import { promises as fs } from 'node:fs'
import path from 'node:path'
import { fileURLToPath } from 'node:url'
import { svelte } from '@sveltejs/vite-plugin-svelte'
import { defineConfig, type Plugin } from 'vite'
// @ts-expect-error Vite config 直接复用 Node ESM 构建脚本，无需单独产出 TS 类型。
import { readBooksCatalog, writeBooksCatalog } from './scripts/books-catalog.mjs'

const PROJECT_ROOT = '/proj/'

function readRequestBody(req: NodeJS.ReadableStream): Promise<string> {
  return new Promise((resolve, reject) => {
    let body = ''
    req.setEncoding('utf8')
    req.on('data', (chunk) => {
      body += chunk
    })
    req.on('end', () => resolve(body))
    req.on('error', reject)
  })
}

function resolvePublicTypFilePath(projectPath: string, publicRoot: string) {
  if (!projectPath.startsWith(PROJECT_ROOT) || !projectPath.endsWith('.typ')) {
    throw new Error(`不支持保存该文件：${projectPath}`)
  }

  const relativePath = projectPath.slice(PROJECT_ROOT.length)
  const parts = relativePath.split('/').filter(Boolean)
  if (parts.length === 0 || parts.some((part) => part === '.' || part === '..')) {
    throw new Error(`非法文件路径：${projectPath}`)
  }

  const filePath = path.resolve(publicRoot, ...parts)
  const normalizedPublicRoot = path.resolve(publicRoot)
  if (!filePath.startsWith(`${normalizedPublicRoot}${path.sep}`)) {
    throw new Error(`非法文件路径：${projectPath}`)
  }

  return filePath
}

function typstSavePlugin(): Plugin {
  const publicRoot = fileURLToPath(new URL('./public', import.meta.url))
  const booksRoot = path.resolve(publicRoot, 'books')

  return {
    name: 'typst-save-plugin',
    configureServer(server) {
      const syncBooksCatalog = async () => {
        try {
          await writeBooksCatalog(publicRoot)
        } catch (error) {
          server.config.logger.warn(
            `[books] 同步 books_catalog.json 失败：${error instanceof Error ? error.message : String(error)}`,
          )
        }
      }

      const shouldSyncCatalog = (filePath: string) =>
        path.resolve(filePath).startsWith(`${booksRoot}${path.sep}`)

      void syncBooksCatalog()

      server.watcher.on('add', (filePath) => {
        if (shouldSyncCatalog(filePath)) void syncBooksCatalog()
      })
      server.watcher.on('change', (filePath) => {
        if (shouldSyncCatalog(filePath)) void syncBooksCatalog()
      })
      server.watcher.on('unlink', (filePath) => {
        if (shouldSyncCatalog(filePath)) void syncBooksCatalog()
      })
      server.watcher.on('addDir', (filePath) => {
        if (shouldSyncCatalog(filePath)) void syncBooksCatalog()
      })
      server.watcher.on('unlinkDir', (filePath) => {
        if (shouldSyncCatalog(filePath)) void syncBooksCatalog()
      })

      server.middlewares.use('/__books_catalog', async (req, res, next) => {
        if (req.method !== 'GET') {
          next()
          return
        }

        try {
          const books = await readBooksCatalog(publicRoot)
          res.statusCode = 200
          res.setHeader('Content-Type', 'application/json; charset=utf-8')
          res.end(JSON.stringify({ books }))
        } catch (error) {
          res.statusCode = 500
          res.end(error instanceof Error ? error.message : String(error))
        }
      })

      server.middlewares.use('/__save_typst_file', async (req, res, next) => {
        if (req.method !== 'POST') {
          next()
          return
        }

        try {
          const body = await readRequestBody(req)
          const payload = JSON.parse(body) as { projectPath?: string; content?: string }
          const projectPath = payload.projectPath?.trim()
          if (!projectPath || typeof payload.content !== 'string') {
            res.statusCode = 400
            res.end('缺少 projectPath 或 content')
            return
          }

          const filePath = resolvePublicTypFilePath(projectPath, publicRoot)
          await fs.mkdir(path.dirname(filePath), { recursive: true })
          await fs.writeFile(filePath, payload.content, 'utf8')

          res.statusCode = 200
          res.setHeader('Content-Type', 'application/json; charset=utf-8')
          res.end(JSON.stringify({ ok: true, filePath }))
        } catch (error) {
          res.statusCode = 500
          res.end(error instanceof Error ? error.message : String(error))
        }
      })
    },
  }
}

// https://vite.dev/config/
export default defineConfig({
  plugins: [svelte(), typstSavePlugin()],
})