feat(db): only update data files if database data has changed

packages/db/data/site-meta.json

@@ -1,3 +1,3 @@
 {
-    "lastUpdate": "2024-07-15T20:43:22.551Z"
+    "lastUpdate": "2024-07-16T03:39:37.072Z"
 }

packages/db/src/index.ts

@@ -1,41 +1,68 @@
-import { writeFile } from 'node:fs/promises';
+import { readFile, writeFile } from 'node:fs/promises';
 import { devvitSourcesQuery, siteTiersQuery, siteUpdatesQuery } from './db-queries.js';
 import { db } from './db.js';
 
-const items = [
-    { query: siteUpdatesQuery, file: './data/site-updates.json' },
-    { query: devvitSourcesQuery, file: './data/devvit-sources.json' },
-    { query: siteTiersQuery, file: './data/site-tiers.json' },
-];
-
-await Promise.all(items.map(async ({ query, file }) => {
-    if (query === siteUpdatesQuery) {
-        const data = (await db.executeQuery(query)).rows;
+async function tryReadJson(path: string) {
+    try {
+        return JSON.parse(await readFile(path, 'utf-8')) as object;
+    }
+    catch (error: unknown) {
+        if (error instanceof Error && 'code' in error && error.code === 'ENOENT') {
+            return null;
+        }
+        throw error;
+    }
+}
 
+const queries = {
+    siteTiers: {
+        data: (await db.executeQuery(siteTiersQuery)).rows,
+        path: './data/site-tiers.json',
+        compareHash: true,
+        isUpdated: true,
+    },
+    siteUpdates: {
         /**
          * Apply sorting here becuase kysely doesn't support sorting yet
          * but will do in a future release
          * 
          * @see https://github.com/kysely-org/kysely/pull/896
          */
-        const sortedData = data.map(update => ({
+        data: (await db.executeQuery(siteUpdatesQuery)).rows.map(update => ({
             ...update,
             ...update.additions && { additions: update.additions.sort((a, b) => a.name.localeCompare(b.name)) },
             ...update.removals && { removals: update.removals.sort((a, b) => a.name.localeCompare(b.name)) },
             ...update.promotions && { promotions: update.promotions.sort((a, b) => a.name.localeCompare(b.name)) },
             ...update.demotions && { demotions: update.demotions.sort((a, b) => a.name.localeCompare(b.name)) },
-        }));
+        })),
+        path: './data/site-updates.json',
+        compareHash: true,
+        isUpdated: true,
+    },
+    devvitSources: {
+        data: (await db.executeQuery(devvitSourcesQuery)).rows,
+        path: './data/devvit-sources.json',
+        compareHash: false,
+        isUpdated: true,
+    },
+};
 
-        await writeFile(file, JSON.stringify(sortedData, null, 4));
-    }
-    else {
-        const data = (await db.executeQuery(query)).rows;
-        await writeFile(file, JSON.stringify(data, null, 4));
-    }
-}));
+await Promise.all(Object.entries(queries).map(async ([_, item]) => {
+    const file = await tryReadJson(item.path);
 
-await writeFile('./data/site-meta.json', JSON.stringify({ lastUpdate: new Date() }, null, 4));
+    if (file && item.compareHash) {
+        item.isUpdated = JSON.stringify(file) !== JSON.stringify(item.data);
+    }
 
-await db.destroy();
+    await writeFile(item.path, JSON.stringify(item.data, null, 4));
+}));
 
+/**
+ * Only update the site-meta.json file if either site-tiers or site-updates
+ * have been updated or if they didn't exist before
+ */
+if (queries.siteTiers.isUpdated || queries.siteUpdates.isUpdated) {
+    await writeFile('./data/site-meta.json', JSON.stringify({ lastUpdate: new Date() }, null, 4));
+}
 
+await db.destroy();