/*
Copyright IBM Corp. 2016 All Rights Reserved.

Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at

                 http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.
*/

package lib

import (
	"bytes"
	"encoding/json"
	"errors"
	"fmt"
	"io/ioutil"
	"net"
	"net/http"
	"net/url"
	"os"
	"path"
	"strconv"
	"strings"

	cfsslapi "github.com/cloudflare/cfssl/api"
	"github.com/cloudflare/cfssl/csr"
	"github.com/cloudflare/cfssl/log"
	"github.com/hyperledger/fabric-ca/api"
	"github.com/hyperledger/fabric-ca/lib/tls"
	"github.com/hyperledger/fabric-ca/util"
	"github.com/hyperledger/fabric/bccsp"
	"github.com/mitchellh/mapstructure"
)

// Client is the fabric-ca client object
type Client struct {
	// The client's home directory
	HomeDir string `json:"homeDir,omitempty"`
	// The client's configuration
	Config *ClientConfig
	// Denotes if the client object is already initialized
	initialized bool
	// File and directory paths
	keyFile, certFile, caCertsDir string
	// The crypto service provider (BCCSP)
	csp bccsp.BCCSP
}

// Init initializes the client
func (c *Client) Init() error {
	if !c.initialized {
		cfg := c.Config
		log.Debugf("Initializing client with config: %+v", cfg)
		if cfg.MSPDir == "" {
			cfg.MSPDir = "msp"
		}
		mspDir, err := util.MakeFileAbs(cfg.MSPDir, c.HomeDir)
		if err != nil {
			return err
		}
		cfg.MSPDir = mspDir
		// Key directory and file
		keyDir := path.Join(mspDir, "keystore")
		err = os.MkdirAll(keyDir, 0700)
		if err != nil {
			return fmt.Errorf("Failed to create keystore directory: %s", err)
		}
		c.keyFile = path.Join(keyDir, "key.pem")
		// Cert directory and file
		certDir := path.Join(mspDir, "signcerts")
		err = os.MkdirAll(certDir, 0755)
		if err != nil {
			return fmt.Errorf("Failed to create signcerts directory: %s", err)
		}
		c.certFile = path.Join(certDir, "cert.pem")
		// CA certs directory
		c.caCertsDir = path.Join(mspDir, "cacerts")
		err = os.MkdirAll(c.caCertsDir, 0755)
		if err != nil {
			return fmt.Errorf("Failed to create cacerts directory: %s", err)
		}
		// Initialize BCCSP (the crypto layer)
		c.csp, err = util.InitBCCSP(&cfg.CSP, mspDir, c.HomeDir)
		if err != nil {
			return err
		}
		// Successfully initialized the client
		c.initialized = true
	}
	return nil
}

// GetServerInfoResponse is the response from the GetServerInfo call
type GetServerInfoResponse struct {
	// CAName is the name of the CA
	CAName string
	// CAChain is the PEM-encoded bytes of the fabric-ca-server's CA chain.
	// The 1st element of the chain is the root CA cert
	CAChain []byte
}

// GetCAInfo returns generic CA information
func (c *Client) GetCAInfo(req *api.GetCAInfoRequest) (*GetServerInfoResponse, error) {
	err := c.Init()
	if err != nil {
		return nil, err
	}
	body, err := util.Marshal(req, "GetCAInfo")
	if err != nil {
		return nil, err
	}
	cainforeq, err := c.newPost("cainfo", body)
	if err != nil {
		return nil, err
	}
	netSI := &serverInfoResponseNet{}
	err = c.SendReq(cainforeq, netSI)
	if err != nil {
		return nil, err
	}
	localSI := &GetServerInfoResponse{}
	err = c.net2LocalServerInfo(netSI, localSI)
	if err != nil {
		return nil, err
	}
	return localSI, nil
}

// Convert from network to local server information
func (c *Client) net2LocalServerInfo(net *serverInfoResponseNet, local *GetServerInfoResponse) error {
	caChain, err := util.B64Decode(net.CAChain)
	if err != nil {
		return err
	}
	local.CAName = net.CAName
	local.CAChain = caChain
	return nil
}

// EnrollmentResponse is the response from Client.Enroll and Identity.Reenroll
type EnrollmentResponse struct {
	Identity   *Identity
	ServerInfo GetServerInfoResponse
}

// Enroll enrolls a new identity
// @param req The enrollment request
func (c *Client) Enroll(req *api.EnrollmentRequest) (*EnrollmentResponse, error) {
	log.Debugf("Enrolling %+v", req)

	err := c.Init()
	if err != nil {
		return nil, err
	}

	// Generate the CSR
	csrPEM, key, err := c.GenCSR(req.CSR, req.Name)
	if err != nil {
		return nil, fmt.Errorf("Failure generating CSR: %s", err)
	}

	reqNet := &api.EnrollmentRequestNet{
		CAName: req.CAName,
	}

	if req.CSR != nil {
		reqNet.SignRequest.Hosts = req.CSR.Hosts
	}
	reqNet.SignRequest.Request = string(csrPEM)
	reqNet.SignRequest.Profile = req.Profile
	reqNet.SignRequest.Label = req.Label

	body, err := util.Marshal(reqNet, "SignRequest")
	if err != nil {
		return nil, err
	}

