Intermediate refactoring...

server/db/database.js

@@ -0,0 +1,57 @@
+import { readFile, writeFile, access, constants } from 'fs/promises'
+
+export function createDatabase(path, initialValue) {
+    return { path, initialValue }
+}
+
+async function withDatabase({ path, initialValue }, fn) {
+    try {
+        await access(path, constants.R_OK)
+    } catch (e) {
+        console.log(`Creating empty database into "${path}"`)
+        await writeFile(path, JSON.stringify(initialValue, null, 2))
+    }
+
+    console.log(`Loading database from "${path}"`)
+    const state = JSON.parse(await readFile(path, 'utf-8'))
+
+    const result = await fn(state)
+
+    console.log(`Saving database to "${path}"`)
+    await writeFile(path, JSON.stringify(state, null, 2))
+
+    return result
+}
+
+function createTable(tableName) {
+    return {
+        create() {},
+        get() {},
+        update() {},
+        delete() {},
+    }
+}
+
+export const User = createTable('users')
+export const Problem = createTable('problems')
+
+export const getUser = (db, id) =>
+    withDatabase(db, state => {
+        return state.users[id]
+    })
+
+export const createUser = (db, { email, username, password }) =>
+    withDatabase(db, state => {
+        state.users[email] = {
+            username,
+            password,
+        }
+    })
+
+export const updateUser = (db, username, { email, password }) =>
+    withDatabase(db, state => {
+        state.users[username] = {
+            email,
+            password,
+        }
+    })