import { BadRequestException } from '@nestjs/common';
import AdmZip from 'adm-zip';
import * as forge from 'node-forge';
import type { UploadedFileLike } from '../auth/types/auth-user';

/**
 * Zertifikatspaket (quick-261001-l4q): alles, was ein Aussteller liefert —
 * Zertifikat mit Kette (.pem/.crt/.cer/.p7b), privater Schluessel (.key),
 * Zertifikatsanfrage (.csr), PFX/P12, gern als ZIP — auf einmal hochladen,
 * erkennen, was was ist, und jedes Teil in jedem passenden Format
 * herunterladen.
 *
 * Zustandslos wie der Rest des Moduls: `analyzeBundle` gibt je Teil den
 * kanonischen PEM-Text zurueck, `exportBundleItem` baut daraus die Datei.
 * Nichts wird gespeichert, Passwoerter werden nie protokolliert.
 */

type BundleFile = Pick<UploadedFileLike, 'buffer' | 'originalname'>;

export type BundleCertRole = 'end-entity' | 'intermediate' | 'root';
export type BundleItemKind = 'certificate' | 'privateKey' | 'csr';

export interface BundleItem {
  id: string;
  kind: BundleItemKind;
  /** Nur bei Zertifikaten. */
  role?: BundleCertRole;
  /** Dateien, in denen dieses Teil gefunden wurde (Duplikate zusammengefasst). */
  sources: string[];
  /** Kanonischer PEM-Text — Grundlage fuer jeden Export. */
  pem: string;
  /** Vorschlag fuer den Dateinamen ohne Endung, aus dem CN abgeleitet. */
  baseName: string;
  cn: string;
  organization: string;
  issuerCn: string;
  notBefore: string | null;
  notAfter: string | null;
  isExpired: boolean | null;
  daysLeft: number | null;
  san: string[];
  keyType: string;
  keyBits: number;
  serialNumber: string;
  sha256: string;
  /** Zertifikat: id des passenden Schluessels; Schluessel/CSR: id des passenden Zertifikats. */
  matchId: string | null;
  /** Zertifikat: ids der Kette darueber (Aussteller, dessen Aussteller ...). */
  chainIds: string[];
  /** Formate, die `exportBundleItem` fuer dieses Teil liefern kann. */
  formats: BundleExportFormat[];
}

export interface BundleAnalysis {
  items: BundleItem[];
  /** PFX/P12 oder verschluesselte Schluessel, die ohne (richtiges) Passwort nicht lesbar sind. */
  locked: string[];
  /** Dateien ohne erkennbares Zertifikat, Schluessel oder CSR. */
  ignored: string[];
}

export type BundleExportFormat =
  | 'crt'
  | 'cer'
  | 'fullchain'
  | 'p7b'
  | 'pfx'
  | 'key'
  | 'key-rsa'
  | 'key-der'
  | 'csr'
  | 'csr-der';

export interface BundleExportInput {
  kind: BundleItemKind;
  pem: string;
  format: BundleExportFormat;
  baseName?: string;
  /** Zertifikat: PEMs der Kette darueber (fuer Fullchain/P7B/PFX). */
  chain?: string[];
  /** Zertifikat: PEM des passenden privaten Schluessels (fuer PFX). */
  keyPem?: string;
  /** PFX: Passwort fuer die neue Datei. */
  password?: string;
}

export interface BundleExportFile {
  filename: string;
  /** Base64 */
  content: string;
  mimeType: string;
}

const MAX_ZIP_ENTRIES = 100;
const MAX_ENTRY_BYTES = 5 * 1024 * 1024;

const PEM_BLOCK = /-----BEGIN ([A-Z0-9 ]+)-----[\s\S]+?-----END \1-----/g;

// ---------------------------------------------------------------------------
// Hilfen
// ---------------------------------------------------------------------------

function binary(buffer: Buffer): forge.util.ByteStringBuffer {
  return forge.util.createBuffer(buffer.toString('binary'));
}

function bytesToBase64(bytes: string): string {
  return Buffer.from(forge.util.bytesToHex(bytes), 'hex').toString('base64');
}

function textToBase64(text: string): string {
  return Buffer.from(text, 'utf-8').toString('base64');
}

function sha256Of(cert: forge.pki.Certificate): string {
  const md = forge.md.sha256.create();
  md.update(forge.asn1.toDer(forge.pki.certificateToAsn1(cert)).getBytes());
  return (md.digest().toHex().match(/.{2}/g) ?? []).join(':').toUpperCase();
}

function field(name: forge.pki.Certificate['subject'], short: string): string {
  return (name.getField(short)?.value as string | undefined) ?? '';
}

