#!/usr/bin/env node
// Report what the latest designbook integration changed, into RecentChanges.md.
//
//   node scripts/designbook-sync.mjs              # working tree vs HEAD
//   node scripts/designbook-sync.mjs --range main..HEAD   # a committed range
//
// Driven by `make designbook-sync`. The designbook is the Claude Design project —
// the upstream source of truth for the *language*. Its local mirror lives IN this
// repo at designbook/ and is pulled via the `/design-sync` skill (the DesignSync
// tool), component by component — NOT by this script. This script only inspects
// what that sync changed and writes a deterministic RecentChanges.md snapshot.
// See designbook/README.md and DesignSystemIntroduction.md §1/§5.

import { execFileSync } from "node:child_process";
import { existsSync, readFileSync, writeFileSync } from "node:fs";
import { dirname, resolve } from "node:path";
import { fileURLToPath } from "node:url";

const repoRoot = resolve(dirname(fileURLToPath(import.meta.url)), "..");

// Pathspecs the report covers: the designbook mirror plus the surfaces derived
// from it (tokens, CSS, the CSS-embedded _styles.js, and the example pages).
const DESIGN_PATHSPECS = ["designbook", "tokens", "src/styles", "src/elements", "examples"];

const LAYER_ORDER = ["Designbook", "Tokens", "Styles", "Components", "Examples", "Other"];
const layerOf = (p) =>
  p.startsWith("designbook/")    ? "Designbook"
  : p.startsWith("tokens/")      ? "Tokens"
  : p.startsWith("src/styles/")  ? "Styles"
  : p.startsWith("src/elements/") ? "Components"
  : p.startsWith("examples/")    ? "Examples"
  : "Other";

const args = process.argv.slice(2);
const argVal = (name) => { const i = args.indexOf(name); return i !== -1 ? args[i + 1] : null; };
const range = argVal("--range");
const nowIso = () => new Date().toISOString().replace(/\.\d+Z$/, "Z");

// Trailing-newline trim only — never .trim(), which would eat the leading status
// column of the first `git status --porcelain` line.
const git = (gitArgs) =>
  execFileSync("git", gitArgs, { cwd: repoRoot, encoding: "utf8" }).replace(/\n+$/, "");

// ---- Sync marker: designbook/.design-sync.json ----
// Records when /design-sync last pulled (lastSyncAt) and the latest known cloud
// project timestamp (remoteUpdatedAt). `make designbook-sync` reports lastSyncAt;
// when remoteUpdatedAt is newer, the local mirror is OUTDATED and we warn.
//   --mark-synced [--remote-updated <iso>] [--project <id>] [--project-name <s>]
//       run this right after /design-sync (sets lastSyncAt = now)
//   --remote-updated <iso>
//       record that the cloud project changed (e.g. from DesignSync.list_projects)
const markerPath = resolve(repoRoot, "designbook/.design-sync.json");
const readMarker = () => existsSync(markerPath) ? JSON.parse(readFileSync(markerPath, "utf8")) : null;
const writeMarker = (m) => writeFileSync(markerPath, JSON.stringify(m, null, 2) + "\n");

if (args.includes("--mark-synced")) {
  const now = nowIso();
  const m = readMarker() || {};
  m.lastSyncAt = now;
  m.remoteUpdatedAt = argVal("--remote-updated") || now;
  if (argVal("--project")) m.projectId = argVal("--project");
  if (argVal("--project-name")) m.projectName = argVal("--project-name");
  writeMarker(m);
  console.log(`Recorded /design-sync at ${now}.`);
} else if (argVal("--remote-updated")) {
  const m = readMarker() || {};
  m.remoteUpdatedAt = argVal("--remote-updated");
  writeMarker(m);
  console.log(`Recorded remote designbook update at ${m.remoteUpdatedAt}.`);
}

const marker = readMarker();
const stale = marker?.lastSyncAt && marker?.remoteUpdatedAt
  && new Date(marker.remoteUpdatedAt) > new Date(marker.lastSyncAt);

function syncStatusLines() {
  if (!marker?.lastSyncAt) {
    return [
      "- Last /design-sync: never recorded",
      "",
      "> WARNING — no /design-sync has been recorded, so the local designbook/ may not",
      "> reflect the Claude Design project. Run `/design-sync` in Claude Code, then",
      "> `node scripts/designbook-sync.mjs --mark-synced`.",
    ];
  }
  const out = [`- Last /design-sync: ${marker.lastSyncAt}`];
  if (stale) {
    out.push(
      "",
      `> WARNING — the Claude Design project changed at ${marker.remoteUpdatedAt}, after the`,
      "> last /design-sync. The local designbook/ is OUTDATED — run `/design-sync` to refresh it.",
    );
  }
  return out;
}

