// ParsePrivateKeyDER parses a PKCS #1, PKCS #8, or elliptic curve
// DER-encoded private key. The key must not be in PEM format.
func ParsePrivateKeyDER(keyDER []byte) (key crypto.Signer, err error) {
	generalKey, err := x509.ParsePKCS8PrivateKey(keyDER)
	if err != nil {
		generalKey, err = x509.ParsePKCS1PrivateKey(keyDER)
		if err != nil {
			generalKey, err = x509.ParseECPrivateKey(keyDER)
			if err != nil {
				// We don't include the actual error into
				// the final error. The reason might be
				// we don't want to leak any info about
				// the private key.
				return nil, cferr.New(cferr.PrivateKeyError,
					cferr.ParseFailed)
			}
		}
	}

	switch generalKey.(type) {
	case *rsa.PrivateKey:
		return generalKey.(*rsa.PrivateKey), nil
	case *ecdsa.PrivateKey:
		return generalKey.(*ecdsa.PrivateKey), nil
	}

	// should never reach here
	return nil, cferr.New(cferr.PrivateKeyError, cferr.ParseFailed)
}

// NewAuthHandlerFromSigner creates a new AuthHandler from the signer
// that is passed in.
func NewAuthHandlerFromSigner(signer signer.Signer) (http.Handler, error) {
	policy := signer.Policy()
	if policy == nil {
		return nil, errors.New(errors.PolicyError, errors.InvalidPolicy)
	}

	if policy.Default == nil && policy.Profiles == nil {
		return nil, errors.New(errors.PolicyError, errors.InvalidPolicy)
	}

	// AuthSign will not respond for profiles that have no auth provider.
	// So if there are no profiles with auth providers in this policy,
	// we return an error.
	haveAuth := (policy.Default.Provider != nil)
	for _, profile := range policy.Profiles {
		if haveAuth {
			break
		}
		haveAuth = (profile.Provider != nil)
	}

	if !haveAuth {
		return nil, errors.New(errors.PolicyError, errors.InvalidPolicy)
	}

	return &api.HTTPHandler{
		Handler: &AuthHandler{
			signer: signer,
		},
		Methods: []string{"POST"},
	}, nil
}

// NewHandlerFromSigner generates a new Handler directly from
// an existing signer.
func NewHandlerFromSigner(signer signer.Signer) (h *api.HTTPHandler, err error) {
	policy := signer.Policy()
	if policy == nil {
		err = errors.New(errors.PolicyError, errors.InvalidPolicy)
		return
	}

	// Sign will only respond for profiles that have no auth provider.
	// So if all of the profiles require authentication, we return an error.
	haveUnauth := (policy.Default.Provider == nil)
	for _, profile := range policy.Profiles {
		haveUnauth = haveUnauth || (profile.Provider == nil)
	}

	if !haveUnauth {
		err = errors.New(errors.PolicyError, errors.InvalidPolicy)
		return
	}

	return &api.HTTPHandler{
		Handler: &Handler{
			signer: signer,
		},
		Methods: []string{"POST"},
	}, nil
}

// ParseCertificatesDER parses a DER encoding of a certificate object and possibly private key,
// either PKCS #7, PKCS #12, or raw x509.
func ParseCertificatesDER(certsDER []byte, password string) (certs []*x509.Certificate, key crypto.Signer, err error) {
	certsDER = bytes.TrimSpace(certsDER)
	pkcs7data, err := pkcs7.ParsePKCS7(certsDER)
	if err != nil {
		var pkcs12data interface{}
		certs = make([]*x509.Certificate, 1)
		pkcs12data, certs[0], err = pkcs12.Decode(certsDER, password)
		if err != nil {
			certs, err = x509.ParseCertificates(certsDER)
			if err != nil {
				return nil, nil, cferr.New(cferr.CertificateError, cferr.DecodeFailed)
			}
		} else {
			key = pkcs12data.(crypto.Signer)
		}
	} else {
		if pkcs7data.ContentInfo != "SignedData" {
			return nil, nil, cferr.Wrap(cferr.CertificateError, cferr.DecodeFailed, errors.New("can only extract certificates from signed data content info"))
		}
		certs = pkcs7data.Content.SignedData.Certificates
	}
	if certs == nil {
		return nil, key, cferr.New(cferr.CertificateError, cferr.DecodeFailed)
	}
	return certs, key, nil
}

