import { readEnv } from '../app-config';
import { httpConfig } from '../nest/app-config/tokens';
import { logDebug, logWarn, logError } from '../nest/audit/audit-log.logger';
import {
  ACCESS_LOG_ATTACHED,
  REQUEST_ID_HEADER,
  UNHANDLED_ERROR,
  acceptRequestId,
  newCorrelationId,
  runWithCorrelation,
} from '../nest/common/request-correlation';
import { isSameHostOrigin } from '../nest/common/same-origin';
import type { ConfigType } from '@nestjs/config';

import compression from 'compression';
import cookieParser from 'cookie-parser';
import cors from 'cors';
import express, { Request, Response, NextFunction } from 'express';
import helmet from 'helmet';
import { AsyncResource } from 'node:async_hooks';

/**
 * Field names redacted from request-log query/body dumps (case-insensitive —
 * lookup lowercases the key first). `secretaccesskey` covers the S3 storage
 * backend's secret field (storage-admin PUT bodies land in the same debug
 * log line as any other request body).
 *
 * Exported (module-level, not per-request) so it can be unit-tested directly
 * without threading LOG_LEVEL through the real logger pipeline.
 */
export const SENSITIVE_KEYS = new Set([
  'password',
  'new_password',
  'current_password',
  'token',
  'jwt',
  'authorization',
  'cookie',
  'client_secret',
  'mfa_token',
  'code',
  'smtp_pass',
  'secretaccesskey',
  // A Web Push subscription's keys: whoever holds them together with the
  // endpoint can encrypt messages for that browser. No other request body has
  // either field, and an `auth` anywhere else would be a credential as well.
  'p256dh',
  'auth',
]);

/**
 * Suffixes that make a field sensitive whatever its prefix. Matched on the end of
 * the key, not anywhere in it: `accessKeyId` is an identifier and stays readable,
 * while `refresh_token`, `code_verifier`, `mapbox_access_token` and the whole
 * `*_api_key` family are secrets nobody needs in a debug log.
 */
const SENSITIVE_SUFFIXES = ['_token', '_key', '_secret', '_password', '_pass', '_verifier'];

function isSensitiveName(name: string): boolean {
  const lower = name.toLowerCase();
  return SENSITIVE_KEYS.has(lower) || SENSITIVE_SUFFIXES.some((suffix) => lower.endsWith(suffix));
}

/**
 * The fields PushSubscription.toJSON() puts next to `endpoint`. Either one is
 * enough to know the object is a subscription, so a body that arrives without
 * its keys (which the route then refuses) still keeps its endpoint out of the log.
 */
const PUSH_SUBSCRIPTION_FIELDS = new Set(['keys', 'expirationtime']);

/**
 * A Web Push endpoint is a capability URL: anyone holding it can post to that
 * browser's push service. It arrives inside a subscription, or on its own in
 * the body that forgets a device. Anywhere else `endpoint` is an ordinary
 * setting (the S3 backend's URL, for one) and stays readable.
 */
function isPushEndpoint(entries: Record<string, unknown>, name: string): boolean {
  if (name.toLowerCase() !== 'endpoint') return false;
  const siblings = Object.keys(entries).filter((k) => k !== name);
  return siblings.length === 0 || siblings.some((k) => PUSH_SUBSCRIPTION_FIELDS.has(k.toLowerCase()));
}

/** Deep-redacts every key in `SENSITIVE_KEYS` (case-insensitive) and every Web Push endpoint from a request-log value. */
export function redact(value: unknown): unknown {
  if (!value || typeof value !== 'object') return value;
  if (Array.isArray(value)) return (value as unknown[]).map(redact);
  const entries = value as Record<string, unknown>;
  // PUT /api/settings names the setting instead of using it as the field:
  // {key: 'carto_api_key', value: '<secret>'}. Neither field name is sensitive
  // on its own, so without this the secret goes into the debug log in cleartext.
  const namedSecret = typeof entries.key === 'string' && isSensitiveName(entries.key);
  const out: Record<string, unknown> = {};
  for (const [k, v] of Object.entries(entries)) {
    const hidden = isSensitiveName(k) || (namedSecret && k === 'value') || isPushEndpoint(entries, k);
    out[k] = hidden ? '[REDACTED]' : redact(v);
  }
  return out;
}

