import { createHash } from 'node:crypto'
import { existsSync, readFileSync, renameSync } from 'node:fs'
import path from 'node:path'
import { defineConfig, loadEnv, 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.
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)
      renameSync(htmlPath, path.resolve(outDir, `index-${hash}.html`))
    },
  }
}

// https://vite.dev/config/
export default defineConfig(({ mode }) => {
  // VITE_BASE_PATH is read here (config/Node context), so it needs an explicit
  // loadEnv call — unlike VITE_BITRIX_ORIGIN, which Vite injects into
  // import.meta.env automatically because it's only read from app code.
  const env = loadEnv(mode, process.cwd(), '')

  return {
    // Needed when the build is served from a subpath (e.g. local/diagram-app/
    // inside the Bitrix docroot) instead of domain root — see
    // docs/bitrix-integration.md §7.
    base: env.VITE_BASE_PATH || '/',
    plugins: [react(), hashIndexHtml()],
    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]',
        },
      },
    },
  }
})