#!/usr/bin/env bun
// Fetch ALL feedback on a PR in one pass: issue comments, review summaries,
// review approvals/change-requests, line-level review comments, and inline
// suggestions. `gh pr view --comments` only returns the issue-stream comments,
// which silently hides everything a reviewer leaves on the Files changed tab.
//
// Usage:
//   bun run pr:comments                    # current branch's PR
//   bun run pr:comments 28838              # by PR number
//   bun run pr:comments '#28838'           # also works
//   bun run pr:comments https://github.com/oven-sh/bun/pull/28838
//   bun run pr:comments 28838 --include-resolved  # also show resolved threads
//   bun run pr:comments 28838 --json              # machine-readable output for jq pipelines
//
// Default output is XML with resolved threads and bot noise (robobun's CI
// status comment, CodeRabbit body-level summaries/walkthroughs) filtered out.
// Pass --include-resolved to restore resolved threads.
//
// JSON mode emits one object per entry with fields:
//   { when, user, tag, state?, suggestion?, location?, body, url?, resolved?, outdated? }
// resolved/outdated come from GitHub's GraphQL reviewThreads and are only
// present on line comments / replies whose thread state was successfully
// fetched. They're omitted entirely on issue comments, review verdicts, and
// any entry where the GraphQL fetch failed — so `resolved == false` in jq
// unambiguously means "confirmed unresolved thread". You can filter with jq,
// e.g. (the PR is optional, defaults to current branch):
//   bun run pr:comments --json | jq '.[] | select(.user == "Jarred-Sumner")'

import { $ } from "bun";

type Json = Record<string, any>;

// `--paginate` is load-bearing: GitHub's REST API defaults to 30 items per
// page, and without it a PR with more than 30 issue comments / reviews /
// line comments would silently truncate — the exact footgun this script is
// supposed to eliminate. gh follows Link: rel=next headers for us and emits
// one concatenated array.
async function gh(path: string): Promise<Json[]> {
  const result = await $`gh api --paginate ${path}`.quiet().nothrow();
  if (result.exitCode !== 0) {
    const stderr = result.stderr.toString().trim();
    console.error(`gh api --paginate ${path} failed (exit ${result.exitCode}).`);
    if (stderr) console.error(stderr);
    console.error("Check that `gh auth status` is healthy and that the PR exists.");
    process.exit(1);
  }
  try {
    return JSON.parse(result.stdout.toString());
  } catch (err) {
    console.error(`Could not parse response from \`gh api --paginate ${path}\` as JSON: ${(err as Error).message}`);
    process.exit(1);
  }
}

// Thread state (isResolved, isOutdated) is only exposed via GraphQL — the REST
// /pulls/N/comments endpoint omits it entirely. Returns a Map from the REST
// comment id (GraphQL `databaseId`) to its thread's state. On any failure we
// warn to stderr and return null so the caller proceeds without annotations
// rather than crashing.
//
// Pagination is fully manual (not `gh api graphql --paginate`) because the
// concatenated output format of gh's --paginate for GraphQL responses is not
// standard JSON. Manual cursor loops let us parse each page with plain
// JSON.parse and also handle nested pagination (per-thread comments) when a
// single thread has more than 100 comments.
type ThreadState = { resolved: boolean; outdated: boolean };

async function runGraphQL(query: string, vars: Record<string, string | number>): Promise<Json | null> {
  const flags = Object.entries(vars).flatMap(([k, v]) => ["-F", `${k}=${v}`]);
  const result = await $`gh api graphql -f query=${query} ${flags}`.quiet().nothrow();
  if (result.exitCode !== 0) {
    console.error(`Warning: gh api graphql failed (exit ${result.exitCode}).`);
    const stderr = result.stderr.toString().trim();
    if (stderr) console.error(`  ${stderr}`);
    return null;
  }
  try {
    return JSON.parse(result.stdout.toString());
  } catch (err) {
    console.error(`Warning: could not parse GraphQL response: ${(err as Error).message}`);
    return null;
  }
}

async function fetchThreadState(repo: string, number: number): Promise<Map<number, ThreadState> | null> {
  const [owner, name] = repo.split("/");

  const threadQuery = `
    query($owner: String!, $name: String!, $number: Int!, $cursor: String) {
      repository(owner: $owner, name: $name) {
        pullRequest(number: $number) {
          reviewThreads(first: 100, after: $cursor) {
            pageInfo { hasNextPage endCursor }
            nodes {
              id
              isResolved
              isOutdated
              comments(first: 100) {
                pageInfo { hasNextPage endCursor }
                nodes { databaseId }
              }
            }
          }
        }
      }
    }
  `;

