import { describe, it, expect, beforeEach, afterEach } from "vitest";
import * as fs from "node:fs";
import * as os from "node:os";
import * as path from "node:path";
import { execFileSync } from "node:child_process";
import { emptyArtifact, serializeArtifact, type Artifact } from "../src/model";
import { validateSidecar } from "./helpers/validateSidecar";

const SCRIPT = path.resolve(__dirname, "../scripts/crossrung-reply.mjs");
let dir: string;
let sidecar: string;

beforeEach(() => {
  dir = fs.mkdtempSync(path.join(os.tmpdir(), "cowriting-crossrung-"));
  sidecar = path.join(dir, "sample.md.json");
  const a = emptyArtifact("docs/sample.md");
  a.anchors["a_1"] = { fingerprint: { text: "alpha", before: "", after: "", lineHint: 0 } };
  a.threads.push({
    id: "t_1",
    anchorId: "a_1",
    status: "open",
    messages: [{ id: "m_1", author: { kind: "human", id: "ben" }, body: "hi", createdAt: "2026-06-10T00:00:00.000Z" }],
  });
  // INV-15 must hold through a FOREIGN writer too
  (a as unknown as Record<string, unknown>).futureSection = [{ id: "f_1" }];
  fs.writeFileSync(sidecar, serializeArtifact(a), "utf8");
});
afterEach(() => fs.rmSync(dir, { recursive: true, force: true }));

function run(...args: string[]): string {
  return execFileSync(process.execPath, [SCRIPT, ...args], { encoding: "utf8" });
}

describe("crossrung-reply stand-in (F5 SLICE-4, PUC-2)", () => {
  it("appends a conforming reply, preserves unknowns, byte-identical to the reference serializer", () => {
    run(sidecar, "t_1", "Reply from the forge", "--author-id", "gitea", "--author-email", "forge@example.org");
    const raw = fs.readFileSync(sidecar, "utf8");
    const parsed = JSON.parse(raw) as Artifact;
    expect(parsed.threads[0].messages).toHaveLength(2);
    const reply = parsed.threads[0].messages[1];
    expect(reply.body).toBe("Reply from the forge");
    expect(reply.author).toEqual({ kind: "human", id: "gitea", email: "forge@example.org" });
    expect(reply.id).toMatch(/^m_/);
    expect((parsed as unknown as Record<string, unknown>).futureSection).toEqual([{ id: "f_1" }]);
    expect(validateSidecar(parsed).valid).toBe(true);
    // the stand-in's independent serialization is byte-identical to the
    // editor's (INV-2 across writers) — the contract-drift tripwire.
    expect(serializeArtifact(parsed)).toBe(raw);
  });

  it("refuses an unknown thread id and leaves the file untouched", () => {
    const before = fs.readFileSync(sidecar, "utf8");
    expect(() => run(sidecar, "t_nope", "x")).toThrow();
    expect(fs.readFileSync(sidecar, "utf8")).toBe(before);
  });

  it("refuses an invalid sidecar (validates BEFORE writing)", () => {
    fs.writeFileSync(sidecar, '{"schemaVersion":1}\n', "utf8");
    expect(() => run(sidecar, "t_1", "x")).toThrow();
  });

  it("refuses a newer-major sidecar (INV-16 holds for foreign writers too)", () => {
    const v2 = JSON.parse(fs.readFileSync(sidecar, "utf8"));
    v2.schemaVersion = 2;
    fs.writeFileSync(sidecar, JSON.stringify(v2, null, 2) + "\n", "utf8");
    const before = fs.readFileSync(sidecar, "utf8");
    expect(() => run(sidecar, "t_1", "x")).toThrow();
    expect(fs.readFileSync(sidecar, "utf8")).toBe(before);
  });
});