#!/usr/bin/env bun
/**
 * Weekly gate: create Saturday's topic-blind quiz, and grade it on close.
 *
 *   bun scripts/srs-gate.ts create             # Trigger A (cron Sat / dispatch)
 *   bun scripts/srs-gate.ts close --issue N    # Trigger B (issues: closed)
 *
 * create — samples ONE unsolved `set:optional` problem per topic scheduled
 * THIS week (daily drills only ever draw from earlier weeks, so every gate
 * problem is a first encounter). Seeded by ISO week number: re-runs pick the
 * same problems, and an existing `Gate — Week N` issue makes the run a no-op.
 * Exhausted optional pools fall back to an unsolved core problem, and the
 * body says so. Boost flags + miss counters from LAST week's gate are cleared
 * here — the boosted topics had their remedial week.
 *
 * close — reads this gate's `/done` results (recorded by srs-logger) from
 * srs.json, computes the first-attempt pass rate (unlogged problems count as
 * failures — skipping a gate problem is not a pass), appends docs/gate-log.md,
 * comments a summary, sets `boost: true` on every topic that failed a gate
 * problem or accumulated ≥ 2 drill misses, and refreshes the README badge
 * endpoint at .github/srs/badge.json.
 */
import { join } from "node:path";
import { parseArgs } from "node:util";

import { github } from "./github.ts";
import {
  campaignWeek,
  fetchCatalog,
  isoWeek,
  loadSchedule,
  loadState,
  rng,
  sample,
  saveState,
  todayET,
} from "./srs.ts";

const ROOT = join(import.meta.dir, "..");
const GATE_LOG = process.env.SRS_GATE_LOG ?? join(ROOT, "docs", "gate-log.md");
const BADGE = process.env.SRS_BADGE ?? join(ROOT, ".github", "srs", "badge.json");
const PASS_TARGET = 70; // percent, first-attempt

const { positionals, values } = parseArgs({
  allowPositionals: true,
  options: { issue: { type: "string" } },
});
const mode = positionals[0];

const gh = await github();
const state = await loadState();
const today = todayET();

// ── Trigger A: create this week's gate ───────────────────────────

async function create(): Promise<void> {
  const week = campaignWeek(today);
  const title = `Gate — Week ${week}`;

  for await (const raw of gh.list(`/repos/${gh.repo}/issues?labels=gate&state=all`)) {
    const issue = raw as { number: number; title: string };
    if (issue.title === title) {
      console.log(`${title} already exists (#${issue.number}); nothing to do`);
      return;
    }
  }

  const schedule = await loadSchedule();
  const topics = Object.entries(schedule)
    .filter(([date]) => campaignWeek(date) === week)
    .sort(([a], [b]) => (a < b ? -1 : 1))
    .map(([, topic]) => topic);
  if (topics.length === 0) {
    console.log(`no topics scheduled in week ${week}; no gate to create`);
    return;
  }

  const catalog = await fetchCatalog(gh);
  const random = rng(`gate-${isoWeek(today)}`);
  const picks: { lc: number; fallback: boolean }[] = [];
  for (const topic of topics) {
    const fresh = (set: string) =>
      [...catalog.problems.values()]
        .filter(
          (p) =>
            p.topic === topic &&
            p.set === set &&
            p.open &&
            !state.problems[p.lc] &&
            !state.drill_pool_used.includes(p.lc),
        )
        .sort((a, b) => a.lc - b.lc);
    const optional = fresh("optional");
    if (optional.length > 0) {
      picks.push({ lc: sample(optional, 1, random)[0]!.lc, fallback: false });
      continue;
    }
    const core = fresh("core");
    if (core.length > 0) picks.push({ lc: sample(core, 1, random)[0]!.lc, fallback: true });
    // Both pools exhausted: the topic is fully solved; nothing to quiz.
  }
  if (picks.length === 0) {
    console.log(`every pool for week ${week} is exhausted; no gate to create`);
    return;
  }

  const lines = picks.map(({ lc, fallback }) => {
    const p = catalog.problems.get(lc)!;
    return `- [LC ${p.lc}](${p.url}) — ${p.difficulty}${fallback ? " *(core fallback — optional pool exhausted)*" : ""}`;
  });
  const body = [
    `**Target: ${PASS_TARGET}% first-attempt pass rate. Timed. Narrate out loud.**`,
    "",
    ...lines,
    "",
    "Log with `/done <number> <pass|fail>` comments, then close this issue.",
  ].join("\n");

  const milestone = catalog.topics.get(topics[0]!)?.milestone;
  const created = (await gh.api(`/repos/${gh.repo}/issues`, {
    method: "POST",
    body: JSON.stringify({ title, body, labels: ["gate"], milestone }),
  })) as { number: number };

  state.gates.push({
    week,
    issue: created.number,
    date: today,
    problems: picks.map((p) => p.lc),
    fallbacks: picks.filter((p) => p.fallback).map((p) => p.lc),
    results: {},
  });