// NewSigner creates a new remote Signer directly from a
// signing policy.
func NewSigner(policy *config.Signing) (*Signer, error) {
	if policy != nil {
		if !policy.Valid() {
			return nil, cferr.New(cferr.PolicyError,
				cferr.InvalidPolicy)
		}
		return &Signer{policy: policy}, nil
	}

	return nil, cferr.New(cferr.PolicyError,
		cferr.InvalidPolicy)
}

// GetKeyDERFromPEM parses a PEM-encoded private key and returns DER-format key bytes.
func GetKeyDERFromPEM(in []byte) ([]byte, error) {
	keyDER, _ := pem.Decode(in)
	if keyDER != nil {
		if procType, ok := keyDER.Headers["Proc-Type"]; ok {
			if strings.Contains(procType, "ENCRYPTED") {
				return nil, cferr.New(cferr.PrivateKeyError, cferr.Encrypted)
			}
		}
		return keyDER.Bytes, nil
	}

	return nil, cferr.New(cferr.PrivateKeyError, cferr.DecodeFailed)
}

// ParseCertificatePEM parses and returns a PEM-encoded certificate,
// can handle PEM encoded PKCS #7 structures.
func ParseCertificatePEM(certPEM []byte) (*x509.Certificate, error) {
	certPEM = bytes.TrimSpace(certPEM)
	cert, rest, err := ParseOneCertificateFromPEM(certPEM)
	if err != nil {
		// Log the actual parsing error but throw a default parse error message.
		log.Debugf("Certificate parsing error: %v", err)
		return nil, cferr.New(cferr.CertificateError, cferr.ParseFailed)
	} else if cert == nil {
		return nil, cferr.New(cferr.CertificateError, cferr.DecodeFailed)
	} else if len(rest) > 0 {
		return nil, cferr.Wrap(cferr.CertificateError, cferr.ParseFailed, errors.New("the PEM file should contain only one object"))
	} else if len(cert) > 1 {
		return nil, cferr.Wrap(cferr.CertificateError, cferr.ParseFailed, errors.New("the PKCS7 object in the PEM file should contain only one certificate"))
	}
	return cert[0], nil
}

func newLocalSigner(root Root, policy *config.Signing) (s signer.Signer, err error) {
	// shouldProvide indicates whether the
	// function *should* have produced a key. If
	// it's true, we should use the signer and
	// error returned. Otherwise, keep looking for
	// signers.
	var shouldProvide bool

	// localSignerList is defined in the
	// universal_signers*.go files. These activate
	// and deactivate signers based on build
	// flags; for example,
	// universal_signers_pkcs11.go contains a list
	// of valid signers when PKCS #11 is turned
	// on.
	for _, possibleSigner := range localSignerList {
		s, shouldProvide, err = possibleSigner(&root, policy)
		if shouldProvide {
			break
		}
	}

	if s == nil {
		err = cferr.New(cferr.PrivateKeyError, cferr.Unknown)
	}

	return s, err
}

// pkcs11Signer looks for token, module, slot, and PIN configuration
// options in the root.
func pkcs11Signer(root *Root, policy *config.Signing) (signer.Signer, bool, error) {
	module := root.Config["pkcs11-module"]
	tokenLabel := root.Config["pkcs11-token-label"]
	privateKeyLabel := root.Config["pkcs11-private-key-label"]
	userPIN := root.Config["pkcs11-user-pin"]
	certFile := root.Config["cert-file"]

	if module == "" && tokenLabel == "" && privateKeyLabel == "" && userPIN == "" {
		return nil, false, nil
	}

	if !pkcs11.Enabled {
		return nil, true, cferr.New(cferr.PrivateKeyError, cferr.Unavailable)
	}

	conf := pkcs11.Config{
		Module: module,
		Token:  tokenLabel,
		Label:  privateKeyLabel,
		PIN:    userPIN,
	}

	s, err := pkcs11.New(certFile, policy, &conf)
	return s, true, err
}

// NewSigner generates a new certificate signer from a Root structure.
// This is one of two standard signers: local or remote. If the root
// structure specifies a force remote, then a remote signer is created,
// otherwise either a remote or local signer is generated based on the
// policy. For a local signer, the CertFile and KeyFile need to be
// defined in Root.
func NewSigner(root Root, policy *config.Signing) (signer.Signer, error) {
	if policy == nil {
		policy = &config.Signing{
			Profiles: map[string]*config.SigningProfile{},
			Default:  config.DefaultConfig(),
		}
	}

