/**
 * Resolve the repo root for the markdown exporter when called from tRPC
 * mutations. Sibling of `apps/mcp-server/src/lib/repo-root.ts`; same
 * contract (env var > pnpm-workspace.yaml walk > cwd), but lives here
 * because the web app's tsconfig and bundle layout differ enough from
 * the MCP server's that a single shared helper would need its own
 * package. Duplication is cheap; the function is twenty lines.
 *
 * In production (Coolify) there is no `plans/` directory and no
 * `pnpm-workspace.yaml` in the bundled image, so the walk returns null
 * and the exporter is skipped cleanly.
 */
import { existsSync } from "node:fs";
import { dirname, join } from "node:path";
import { fileURLToPath } from "node:url";

const WORKSPACE_MARKER = "pnpm-workspace.yaml";
const MAX_WALK = 10;

function findByMarker(start: string): string | null {
  let dir = start;
  for (let i = 0; i < MAX_WALK; i++) {
    if (existsSync(join(dir, WORKSPACE_MARKER))) return dir;
    const parent = dirname(dir);
    if (parent === dir) return null;
    dir = parent;
  }
  return null;
}

export function resolveRepoRoot(): string | null {
  const env = process.env.MARKDOWN_BACKLOG_REPO_ROOT?.trim();
  if (env === "" || env === "0" || env?.toLowerCase() === "off") return null;
  if (env && env.length > 0) return env;

  const fileDir = dirname(fileURLToPath(import.meta.url));
  const fromFile = findByMarker(fileDir);
  if (fromFile) return fromFile;

  const fromCwd = findByMarker(process.cwd());
  if (fromCwd) return fromCwd;

  return null;
}