import { Hono } from 'hono';
import { bodyLimit } from 'hono/body-limit';
import { validateLead, type LeadResponse } from '@kvarta/shared/lead';
import type { Db } from './db/index.js';
import { saveLead } from './leads.js';
import { notifyLater, type Notifier } from './notifier.js';

export type AppDeps = {
  db: Db;
  now: () => Date;
  notifier: Notifier;
  version?: string;
};

export const MAX_BODY_BYTES = 16 * 1024;
const USER_AGENT_MAX = 500;

export function createApp(deps: AppDeps) {
  const app = new Hono();
  const reply = (body: LeadResponse, status: 200 | 201 | 400 | 413 | 415 | 500) => Response.json(body, { status });

  app.onError((err) => {
    console.error(err);
    return reply({ ok: false, error: 'server' }, 500);
  });

  app.get('/api/health', (c) => c.json({ ok: true, version: deps.version ?? 'dev' }));

  app.post(
    '/api/lead',
    async (c, next) => {
      const type = c.req.header('content-type')?.split(';')[0]?.trim().toLowerCase();
      if (type !== 'application/json') return reply({ ok: false, error: 'bad_request' }, 415);
      await next();
    },
    bodyLimit({ maxSize: MAX_BODY_BYTES, onError: () => reply({ ok: false, error: 'bad_request' }, 413) }),
    async (c) => {
      let body: unknown;
      try {
        body = await c.req.json();
      } catch {
        return reply({ ok: false, error: 'bad_request' }, 400);
      }

      const result = validateLead(body);
      if (!result.ok) return reply({ ok: false, error: 'validation', fieldErrors: result.fieldErrors }, 400);

      const userAgent = c.req.header('user-agent')?.slice(0, USER_AGENT_MAX) ?? null;
      const saved = saveLead(deps.db, result.data, { now: deps.now(), userAgent });
      if (saved.kind === 'unchanged') return reply({ ok: true, duplicate: true, clarified: false }, 200);
      notifyLater(deps.notifier, saved.event);
      if (saved.kind === 'clarified') return reply({ ok: true, duplicate: true, clarified: true }, 200);
      return reply({ ok: true, duplicate: false }, 201);
    },
  );

  return app;
}