	if !policy.Valid() {
		return nil, cferr.New(cferr.PolicyError, cferr.InvalidPolicy)
	}

	var s signer.Signer
	var err error
	if root.ForceRemote {
		s, err = remote.NewSigner(policy)
	} else {
		if policy.NeedsLocalSigner() && policy.NeedsRemoteSigner() {
			s, err = newUniversalSigner(root, policy)
		} else {
			if policy.NeedsLocalSigner() {
				s, err = newLocalSigner(root, policy)
			}
			if policy.NeedsRemoteSigner() {
				s, err = remote.NewSigner(policy)
			}
		}
	}

	return s, err
}

// post connects to the remote server and returns a Response struct
func (srv *server) post(url string, jsonData []byte) (*api.Response, error) {
	buf := bytes.NewBuffer(jsonData)
	resp, err := http.Post(url, "application/json", buf)
	if err != nil {
		return nil, errors.Wrap(errors.APIClientError, errors.ClientHTTPError, err)
	}
	body, err := ioutil.ReadAll(resp.Body)
	if err != nil {
		return nil, errors.Wrap(errors.APIClientError, errors.IOError, err)
	}
	resp.Body.Close()

	if resp.StatusCode != http.StatusOK {
		return nil, errors.Wrap(errors.APIClientError, errors.ClientHTTPError, stderr.New(string(body)))
	}

	var response api.Response
	err = json.Unmarshal(body, &response)
	if err != nil {
		log.Debug("Unable to parse response body:", string(body))
		return nil, errors.Wrap(errors.APIClientError, errors.JSONError, err)
	}

	if !response.Success || response.Result == nil {
		if len(response.Errors) > 0 {
			return nil, errors.Wrap(errors.APIClientError, errors.ServerRequestFailed, stderr.New(response.Errors[0].Message))
		}
		return nil, errors.New(errors.APIClientError, errors.ServerRequestFailed)
	}

	return &response, nil
}

// Generate creates a new CSR from a CertificateRequest structure and
// an existing key. The KeyRequest field is ignored.
func Generate(priv crypto.Signer, req *CertificateRequest) (csr []byte, err error) {
	sigAlgo := helpers.SignerAlgo(priv, crypto.SHA256)
	if sigAlgo == x509.UnknownSignatureAlgorithm {
		return nil, cferr.New(cferr.PrivateKeyError, cferr.Unavailable)
	}

	var tpl = x509.CertificateRequest{
		Subject:            req.Name(),
		SignatureAlgorithm: sigAlgo,
	}

	for i := range req.Hosts {
		if ip := net.ParseIP(req.Hosts[i]); ip != nil {
			tpl.IPAddresses = append(tpl.IPAddresses, ip)
		} else {
			tpl.DNSNames = append(tpl.DNSNames, req.Hosts[i])
		}
	}

	csr, err = x509.CreateCertificateRequest(rand.Reader, &tpl, priv)
	if err != nil {
		log.Errorf("failed to generate a CSR: %v", err)
		err = cferr.Wrap(cferr.CSRError, cferr.BadRequest, err)
		return
	}
	block := pem.Block{
		Type:  "CERTIFICATE REQUEST",
		Bytes: csr,
	}

	log.Info("encoded CSR")
	csr = pem.EncodeToMemory(&block)
	return
}

// Sign is used with an OCSP signer to request the issuance of
// an OCSP response.
func (s StandardSigner) Sign(req SignRequest) ([]byte, error) {
	if req.Certificate == nil {
		return nil, cferr.New(cferr.OCSPError, cferr.ReadFailed)
	}

	// Verify that req.Certificate is issued under s.issuer
	if bytes.Compare(req.Certificate.RawIssuer, s.issuer.RawSubject) != 0 {
		return nil, cferr.New(cferr.OCSPError, cferr.IssuerMismatch)
	}
	if req.Certificate.CheckSignatureFrom(s.issuer) != nil {
		return nil, cferr.New(cferr.OCSPError, cferr.IssuerMismatch)
	}

	// Round thisUpdate times down to the nearest hour
	thisUpdate := time.Now().Truncate(time.Hour)
	nextUpdate := thisUpdate.Add(s.interval)

	status, ok := StatusCode[req.Status]
	if !ok {
		return nil, cferr.New(cferr.OCSPError, cferr.InvalidStatus)
	}

