import Database from 'better-sqlite3'
import { hashSync } from 'bcryptjs'
import { createHash } from 'node:crypto'
import { copyFileSync, existsSync, mkdirSync, readFileSync, readdirSync, statSync } from 'node:fs'
import { dirname, resolve } from 'node:path'
import { defaultSiteDocument, siteDocumentSchema } from './site-schema'

let database: Database.Database | undefined

const now = () => new Date().toISOString()

export function useDatabase() {
  if (database) return database

  const config = useRuntimeConfig()
  const databasePath = resolve(process.cwd(), config.databasePath)
  mkdirSync(dirname(databasePath), { recursive: true })

  database = new Database(databasePath)
  database.pragma('journal_mode = WAL')
  database.pragma('foreign_keys = ON')
  database.pragma('busy_timeout = 5000')

  database.exec(`
    CREATE TABLE IF NOT EXISTS schema_migrations (
      filename TEXT PRIMARY KEY,
      checksum TEXT NOT NULL,
      applied_at TEXT NOT NULL
    )
  `)
  const migrationDir = resolve(process.cwd(), 'server/database/migrations')
  const migrations = readdirSync(migrationDir).filter(name => name.endsWith('.sql')).sort().map((filename) => {
    const sql = readFileSync(resolve(migrationDir, filename), 'utf8')
    return { filename, sql, checksum: createHash('sha256').update(sql).digest('hex') }
  })
  const applied = new Map((database.prepare('SELECT filename, checksum FROM schema_migrations').all() as Array<{ filename: string; checksum: string }>).map(row => [row.filename, row.checksum]))
  for (const migration of migrations) {
    const recordedChecksum = applied.get(migration.filename)
    if (recordedChecksum && recordedChecksum !== migration.checksum) throw new Error(`Migration ${migration.filename} was modified after being applied`)
  }
  const pending = migrations.filter(migration => !applied.has(migration.filename))
  if (pending.length && existsSync(databasePath) && statSync(databasePath).size > 0) {
    database.pragma('wal_checkpoint(TRUNCATE)')
    copyFileSync(databasePath, `${databasePath}.pre-migration-${Date.now()}.bak`)
  }
  const applyMigration = database.transaction((migration: typeof migrations[number]) => {
    database!.exec(migration.sql)
    database!.prepare('INSERT INTO schema_migrations (filename, checksum, applied_at) VALUES (?, ?, ?)').run(migration.filename, migration.checksum, now())
  })
  pending.forEach(migration => applyMigration(migration))

  seedInitialData(database)
  return database
}

function seedInitialData(db: Database.Database) {
  const timestamp = now()
  const siteExists = db.prepare('SELECT 1 FROM site_documents WHERE document_key = ?').get('website')
  if (!siteExists) {
    const json = JSON.stringify(defaultSiteDocument)
    db.prepare(`
      INSERT INTO site_documents (document_key, draft_json, published_json, updated_at, published_at)
      VALUES (?, ?, ?, ?, ?)
    `).run('website', json, json, timestamp, timestamp)
  }

  const userCount = db.prepare('SELECT COUNT(*) AS count FROM admin_users').get() as { count: number }
  if (userCount.count === 0) {
    const config = useRuntimeConfig()
    const password = config.initialAdminPassword || (import.meta.dev ? 'DevOnly-ChangeMe-2026!' : '')
    if (!password) {
      throw new Error('NUXT_INITIAL_ADMIN_PASSWORD must be set before the first production start')
    }
    db.prepare(`
      INSERT INTO admin_users (username, password_hash, display_name, created_at, updated_at)
      VALUES (?, ?, ?, ?, ?)
    `).run(config.initialAdminUsername, hashSync(password, 12), '超级管理员', timestamp, timestamp)
  }
}

export function readSiteDocument(mode: 'draft' | 'published' = 'published') {
  const db = useDatabase()
  const row = db.prepare('SELECT draft_json, published_json, updated_at, published_at FROM site_documents WHERE document_key = ?')
    .get('website') as { draft_json: string; published_json: string; updated_at: string; published_at: string }
  return {
    data: siteDocumentSchema.parse(normalizeLegacyDocument(JSON.parse(mode === 'draft' ? row.draft_json : row.published_json))),
    updatedAt: row.updated_at,
    publishedAt: row.published_at,
  }
}

function normalizeLegacyDocument(input: unknown) {
  if (!input || typeof input !== 'object') return input
  const document = structuredClone(input) as Record<string, any>
  if (Array.isArray(document.products)) {
    document.products = document.products.map((product: Record<string, any>, index: number) => {
      const fallback = defaultSiteDocument.products[index]
      const slug = product.slug || fallback?.slug || `product-${index + 1}`
      return {
        slug,
        title: product.title || fallback?.title || `产品 ${index + 1}`,
        subtitle: product.subtitle || '',
        type: product.type || fallback?.type || 'course',
        summary: product.summary || fallback?.summary || '',
        content: product.content || fallback?.content || '',
        image: product.image || fallback?.image || '/images/hero-bg-v3.webp',
        href: product.href || `/products/${slug}`,
        status: product.status || 'published',
      }
    })
  }
  document.articles ??= structuredClone(defaultSiteDocument.articles)
  document.team ??= structuredClone(defaultSiteDocument.team)
  document.channels ??= structuredClone(defaultSiteDocument.channels)
  document.legal ??= structuredClone(defaultSiteDocument.legal)
  document.brand = { ...defaultSiteDocument.brand, ...(document.brand || {}) }
  document.teacher = { ...defaultSiteDocument.teacher, ...(document.teacher || {}) }
  return document
}