  // Inner pagination: if a single thread has more than 100 comments we have
  // to issue additional queries scoped to that thread to pick up the rest.
  const innerQuery = `
    query($threadId: ID!, $cursor: String) {
      node(id: $threadId) {
        ... on PullRequestReviewThread {
          comments(first: 100, after: $cursor) {
            pageInfo { hasNextPage endCursor }
            nodes { databaseId }
          }
        }
      }
    }
  `;

  const map = new Map<number, ThreadState>();
  let cursor: string | undefined = undefined;

  while (true) {
    const vars: Record<string, string | number> = { owner, name, number };
    if (cursor) vars.cursor = cursor;

    const page = await runGraphQL(threadQuery, vars);
    if (!page) return null;
    const threadsField = page?.data?.repository?.pullRequest?.reviewThreads;
    if (!threadsField) return null;

    for (const t of threadsField.nodes ?? []) {
      const state: ThreadState = { resolved: !!t.isResolved, outdated: !!t.isOutdated };
      for (const c of t.comments?.nodes ?? []) {
        if (typeof c.databaseId === "number") map.set(c.databaseId, state);
      }

      // Paginate inner comments only when this thread overflowed the first 100.
      let innerCursor: string | undefined = t.comments?.pageInfo?.hasNextPage
        ? t.comments.pageInfo.endCursor
        : undefined;
      while (innerCursor) {
        const innerVars: Record<string, string | number> = { threadId: t.id, cursor: innerCursor };
        const innerPage = await runGraphQL(innerQuery, innerVars);
        if (!innerPage) return null;
        const innerComments = innerPage?.data?.node?.comments;
        if (!innerComments) break;
        for (const c of innerComments.nodes ?? []) {
          if (typeof c.databaseId === "number") map.set(c.databaseId, state);
        }
        innerCursor = innerComments.pageInfo?.hasNextPage ? innerComments.pageInfo.endCursor : undefined;
      }
    }

    if (!threadsField.pageInfo?.hasNextPage) break;
    cursor = threadsField.pageInfo.endCursor;
  }

  return map;
}

async function resolvePr(arg: string | undefined): Promise<{ repo: string; number: number }> {
  const urlMatch = arg?.match(/github\.com\/([^\/]+\/[^\/]+)\/pull\/(\d+)/);
  if (urlMatch) return { repo: urlMatch[1], number: Number(urlMatch[2]) };

  const repoResult = await $`gh repo view --json nameWithOwner -q .nameWithOwner`.quiet().nothrow();
  if (repoResult.exitCode !== 0) {
    console.error("Could not determine the GitHub repo for the current directory.");
    console.error("Run this inside a repo with a GitHub remote, or pass a PR URL instead:");
    console.error("  bun run pr:comments https://github.com/oven-sh/bun/pull/28838");
    process.exit(1);
  }
  const repo = repoResult.stdout.toString().trim();

  if (arg) {
    // PR numbers are positive integers. `Number.isFinite` would accept 1.5,
    // -1, and 0, all of which would just produce a confusing gh api error
    // later. Require a positive integer up front for a clearer message.
    const n = Number(arg.replace(/^#/, ""));
    if (!Number.isInteger(n) || n <= 0) {
      console.error(`Error: "${arg}" is not a PR number or URL.`);
      console.error(`Usage: bun run pr:comments [<number> | #<number> | <url>]`);
      process.exit(1);
    }
    return { repo, number: n };
  }

