import { execFileSync } from "node:child_process";
import { existsSync, readFileSync } from "node:fs";
import { describe, expect, it } from "vitest";

// The code says WHY; the plan that produced it stays in the private ops repo. A comment that cites
// `E28 review J4`, `(R6 S3b)` or `deep-review round 5` names a document no reader of this repo has,
// so the citation is noise at best, and at worst a rule that only makes sense next to the plan. All
// of them were taken out at once (2026-10-04); this keeps new ones out of every tracked text file and
// every new one not yet added (comments, docstrings, test titles, lint messages alike).
//
// Not scanned: Markdown (the docs and the changelog keep a decision's date and its epic as history)
// and the Alembic migrations (each one is a dated record of what changed).

const REPO = new URL("../../../", import.meta.url);
const SKIPPED =
  /\.(md|webp|png|jpe?g|ico|woff2?)$|^backend\/alembic\/versions\/|package-lock\.json$/;
// the guard itself, and the metric that counts epics by the same definition
const ALLOWED = new Set([
  "frontend/src/lib/planCodes.contract.test.ts",
  "scripts/audit_metrics.py",
]);
// Named exceptions, cut from a line before it is matched: TV episode notation (`S2 · E5`), a test
// fixture's season or episode title (`title="S1"`, `title: "E1"`) and ruff's default rule families.
// Anything else that looks like a code is one — `"""E30:`, `it("E36:`, `# S6:` and `S3's` included.
const NOT_CODES = /\bS\d{1,2} ?·? ?E\d+|\btitle[=:] ?"[ES]\d{1,2}"|\bE4\/E7\/E9\b/g;
const PLAN_CODES = [
  // an epic (`E28`, `E9.5`, `E28/E30`), an older roadmap item (`R14`), a sprint (`S6`, `S3e2`), a
  // phase (`P1`) or a plan's decision (`D1`, `D6-A`) — not `E2E`, not a ruff rule (`S110`), not
  // `S3h`, the media-card decision docs/DESIGN.md is headed by
  /\b(?:E\d{1,2}(?:\.\d+)?|R\d{1,2}|S(?!3h\b)\d{1,2}(?:[a-z]\d?)?|P\d|D\d{1,2})\b/,
  // a review round (`round 4`, `deep-review`)
  /\b[Rr]ound[ -]\d|deep-review/,
];

const isPlanCode = (line: string) => {
  const rest = line.replace(NOT_CODES, "");
  return PLAN_CODES.some((re) => re.test(rest));
};

function tracked(): string[] {
  const out = execFileSync(
    "git",
    ["ls-files", "-z", "--cached", "--others", "--exclude-standard"],
    {
      cwd: REPO,
      encoding: "utf-8",
    },
  );
  // a file deleted but not yet staged is still listed
  return out
    .split("\0")
    .filter((f) => f && !SKIPPED.test(f) && !ALLOWED.has(f) && existsSync(new URL(f, REPO)));
}

describe("plan codes", () => {
  it("are recognised in each form the purged citations took", () => {
    const cited = [
      '"""E30: the new sink.',
      'it("E36: keeps x", () => {',
      "// both sides (E28/E30)",
      "# D1: a newly shared download is downloadable by default",
      "// binge stays under the viewer's control (D6-A)",
      "// (owner decision D4)",
      "# the roadmap's R6/R7 pair",
      "// held since E9.5",
      "// (S6) moved it",
      "# S6: attach the acting user's cookie",
      '"""S6 — per-user cookies',
      "// S3's canonical upsert",
      "// S1 justified that",
      "// the order since P1",
      '"""P1\'s invariant',
      "// a sprint then a roadmap item: S2 R14",
      "// deep-review round 4 found it",
    ];
    const clean = [
      'title="E1",',
      'title: "S1",',
      "# ruff's default rule set (E4/E7/E9 + F)",
      "// an E2E run",
      "// S2 · E5 is the second episode",
      'expect(btn.textContent).toContain("S2 · E1");',
      "// the S3h media card",
      '"S110", "S112",',
      "# the JPEG SOI marker (0xFF 0xD8 0xFF)",
      "// a 3D view",
    ];
    expect(cited.filter((l) => !isPlanCode(l))).toEqual([]);
    expect(clean.filter(isPlanCode)).toEqual([]);
  });

  it("are not cited in the code", () => {
    const files = tracked();
    expect(files.length).toBeGreaterThan(1000); // a scan that reads nothing is green over nothing
    const hits = files.flatMap((f) =>
      readFileSync(new URL(f, REPO), "utf-8")
        .split("\n")
        .flatMap((line, i) => (isPlanCode(line) ? [`${f}:${i + 1}: ${line.trim()}`] : [])),
    );
    expect(hits).toEqual([]);
  });
});