	// Send the CSR to the fabric-ca server with basic auth header
	post, err := c.newPost("enroll", body)
	if err != nil {
		return nil, err
	}
	post.SetBasicAuth(req.Name, req.Secret)
	var result enrollmentResponseNet
	err = c.SendReq(post, &result)
	if err != nil {
		return nil, err
	}

	// Create the enrollment response
	return c.newEnrollmentResponse(&result, req.Name, key)
}

// newEnrollmentResponse creates a client enrollment response from a network response
// @param result The result from server
// @param id Name of identity being enrolled or reenrolled
// @param key The private key which was used to sign the request
func (c *Client) newEnrollmentResponse(result *enrollmentResponseNet, id string, key bccsp.Key) (*EnrollmentResponse, error) {
	log.Debugf("newEnrollmentResponse %s", id)
	certByte, err := util.B64Decode(result.Cert)
	if err != nil {
		return nil, fmt.Errorf("Invalid response format from server: %s", err)
	}
	resp := &EnrollmentResponse{
		Identity: newIdentity(c, id, key, certByte),
	}
	err = c.net2LocalServerInfo(&result.ServerInfo, &resp.ServerInfo)
	if err != nil {
		return nil, err
	}
	return resp, nil
}

// GenCSR generates a CSR (Certificate Signing Request)
func (c *Client) GenCSR(req *api.CSRInfo, id string) ([]byte, bccsp.Key, error) {
	log.Debugf("GenCSR %+v", req)

	err := c.Init()
	if err != nil {
		return nil, nil, err
	}

	cr := c.newCertificateRequest(req)
	cr.CN = id

	if cr.KeyRequest == nil {
		cr.KeyRequest = csr.NewBasicKeyRequest()
	}

	key, cspSigner, err := util.BCCSPKeyRequestGenerate(cr, c.csp)
	if err != nil {
		log.Debugf("failed generating BCCSP key: %s", err)
		return nil, nil, err
	}

	csrPEM, err := csr.Generate(cspSigner, cr)
	if err != nil {
		log.Debugf("failed generating CSR: %s", err)
		return nil, nil, err
	}

	return csrPEM, key, nil
}

// newCertificateRequest creates a certificate request which is used to generate
// a CSR (Certificate Signing Request)
func (c *Client) newCertificateRequest(req *api.CSRInfo) *csr.CertificateRequest {
	cr := csr.CertificateRequest{}
	if req != nil && req.Names != nil {
		cr.Names = req.Names
	}
	if req != nil && req.Hosts != nil {
		cr.Hosts = req.Hosts
	} else {
		// Default requested hosts are local hostname
		hostname, _ := os.Hostname()
		if hostname != "" {
			cr.Hosts = make([]string, 1)
			cr.Hosts[0] = hostname
		}
	}
	if req != nil && req.KeyRequest != nil {
		cr.KeyRequest = req.KeyRequest
	}
	if req != nil {
		cr.CA = req.CA
		cr.SerialNumber = req.SerialNumber
	}
	return &cr
}

// LoadMyIdentity loads the client's identity from disk
func (c *Client) LoadMyIdentity() (*Identity, error) {
	err := c.Init()
	if err != nil {
		return nil, err
	}
	return c.LoadIdentity(c.keyFile, c.certFile)
}

// StoreMyIdentity stores my identity to disk
func (c *Client) StoreMyIdentity(cert []byte) error {
	err := c.Init()
	if err != nil {
		return err
	}
	err = util.WriteFile(c.certFile, cert, 0644)
	if err != nil {
		return fmt.Errorf("Failed to store my certificate: %s", err)
	}
	log.Infof("Stored client certificate at %s", c.certFile)
	return nil
}

// LoadIdentity loads an identity from disk
func (c *Client) LoadIdentity(keyFile, certFile string) (*Identity, error) {
	log.Debug("Loading identity: keyFile=%s, certFile=%s", keyFile, certFile)
	err := c.Init()
	if err != nil {
		return nil, err
	}
	cert, err := util.ReadFile(certFile)
	if err != nil {
		log.Debugf("No cert found at %s", certFile)
		return nil, err
	}
	key, _, _, err := util.GetSignerFromCertFile(certFile, c.csp)
	if err != nil {
		// Fallback: attempt to read out of keyFile and import
		log.Debugf("No key found in BCCSP keystore, attempting fallback")
		key, err = util.ImportBCCSPKeyFromPEM(keyFile, c.csp, true)
		if err != nil {
			return nil, fmt.Errorf("Could not find the private key in BCCSP keystore nor in keyfile %s: %s", keyFile, err)
		}
	}
	return c.NewIdentity(key, cert)
}