/** Dateiname ohne Pfad und ohne gefaehrliche Zeichen, z. B. „*.example.de“ -> „wildcard.example.de“. */
export function safeBaseName(raw: string, fallback: string): string {
  const cleaned = raw
    .replace(/^\*\./, 'wildcard.')
    .replace(/[^A-Za-z0-9._-]+/g, '_')
    .replace(/^[._]+/, '')
    .slice(0, 80);
  return cleaned || fallback;
}

function certRole(cert: forge.pki.Certificate): BundleCertRole {
  const bc = cert.getExtension('basicConstraints') as { cA?: boolean } | null;
  if (!bc?.cA) return 'end-entity';
  return cert.subject.hash === cert.issuer.hash ? 'root' : 'intermediate';
}

function publicKeyInfo(key: unknown): { keyType: string; keyBits: number; modulus: string } {
  // node-forge liefert RSA-Schluessel mit `n`; EC-Schluessel kennt es nur
  // eingeschraenkt (siehe Kommentar in CertManagerService.parseCert).
  const k = key as { n?: forge.jsbn.BigInteger };
  if (k?.n) return { keyType: 'RSA', keyBits: k.n.bitLength(), modulus: k.n.toString(16) };
  return { keyType: 'EC', keyBits: 0, modulus: '' };
}

function sanOf(extensions: unknown[] | undefined): string[] {
  const ext = (extensions ?? []).find((e) => (e as { name?: string }).name === 'subjectAltName') as
    | { altNames?: { type: number; value?: string; ip?: string }[] }
    | undefined;
  return (ext?.altNames ?? []).map((n) =>
    n.type === 2 ? (n.value ?? '') : `IP:${n.ip ?? n.value ?? ''}`,
  );
}

// ---------------------------------------------------------------------------
// Einsammeln: Dateien (inkl. ZIP) -> rohe Teile
// ---------------------------------------------------------------------------

interface RawKey {
  source: string;
  pem: string;
  modulus: string;
  keyType: string;
  keyBits: number;
}

interface RawCsr {
  source: string;
  pem: string;
}

interface Collected {
  certs: { source: string; cert: forge.pki.Certificate }[];
  keys: RawKey[];
  csrs: RawCsr[];
  locked: string[];
  ignored: string[];
}

function expandZips(files: BundleFile[]): { name: string; buffer: Buffer }[] {
  const out: { name: string; buffer: Buffer }[] = [];
  for (const file of files) {
    if (!file.originalname.toLowerCase().endsWith('.zip')) {
      out.push({ name: file.originalname, buffer: file.buffer });
      continue;
    }
    let zip: AdmZip;
    try {
      zip = new AdmZip(file.buffer);
    } catch {
      throw new BadRequestException(`"${file.originalname}" is not a readable ZIP archive`);
    }
    const entries = zip
      .getEntries()
      .filter((e) => !e.isDirectory && !e.entryName.startsWith('__MACOSX/'));
    if (entries.length > MAX_ZIP_ENTRIES) {
      throw new BadRequestException(`"${file.originalname}" contains too many files`);
    }
    for (const entry of entries) {
      // Groesse aus dem Kopf pruefen, BEVOR entpackt wird (Zip-Bombe).
      if (entry.header.size > MAX_ENTRY_BYTES) {
        throw new BadRequestException(
          `"${entry.entryName}" in "${file.originalname}" is too large`,
        );
      }
      const name = entry.entryName.split('/').pop() ?? entry.entryName;
      out.push({ name, buffer: entry.getData() });
    }
  }
  return out;
}

function addKey(c: Collected, source: string, privateKey: forge.pki.rsa.PrivateKey): void {
  const info = publicKeyInfo(privateKey);
  const pem = forge.pki.privateKeyInfoToPem(
    forge.pki.wrapRsaPrivateKey(forge.pki.privateKeyToAsn1(privateKey)),
  );
  c.keys.push({ source, pem, ...info });
}

