#!/usr/bin/env bun
/**
 * Process `/done <lc> <pass|fail>` comments on the `📋 Today` brief and on
 * gate issues, and move problems along the interval ladder.
 *
 * Transitions (see srs.ts):
 * - pass: new → +2 → +5 → +10 → retired; next_review = today + new interval.
 * - fail: back to +2, due in 2 days.
 * - First-ever log of a problem enters the ladder at +2 either way; a failed
 *   blind drill additionally increments its topic's recognition-miss counter
 *   (a signal the gate's boost logic reads). Drills join drill_pool_used so
 *   they are never served twice.
 * - A clean first PASS also closes the problem's sub-issue.
 *
 * Feedback is never silent: a clean parse gets a 👍 reaction, anything else
 * gets a reply naming the exact parse error. Only the repo owner is heard.
 *
 * Input: GITHUB_EVENT_PATH (issue_comment payload) in Actions, or
 *   --issue N --author LOGIN --comment-id N --body "..." locally.
 */
import { parseArgs } from "node:util";

import { github } from "./github.ts";
import { projectMirror, reportMirror } from "./srs-project.ts";
import {
  type Attempt,
  addDays,
  fail,
  fetchCatalog,
  loadState,
  pass,
  saveState,
  TODAY_TITLE,
  todayET,
} from "./srs.ts";

const DRY = process.env.SRS_DRY === "1";

// ── event input ──────────────────────────────────────────────────

interface Input {
  issue: number;
  issueTitle: string;
  issueLabels: string[];
  author: string;
  commentId: number;
  body: string;
}

async function readInput(): Promise<Input> {
  if (process.env.GITHUB_EVENT_PATH) {
    const event = JSON.parse(await Bun.file(process.env.GITHUB_EVENT_PATH).text());
    return {
      issue: event.issue.number,
      issueTitle: event.issue.title,
      issueLabels: (event.issue.labels ?? []).map((l: { name: string }) => l.name),
      author: event.comment.user.login,
      commentId: event.comment.id,
      body: event.comment.body ?? "",
    };
  }
  const { values } = parseArgs({
    options: {
      issue: { type: "string" },
      author: { type: "string" },
      "comment-id": { type: "string" },
      body: { type: "string" },
      title: { type: "string" },
      labels: { type: "string" },
    },
  });
  return {
    issue: Number(values.issue),
    issueTitle: values.title ?? TODAY_TITLE,
    issueLabels: values.labels?.split(",") ?? [],
    author: values.author ?? "",
    commentId: Number(values["comment-id"] ?? 0),
    body: values.body ?? "",
  };
}

const gh = await github();
const input = await readInput();
const owner = gh.repo.split("/")[0]!;

if (input.author !== owner) {
  console.log(`ignoring comment by @${input.author} (owner only)`);
  process.exit(0);
}
const isGate = input.issueLabels.includes("gate");
const isToday = input.issueTitle === TODAY_TITLE;
if (!isGate && !isToday) {
  console.log("not the Today brief or a gate issue; ignoring");
  process.exit(0);
}

// ── parse ────────────────────────────────────────────────────────

interface Command {
  lc: number;
  result: "pass" | "fail";
}

const commands: Command[] = [];
const errors: string[] = [];
for (const raw of input.body.split("\n")) {
  const line = raw.trim();
  if (!line.startsWith("/done")) continue;
  const m = line.match(/^\/done\s+(\d+)\s+(pass|fail)\s*$/);
  if (m) commands.push({ lc: Number(m[1]), result: m[2] as Command["result"] });
  else errors.push(`cannot parse \`${line}\` — expected \`/done <number> <pass|fail>\``);
}

if (commands.length === 0 && errors.length === 0) {
  console.log("no /done lines; nothing to do");
  process.exit(0);
}