/**
 * The global request pipeline shared by the legacy Express app and the NestJS
 * instance. Both mount the *exact same* config so a request hitting a migrated
 * Nest route is protected identically to one hitting the legacy fallback
 * (helmet/CSP, CORS, HSTS, forced-HTTPS, the global MFA policy and request
 * logging). Keeping it in one place is what makes the strangler dispatch
 * behaviourally transparent — and is the prerequisite for retiring Express,
 * since the Nest instance must carry the whole shell on its own.
 *
 * Body parsing is NOT here: the Nest instance does it, with the limit pinned in
 * bootstrap.ts. The flag that used to switch a second parser on had exactly one
 * caller, which passed false.
 */
/**
 * Turns a configured routing base URL into the origin CSP needs.
 *
 * Only the origin: a CSP source with a path only matches that path prefix, and a router
 * is asked at several of them (`/route/v1/...`, `/table/v1/...`). Anything that is not an
 * absolute http(s) URL is dropped rather than passed through — a bad value in a settings
 * row must not be able to widen the policy.
 */
export function routingCspOrigins(baseUrls: (string | null | undefined)[]): string[] {
  const origins = new Set<string>();
  for (const raw of baseUrls) {
    if (!raw) continue;
    try {
      const url = new URL(raw.trim());
      if (url.protocol !== 'http:' && url.protocol !== 'https:') continue;
      origins.add(url.origin);
    } catch {
      // Not a URL; the client falls back to the public hosts, so the policy stays as it was.
    }
  }
  return [...origins];
}

export function applyGlobalMiddleware(
  app: express.Application,
  opts: {
    /** The boot-stable half (trust proxy, HSTS subdomains), from the `httpConfig` token. */
    http?: ConfigType<typeof httpConfig>;
    /**
     * Extra origins the browser may talk to, from the instance's own settings — today the
     * self-hosted routing engine (#1797). Read once at apply time like everything else
     * here, so changing it takes a restart; the alternative is a database read on every
     * request for a value that changes about once in a deployment's life.
     */
    extraConnectSrc?: string[];
  } = {},
): void {
  // The whole pipeline is configured at APPLY time (the per-request closures
  // capture these values), so a snapshot is the correct semantic. bootstrap
  // threads in the DI-loaded httpConfig; a direct caller gets the same token
  // factory evaluated now. The live half (origins, forced HTTPS) is read here
  // too, once, so both halves freeze at the same point.
  const { http = httpConfig(), extraConnectSrc = [] } = opts;
  const liveHttp = readEnv().http;
  const { nodeEnv, isProduction } = readEnv().app;

  // Request correlation comes first, so the whole pipeline and every line the
  // request logs run under its id. An X-Request-Id set by the proxy in front is
  // kept when it looks like an id, so its logs and ours line up; anything else
  // is replaced. The response always says which id it got. The body parsers
  // bootstrap.ts registers later resume from stream events, but raw-body and
  // multer bind their callbacks with AsyncResource, so a handler reached after
  // a body still runs under this id (REQID-007, REQID-008).
  app.use((req: Request, res: Response, next: NextFunction) => {
    const id = acceptRequestId(req.headers['x-request-id']) ?? newCorrelationId();
    res.setHeader(REQUEST_ID_HEADER, id);
    runWithCorrelation({ id, kind: 'http' }, next);
  });

  // Trust first proxy (nginx/Docker) for correct req.ip
  if (isProduction || http.trustProxyRaw) {
    app.set('trust proxy', http.trustProxy);
  }

  // Compress responses (gzip via Accept-Encoding). The Atlas admin-0 country
  // GeoJSON is ~30 MB uncompressed, which stalls/aborts (~8s → net::ERR_FAILED)
  // behind reverse proxies and Cloudflare Tunnel (#1254); gzip brings it to ~4 MB.
  // SSE responses (the /mcp StreamableHTTP transport) must NOT be buffered, so
  // they are excluded explicitly.
  app.use(
    compression({
      filter: (req, res) => {
        const type = res.getHeader('Content-Type');
        if (typeof type === 'string' && type.includes('text/event-stream')) return false;
        return compression.filter(req, res);
      },
    }),
  );

  const allowedOrigins = liveHttp.corsOrigins;

