import { NextRequest, NextResponse } from 'next/server';
import { timingSafeEqual } from 'node:crypto';
import { z } from 'zod';
import { eq } from 'drizzle-orm';

import { db } from '@/lib/db';
import { ports } from '@/lib/db/schema/ports';
import { websiteSubmissions } from '@/lib/db/schema/website-submissions';
import { env } from '@/lib/env';
import {
  AppError,
  errorResponse,
  RateLimitError,
  UnauthorizedError,
  ValidationError,
} from '@/lib/errors';
import { logger } from '@/lib/logger';
import { checkRateLimit, rateLimiters } from '@/lib/rate-limit';

/**
 * POST /api/public/website-inquiries
 *
 * Capture endpoint for the marketing website's dual-write. The website
 * server (`/server/api/register.ts`, `/server/api/contact.ts`) calls this
 * AFTER its existing NocoDB write succeeds, sending the same payload as a
 * server-to-server fire-and-forget POST. The CRM stores the raw payload
 * in `website_submissions` for later analysis / promotion to entities.
 *
 * Auth: shared-secret in `X-Webhook-Secret` header, timing-safe compared
 *   against `WEBSITE_INTAKE_SECRET`. If the env var is unset on this
 *   instance, the endpoint refuses every request with 503 - the correct
 *   posture for dev/staging that hasn't been wired up yet.
 *
 * Idempotency: payload carries a `submission_id` UUID. The unique index
 *   on `website_submissions.submission_id` makes redelivery a no-op; the
 *   handler returns 200 + the existing record's id instead of erroring.
 *
 * No emails / no `interests` rows are created here. The endpoint's job is
 * pure data capture. A separate "promote" step (future) will turn captured
 * submissions into proper `clients` + `interests` rows once we trust the
 * pipeline.
 */

const SubmissionSchema = z.object({
  submission_id: z.string().uuid(),
  kind: z.enum(['berth_inquiry', 'residence_inquiry', 'contact_form']),
  payload: z.record(z.string(), z.unknown()),
  legacy_nocodb_id: z.string().optional(),
  /** Defaults to port-nimara since that's currently the only port with a
   *  public marketing site. Future ports can override per-submission. */
  port_slug: z.string().default('port-nimara'),
  /** UTM attribution. Opportunistic — the website's tracker pulls
   *  these from the query string (or referrer) at submit time. Capped
   *  at 200 chars per part to defend against pathological strings. */
  utm_source: z.string().max(200).nullable().optional(),
  utm_medium: z.string().max(200).nullable().optional(),
  utm_campaign: z.string().max(200).nullable().optional(),
  utm_term: z.string().max(200).nullable().optional(),
  utm_content: z.string().max(200).nullable().optional(),
});

function verifySecret(header: string | null): boolean {
  const expected = env.WEBSITE_INTAKE_SECRET;
  if (!expected) return false;
  if (!header) return false;
  // Timing-safe compare requires equal-length buffers; pad to whichever is
  // longer so an early-exit on length mismatch can't leak the secret length.
  const a = Buffer.from(header);
  const b = Buffer.from(expected);
  const pad = Buffer.alloc(Math.max(a.length, b.length));
  const aPad = Buffer.concat([a, pad]).subarray(0, pad.length);
  const bPad = Buffer.concat([b, pad]).subarray(0, pad.length);
  return timingSafeEqual(aPad, bPad) && a.length === b.length;
}

export async function POST(req: NextRequest) {
  // Refuse outright if the CRM hasn't been wired up - safer than letting
  // unauthenticated traffic in just because the env var was forgotten.
  if (!env.WEBSITE_INTAKE_SECRET) {
    return errorResponse(
      new AppError(503, 'Website intake is not configured on this server.', 'NOT_CONFIGURED'),
    );
  }

  // Auth gate - shared secret in header, timing-safe compare.
  const secretHeader = req.headers.get('x-webhook-secret');
  if (!verifySecret(secretHeader)) {
    return errorResponse(new UnauthorizedError());
  }