	// If the OCSP responder is the same as the issuer, there is no need to
	// include any certificate in the OCSP response, which decreases the byte size
	// of OCSP responses dramatically.
	certificate := s.responder
	if s.issuer == s.responder || bytes.Equal(s.issuer.Raw, s.responder.Raw) {
		certificate = nil
	}

	template := ocsp.Response{
		Status:          status,
		SerialNumber:    req.Certificate.SerialNumber,
		ThisUpdate:      thisUpdate,
		NextUpdate:      nextUpdate,
		Certificate:     certificate,
		ExtraExtensions: req.Extensions,
	}

	if status == ocsp.Revoked {
		template.RevokedAt = req.RevokedAt
		template.RevocationReason = req.Reason
	}

	return ocsp.CreateResponse(s.issuer, s.responder, template, s.key)
}

// NewBundlerFromPEM creates a new Bundler from PEM-encoded root certificates and
// intermediate certificates.
// If caBundlePEM is nil, the resulting Bundler can only do "Force" bundle.
func NewBundlerFromPEM(caBundlePEM, intBundlePEM []byte) (*Bundler, error) {
	log.Debug("parsing root certificates from PEM")
	roots, err := helpers.ParseCertificatesPEM(caBundlePEM)
	if err != nil {
		log.Errorf("failed to parse root bundle: %v", err)
		return nil, errors.New(errors.RootError, errors.ParseFailed)
	}

	log.Debug("parse intermediate certificates from PEM")
	intermediates, err := helpers.ParseCertificatesPEM(intBundlePEM)
	if err != nil {
		log.Errorf("failed to parse intermediate bundle: %v", err)
		return nil, errors.New(errors.IntermediatesError, errors.ParseFailed)
	}

	b := &Bundler{
		KnownIssuers:     map[string]bool{},
		IntermediatePool: x509.NewCertPool(),
	}

	log.Debug("building certificate pools")

	// RootPool will be nil if caBundlePEM is nil, also
	// that translates to caBundleFile is "".
	// Systems root store will be used.
	if caBundlePEM != nil {
		b.RootPool = x509.NewCertPool()
	}

	for _, c := range roots {
		b.RootPool.AddCert(c)
		b.KnownIssuers[string(c.Signature)] = true
	}

	for _, c := range intermediates {
		b.IntermediatePool.AddCert(c)
		b.KnownIssuers[string(c.Signature)] = true
	}

	log.Debug("bundler set up")
	return b, nil
}

// ParseCertificatesPEM parses a sequence of PEM-encoded certificate and returns them,
// can handle PEM encoded PKCS #7 structures.
func ParseCertificatesPEM(certsPEM []byte) ([]*x509.Certificate, error) {
	var certs []*x509.Certificate
	var err error
	certsPEM = bytes.TrimSpace(certsPEM)
	for len(certsPEM) > 0 {
		var cert []*x509.Certificate
		cert, certsPEM, err = ParseOneCertificateFromPEM(certsPEM)
		if err != nil {

			return nil, cferr.New(cferr.CertificateError, cferr.ParseFailed)
		} else if cert == nil {
			break
		}

		certs = append(certs, cert...)
	}
	if len(certsPEM) > 0 {
		return nil, cferr.New(cferr.CertificateError, cferr.DecodeFailed)
	}
	return certs, nil
}

// getMatchingProfile returns the SigningProfile that matches the profile passed.
// if an empty profile string is passed it returns the default profile.
func (s *Signer) getMatchingProfile(profile string) (*config.SigningProfile, error) {
	if profile == "" {
		return s.policy.Default, nil
	}

	for p, signingProfile := range s.policy.Profiles {
		if p == profile {
			return signingProfile, nil
		}
	}

	return nil, cferr.New(cferr.PolicyError, cferr.UnknownProfile)
}

// authReq is the common logic for AuthSign and AuthInfo -- perform the given
// request, and return the resultant certificate.
// The target is either 'sign' or 'info'.
func (srv *server) authReq(req, ID []byte, provider auth.Provider, target string) ([]byte, error) {
	url := srv.getURL("auth" + target)

	token, err := provider.Token(req)
	if err != nil {
		return nil, errors.Wrap(errors.APIClientError, errors.AuthenticationFailure, err)
	}

	aReq := &auth.AuthenticatedRequest{
		Timestamp:     time.Now().Unix(),
		RemoteAddress: ID,
		Token:         token,
		Request:       req,
	}

