+
+  async function writeConfig(): Promise<void> {
+    const { config } = sharedStore;
+    await repository.writeConfig(config);
+    lastConfigOnDisk = config;
+  }
+
+  async function readConfig(): Promise<boolean> {
+    const result = await repository.readConfig();
+    if (result.found) {
+      try {
+        // This cast is unsound if the config file is invalid,
+        // but we'll throw an error in the end anyways.
+        sharedStore.loadConfig(result.data as Config);
+      } catch (error) {
+        log.error('Failed to apply config snapshot', result.data, error);
+        return true;
+      }
+      lastConfigOnDisk = sharedStore.config;
+      if (!deepEqual(result.data, lastConfigOnDisk, { strict: true })) {
+        await writeConfig();
+      }
+    }
+    return result.found;
+  }
+
+  if (!(await readConfig())) {
+    log.info('Config file was not found');
+    await writeConfig();
+    log.info('Created config file');
+  }
+
+  const disposeReaction = reaction(
+    () => sharedStore.config,
+    debounce((config) => {
+      // We can compare snapshots by reference, since it is only recreated on store changes.
+      if (lastConfigOnDisk !== config) {
+        writeConfig().catch((error) => {
+          log.error('Failed to write config on config change', error);
+        });
+      }
+    }, debounceTime),
+  );
+
+  const disposeWatcher = repository.watchConfig(async () => {
+    try {
+      await readConfig();
+    } catch (error) {
+      log.error('Failed to read config', error);
+    }
+  }, debounceTime);
+
+  return () => {
+    disposeWatcher();
+    disposeReaction();
+  };
+}