  // No argument — look up a PR for the current branch.
  const branch = (await $`git branch --show-current`.quiet().text()).trim();
  // Don't merge stderr into stdout — `gh` occasionally emits diagnostic lines
  // like "A new release of gh is available" to stderr, which would corrupt the
  // JSON we're about to parse. Bun's $ already captures the two streams separately.
  const lookup = await $`gh pr view --json number`.quiet().nothrow();
  if (lookup.exitCode !== 0) {
    console.error(`No pull request found for the current branch (${branch || "detached HEAD"}).`);
    console.error("");
    console.error("Options:");
    console.error("  - Pass a PR number:        bun run pr:comments 28838");
    console.error("  - Pass a PR URL:           bun run pr:comments https://github.com/oven-sh/bun/pull/28838");
    console.error("  - Push this branch and open a PR first");
    process.exit(1);
  }
  try {
    const view = JSON.parse(lookup.stdout.toString().trim());
    return { repo, number: view.number };
  } catch {
    console.error(`Could not parse "gh pr view" output. Pass a PR number or URL instead.`);
    process.exit(1);
  }
}

function fmtDate(iso: string): string {
  return new Date(iso).toISOString().replace("T", " ").slice(0, 16);
}

function indent(text: string, prefix = "  "): string {
  return text
    .split("\n")
    .map(l => prefix + l)
    .join("\n");
}

function xmlEscape(s: string): string {
  return s.replace(/[<>&"']/g, c => ({ "<": "&lt;", ">": "&gt;", "&": "&amp;", '"': "&quot;", "'": "&apos;" })[c]!);
}

// CodeRabbit appends a collapsed "🤖 Prompt for AI Agents" <details> block with
// a fenced code block containing the actionable instruction. When present, that
// block is the only part worth feeding back to an agent — the prose above it is
// the human-facing duplicate. Otherwise: strip HTML comments (bot watermarks
// like `<!-- generated-comment ... -->`) and cap length so one giant CI report
// doesn't drown out review feedback.
const aiPromptRe = /<summary>[^<]*🤖[^<]*AI [Aa]gents[^<]*<\/summary>\s*```[^\n]*\n([\s\S]*?)```/;

function cleanBody(body: string, max = 1000): string {
  const aiPrompt = body.match(aiPromptRe);
  if (aiPrompt) return aiPrompt[1].trim();

  const stripped = body.replace(/<!--[\s\S]*?-->/g, "").trim();
  if (stripped.length <= max) return stripped;
  return stripped.slice(0, max) + `\n... [${stripped.length - max} more chars truncated]`;
}

function xmlAttr(name: string, value: string | boolean | undefined): string {
  if (value === undefined || value === false) return "";
  if (value === true) return ` ${name}="true"`;
  return ` ${name}="${xmlEscape(value)}"`;
}

const rawArgs = process.argv.slice(2);
const jsonMode = rawArgs.includes("--json");
const includeResolved = rawArgs.includes("--include-resolved");
const positional = rawArgs.filter(a => !a.startsWith("--"))[0];

const { repo, number } = await resolvePr(positional);

const [issueComments, reviews, reviewComments, threadState] = await Promise.all([
  gh(`repos/${repo}/issues/${number}/comments`),
  gh(`repos/${repo}/pulls/${number}/reviews`),
  gh(`repos/${repo}/pulls/${number}/comments`),
  fetchThreadState(repo, number),
]);

type Entry = {
  when: string;
  user: string;
  tag: "issue-comment" | "review" | "line-comment" | "reply";
  state?: string;
  suggestion?: boolean;
  location?: string;
  body: string;
  url?: string;
  // Present only on line-level entries whose thread state we successfully
  // looked up. Omitted entirely on issue comments, review verdicts, and any
  // thread entry where the GraphQL fetch failed — that way `resolved == false`
  // in jq unambiguously means "confirmed unresolved thread" with no overlap
  // between "not applicable" and "unknown". A stderr warning is printed when
  // the thread-state fetch fails so the omission is visible.
  resolved?: boolean;
  outdated?: boolean;
};

const entries: Entry[] = [];

for (const c of issueComments) {
  entries.push({
    when: c.created_at,
    user: c.user?.login ?? "?",
    tag: "issue-comment",
    body: c.body ?? "",
    url: c.html_url,
  });
}

