import { readdirSync, readFileSync, statSync } from "node:fs";
import { createHash } from "node:crypto";
import { join, relative } from "node:path";

export type SnapshotEntry = { path: string; sha256: string };

/**
 * Recursively collect all files under root, sorted by relative path, with
 * sha256 of post-normalized contents (LF line endings, single trailing
 * newline). Used by the byte-identical reconstruction test.
 */
export function computeSnapshot(root: string): SnapshotEntry[] {
  const out: SnapshotEntry[] = [];
  walk(root, root, out);
  out.sort((a, b) => (a.path < b.path ? -1 : a.path > b.path ? 1 : 0));
  return out;
}

function walk(root: string, dir: string, out: SnapshotEntry[]): void {
  for (const name of readdirSync(dir)) {
    const full = join(dir, name);
    const stat = statSync(full);
    if (stat.isDirectory()) {
      if (name === "node_modules" || name === ".turbo") continue;
      walk(root, full, out);
    } else if (stat.isFile()) {
      const raw = readFileSync(full, "utf8");
      const normalized = raw.replace(/\r\n/g, "\n").replace(/\n*$/, "\n");
      const sha = createHash("sha256").update(normalized).digest("hex");
      out.push({ path: relative(root, full).replace(/\\/g, "/"), sha256: sha });
    }
  }
}