	jsonData, err := json.Marshal(aReq)
	if err != nil {
		return nil, errors.Wrap(errors.APIClientError, errors.JSONError, err)
	}

	response, err := srv.post(url, jsonData)
	if err != nil {
		return nil, err
	}

	result, ok := response.Result.(map[string]interface{})
	if !ok {
		return nil, errors.New(errors.APIClientError, errors.JSONError)
	}

	cert, ok := result["certificate"].(string)
	if !ok {
		return nil, errors.New(errors.APIClientError, errors.JSONError)
	}

	return []byte(cert), nil
}

// New returns a new PKCS #11 signer.
func New(caCertFile string, policy *config.Signing, cfg *Config) (signer.Signer, error) {
	if cfg == nil {
		return nil, errors.New(errors.PrivateKeyError, errors.ReadFailed)
	}

	log.Debugf("Loading PKCS #11 module %s", cfg.Module)
	certData, err := ioutil.ReadFile(caCertFile)
	if err != nil {
		return nil, errors.New(errors.PrivateKeyError, errors.ReadFailed)
	}

	cert, err := helpers.ParseCertificatePEM(certData)
	if err != nil {
		return nil, err
	}

	priv, err := pkcs11key.New(cfg.Module, cfg.Token, cfg.PIN, cfg.Label)
	if err != nil {
		return nil, errors.New(errors.PrivateKeyError, errors.ReadFailed)
	}
	sigAlgo := signer.DefaultSigAlgo(priv)

	return local.NewSigner(priv, cert, sigAlgo, policy)
}

// NewPKCS11Signer returns a new PKCS #11 signer.
func NewPKCS11Signer(cfg ocspConfig.Config) (ocsp.Signer, error) {
	log.Debugf("Loading PKCS #11 module %s", cfg.PKCS11.Module)
	certData, err := ioutil.ReadFile(cfg.CACertFile)
	if err != nil {
		return nil, errors.New(errors.CertificateError, errors.ReadFailed)
	}

	cert, err := helpers.ParseCertificatePEM(certData)
	if err != nil {
		return nil, err
	}

	PKCS11 := cfg.PKCS11
	priv, err := pkcs11key.New(
		PKCS11.Module,
		PKCS11.TokenLabel,
		PKCS11.PIN,
		PKCS11.PrivateKeyLabel)
	if err != nil {
		return nil, errors.New(errors.PrivateKeyError, errors.ReadFailed)
	}

	return ocsp.NewSigner(cert, cert, priv, cfg.Interval)
}

// RenewFromSigner re-creates a root certificate from the CA cert and crypto.Signer.
// The resulting root certificate will have ca certificate
// as the template and have the same expiry length. E.g. the exsiting CA
// is valid for a year from Jan 01 2015 to Jan 01 2016, the renewed certificate
// will be valid from now and expire in one year as well.
func RenewFromSigner(ca *x509.Certificate, priv crypto.Signer) ([]byte, error) {
	if !ca.IsCA {
		return nil, errors.New("input certificate is not a CA cert")
	}

	// matching certificate public key vs private key
	switch {
	case ca.PublicKeyAlgorithm == x509.RSA:

		var rsaPublicKey *rsa.PublicKey
		var ok bool
		if rsaPublicKey, ok = priv.Public().(*rsa.PublicKey); !ok {
			return nil, cferr.New(cferr.PrivateKeyError, cferr.KeyMismatch)
		}
		if ca.PublicKey.(*rsa.PublicKey).N.Cmp(rsaPublicKey.N) != 0 {
			return nil, cferr.New(cferr.PrivateKeyError, cferr.KeyMismatch)
		}
	case ca.PublicKeyAlgorithm == x509.ECDSA:
		var ecdsaPublicKey *ecdsa.PublicKey
		var ok bool
		if ecdsaPublicKey, ok = priv.Public().(*ecdsa.PublicKey); !ok {
			return nil, cferr.New(cferr.PrivateKeyError, cferr.KeyMismatch)
		}
		if ca.PublicKey.(*ecdsa.PublicKey).X.Cmp(ecdsaPublicKey.X) != 0 {
			return nil, cferr.New(cferr.PrivateKeyError, cferr.KeyMismatch)
		}
	default:
		return nil, cferr.New(cferr.PrivateKeyError, cferr.NotRSAOrECC)
	}

	req := csr.ExtractCertificateRequest(ca)

	cert, _, err := NewFromSigner(req, priv)
	return cert, err

}