for (const r of reviews) {
  // Skip the empty "COMMENTED" review stub that GitHub emits as a container
  // for line-level comments — the real content is in reviewComments below.
  if (!r.body && r.state === "COMMENTED") continue;
  // PENDING reviews are drafts the viewer hasn't submitted yet. They have
  // submitted_at=null (which would crash the sort below) and aren't visible
  // to anyone else, so skip them.
  if (r.state === "PENDING") continue;
  entries.push({
    when: r.submitted_at,
    user: r.user?.login ?? "?",
    tag: "review",
    state: (r.state ?? "unknown").toLowerCase().replace(/_/g, "-"),
    body: r.body || "(no body)",
    url: r.html_url,
  });
}

for (const c of reviewComments) {
  const loc = c.path ? `${c.path}${c.line ? `:${c.line}` : ""}` : undefined;
  // Only annotate when we have confirmed thread state. If threadState is null
  // (GraphQL fetch failed) or this comment isn't in the map, we omit both
  // fields rather than setting them to null — see the Entry type comment.
  const state = threadState?.get(c.id);
  const body = c.body ?? "";
  const entry: Entry = {
    when: c.created_at,
    user: c.user?.login ?? "?",
    tag: c.in_reply_to_id ? "reply" : "line-comment",
    suggestion: /```suggestion\b/.test(body) || undefined,
    location: loc,
    body,
    url: c.html_url,
  };
  if (state) {
    entry.resolved = state.resolved;
    entry.outdated = state.outdated;
  }
  entries.push(entry);
}

entries.sort((a, b) => a.when.localeCompare(b.when));

// Bot-noise filter. CodeRabbit posts (a) line comments with an AI-agent prompt
// — keep those — and (b) body-level entries (issue comments, review summaries)
// that either have no AI prompt at all (Walkthrough, Reviews paused) or just
// aggregate the line comments verbatim. Drop both (b) cases.
const isLineLevel = (e: Entry) => e.tag === "line-comment" || e.tag === "reply";
const coderabbitHasLineComments = entries.some(e => e.user === "coderabbitai[bot]" && isLineLevel(e));

function isBotNoise(e: Entry): boolean {
  // robobun's auto-updated CI status comment (the one it edits in place on
  // every push) carries this watermark so the bot can find it again. Other
  // robobun comments are kept.
  if (e.user === "robobun" && e.body.includes("<!-- generated-comment ")) return true;
  if (e.user === "coderabbitai[bot]" && !isLineLevel(e)) {
    if (!aiPromptRe.test(e.body)) return true;
    if (coderabbitHasLineComments) return true;
  }
  return false;
}

// Resolved threads are noise when you're looking for what's actionable. Only
// drop entries we know are resolved — issue comments and review verdicts have
// no thread state and always pass through.
const resolvedHidden = entries.reduce((n, e) => n + (e.resolved === true ? 1 : 0), 0);
const visible = entries.filter(e => !isBotNoise(e) && (includeResolved || e.resolved !== true));

if (jsonMode) {
  process.stdout.write(JSON.stringify(visible, null, 2) + "\n");
  process.exit(0);
}

const url = `https://github.com/${repo}/pull/${number}`;
const hiddenAttr = !includeResolved && resolvedHidden > 0 ? xmlAttr("resolved-hidden", String(resolvedHidden)) : "";
console.log(
  `<pr-comments${xmlAttr("repo", repo)}${xmlAttr("number", String(number))}${xmlAttr("url", url)}${hiddenAttr}>`,
);
for (const e of visible) {
  const attrs =
    xmlAttr("user", e.user) +
    xmlAttr("when", fmtDate(e.when)) +
    xmlAttr("state", e.state) +
    xmlAttr("location", e.location) +
    xmlAttr("suggestion", e.suggestion) +
    xmlAttr("resolved", e.resolved) +
    xmlAttr("outdated", e.outdated) +
    xmlAttr("url", e.url);
  const body = cleanBody(e.body);
  if (body) {
    console.log(`  <${e.tag}${attrs}>`);
    console.log(indent(xmlEscape(body), "    "));
    console.log(`  </${e.tag}>`);
  } else {
    console.log(`  <${e.tag}${attrs} />`);
  }
}
console.log(`</pr-comments>`);