  // With ALLOWED_ORIGINS set, a request from anywhere else is refused outright.
  // Two things keep that from hitting the instance's own pages (#2543): a request
  // whose Origin is the host it was sent to is same-origin and always passes, and
  // a refusal is a 403 naming the cause instead of an unhandled error, which the
  // exception filter turned into a bare 500 on the login screen.
  const warnedOrigins = new Set<string>();
  const corsOptions: cors.CorsOptions | cors.CorsOptionsDelegate<Request> = allowedOrigins
    ? (req: Request, callback: (err: Error | null, options?: cors.CorsOptions) => void) => {
        const origin = req.headers.origin;
        if (!origin || allowedOrigins.includes(origin) || isSameHostOrigin(origin, req.headers.host)) {
          callback(null, { origin: true, credentials: true });
          return;
        }
        if (!warnedOrigins.has(origin) && warnedOrigins.size < 50) {
          warnedOrigins.add(origin);
          logWarn(
            `CORS: refused origin ${origin} for host ${req.headers.host ?? '(none)'}; add it to ALLOWED_ORIGINS if it is yours`,
          );
        }
        callback(Object.assign(new Error('Not allowed by CORS'), { statusCode: 403 }));
      }
    : { origin: isProduction ? false : true, credentials: true };

  const shouldForceHttps = liveHttp.forceHttps;
  // HSTS is worth enabling any time we're serving production traffic,
  // not only when FORCE_HTTPS is set. Self-hosters behind Traefik /
  // Caddy / Cloudflare Tunnel typically leave FORCE_HTTPS unset (the
  // proxy handles the redirect for them), and the previous "HSTS off by
  // default" meant those instances never advertised HSTS at all.
  //
  // `includeSubDomains` stays OFF by default on purpose: an instance
  // running on an apex domain would otherwise force HTTPS on every
  // sibling subdomain the same operator may still be running over plain
  // HTTP. Operators who want the stricter policy opt in with
  // `HSTS_INCLUDE_SUBDOMAINS=true`.
  // nodeEnv compared case-sensitively here on purpose (legacy parity — the
  // trust-proxy/CORS checks above are the case-insensitive ones).
  const hstsActive = shouldForceHttps || nodeEnv === 'production';
  const hstsIncludeSubdomains = http.hstsIncludeSubdomains;

