import react from "@vitejs/plugin-react";
import { defineConfig } from "vite";
import { fileURLToPath } from "node:url";
import path from "node:path";

const __dirname = path.dirname(fileURLToPath(import.meta.url));

/**
 * GWT slot apps (ECC reference sample **Agent_self_monitoring**) ship with:
 * - `index.html` at archive root
 * - **Relative** script URLs: `static/js/main.<hash>.js` (no hard-coded `/si/...` prefix)
 * - `asset-manifest.json`: `{ "main.js": "static/js/main.<hash>.js" }`
 *
 * So production **`base` defaults to `./`**, so bundles resolve next to `index.html` under any
 * host path (`/si/App/ver/`, `/ameyo40/si/.../`, etc.).
 *
 * Set **`VITE_GWT_BASE`** only if you intentionally need absolute URLs (e.g. `/si/MyApp/1.0.0/`).
 *
 * `vite dev` uses **`base: '/'`** so `/app/main.tsx` resolves on localhost.
 */
/** Collapse `/si//gwt//…` and avoid `…/ver//static/…` when Vite joins base + `static/js/…`. */
function normalizeVitePublicBase(raw: string): string {
  const s = raw.trim();
  if (s.startsWith("/")) {
    return `/${s.split("/").filter(Boolean).join("/")}`;
  }
  return s;
}

function buildBase(): string {
  const raw = process.env.VITE_GWT_BASE?.trim();
  if (raw) {
    let b = normalizeVitePublicBase(raw);
    if (!b.endsWith("/")) b = `${b}/`;
    console.info(`[vite] base (VITE_GWT_BASE): ${b}`);
    return b;
  }
  console.info("[vite] base: ./ (relative — aligned with ECC GWT sample app layout)");
  return "./";
}

/** ECC / some proxies mis-handle `…/ver//static/js/…` (403). Collapse before `static/js/`. */
function collapseDoubleSlashBeforeStaticJs(html: string): string {
  let next = html;
  let prev: string;
  do {
    prev = next;
    next = prev.replace(/\/\/+(static\/js\/)/g, "/$1");
  } while (next !== prev);
  return next;
}

export default defineConfig(({ command }) => ({
  plugins: [
    react(),
    {
      name: "collapse-double-slash-before-static-js",
      enforce: "post",
      transformIndexHtml: {
        order: "post",
        handler(html: string) {
          return collapseDoubleSlashBeforeStaticJs(html);
        }
      }
    }
  ],
  base: command === "serve" ? "/" : buildBase(),
  build: {
    outDir: "dist",
    emptyOutDir: true,
    chunkSizeWarningLimit: 12000,
    rollupOptions: {
      output: {
        entryFileNames: "static/js/main.[hash].js",
        chunkFileNames: "static/js/[name].[hash].js",
        assetFileNames: (assetInfo) => {
          const n = assetInfo.name ?? "";
          if (n.endsWith(".css")) return "static/css/[name].[hash][extname]";
          return "static/media/[name].[hash][extname]";
        }
      }
    }
  }
}));