import type { Db, EventInsert } from './db.js';
import type { DetailPr } from './github/queries.js';

const EXCERPT_LEN = 280;

function excerpt(text: string): string {
  const clean = text.replace(/\s+/g, ' ').trim();
  return clean.length > EXCERPT_LEN ? `${clean.slice(0, EXCERPT_LEN - 1)}…` : clean;
}

const HUNK_LINES = 8;
const HUNK_CHARS = 1200;

/** GitHub's diffHunk ends at the commented line — keep the trailing context. */
function trimHunk(hunk: string | undefined): string | null {
  if (!hunk) return null;
  const lines = hunk.split('\n');
  const out = lines.slice(-HUNK_LINES).join('\n');
  return out.length > HUNK_CHARS ? out.slice(-HUNK_CHARS) : out;
}

export interface TimelineOpts {
  user: string;
  /** First-ever sync: mark the historical backfill as already read. */
  backfillAsRead: boolean;
}

/** Extract timeline events from a PR detail node and upsert them.
 *  Returns the number of events that were new to the database. */
export function ingestTimeline(db: Db, pr: DetailPr, opts: TimelineOpts): number {
  const events: EventInsert[] = [];

  for (const c of pr.comments.nodes) {
    events.push({
      id: c.id,
      prId: pr.id,
      kind: 'issue_comment',
      actor: c.author?.login ?? 'ghost',
      createdAt: c.createdAt,
      updatedAt: c.updatedAt,
      bodyExcerpt: excerpt(c.bodyText),
      url: c.url,
      reviewState: null,
      threadId: null,
      path: null,
      diffHunk: null,
      read: false,
    });
  }

  for (const thread of pr.reviewThreads.nodes) {
    for (const c of thread.comments.nodes) {
      events.push({
        id: c.id,
        prId: pr.id,
        kind: 'review_comment',
        actor: c.author?.login ?? 'ghost',
        createdAt: c.createdAt,
        updatedAt: c.updatedAt,
        bodyExcerpt: excerpt(c.bodyText),
        url: c.url,
        reviewState: null,
        threadId: thread.id,
        path: thread.path,
        diffHunk: trimHunk(c.diffHunk),
        read: false,
      });
    }
  }

  for (const r of pr.reviews.nodes) {
    if (r.state === 'PENDING') continue;
    // Empty COMMENTED reviews are wrappers around inline comments — skip to avoid
    // duplicating the thread items.
    if (r.state === 'COMMENTED' && r.bodyText.trim() === '') continue;
    events.push({
      id: r.id,
      prId: pr.id,
      kind: 'review',
      actor: r.author?.login ?? 'ghost',
      createdAt: r.submittedAt ?? '',
      updatedAt: null,
      bodyExcerpt: excerpt(r.bodyText),
      url: r.url,
      reviewState: r.state,
      threadId: null,
      path: null,
      diffHunk: null,
      read: false,
    });
  }

  let newCount = 0;
  for (const e of events) {
    if (!e.createdAt) continue;
    if (db.hasEvent(e.id)) {
      db.upsertEvent(e); // refresh excerpt/updated_at; read untouched
      continue;
    }
    newCount++;
    const read = opts.backfillAsRead || e.actor === opts.user;
    db.upsertEvent({ ...e, read });
  }
  return newCount;
}