// NewBundlerFromPEM creates a new Bundler from PEM-encoded root certificates and
// intermediate certificates.
func NewBundlerFromPEM(caBundlePEM, intBundlePEM []byte) (*Bundler, error) {
	b := &Bundler{
		RootPool:         x509.NewCertPool(),
		IntermediatePool: x509.NewCertPool(),
		KnownIssuers:     map[string]bool{},
	}

	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")
	var intermediates []*x509.Certificate
	if intermediates, err = helpers.ParseCertificatesPEM(intBundlePEM); err != nil {
		log.Errorf("failed to parse intermediate bundle: %v", err)
		return nil, errors.New(errors.IntermediatesError, errors.ParseFailed)
	}

	log.Debug("building certificate pools")
	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
}

// Dial initiates a TLS connection to an outbound server. It returns a
// TLS connection to the server.
func Dial(address string, tr *Transport) (*tls.Conn, error) {
	host, _, err := net.SplitHostPort(address)
	if err != nil {
		// Assume address is a hostname, and that it should
		// use the HTTPS port number.
		host = address
		address = net.JoinHostPort(address, "443")
	}

	cfg, err := tr.TLSClientAuthClientConfig(host)
	if err != nil {
		return nil, err
	}

	conn, err := tls.Dial("tcp", address, cfg)
	if err != nil {
		return nil, err
	}

	state := conn.ConnectionState()
	if len(state.VerifiedChains) == 0 {
		return nil, errors.New(errors.CertificateError, errors.VerifyFailed)
	}

	for _, chain := range state.VerifiedChains {
		for _, cert := range chain {
			revoked, ok := revoke.VerifyCertificate(cert)
			if (!tr.RevokeSoftFail && !ok) || revoked {
				return nil, errors.New(errors.CertificateError, errors.VerifyFailed)
			}
		}
	}

	return conn, nil
}

// Sign signs a new certificate based on the PEM-encoded client
// certificate or certificate request with the signing profile, specified by profileName.
// The certificate will be valid for the host named in  the hostName parameter.
func (s *Signer) Sign(hostName string, in []byte, profileName string) (cert []byte, err error) {
	profile := s.Policy.Profiles[profileName]

	block, _ := pem.Decode(in)
	if block == nil {
		return nil, cferr.New(cferr.CertificateError, cferr.DecodeFailed, err)
	}

	var template *x509.Certificate
	switch block.Type {
	case "CERTIFICATE":
		template, err = helpers.ParseSelfSignedCertificatePEM(in)
	case "CERTIFICATE REQUEST":
		template, err = s.parseCertificateRequest(block.Bytes)
	default:
		return nil, cferr.New(cferr.CertificateError, cferr.ParseFailed, errors.New("Not a certificate or csr."))
	}
	if err != nil {
		return
	}

	if ip := net.ParseIP(hostName); ip != nil {
		template.IPAddresses = []net.IP{ip}
	} else {
		template.DNSNames = []string{hostName}
	}
	return s.sign(template, profile)
}

// 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)
}

// NewSignHandlerFromSigner generates a new SignHandler directly from
// an existing signer.
func NewSignHandlerFromSigner(s signer.Signer) (h http.Handler, err error) {
	policy := s.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 {
		if !haveUnauth {
			break
		}
		haveUnauth = (profile.Provider == nil)
	}

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

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

// ParsePrivateKeyPEM parses and returns a PEM-encoded private
// key. The private key may be either an unencrypted PKCS#8, PKCS#1,
// or elliptic private key.
func ParsePrivateKeyPEM(keyPEM []byte) (key interface{}, err error) {
	keyDER, _ := pem.Decode(keyPEM)
	if keyDER == nil {
		return nil, cferr.New(cferr.PrivateKeyError, cferr.DecodeFailed, nil)
	}
	if procType, ok := keyDER.Headers["Proc-Type"]; ok {
		if strings.Contains(procType, "ENCRYPTED") {
			return nil, cferr.New(cferr.PrivateKeyError, cferr.Encrypted, nil)
		}
	}
	key, err = x509.ParsePKCS8PrivateKey(keyDER.Bytes)
	if err != nil {
		key, err = x509.ParsePKCS1PrivateKey(keyDER.Bytes)
		if err != nil {
			key, err = x509.ParseECPrivateKey(keyDER.Bytes)
			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, nil)
			}
		}
	}
	return
}