function collectPemText(c: Collected, source: string, text: string, password: string): boolean {
  let found = false;
  for (const match of text.matchAll(PEM_BLOCK)) {
    const [block, type] = match;
    try {
      if (type === 'CERTIFICATE' || type === 'TRUSTED CERTIFICATE') {
        c.certs.push({ source, cert: forge.pki.certificateFromPem(block) });
        found = true;
      } else if (type === 'PRIVATE KEY' || type === 'RSA PRIVATE KEY') {
        const key = forge.pki.privateKeyFromPem(block) as forge.pki.rsa.PrivateKey;
        addKey(c, source, key);
        found = true;
      } else if (type === 'ENCRYPTED PRIVATE KEY') {
        const key = password ? forge.pki.decryptRsaPrivateKey(block, password) : null;
        if (key) addKey(c, source, key as forge.pki.rsa.PrivateKey);
        else c.locked.push(source);
        found = true;
      } else if (type === 'EC PRIVATE KEY') {
        // node-forge kann EC nicht umrechnen — Teil bleibt im Original erhalten.
        c.keys.push({ source, pem: block, modulus: '', keyType: 'EC', keyBits: 0 });
        found = true;
      } else if (type === 'CERTIFICATE REQUEST' || type === 'NEW CERTIFICATE REQUEST') {
        c.csrs.push({
          source,
          pem: block.replace(/NEW CERTIFICATE REQUEST/g, 'CERTIFICATE REQUEST'),
        });
        found = true;
      } else if (type === 'PKCS7') {
        const p7 = forge.pkcs7.messageFromPem(block);
        for (const cert of 'certificates' in p7 ? p7.certificates : [])
          c.certs.push({ source, cert });
        found = true;
      }
    } catch {
      // PKCS#8 mit EC-Schluessel o. ae.: node-forge kann ihn nicht lesen —
      // im Original behalten statt zu verwerfen.
      if (type === 'PRIVATE KEY') {
        c.keys.push({ source, pem: block, modulus: '', keyType: 'EC', keyBits: 0 });
        found = true;
      }
    }
  }
  return found;
}

function collectPfx(c: Collected, source: string, buffer: Buffer, password: string): void {
  let p12: forge.pkcs12.Pkcs12Pfx | null = null;
  for (const candidate of password ? [password, ''] : ['']) {
    try {
      p12 = forge.pkcs12.pkcs12FromAsn1(forge.asn1.fromDer(binary(buffer)), candidate);
      break;
    } catch {
      // naechstes Passwort versuchen
    }
  }
  if (!p12) {
    c.locked.push(source);
    return;
  }
  for (const bag of p12.getBags({ bagType: forge.pki.oids.certBag })[forge.pki.oids.certBag] ??
    []) {
    if (bag.cert) c.certs.push({ source, cert: bag.cert });
  }
  for (const oid of [forge.pki.oids.pkcs8ShroudedKeyBag, forge.pki.oids.keyBag]) {
    for (const bag of p12.getBags({ bagType: oid })[oid] ?? []) {
      if (bag.key) addKey(c, source, bag.key as forge.pki.rsa.PrivateKey);
    }
  }
}

function collectDer(c: Collected, source: string, buffer: Buffer): boolean {
  try {
    const asn1 = forge.asn1.fromDer(binary(buffer));
    try {
      c.certs.push({ source, cert: forge.pki.certificateFromAsn1(asn1) });
      return true;
    } catch {
      /* kein einzelnes Zertifikat */
    }
    try {
      const p7 = forge.pkcs7.messageFromAsn1(asn1);
      const certs = 'certificates' in p7 ? p7.certificates : [];
      for (const cert of certs) c.certs.push({ source, cert });
      if (certs.length > 0) return true;
    } catch {
      /* kein PKCS#7 */
    }
    try {
      forge.pki.certificationRequestFromAsn1(asn1);
      const body = forge.asn1.toDer(asn1).getBytes();
      c.csrs.push({ source, pem: forge.pem.encode({ type: 'CERTIFICATE REQUEST', body }) });
      return true;
    } catch {
      /* keine CSR */
    }
  } catch {
    /* kein DER */
  }
  return false;
}

