import express, { type Express } from 'express';
import { existsSync } from 'node:fs';
import { join } from 'node:path';
import type { StatePayload, SyncEventPayload } from '../shared/types.js';
import type { Db } from './db.js';
import { rootDir } from './config.js';
import { addClient } from './sse.js';
import { buildFailureReport } from './failures.js';

export interface RouteDeps {
  db: Db;
  triggerSync: () => Promise<void>;
}

export function buildSyncPayload(db: Db, changedPrIds: string[] = [], newEventCount = 0): SyncEventPayload {
  return {
    lastSyncAt: db.getMeta('last_sync_at'),
    error: db.getMeta('last_sync_error'),
    changedPrIds,
    newEventCount,
    unreadCount: db.unreadCounts().total,
  };
}

export function createApp({ db, triggerSync }: RouteDeps): Express {
  const app = express();
  app.use(express.json());

  app.get('/api/state', (_req, res) => {
    const { byPr, total } = db.unreadCounts();
    const payload: StatePayload = {
      prs: db.getOpenSnapshots(),
      lastSyncAt: db.getMeta('last_sync_at'),
      lastSyncError: db.getMeta('last_sync_error'),
      unreadCountsByPr: byPr,
      unreadTotal: total,
      failuresByPr: db.failureSummaries(),
    };
    res.json(payload);
  });

  app.get('/api/prs/:id/failures', (req, res) => {
    res.json(db.failureReportRows(req.params.id).map(buildFailureReport));
  });

  app.get('/api/timeline', (req, res) => {
    const limit = Math.min(Number(req.query.limit) || 50, 200);
    const before = typeof req.query.before === 'string' ? req.query.before : undefined;
    const unreadOnly = req.query.unread === '1';
    const prId = typeof req.query.pr === 'string' ? req.query.pr : undefined;
    res.json(db.timeline({ limit, before, unreadOnly, prId }));
  });

  app.post('/api/timeline/:id/read', (req, res) => {
    db.markRead(req.params.id, true, new Date().toISOString());
    res.json({ ok: true });
  });

  app.post('/api/timeline/:id/unread', (req, res) => {
    db.markRead(req.params.id, false, new Date().toISOString());
    res.json({ ok: true });
  });

  app.post('/api/timeline/read-all', (req, res) => {
    const before = typeof req.body?.before === 'string' ? req.body.before : undefined;
    const changed = db.markAllRead(new Date().toISOString(), before);
    res.json({ ok: true, changed });
  });

  app.post('/api/prs/:id/read-all', (req, res) => {
    const changed = db.markAllReadForPr(req.params.id, new Date().toISOString());
    res.json({ ok: true, changed });
  });

  app.post('/api/sync', (_req, res) => {
    void triggerSync();
    res.json({ ok: true });
  });

  app.get('/api/events', (_req, res) => {
    addClient(res, buildSyncPayload(db));
  });

  const webDist = join(rootDir, 'web', 'dist');
  if (existsSync(webDist)) {
    app.use(express.static(webDist));
    app.get(/^\/(?!api\/).*/, (_req, res) => {
      res.sendFile(join(webDist, 'index.html'));
    });
  }

  return app;
}