feat: add SQLite-backed book data access layer

server/db.test.ts

@@ -0,0 +1,95 @@
+import { afterEach, describe, expect, it, setSystemTime } from 'bun:test'
+import { createEmptyBook, createEmptyTeachingDesign } from '../src/domain/teachingDesign'
+import { createBook, deleteBook, getBook, listBooks, openDb, renameBook, saveBookData } from './db'
+
+afterEach(() => {
+  setSystemTime()
+})
+
+describe('db', () => {
+  it('creates a book with empty data', () => {
+    const db = openDb(':memory:')
+    const created = createBook(db, '示例整本')
+
+    expect(created.name).toBe('示例整本')
+    expect(created.data.designs).toEqual([])
+    expect(created.data.schemaVersion).toBe(1)
+  })
+
+  it('retrieves a created book by id', () => {
+    const db = openDb(':memory:')
+    const created = createBook(db, '示例整本')
+
+    expect(getBook(db, created.id)).toEqual(created)
+  })
+
+  it('returns null for a missing book', () => {
+    const db = openDb(':memory:')
+    expect(getBook(db, 'missing')).toBeNull()
+  })
+
+  it('lists books ordered by most recently updated, with lesson counts', () => {
+    const db = openDb(':memory:')
+    setSystemTime(new Date('2026-01-01T00:00:00.000Z'))
+    const first = createBook(db, '第一本')
+    setSystemTime(new Date('2026-01-02T00:00:00.000Z'))
+    const second = createBook(db, '第二本')
+
+    const data = createEmptyBook()
+    data.designs.push(createEmptyTeachingDesign('1.md'))
+    setSystemTime(new Date('2026-01-03T00:00:00.000Z'))
+    saveBookData(db, first.id, data)
+
+    const books = listBooks(db)
+
+    expect(books.map((book) => book.id)).toEqual([first.id, second.id])
+    expect(books[0]?.lessonCount).toBe(1)
+    expect(books[1]?.lessonCount).toBe(0)
+  })
+
+  it('saves book data and updates updated_at', () => {
+    const db = openDb(':memory:')
+    const created = createBook(db, '示例整本')
+    const data = createEmptyBook()
+    data.cover.courseName = 'Web 前端开发'
+
+    setSystemTime(new Date('2026-02-01T00:00:00.000Z'))
+    const result = saveBookData(db, created.id, data)
+
+    expect(result).toEqual({ id: created.id, name: '示例整本', updatedAt: '2026-02-01T00:00:00.000Z' })
+    expect(getBook(db, created.id)?.data.cover.courseName).toBe('Web 前端开发')
+  })
+
+  it('returns null when saving data for a missing book', () => {
+    const db = openDb(':memory:')
+    expect(saveBookData(db, 'missing', createEmptyBook())).toBeNull()
+  })
+
+  it('renames a book without changing updated_at', () => {
+    const db = openDb(':memory:')
+    const created = createBook(db, '旧名称')
+
+    const result = renameBook(db, created.id, '新名称')
+
+    expect(result).toEqual({ id: created.id, name: '新名称', updatedAt: created.updatedAt })
+    expect(getBook(db, created.id)?.name).toBe('新名称')
+  })
+
+  it('returns null when renaming a missing book', () => {
+    const db = openDb(':memory:')
+    expect(renameBook(db, 'missing', '新名称')).toBeNull()
+  })
+
+  it('deletes a book', () => {
+    const db = openDb(':memory:')
+    const created = createBook(db, '示例整本')
+
+    expect(deleteBook(db, created.id)).toBe(true)
+    expect(getBook(db, created.id)).toBeNull()
+  })
+
+  it('returns false when deleting a missing book', () => {
+    const db = openDb(':memory:')
+    expect(deleteBook(db, 'missing')).toBe(false)
+  })
+})

server/db.ts

@@ -0,0 +1,117 @@
+import { Database } from 'bun:sqlite'
+import { createEmptyBook, type TeachingBook } from '../src/domain/teachingDesign'
+
+export interface BookSummary {
+  id: string
+  name: string
+  updatedAt: string
+  lessonCount: number
+}
+
+export interface BookRecord {
+  id: string
+  name: string
+  updatedAt: string
+  data: TeachingBook
+}
+
+export interface BookMeta {
+  id: string
+  name: string
+  updatedAt: string
+}
+
+interface BookRow {
+  id: string
+  name: string
+  data: string
+  updated_at: string
+}
+
+const SCHEMA = `
+  CREATE TABLE IF NOT EXISTS books (
+    id TEXT PRIMARY KEY,
+    name TEXT NOT NULL,
+    data TEXT NOT NULL,
+    created_at TEXT NOT NULL,
+    updated_at TEXT NOT NULL
+  )
+`
+
+export function openDb(path: string): Database {
+  const db = new Database(path)
+  db.run(SCHEMA)
+  return db
+}
+
+export function listBooks(db: Database): BookSummary[] {
+  const rows = db
+    .query<BookRow, []>('SELECT id, name, data, updated_at FROM books ORDER BY updated_at DESC')
+    .all()
+
+  return rows.map((row) => ({
+    id: row.id,
+    name: row.name,
+    updatedAt: row.updated_at,
+    lessonCount: (JSON.parse(row.data) as TeachingBook).designs.length,
+  }))
+}
+
+export function createBook(db: Database, name: string): BookRecord {
+  const id = crypto.randomUUID()
+  const now = new Date().toISOString()
+  const data = createEmptyBook()
+  data.updatedAt = now
+
+  db.run('INSERT INTO books (id, name, data, created_at, updated_at) VALUES (?, ?, ?, ?, ?)', [
+    id,
+    name,
+    JSON.stringify(data),
+    now,
+    now,
+  ])
+
+  return { id, name, updatedAt: now, data }
+}
+
+export function getBook(db: Database, id: string): BookRecord | null {
+  const row = db
+    .query<BookRow, [string]>('SELECT id, name, data, updated_at FROM books WHERE id = ?')
+    .get(id)
+  if (!row) return null
+
+  return {
+    id: row.id,
+    name: row.name,
+    updatedAt: row.updated_at,
+    data: JSON.parse(row.data) as TeachingBook,
+  }
+}
+
+export function saveBookData(db: Database, id: string, data: TeachingBook): BookMeta | null {
+  const existing = db
+    .query<{ name: string }, [string]>('SELECT name FROM books WHERE id = ?')
+    .get(id)
+  if (!existing) return null
+
+  const now = new Date().toISOString()
+  db.run('UPDATE books SET data = ?, updated_at = ? WHERE id = ?', [JSON.stringify(data), now, id])
+
+  return { id, name: existing.name, updatedAt: now }
+}
+
+export function renameBook(db: Database, id: string, name: string): BookMeta | null {
+  const existing = db
+    .query<{ updated_at: string }, [string]>('SELECT updated_at FROM books WHERE id = ?')
+    .get(id)
+  if (!existing) return null
+
+  db.run('UPDATE books SET name = ? WHERE id = ?', [name, id])
+
+  return { id, name, updatedAt: existing.updated_at }
+}
+
+export function deleteBook(db: Database, id: string): boolean {
+  const result = db.run('DELETE FROM books WHERE id = ?', [id])
+  return result.changes > 0
+}