function collect(files: BundleFile[], password: string): Collected {
  const c: Collected = { certs: [], keys: [], csrs: [], locked: [], ignored: [] };
  for (const { name, buffer } of expandZips(files)) {
    const ext = name.split('.').pop()?.toLowerCase() ?? '';
    if (ext === 'pfx' || ext === 'p12') {
      collectPfx(c, name, buffer, password);
      continue;
    }
    const head = buffer.subarray(0, 4096).toString('latin1');
    const found = head.includes('-----BEGIN')
      ? collectPemText(c, name, buffer.toString('utf-8'), password)
      : collectDer(c, name, buffer);
    if (!found) c.ignored.push(name);
  }
  return c;
}

// ---------------------------------------------------------------------------
// analyzeBundle
// ---------------------------------------------------------------------------

const CERT_FORMATS: BundleExportFormat[] = ['crt', 'cer', 'fullchain', 'p7b', 'pfx'];

export function analyzeBundle(files: BundleFile[], password = ''): BundleAnalysis {
  if (files.length === 0) throw new BadRequestException('No files provided');
  const c = collect(files, password);

  // Zertifikate nach Fingerabdruck zusammenfassen (PEM und PFX enthalten oft dieselben).
  const certMap = new Map<string, { cert: forge.pki.Certificate; sources: Set<string> }>();
  for (const { source, cert } of c.certs) {
    const fp = sha256Of(cert);
    const entry = certMap.get(fp) ?? { cert, sources: new Set<string>() };
    entry.sources.add(source);
    certMap.set(fp, entry);
  }

  const now = Date.now();
  const certItems: BundleItem[] = [...certMap.entries()].map(([fp, { cert, sources }]) => {
    const info = publicKeyInfo(cert.publicKey);
    const cn = field(cert.subject, 'CN');
    const notAfter = cert.validity.notAfter;
    const role = certRole(cert);
    return {
      id: `cert-${fp.replace(/:/g, '').slice(0, 16).toLowerCase()}`,
      kind: 'certificate',
      role,
      sources: [...sources],
      pem: forge.pki.certificateToPem(cert),
      baseName: safeBaseName(cn, role === 'end-entity' ? 'zertifikat' : 'ca'),
      cn,
      organization: field(cert.subject, 'O'),
      issuerCn: field(cert.issuer, 'CN'),
      notBefore: cert.validity.notBefore.toISOString(),
      notAfter: notAfter.toISOString(),
      isExpired: notAfter.getTime() < now,
      daysLeft: Math.ceil((notAfter.getTime() - now) / 86_400_000),
      san: sanOf(cert.extensions),
      keyType: info.keyType,
      keyBits: info.keyBits,
      serialNumber: cert.serialNumber,
      sha256: fp,
      matchId: null,
      chainIds: [],
      formats: CERT_FORMATS,
      // nur intern fuer Kette/Zuordnung, wird unten entfernt
      _cert: cert,
      _modulus: info.modulus,
    } as BundleItem & { _cert: forge.pki.Certificate; _modulus: string };
  });

  // Kette: zu jedem Zertifikat den Aussteller im Paket suchen.
  type Internal = BundleItem & { _cert: forge.pki.Certificate; _modulus: string };
  const internals = certItems as Internal[];
  for (const item of internals) {
    let current = item._cert;
    const seen = new Set<string>([item.id]);
    for (let depth = 0; depth < 10; depth++) {
      if (current.subject.hash === current.issuer.hash) break;
      const issuer = internals.find(
        (o) => !seen.has(o.id) && o._cert.subject.hash === current.issuer.hash,
      );
      if (!issuer) break;
      item.chainIds.push(issuer.id);
      seen.add(issuer.id);
      current = issuer._cert;
    }
  }