  // RFC 8414 / RFC 9728 / RFC 7591: discovery docs and DCR are world-readable/writable.
  // /mcp needs open CORS so external MCP clients (ChatGPT, Claude.ai, Inspector) can call it
  // with Bearer tokens from any origin. /oauth/register and /oauth/authorize need it for
  // browser-based DCR/authorization preflights — the global cors({ origin: false }) would
  // answer OPTIONS without Access-Control-Allow-Origin before the SDK's own cors() runs.
  // All /.well-known/* paths get open CORS so clients probing openid-configuration or the
  // RFC 8414 path-suffixed AS metadata form don't get CORS-blocked (they get 404 JSON instead).
  //
  // `exposedHeaders` is load-bearing, not cosmetic. Without Access-Control-Expose-Headers the
  // Fetch spec forbids a browser-context client (Claude Desktop connectors, Claude.ai, MCP
  // Inspector) from *reading* Mcp-Session-Id off the initialize response — so it can never echo
  // the header back, every request looks like a fresh initialize, and the server mints a new
  // session per tool call until the per-user cap wedges the connection. Same reasoning for
  // WWW-Authenticate, which carries the RFC 9728 resource-metadata challenge that drives
  // OAuth discovery.
  app.use((req: Request, _res: Response, next: NextFunction) => {
    if (
      req.path.startsWith('/.well-known/') ||
      req.path === '/oauth/register' ||
      req.path === '/oauth/authorize' ||
      req.path === '/oauth/userinfo' ||
      req.path === '/mcp'
    ) {
      cors({
        origin: '*',
        credentials: false,
        exposedHeaders: ['Mcp-Session-Id', 'MCP-Protocol-Version', 'WWW-Authenticate'],
      })(req, _res, next);
    } else {
      next();
    }
  });
  app.use(cors(corsOptions));
  app.use(
    helmet({
      contentSecurityPolicy: {
        directives: {
          defaultSrc: ["'self'"],
          // 'unsafe-eval' is load-bearing, not leftover: heic-to's libheif build
          // initialises embind through new Function(), and that is what converts
          // an iPhone .heic the moment somebody picks one. 'wasm-unsafe-eval'
          // alone was tried first and was not enough (93b51a0b). The package
          // ships a CSP-safe entry point at heic-to/csp; dropping this directive
          // means switching client/src/utils/convertHeic.ts over to it and
          // verifying a real .heic upload in a browser, not just deleting the
          // string here.
          scriptSrc: ["'self'", "'wasm-unsafe-eval'", "'unsafe-eval'"],
          styleSrc: ["'self'", "'unsafe-inline'", 'https://fonts.googleapis.com', 'https://unpkg.com'],
          imgSrc: ["'self'", 'data:', 'blob:', 'https:'],
          connectSrc: [
            "'self'",
            'ws:',
            'wss:',
            'https://nominatim.openstreetmap.org',
            'https://overpass-api.de',
            'https://places.googleapis.com',
            'https://api.openweathermap.org',
            'https://en.wikipedia.org',
            'https://commons.wikimedia.org',
            // Both forms here too: CARTO documents the apex host on its key page,
            // so that is the template users paste in, and the {s} sharded form is
            // what TREK ships (#2054).
            'https://basemaps.cartocdn.com',
            'https://*.basemaps.cartocdn.com',
            // Both forms: a CSP wildcard host never matches the apex, and OSM
            // serves everything from the bare tile.openstreetmap.org since it
            // retired the a/b/c/d shards (#1733). The sharded hosts stay listed
            // for tile templates users saved before that.
            'https://tile.openstreetmap.org',
            'https://*.tile.openstreetmap.org',
            // The other two raster presets TREK ships. `mode: 'no-cors'` relaxes
            // CORS, not CSP, so without these the tile prefetch is refused in the
            // document and never reaches the Service Worker that would cache it
            // (#2180). routing.openstreetmap.de below is a different host.
            'https://tile.openstreetmap.de',
            'https://tiles.stadiamaps.com',
            // OpenTopoMap is the key-free raster layer offered only by the Tours
            // planner. Leaflet uses its a/b/c shards; the apex is named too so a
            // future unsharded template does not repeat the OSM CSP gap above.
            'https://tile.opentopomap.org',
            'https://*.tile.opentopomap.org',
            // The imagery host, for the same reason and one more. Leaflet fetches a tile
            // as an <img>, which img-src's blanket `https:` waves through, so the satellite
            // view worked on Leaflet with this host missing. A GL map reads the raster
            // through fetch to hand it to WebGL, and the prefetch does too, so both were
            // refused here while nothing in the app could see it: the switch flipped, the
            // layer went on, and no tile ever arrived (#2307).
            'https://server.arcgisonline.com',
            // Amap's raster tiles, for an install whose users are in China, for the
            // same reason as the hosts above (#2180). Road (webrd01..04) and
            // satellite (webst01..04) are numbered shards of one domain, so the
            // wildcard is the whole list.
            'https://*.is.autonavi.com',
            'https://unpkg.com',
            'https://open-meteo.com',
            'https://api.open-meteo.com',
            'https://geocoding-api.open-meteo.com',
            'https://api.frankfurter.dev',
            'https://router.project-osrm.org/route/v1/',
            'https://routing.openstreetmap.de/',
            // The second routing engine, shipped as a default the same way the OSRM hosts
            // above are. It is asked only when a leg should avoid tolls, motorways or a
            // ferry — which the OSRM hosts answer with HTTP 400, because their car profile
            // carries no excludable classes. Origin only, no path: unlike OSRM this one is
            // a POST to /route and would grow more endpoints if isochrones ever land.
            'https://valhalla1.openstreetmap.de',
            'https://api.mapbox.com',
            'https://*.tiles.mapbox.com',
            'https://events.mapbox.com',
            'https://tiles.openfreemap.org',
            // A self-hosted routing engine, when the instance has one configured. Without
            // this the browser blocks it silently: no error the app can catch, just legs
            // that never route (#1797).
            ...extraConnectSrc,
          ],
          workerSrc: ["'self'", 'blob:'],
          childSrc: ["'self'", 'blob:'],
          // blob: because a picked clip is previewed and its poster frame grabbed
          // through a <video> on an object URL, before any byte reaches the server.
          // Unset, this fell back to default-src, which refuses blob: outright: the
          // editor showed nothing and every clip landed without a poster, so its
          // thumbnail answered 404 (#2341). Invisible in dev, where Vite serves the
          // document without this header.
          mediaSrc: ["'self'", 'blob:'],
          fontSrc: ["'self'", 'https://fonts.gstatic.com', 'data:'],
          // 'self' so same-origin file previews can embed PDFs via <object>/<embed>
          // (Firefox/Chrome enforce object-src; 'none' broke inline PDF previews there).
          objectSrc: ["'self'"],
          // 'self' so the app can embed same-origin, sandboxed plugin frames
          // (/plugin-frame/*). Those frames are sandboxed WITHOUT allow-same-origin,
          // so they run at an opaque origin and get their own locked-down CSP.
          frameSrc: ["'self'"],
          frameAncestors: ["'self'"],
          // Restrict <form> submission targets (form-action has no default-src
          // fallback, so it must be set explicitly).
          formAction: ["'self'"],
          upgradeInsecureRequests: shouldForceHttps ? [] : null,
        },
      },
      crossOriginEmbedderPolicy: false,
      hsts: hstsActive ? { maxAge: 31536000, includeSubDomains: hstsIncludeSubdomains } : false,
      referrerPolicy: { policy: 'strict-origin-when-cross-origin' },
    }),
  );