// 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
}

// NewBundler creates a new Bundler from the files passed in; these
// files should contain a list of valid root certificates and a list
// of valid intermediate certificates, respectively.
func NewBundler(caBundleFile, intBundleFile string) (*Bundler, error) {
	log.Debug("Loading CA bundle: ", caBundleFile)
	caBundlePEM, err := ioutil.ReadFile(caBundleFile)
	if err != nil {
		log.Errorf("root bundle failed to load: %v", err)
		return nil, errors.New(errors.RootError, errors.None, err)
	}

	log.Debug("Loading Intermediate bundle: ", intBundleFile)
	intBundlePEM, err := ioutil.ReadFile(intBundleFile)
	if err != nil {
		log.Errorf("intermediate bundle failed to load: %v", err)
		return nil, errors.New(errors.IntermediatesError, errors.None, err)
	}

	if _, err := os.Stat(IntermediateStash); err != nil && os.IsNotExist(err) {
		log.Infof("intermediate stash directory %s doesn't exist, creating", IntermediateStash)
		err = os.MkdirAll(IntermediateStash, 0755)
		if err != nil {
			log.Errorf("failed to create intermediate stash directory %s: %v", err)
			return nil, err
		}
		log.Infof("intermediate stash directory %s created", IntermediateStash)
	}
	return NewBundlerFromPEM(caBundlePEM, intBundlePEM)
}

// 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
}

// 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) ([]*x509.Certificate, crypto.Signer, error) {
	var certs []*x509.Certificate
	var key crypto.Signer
	certsDER = bytes.TrimSpace(certsDER)
	pkcs7data, err := pkcs7.ParsePKCS7(certsDER)
	if err != nil {
		pkcs12data, err := pkcs12.ParsePKCS12(certsDER, []byte(password))
		if err != nil {
			certs, err = x509.ParseCertificates(certsDER)
			if err != nil {
				return nil, nil, cferr.New(cferr.CertificateError, cferr.DecodeFailed)
			}
		} else {
			key = pkcs12data.PrivateKey
			certs = pkcs12data.Certificates
		}
	} 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
}

// BundleFromRemote fetches the certificate chain served by the server at
// serverName (or ip, if the ip argument is not the empty string). It
// is expected that the method will be able to make a connection at
// port 443. The chain used by the server in this connection is
// used to rebuild the bundle.
func (b *Bundler) BundleFromRemote(serverName, ip string) (*Bundle, error) {
	config := &tls.Config{
		RootCAs:    b.RootPool,
		ServerName: serverName,
	}

	// Dial by IP if present
	var dialName string
	if ip != "" {
		dialName = ip + ":443"
	} else {
		dialName = serverName + ":443"
	}

	log.Debugf("bundling from remote %s", dialName)
	conn, err := tls.Dial("tcp", dialName, config)
	var dialError string
	// If there's an error in tls.Dial, try again with
	// InsecureSkipVerify to fetch the remote bundle to (re-)bundle with.
	// If the bundle is indeed not usable (expired, mismatched hostnames, etc.),
	// report the error.
	// Otherwise, create a working bundle and insert the tls error in the bundle.Status.
	if err != nil {
		log.Debugf("dial failed: %v", err)
		// record the error msg
		dialError = fmt.Sprintf("Failed rigid TLS handshake with %s: %v", dialName, err)
		// dial again with InsecureSkipVerify
		log.Debugf("try again with InsecureSkipVerify.")
		config.InsecureSkipVerify = true
		conn, err = tls.Dial("tcp", dialName, config)
		if err != nil {
			log.Debugf("dial with InsecureSkipVerify failed: %v", err)
			return nil, errors.New(errors.DialError, errors.Unknown, err)
		}
	}

	connState := conn.ConnectionState()

	certs := connState.PeerCertificates

	err = conn.VerifyHostname(serverName)
	if err != nil {
		log.Debugf("failed to verify hostname: %v", err)
		return nil, errors.New(errors.CertificateError, errors.VerifyFailed, err)
	}
	// verify peer intermediates and store them if there is any missing from the bundle.
	// Don't care if there is error, will throw it any way in Bundle() call.
	b.fetchIntermediates(certs)

	// Bundle with remote certs. Inject the initial dial error, if any, to the status reporting.
	bundle, err := b.Bundle(certs, nil, Ubiquitous)
	if err != nil {
		return nil, err
	} else if dialError != "" {
		bundle.Status.Messages = append(bundle.Status.Messages, dialError)
	}
	return bundle, 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() {
			// Currently we don't support a hybrid signer
			return nil, cferr.New(cferr.PolicyError, cferr.InvalidPolicy)
		}

		if policy.NeedsLocalSigner() {
			// 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)
			}
		}

		if policy.NeedsRemoteSigner() {
			s, err = remote.NewSigner(policy)
		}
	}

	return s, err
}

// ParseCertificatePEM parses and returns a PEM-encoded certificate.
func ParseCertificatePEM(certPEM []byte) (*x509.Certificate, error) {
	certPEM = bytes.TrimSpace(certPEM)
	cert, rest, err := ParseOneCertificateFromPEM(certPEM)
	if err != nil {
		return nil, cferr.New(cferr.CertificateError, cferr.ParseFailed, err)
	} else if cert == nil {
		return nil, cferr.New(cferr.CertificateError, cferr.DecodeFailed, nil)
	} else if len(rest) > 0 {
		return nil, cferr.New(cferr.CertificateError, cferr.ParseFailed, errors.New("The PEM file should contain only one certificate."))
	}
	return cert, 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
}

// 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
}

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
}