  // Rate limit. All website-side traffic shares the website's egress IP,
  // so we use a dedicated bucket sized to accommodate normal traffic
  // (500/hr) rather than the 5/hr publicForm bucket meant for individual
  // human submissions. The shared-secret header is the real abuse
  // boundary; this limiter is just a backstop if the secret ever leaks.
  const ip = req.headers.get('x-forwarded-for')?.split(',')[0]?.trim() ?? 'unknown';
  const rl = await checkRateLimit(ip, rateLimiters.websiteIntake);
  if (!rl.allowed) {
    const retryAfter = Math.max(1, Math.ceil((rl.resetAt - Date.now()) / 1000));
    return errorResponse(new RateLimitError(retryAfter));
  }

  // Parse + validate body. Reject anything that doesn't conform - the
  // website is a known caller; a malformed payload signals tampering.
  let parsed;
  try {
    const body = await req.json();
    parsed = SubmissionSchema.parse(body);
  } catch (err) {
    return errorResponse(
      new ValidationError('Invalid payload', [
        { field: 'body', message: err instanceof Error ? err.message : 'parse error' },
      ]),
    );
  }

  // Resolve port. We require the slug to exist; can't capture submissions
  // for a port the CRM doesn't know about.
  const [port] = await db
    .select({ id: ports.id })
    .from(ports)
    .where(eq(ports.slug, parsed.port_slug))
    .limit(1);
  if (!port) {
    // Don't echo the input slug back in the error - generic message is
    // sufficient and avoids the input-reflection pattern that complicates
    // log-injection / audit reviews. The slug is logged server-side
    // for debugging.
    logger.warn(
      { portSlug: parsed.port_slug, submissionId: parsed.submission_id },
      'website-inquiry rejected: unknown port',
    );
    return errorResponse(new ValidationError('Unknown port'));
  }

  // Idempotent insert. Two parallel requests carrying the same submission_id
  // could both pass any pre-check, so we don't pre-check at all - the unique
  // index on submission_id is the source of truth, and `onConflictDoNothing`
  // keeps the second request's INSERT from raising 23505. When the conflict
  // hits, `returning()` yields zero rows and we look up the existing row to
  // return its id, mirroring the first-delivery shape so the website never
  // sees a difference between fresh and dup.
  const insertResult = await db
    .insert(websiteSubmissions)
    .values({
      portId: port.id,
      submissionId: parsed.submission_id,
      kind: parsed.kind,
      payload: parsed.payload,
      legacyNocodbId: parsed.legacy_nocodb_id ?? null,
      sourceIp: ip,
      userAgent: req.headers.get('user-agent') ?? null,
      utmSource: parsed.utm_source ?? null,
      utmMedium: parsed.utm_medium ?? null,
      utmCampaign: parsed.utm_campaign ?? null,
      utmTerm: parsed.utm_term ?? null,
      utmContent: parsed.utm_content ?? null,
    })
    .onConflictDoNothing({ target: websiteSubmissions.submissionId })
    .returning({ id: websiteSubmissions.id });

  if (insertResult[0]) {
    logger.info(
      {
        submissionId: parsed.submission_id,
        kind: parsed.kind,
        portSlug: parsed.port_slug,
        legacyNocodbId: parsed.legacy_nocodb_id,
      },
      'website inquiry captured',
    );
    // L34 carve-out: deliberate bespoke `{ id, deduped }` shape (NOT the
    // `{ data }` envelope). This is the public website's intake contract —
    // the external marketing site reads `id`/`deduped` off the JSON root.
    // Both return sites below share this shape on purpose. Changing it
    // would be a breaking cross-repo change.
    return NextResponse.json({ id: insertResult[0].id, deduped: false });
  }

  // Conflict path: row already exists. Fetch its id so the response shape
  // stays identical regardless of which request "won" the race.
  const existing = await db
    .select({ id: websiteSubmissions.id })
    .from(websiteSubmissions)
    .where(eq(websiteSubmissions.submissionId, parsed.submission_id))
    .limit(1);
  if (existing[0]) {
    return NextResponse.json({ id: existing[0].id, deduped: true });
  }

  // Should be unreachable - the conflict means a row exists, so the lookup
  // above should always find it. If it doesn't (e.g. simultaneous DELETE),
  // surface a 500 explicitly rather than silently 200ing a missing id.
  logger.error(
    { submissionId: parsed.submission_id },
    'website-inquiry conflict but row not found on lookup',
  );
  return errorResponse(new Error('website-inquiry conflict but row not found on lookup'));
}