import { createHash } from 'node:crypto'
import { existsSync, readFileSync, renameSync, writeFileSync } from 'node:fs'
import path from 'node:path'
import { defineConfig, type Plugin } from 'vite'
import react from '@vitejs/plugin-react'

// Vite always writes the HTML entry under its source name (index.html stays
// index.html) — it only content-hashes what that HTML references (JS/CSS),
// never the HTML file itself. The backend now reads the actual deployed
// filename at deploy time instead of hardcoding it on the main portal, so
// index.html needs a unique name too.
//
// index.html isn't part of the same bundle object the JS/CSS live in
// (confirmed empirically — it never showed up in generateBundle's `bundle`),
// so this hashes and renames the file directly on disk after the whole build
// has finished writing it, rather than fighting the bundler's own emit step.
// Stable entry point for hosts: never hashed, always present next to the build.
const MANIFEST_FILE_NAME = 'app.json'

function hashIndexHtml(): Plugin {
  let outDir = 'dist'
  return {
    name: 'hash-index-html',
    apply: 'build',
    configResolved(config) {
      outDir = config.build.outDir
    },
    closeBundle() {
      const htmlPath = path.resolve(outDir, 'index.html')
      if (!existsSync(htmlPath)) return

      // Hashing the final content (already contains the hashed JS/CSS refs)
      // means this name only changes when something meaningful actually did.
      const hash = createHash('md5').update(readFileSync(htmlPath)).digest('hex').slice(0, 8)
      const fileName = `index-${hash}.html`
      renameSync(htmlPath, path.resolve(outDir, fileName))

      // Manifest with a STABLE name, so an embedding host can look the hashed
      // entry up at runtime instead of hardcoding it (and re-deploying itself
      // on every rebuild of this app). See docs/bitrix-integration.md §7.
      writeFileSync(
        path.resolve(outDir, MANIFEST_FILE_NAME),
        `${JSON.stringify({ index: fileName }, null, 2)}
`,
      )
    },
  }
}

// https://vite.dev/config/
export default defineConfig(() => {
  return {
    // Relative, so the build works from any directory it gets deployed to
    // without being told where that is. The host always opens a concrete file
    // (index-<hash>.html, see hashIndexHtml below), so asset URLs resolve
    // against that file's own location — there is no client-side routing that
    // would need an absolute base. This replaces the earlier VITE_BASE_PATH:
    // a build-time path that had to match the deploy directory exactly, and
    // silently produced a blank iframe when it didn't (html loads, its JS 404s).
    base: './',
    plugins: [react(), hashIndexHtml()],
    // Порт фиксирован: portal-front проксирует сюда сборку в dev-режиме
    // (см. docs/portal-front-integration.md, раздел 2). strictPort, чтобы
    // при занятом порте preview падал, а не уезжал на соседний молча.
    preview: {
      port: 5800,
      strictPort: true,
    },
    build: {
      // Same content hash Vite computes by default — just without its default
      // "assets/" subfolder prefix. The deploy target's own folder is itself
      // named assets (local/modules/vniigaz.bpmn/assets/), so keeping Vite's
      // default pattern would nest output at .../assets/assets/index-*.js (404).
      rolldownOptions: {
        output: {
          entryFileNames: '[name]-[hash].js',
          chunkFileNames: '[name]-[hash].js',
          assetFileNames: '[name]-[hash][extname]',
        },
      },
    },
  }
})