  // Last week's boosted topics had their remedial week: clear flags/counters.
  for (const t of Object.values(state.topics)) {
    if (t.boost) {
      t.boost = false;
      t.misses = 0;
    }
  }

  await saveState(state);
  console.log(`created #${created.number} ${title}: ${picks.map((p) => `LC ${p.lc}`).join(", ")}`);
}

// ── Trigger B: grade a closed gate ───────────────────────────────

async function close(issueNumber: number): Promise<void> {
  const gate = state.gates.find((g) => g.issue === issueNumber);
  if (!gate) {
    console.log(`issue #${issueNumber} has no gate record in srs.json; ignoring`);
    return;
  }
  if (gate.rate !== undefined) {
    console.log(`gate #${issueNumber} already graded (${gate.rate}%); nothing to do`);
    return;
  }

  const catalog = await fetchCatalog(gh);
  const passes = gate.problems.filter((lc) => gate.results[lc] === "pass");
  const unlogged = gate.problems.filter((lc) => gate.results[lc] === undefined);
  const rate = Math.round((passes.length / gate.problems.length) * 100);
  gate.rate = rate;
  const passed = rate >= PASS_TARGET;

  // Boost: explicit gate failures, plus topics with ≥ 2 recognition misses.
  const boosted: number[] = [];
  for (const lc of gate.problems) {
    if (gate.results[lc] === "fail") {
      const topic = catalog.problems.get(lc)?.topic;
      if (topic !== undefined) {
        (state.topics[topic] ??= { misses: 0, boost: false }).boost = true;
        boosted.push(topic);
      }
    }
  }
  for (const [topic, t] of Object.entries(state.topics)) {
    if (t.misses >= 2 && !t.boost) {
      t.boost = true;
      boosted.push(Number(topic));
    }
  }

  // Gate log row.
  const log = await Bun.file(GATE_LOG).text();
  const problems = gate.problems.map((lc) => `LC ${lc}`).join(" · ");
  await Bun.write(
    GATE_LOG,
    `${log.trimEnd()}\n| ${gate.week} | ${today} | ${problems} | ${rate}% | ${passed ? "pass" : "fail"} |\n`,
  );

  // Badge endpoint (shields.io schema).
  await Bun.write(
    BADGE,
    `${JSON.stringify(
      {
        schemaVersion: 1,
        label: "gate pass rate",
        message: `${rate}%`,
        color: passed ? "brightgreen" : "red",
      },
      null,
      2,
    )}\n`,
  );

  await saveState(state);

  const summary = [
    `## Gate — Week ${gate.week}: **${rate}%** first-attempt (target ${PASS_TARGET}%) — ${passed ? "✅ pass" : "❌ fail"}`,
    "",
    ...gate.problems.map((lc) => {
      const r = gate.results[lc];
      return `- LC ${lc} — ${r === "pass" ? "✅ pass" : r === "fail" ? "❌ fail" : "⬜ not logged (counted as fail)"}`;
    }),
    "",
    unlogged.length ? `${unlogged.length} problem(s) were never logged.` : "",
    boosted.length
      ? `Boosted topics for next week's drills: ${[...new Set(boosted)].map((t) => `#${t}`).join(", ")}.`
      : "No topics boosted.",
    "",
    "Logged to `docs/gate-log.md`.",
  ]
    .filter((l) => l !== "")
    .join("\n");
  await gh.api(`/repos/${gh.repo}/issues/${issueNumber}/comments`, {
    method: "POST",
    body: JSON.stringify({ body: summary }),
  });
  console.log(`graded gate #${issueNumber}: ${rate}% (${passed ? "pass" : "fail"})`);
}

// ── dispatch ─────────────────────────────────────────────────────

async function eventIssueNumber(): Promise<number> {
  if (values.issue) return Number(values.issue);
  if (!process.env.GITHUB_EVENT_PATH) return NaN;
  const event: unknown = JSON.parse(await Bun.file(process.env.GITHUB_EVENT_PATH).text());
  if (
    event &&
    typeof event === "object" &&
    "issue" in event &&
    event.issue &&
    typeof event.issue === "object" &&
    "number" in event.issue &&
    typeof event.issue.number === "number"
  ) {
    return event.issue.number;
  }
  return NaN;
}

if (mode === "create") {
  await create();
} else if (mode === "close") {
  const issueNumber = await eventIssueNumber();
  if (!Number.isFinite(issueNumber)) throw new Error("close mode needs --issue N or an event");
  await close(issueNumber);
} else {
  throw new Error(`usage: srs-gate.ts create | close --issue N (got "${mode}")`);
}