// ---- Collect changes ----
let changes;
let source;

if (range) {
  source = `range ${range}`;
  const numstat = git(["diff", "--numstat", range, "--", ...DESIGN_PATHSPECS]);
  const status = git(["diff", "--name-status", range, "--", ...DESIGN_PATHSPECS]);
  const counts = numstatMap(numstat);
  changes = (status ? status.split("\n") : []).map((line) => {
    const [code, ...rest] = line.split("\t");
    const path = rest[rest.length - 1];                 // rename → new path
    return { path, status: statusWord(code), ...(counts.get(path) || {}) };
  });
} else {
  source = "working tree (uncommitted)";
  // Intent-to-add so freshly-synced (untracked) files show up in the numstat diff.
  try { git(["add", "-N", "--", ...DESIGN_PATHSPECS]); } catch { /* nothing to add */ }
  const counts = numstatMap(git(["diff", "--numstat", "HEAD", "--", ...DESIGN_PATHSPECS]));
  const porcelain = git(["status", "--porcelain", "--", ...DESIGN_PATHSPECS]);
  changes = (porcelain ? porcelain.split("\n") : []).map((line) => {
    let path = line.slice(3);
    if (path.includes(" -> ")) path = path.split(" -> ")[1];
    return { path, status: statusWord(line.slice(0, 2)), ...(counts.get(path) || {}) };
  });
}

// The sync marker is bookkeeping, not design content — keep it out of the report.
changes = changes.filter((c) => c.path !== "designbook/.design-sync.json");

function numstatMap(out) {
  const m = new Map();
  for (const line of out ? out.split("\n") : []) {
    const [added, removed, ...rest] = line.split("\t");
    m.set(rest.join("\t"), { added, removed });
  }
  return m;
}
function statusWord(code) {
  const c = code.replace(/\s/g, "");
  return c.includes("D") ? "deleted"
    : c.includes("R") ? "renamed"
    : c.includes("A") || c.includes("?") ? "added"
    : "modified";
}

// ---- Render RecentChanges.md ----
const lines = [
  "# Recent Changes",
  "",
  "Snapshot of the last designbook integration. Regenerated by `make designbook-sync`.",
  "",
  `- Generated: ${nowIso()}`,
  `- Compared: ${source}`,
  ...syncStatusLines(),
  "",
  "> This file is overwritten on every run — a snapshot, not a log. Fold notable entries",
  "> into `CHANGELOG.md` under `## [Unreleased]` before releasing; that is the file CI",
  "> enforces (`pnpm check`). The designbook itself is synced via `/design-sync`, not this script.",
  "",
];

if (changes.length === 0) {
  lines.push("## No changes", "", "The design surface is unchanged since the last sync.");
} else {
  lines.push("## Changed files", "");
  for (const layer of LAYER_ORDER) {
    const group = changes.filter((c) => layerOf(c.path) === layer);
    if (!group.length) continue;
    lines.push(`### ${layer}`);
    for (const c of group.sort((a, b) => a.path.localeCompare(b.path))) {
      const tag = c.status.toUpperCase().padEnd(8);
      const delta =
        c.status === "deleted" ? ""
        : c.added != null && c.added !== "-" ? ` (+${c.added} / -${c.removed})`
        : c.added === "-" ? " (binary)"
        : "";
      lines.push(`- \`${tag}\` ${c.path}${delta}`);
    }
    lines.push("");
  }
  if (changes.some((c) => c.path === "src/elements/_styles.js")) {
    lines.push("> `src/elements/_styles.js` was regenerated from `components.css` — do not edit it by hand.", "");
  }
}

writeFileSync(resolve(repoRoot, "RecentChanges.md"), lines.join("\n").replace(/\n+$/, "\n"));
console.log(`Wrote RecentChanges.md — ${changes.length} changed file(s).`);

// Surface sync freshness on stdout — this is what tells the user whether the
// snapshot reflects the latest design.
if (!marker?.lastSyncAt) {
  console.warn("WARNING: no /design-sync recorded — run /design-sync, then `node scripts/designbook-sync.mjs --mark-synced`.");
} else {
  console.log(`Last /design-sync: ${marker.lastSyncAt}`);
  if (stale) {
    console.warn(`WARNING: Claude Design project changed at ${marker.remoteUpdatedAt} — local designbook/ is OUTDATED. Run /design-sync.`);
  }
}