#!/usr/bin/env bun
/**
 * Close the GitHub issue for every topic whose required (core) problems are done.
 *
 * Each `topic`-labelled issue owns its problems as GitHub sub-issues, and each
 * problem carries exactly one `set:` label — `set:core` is required, while
 * `set:optional` and `set:deferred` are extra credit. A topic is finished when
 * every one of its core sub-issues is closed; optional/deferred state is
 * ignored, matching the day rule in each topic body ("Core problems first").
 *
 * Like close-solved.ts this reconciles state instead of reacting to an event
 * payload: re-runs are no-ops, backfilling needs no special casing, and only
 * open topics are touched, so reopening a problem never reopens its topic.
 *
 *   bun apps/cli/close-topics.ts            # close finished topics
 *   bun apps/cli/close-topics.ts --dry-run  # report only, touch nothing
 *
 * Auth: GH_TOKEN / GITHUB_TOKEN, else falls back to `gh auth token`.
 */
import { github } from "./github.ts";
import { markdownTable, printTable, writeStepSummary } from "./report.ts";

const DRY =
  process.argv.includes("--dry-run") ||
  process.env.DRY_RUN === "1" ||
  process.env.DRY_RUN === "true";

const gh = await github();

// ── open topic issues ────────────────────────────────────────────

interface Topic {
  number: number;
  title: string;
}

/**
 * Narrow one element of the /issues payload to the fields this script needs.
 * The `topic` label filter cannot exclude pull requests, so drop those here.
 */
function readTopic(value: unknown): Topic | undefined {
  if (!value || typeof value !== "object") return;
  if ("pull_request" in value) return; // the /issues route also lists PRs
  if (!("number" in value) || typeof value.number !== "number") return;
  if (!("title" in value) || typeof value.title !== "string") return;
  return { number: value.number, title: value.title };
}

const topics: Topic[] = [];
for await (const raw of gh.list(`/repos/${gh.repo}/issues?labels=topic&state=open`)) {
  const topic = readTopic(raw);
  if (topic) topics.push(topic);
}
topics.sort((a, b) => a.number - b.number);

// ── core sub-issue state per topic ───────────────────────────────

interface Core {
  /** Core sub-issues, closed and open alike, lowest number first. */
  all: number[];
  /** The core sub-issues still open — non-empty means the topic stays open. */
  pending: number[];
}

/**
 * Read a topic's core sub-issue state. The sub_issues payload carries the full
 * issue objects (state + labels), so no per-problem follow-up request is needed.
 */
async function readCore(topic: number): Promise<Core> {
  const all: number[] = [];
  const pending: number[] = [];
  for await (const raw of gh.list(`/repos/${gh.repo}/issues/${topic}/sub_issues`)) {
    if (!raw || typeof raw !== "object") continue;
    if (!("number" in raw) || typeof raw.number !== "number") continue;
    if (!("state" in raw) || typeof raw.state !== "string") continue;
    if (!("labels" in raw) || !Array.isArray(raw.labels)) continue;

    const core = raw.labels.some(
      (label) =>
        label &&
        typeof label === "object" &&
        "name" in label &&
        label.name === "set:core",
    );
    if (!core) continue;

    all.push(raw.number);
    if (raw.state === "open") pending.push(raw.number);
  }
  all.sort((a, b) => a - b);
  pending.sort((a, b) => a - b);
  return { all, pending };
}

// ── reconcile ────────────────────────────────────────────────────

const report: string[][] = [];
let closed = 0;

for (const topic of topics) {
  const core = await readCore(topic.number);
  const progress = `${core.all.length - core.pending.length}/${core.all.length}`;

  // A topic with no core sub-issues has nothing to complete: never close it,
  // since that would be indistinguishable from a mis-labelled problem set.
  if (core.all.length === 0) {
    report.push([`#${topic.number}`, topic.title, progress, "no core set"]);
    continue;
  }
  if (core.pending.length > 0) {
    report.push([
      `#${topic.number}`,
      topic.title,
      progress,
      `open: ${core.pending.map((n) => `#${n}`).join(" ")}`,
    ]);
    continue;
  }
  if (DRY) {
    report.push([`#${topic.number}`, topic.title, progress, "would close"]);
    continue;
  }

  await gh.closeIssue(
    topic.number,
    `Core set complete — all ${core.all.length} core problems closed ` +
      `(${core.all.map((n) => `#${n}`).join(", ")}).\n\n` +
      "Closed automatically by `close-topics`. Optional and deferred problems " +
      "stay open as extra credit.",
  );
  report.push([`#${topic.number}`, topic.title, progress, "closed"]);
  closed++;
}

// ── report ───────────────────────────────────────────────────────

const rows = [["topic", "title", "core", "status"], ...report];
printTable(rows);

const finished = report.filter((r) => r[3] === "closed" || r[3] === "would close");
console.log(
  `\n${topics.length} open topics · ` +
    `${DRY ? `would close ${finished.length}` : `closed ${closed}`}`,
);

await writeStepSummary(
  `### close-topics${DRY ? " (dry run)" : ""}\n\n` +
    `${topics.length} open topic issues, ${finished.length} with a complete core set.\n\n` +
    (report.length ? `${markdownTable(rows)}\n` : "No open topics.\n"),
);