  // Schluessel: Duplikate zusammenfassen, dem Zertifikat zuordnen.
  const keyMap = new Map<string, { key: RawKey; sources: Set<string> }>();
  for (const key of c.keys) {
    const id = key.modulus || key.pem;
    const entry = keyMap.get(id) ?? { key, sources: new Set<string>() };
    entry.sources.add(key.source);
    keyMap.set(id, entry);
  }
  const keyItems: BundleItem[] = [...keyMap.values()].map(({ key, sources }, i) => {
    const cert = key.modulus ? internals.find((o) => o._modulus === key.modulus) : undefined;
    const id = `key-${i + 1}`;
    if (cert) cert.matchId = id;
    const isRsa = key.keyType === 'RSA';
    return {
      id,
      kind: 'privateKey',
      sources: [...sources],
      pem: key.pem,
      baseName:
        cert?.baseName ??
        safeBaseName(
          sources
            .values()
            .next()
            .value?.replace(/\.[^.]+$/, '') ?? '',
          'schluessel',
        ),
      cn: cert?.cn ?? '',
      organization: '',
      issuerCn: '',
      notBefore: null,
      notAfter: null,
      isExpired: null,
      daysLeft: null,
      san: [],
      keyType: key.keyType,
      keyBits: key.keyBits,
      serialNumber: '',
      sha256: '',
      matchId: cert?.id ?? null,
      chainIds: [],
      formats: isRsa ? ['key', 'key-rsa', 'key-der'] : ['key'],
    };
  });

  // CSRs: Duplikate zusammenfassen, Details lesen, dem Zertifikat zuordnen.
  const csrMap = new Map<string, { pem: string; sources: Set<string> }>();
  for (const csr of c.csrs) {
    const norm = csr.pem.replace(/\s+/g, '');
    const entry = csrMap.get(norm) ?? { pem: csr.pem, sources: new Set<string>() };
    entry.sources.add(csr.source);
    csrMap.set(norm, entry);
  }
  const csrItems: BundleItem[] = [...csrMap.values()].map(({ pem, sources }, i) => {
    let cn = '';
    let organization = '';
    let info = { keyType: '', keyBits: 0, modulus: '' };
    let san: string[] = [];
    try {
      const csr = forge.pki.certificationRequestFromPem(pem);
      cn = field(csr.subject as forge.pki.Certificate['subject'], 'CN');
      organization = field(csr.subject as forge.pki.Certificate['subject'], 'O');
      info = publicKeyInfo(csr.publicKey);
      const ext = csr.getAttribute({ name: 'extensionRequest' }) as {
        extensions?: unknown[];
      } | null;
      san = sanOf(ext?.extensions);
    } catch {
      // EC-CSR: node-forge liest sie nicht — Teil bleibt trotzdem herunterladbar.
    }
    const cert = info.modulus ? internals.find((o) => o._modulus === info.modulus) : undefined;
    return {
      id: `csr-${i + 1}`,
      kind: 'csr',
      sources: [...sources],
      pem,
      baseName: cert?.baseName ?? safeBaseName(cn, 'anfrage'),
      cn,
      organization,
      issuerCn: '',
      notBefore: null,
      notAfter: null,
      isExpired: null,
      daysLeft: null,
      san,
      keyType: info.keyType,
      keyBits: info.keyBits,
      serialNumber: '',
      sha256: '',
      matchId: cert?.id ?? null,
      chainIds: [],
      formats: ['csr', 'csr-der'],
    };
  });

  // Reihenfolge: Serverzertifikat(e), Zwischen-, Stammzertifikate, Schluessel, CSR.
  const roleOrder: Record<BundleCertRole, number> = { 'end-entity': 0, intermediate: 1, root: 2 };
  internals.sort(
    (a, b) =>
      roleOrder[a.role ?? 'end-entity'] - roleOrder[b.role ?? 'end-entity'] ||
      b.chainIds.length - a.chainIds.length,
  );
  const certsClean: BundleItem[] = internals.map(({ _cert, _modulus, ...rest }) => rest);

  return {
    items: [...certsClean, ...keyItems, ...csrItems],
    locked: [...new Set(c.locked)],
    ignored: [...new Set(c.ignored)],
  };
}

