import type { NextConfig } from "next";
import { existsSync, readFileSync } from "node:fs";
import { dirname, join } from "node:path";

// Load NEXT_PUBLIC_* vars from the monorepo root .env so a fresh
// `pnpm dev` works without a per-developer canvas/.env.local. Next.js
// only auto-loads .env from the project root by default — but our
// canonical config (NEXT_PUBLIC_PLATFORM_URL, NEXT_PUBLIC_WS_URL,
// MOLECULE_ENV, etc.) lives at the monorepo root, gitignored, shared
// by the Go platform binary. Without this, the canvas falls back to
// `window.location` (`ws://localhost:3000/ws`) and the WS pill stays
// "Reconnecting" forever because Next.js dev doesn't serve /ws.
//
// Mirrors workspace-server/cmd/server/dotenv.go's monorepo-rooted .env
// loader. Both processes look for the SAME marker (`workspace-server/
// go.mod`) so a developer renaming or relocating the repo only has to
// update one heuristic. Production is unaffected: `output: "standalone"`
// bakes resolved env into the build, and the marker file isn't shipped.
loadMonorepoEnv();

const nextConfig: NextConfig = {
  output: "standalone",
};

export default nextConfig;

function loadMonorepoEnv() {
  const root = findMonorepoRoot(__dirname);
  if (!root) return;
  const envPath = join(root, ".env");
  if (!existsSync(envPath)) return;
  const body = readFileSync(envPath, "utf8");
  let loaded = 0;
  let skipped = 0;
  for (const line of body.split(/\r?\n/)) {
    const kv = parseLine(line);
    if (!kv) continue;
    const [k, v] = kv;
    // Existing env wins. NOTE: an explicitly-set empty string
    // (`KEY=` exported from a parent shell, where Node represents it
    // as `""` not `undefined`) counts as "set" — we keep the empty
    // value rather than backfilling from the file. Matches Go's
    // os.LookupEnv check in workspace-server/cmd/server/dotenv.go so
    // both processes treat the same input identically. Operators who
    // want the file value to win must `unset KEY` in the launching
    // shell.
    if (process.env[k] !== undefined) {
      skipped++;
      continue;
    }
    process.env[k] = v;
    loaded++;
  }
  // eslint-disable-next-line no-console
  console.log(
    `[next.config] loaded ${loaded} vars from ${envPath} (${skipped} already set in env)`,
  );
}

function findMonorepoRoot(start: string): string | null {
  let dir = start;
  for (let i = 0; i < 6; i++) {
    if (existsSync(join(dir, "workspace-server", "go.mod"))) return dir;
    const parent = dirname(dir);
    if (parent === dir) break;
    dir = parent;
  }
  return null;
}

// Mirror of workspace-server/cmd/server/dotenv.go's parseDotEnvLine
// — same rules so the two loaders agree on every line in the shared
// .env. If you change one parser, change the other.
function parseLine(raw: string): [string, string] | null {
  let line = raw.replace(/^/, "").trim();
  if (line === "" || line.startsWith("#")) return null;
  // `export ` prefix uses a literal space — `export\tFOO=bar` with a
  // tab is intentionally rejected, matching the Go mirror in
  // workspace-server/cmd/server/dotenv.go. Shells emit the prefix
  // with a space; tabs would only appear in hand-mangled files.
  if (line.startsWith("export ")) line = line.slice("export ".length).trimStart();
  const eq = line.indexOf("=");
  if (eq <= 0) return null;
  const k = line.slice(0, eq).trim();
  let v = line.slice(eq + 1).replace(/^[ \t]+/, "");
  if (v.length >= 2 && (v[0] === '"' || v[0] === "'")) {
    const quote = v[0];
    const end = v.indexOf(quote, 1);
    if (end >= 0) return [k, v.slice(1, end)];
    // unterminated — fall through to bare-value handling
  }
  for (let i = 0; i < v.length; i++) {
    if (v[i] !== "#") continue;
    if (i === 0 || v[i - 1] === " " || v[i - 1] === "\t") {
      v = v.slice(0, i);
      break;
    }
  }
  return [k, v.trim()];
}