import { readdir, readFile, writeFile } from "node:fs/promises"
import path from "node:path"
import { gzipSync } from "node:zlib"
import tailwindcss from "@tailwindcss/vite"
import { tanstackRouter } from "@tanstack/router-plugin/vite"
import react from "@vitejs/plugin-react-swc"
import { defineConfig, type Plugin } from "vite"

/** Compress once at build time, including text copied from public/. */
function precompress(): Plugin {
  async function compress(directory: string): Promise<void> {
    const entries = await readdir(directory, { withFileTypes: true })
    await Promise.all(
      entries.map(async (entry) => {
        const file = path.join(directory, entry.name)
        if (entry.isDirectory()) return compress(file)
        if (!/\.(?:js|css|html|svg|json|webmanifest)$/.test(entry.name)) return
        const original = await readFile(file)
        if (original.length < 1024) return
        const compressed = gzipSync(original, { level: 9 })
        if (compressed.length < original.length)
          await writeFile(`${file}.gz`, compressed)
      }),
    )
  }
  return {
    name: "precompressed-assets",
    apply: "build",
    async writeBundle({ dir }) {
      if (dir) await compress(dir)
    },
  }
}

// https://vitejs.dev/config/
export default defineConfig({
  // A portal serves this bundle under a path of its own and caches one copy
  // for every instance, so asset URLs have to be absolute under that
  // prefix. Unset — every ordinary build — this stays "/".
  base: process.env.VITE_BASE || "/",
  resolve: {
    alias: {
      "@": path.resolve(__dirname, "./src"),
    },
  },
  build: {
    // The entry holds React, the router, the query client and the shell, and
    // cannot get below this. A bigger chunk than that is worth a warning.
    chunkSizeWarningLimit: 850,
    rollupOptions: {
      onwarn(warning, defaultHandler) {
        // Zod's own comments name `@__PURE__`, which Rollup reads as a
        // misplaced annotation. Nothing to fix on our side.
        if (
          warning.code === "INVALID_ANNOTATION" &&
          warning.id?.includes("/node_modules/zod/")
        )
          return
        defaultHandler(warning)
      },
    },
  },
  plugins: [
    tanstackRouter({
      target: "react",
      autoCodeSplitting: true,
    }),
    react(),
    tailwindcss(),
    precompress(),
  ],
})