  // The instance's own hostname, when the operator configured one. The redirect
  // below is a 301, so echoing a client-supplied Host header would let a stranger
  // park a foreign origin in a visitor's cache. Falls back to the request Host for
  // instances that never set APP_URL, which is what it always did.
  const configuredHost = (() => {
    const url = readEnv().app.appUrl;
    try {
      return url ? new URL(url).host : null;
    } catch {
      return null;
    }
  })();

  if (shouldForceHttps) {
    app.use((req: Request, res: Response, next: NextFunction) => {
      if (req.path === '/api/health' || req.path === '/api/health/ready') return next();
      if (req.secure || req.headers['x-forwarded-proto'] === 'https') return next();
      res.redirect(301, 'https://' + (configuredHost ?? req.headers.host) + req.url);
    });
  }

  app.use(cookieParser());

  // Request logging with sensitive field redaction (SENSITIVE_KEYS/redact above).
  // The line is written in the request's own correlation context (the 'finish'
  // listener would otherwise run in whatever context the socket emits from),
  // and a 5xx carries the stack the exception filter left on res.locals, so
  // the request line, its id and the failure are one entry.
  app.use((req: Request, res: Response, next: NextFunction) => {
    if (req.path === '/api/health' || req.path === '/api/health/ready') return next();
    const startedAt = Date.now();
    res.locals[ACCESS_LOG_ATTACHED] = true;
    let reported = false;
    const failureSuffix = (): string => {
      const failure: unknown = res.locals[UNHANDLED_ERROR];
      if (failure === undefined) return '';
      return `\n${failure instanceof Error ? (failure.stack ?? failure.message) : String(failure)}`;
    };
    // A response the filter had to cut off after its headers went out never
    // finishes; it is reported when the socket closes, with its failure.
    res.on(
      'close',
      AsyncResource.bind(() => {
        if (reported || res.locals[UNHANDLED_ERROR] === undefined) return;
        reported = true;
        logError(
          `${req.method} ${req.path} aborted after headers ${Date.now() - startedAt}ms ip=${req.ip}${failureSuffix()}`,
        );
      }),
    );
    res.on(
      'finish',
      AsyncResource.bind(() => {
        reported = true;
        const ms = Date.now() - startedAt;
        if (res.statusCode >= 500) {
          logError(`${req.method} ${req.path} ${res.statusCode} ${ms}ms ip=${req.ip}${failureSuffix()}`);
        } else if (res.statusCode === 401 || res.statusCode === 403) {
          logDebug(`${req.method} ${req.path} ${res.statusCode} ${ms}ms ip=${req.ip}`);
        } else if (res.statusCode >= 400) {
          logWarn(`${req.method} ${req.path} ${res.statusCode} ${ms}ms ip=${req.ip}`);
        }
        const q = Object.keys(req.query).length ? ` query=${JSON.stringify(redact(req.query))}` : '';
        const b = req.body && Object.keys(req.body).length ? ` body=${JSON.stringify(redact(req.body))}` : '';
        logDebug(`${req.method} ${req.path} ${res.statusCode} ${ms}ms ip=${req.ip}${q}${b}`);
      }),
    );
    next();
  });
}