// ── apply ────────────────────────────────────────────────────────

const state = await loadState();
const catalog = await fetchCatalog(gh);
const today = todayET();
const mirror = await projectMirror(owner, gh.repo);
const applied: string[] = [];

const gate = isGate ? state.gates.find((g) => g.issue === input.issue) : undefined;
if (isGate && !gate) errors.push(`no gate record for issue #${input.issue} in srs.json`);

for (const cmd of commands) {
  const known = catalog.problems.get(cmd.lc);
  const entry = state.problems[cmd.lc];

  if (!entry && !known) {
    errors.push(`LC ${cmd.lc} is not in the curriculum`);
    continue;
  }

  if (gate && known && gate.problems.includes(cmd.lc)) {
    gate.results[cmd.lc] = cmd.result;
  }

  if (!entry) {
    // First-ever attempt: enters the ladder at +2 regardless of result — a
    // pass earns a +2 review, a fail must be re-solved just as soon.
    const kind: Attempt["kind"] = gate ? "gate" : known!.set === "optional" ? "drill" : "first";
    const p: (typeof state.problems)[string] = {
      issue: known!.issue,
      topic: known!.topic,
      difficulty: known!.difficulty.toLowerCase(),
      set: known!.set,
      solved_on: today,
      stage: "+2",
      next_review: addDays(today, 2),
      history: [{ date: today, kind, result: cmd.result }],
    };
    state.problems[cmd.lc] = p;
    if (kind === "drill") {
      if (!state.drill_pool_used.includes(cmd.lc)) state.drill_pool_used.push(cmd.lc);
      if (cmd.result === "fail") {
        const t = (state.topics[known!.topic] ??= { misses: 0, boost: false });
        t.misses++;
        applied.push(`LC ${cmd.lc}: recognition miss — topic #${known!.topic} misses=${t.misses}`);
      }
    }
    if (!DRY) {
      await mirror.setFirstAttempt(known!.issue, cmd.result);
      await mirror.setStage(known!.issue, "+2");
      await mirror.setTargetDate(known!.issue, p.next_review!);
      if (cmd.result === "pass" && known!.open) {
        await gh.closeIssue(
          known!.issue,
          `First attempt passed (${kind}) — entering the review ladder at +2. Logged by \`srs-logger\`.`,
        );
      }
    }
    applied.push(`LC ${cmd.lc}: first ${kind} ${cmd.result} → stage +2, review ${p.next_review}`);
    continue;
  }

  // Already on the ladder: a review (or a gate/drill re-encounter).
  if (entry.stage === "retired") {
    errors.push(`LC ${cmd.lc} is already retired`);
    continue;
  }
  entry.history.push({ date: today, kind: "review", result: cmd.result });
  if (cmd.result === "pass") {
    pass(entry, today);
  } else {
    fail(entry, today);
  }
  delete entry.defer_until; // once touched, it lives by next_review alone
  if (!DRY) {
    await mirror.setStage(entry.issue, entry.stage);
    await mirror.setTargetDate(entry.issue, entry.next_review ?? null);
  }
  applied.push(
    `LC ${cmd.lc}: review ${cmd.result} → stage ${entry.stage}` +
      (entry.next_review ? `, review ${entry.next_review}` : " — retired 🎉"),
  );
}

// ── persist + respond ────────────────────────────────────────────

if (!DRY) await saveState(state);

for (const line of applied) console.log(line);
for (const line of errors) console.log(`error: ${line}`);

if (!DRY && input.commentId) {
  if (errors.length === 0) {
    await gh.api(`/repos/${gh.repo}/issues/comments/${input.commentId}/reactions`, {
      method: "POST",
      body: JSON.stringify({ content: "+1" }),
    });
  } else {
    await gh.api(`/repos/${gh.repo}/issues/${input.issue}/comments`, {
      method: "POST",
      body: JSON.stringify({
        body: `Could not log everything:\n\n${errors.map((e) => `- ${e}`).join("\n")}${applied.length ? `\n\nApplied anyway:\n\n${applied.map((a) => `- ${a}`).join("\n")}` : ""}`,
      }),
    });
  }
}

await reportMirror(mirror);