// ---------------------------------------------------------------------------
// exportBundleItem
// ---------------------------------------------------------------------------

const MIME = {
  pem: 'application/x-pem-file',
  der: 'application/x-x509-ca-cert',
  p7b: 'application/x-pkcs7-certificates',
  pfx: 'application/x-pkcs12',
  key: 'application/x-pem-file',
  octet: 'application/octet-stream',
} as const;

function pemBody(pem: string): string {
  const [msg] = forge.pem.decode(pem);
  if (!msg) throw new Error('no PEM block');
  return msg.body;
}

export function exportBundleItem(input: BundleExportInput): BundleExportFile {
  const { kind, pem, format, chain = [], keyPem, password } = input;
  const base = safeBaseName(
    input.baseName ?? '',
    kind === 'csr' ? 'anfrage' : kind === 'privateKey' ? 'schluessel' : 'zertifikat',
  );

  if (!pem || typeof pem !== 'string') throw new BadRequestException('No PEM provided');
  if (format === 'pfx' && (!password || password.trim() === '')) {
    throw new BadRequestException('A password is required for PFX output');
  }

  try {
    if (kind === 'certificate') {
      const cert = forge.pki.certificateFromPem(pem);
      const chainCerts = chain.map((p) => forge.pki.certificateFromPem(p));
      switch (format) {
        case 'crt':
          return {
            filename: `${base}.crt`,
            content: textToBase64(forge.pki.certificateToPem(cert)),
            mimeType: MIME.pem,
          };
        case 'cer':
          return {
            filename: `${base}.cer`,
            content: bytesToBase64(forge.asn1.toDer(forge.pki.certificateToAsn1(cert)).getBytes()),
            mimeType: MIME.der,
          };
        case 'fullchain': {
          const text = [cert, ...chainCerts].map((x) => forge.pki.certificateToPem(x)).join('');
          return {
            filename: `${base}-fullchain.pem`,
            content: textToBase64(text),
            mimeType: MIME.pem,
          };
        }
        case 'p7b': {
          const p7 = forge.pkcs7.createSignedData();
          for (const x of [cert, ...chainCerts]) p7.addCertificate(x);
          const text = forge.pem.encode({
            type: 'PKCS7',
            body: forge.asn1.toDer(p7.toAsn1()).getBytes(),
          });
          return { filename: `${base}.p7b`, content: textToBase64(text), mimeType: MIME.p7b };
        }
        case 'pfx': {
          const key = keyPem
            ? (forge.pki.privateKeyFromPem(keyPem) as forge.pki.rsa.PrivateKey)
            : null;
          const p12 = forge.pkcs12.toPkcs12Asn1(
            // null = reines Zertifikatsbuendel ohne Schluessel (siehe
            // CertManagerService.mergeCerts).
            key,
            [cert, ...chainCerts],
            password as string, // oben geprueft: PFX verlangt ein Passwort
            { algorithm: '3des', friendlyName: input.baseName || undefined },
          );
          return {
            filename: `${base}.pfx`,
            content: bytesToBase64(forge.asn1.toDer(p12).getBytes()),
            mimeType: MIME.pfx,
          };
        }
      }
    } else if (kind === 'privateKey') {
      switch (format) {
        case 'key':
          return {
            filename: `${base}.key`,
            content: textToBase64(`${pem.trim()}\n`),
            mimeType: MIME.key,
          };
        case 'key-rsa': {
          const key = forge.pki.privateKeyFromPem(pem);
          return {
            filename: `${base}.rsa.key`,
            content: textToBase64(forge.pki.privateKeyToPem(key)),
            mimeType: MIME.key,
          };
        }
        case 'key-der': {
          const key = forge.pki.privateKeyFromPem(pem);
          const info = forge.pki.wrapRsaPrivateKey(forge.pki.privateKeyToAsn1(key));
          return {
            filename: `${base}.key.der`,
            content: bytesToBase64(forge.asn1.toDer(info).getBytes()),
            mimeType: MIME.octet,
          };
        }
      }
    } else if (kind === 'csr') {
      switch (format) {
        case 'csr':
          return {
            filename: `${base}.csr`,
            content: textToBase64(`${pem.trim()}\n`),
            mimeType: MIME.pem,
          };
        case 'csr-der':
          return {
            filename: `${base}.csr.der`,
            content: bytesToBase64(pemBody(pem)),
            mimeType: MIME.octet,
          };
      }
    }
  } catch {
    // Passwort und Schluessel nie protokollieren oder zurueckgeben.
    throw new BadRequestException(`Failed to export ${kind} as ${format}`);
  }
  throw new BadRequestException(`Unsupported format "${format}" for ${kind}`);
}