// NewIdentity creates a new identity
func (c *Client) NewIdentity(key bccsp.Key, cert []byte) (*Identity, error) {
	name, err := util.GetEnrollmentIDFromPEM(cert)
	if err != nil {
		return nil, err
	}
	return newIdentity(c, name, key, cert), nil
}

// LoadCSRInfo reads CSR (Certificate Signing Request) from a file
// @parameter path The path to the file contains CSR info in JSON format
func (c *Client) LoadCSRInfo(path string) (*api.CSRInfo, error) {
	csrJSON, err := ioutil.ReadFile(path)
	if err != nil {
		return nil, err
	}
	var csrInfo api.CSRInfo
	err = util.Unmarshal(csrJSON, &csrInfo, "LoadCSRInfo")
	if err != nil {
		return nil, err
	}
	return &csrInfo, nil
}

// GetCertFilePath returns the path to the certificate file for this client
func (c *Client) GetCertFilePath() string {
	return c.certFile
}

// NewGet create a new GET request
func (c *Client) newGet(endpoint string) (*http.Request, error) {
	curl, err := c.getURL(endpoint)
	if err != nil {
		return nil, err
	}
	req, err := http.NewRequest("GET", curl, bytes.NewReader([]byte{}))
	if err != nil {
		return nil, fmt.Errorf("Failed creating GET request for %s: %s", curl, err)
	}
	return req, nil
}

// NewPost create a new post request
func (c *Client) newPost(endpoint string, reqBody []byte) (*http.Request, error) {
	curl, err := c.getURL(endpoint)
	if err != nil {
		return nil, err
	}
	req, err := http.NewRequest("POST", curl, bytes.NewReader(reqBody))
	if err != nil {
		return nil, fmt.Errorf("Failed posting to %s: %s", curl, err)
	}
	return req, nil
}

// SendReq sends a request to the fabric-ca-server and fills in the result
func (c *Client) SendReq(req *http.Request, result interface{}) (err error) {

	reqStr := util.HTTPRequestToString(req)
	log.Debugf("Sending request\n%s", reqStr)

	err = c.Init()
	if err != nil {
		return err
	}

	var tr = new(http.Transport)

	if c.Config.TLS.Enabled {
		log.Info("TLS Enabled")

		err = tls.AbsTLSClient(&c.Config.TLS, c.HomeDir)
		if err != nil {
			return err
		}

		tlsConfig, err2 := tls.GetClientTLSConfig(&c.Config.TLS, c.csp)
		if err2 != nil {
			return fmt.Errorf("Failed to get client TLS config: %s", err2)
		}

		tr.TLSClientConfig = tlsConfig
	}

	httpClient := &http.Client{Transport: tr}
	resp, err := httpClient.Do(req)
	if err != nil {
		return fmt.Errorf("POST failure [%s]; not sending\n%s", err, reqStr)
	}
	var respBody []byte
	if resp.Body != nil {
		respBody, err = ioutil.ReadAll(resp.Body)
		defer resp.Body.Close()
		if err != nil {
			return fmt.Errorf("Failed to read response [%s] of request:\n%s", err, reqStr)
		}
		log.Debugf("Received response\n%s", util.HTTPResponseToString(resp))
	}
	var body *cfsslapi.Response
	if respBody != nil && len(respBody) > 0 {
		body = new(cfsslapi.Response)
		err = json.Unmarshal(respBody, body)
		if err != nil {
			return fmt.Errorf("Failed to parse response: %s\n%s", err, respBody)
		}
		if len(body.Errors) > 0 {
			msg := body.Errors[0].Message
			return fmt.Errorf("Error response from server was: %s", msg)
		}
	}
	scode := resp.StatusCode
	if scode >= 400 {
		return fmt.Errorf("Failed with server status code %d for request:\n%s", scode, reqStr)
	}
	if body == nil {
		return fmt.Errorf("Empty response body:\n%s", reqStr)
	}
	if !body.Success {
		return fmt.Errorf("Server returned failure for request:\n%s", reqStr)
	}
	log.Debugf("Response body result: %+v", body.Result)
	if result != nil {
		return mapstructure.Decode(body.Result, result)
	}
	return nil
}

func (c *Client) getURL(endpoint string) (string, error) {
	nurl, err := NormalizeURL(c.Config.URL)
	if err != nil {
		return "", err
	}
	rtn := fmt.Sprintf("%s/%s", nurl, endpoint)
	return rtn, nil
}

// CheckEnrollment returns an error if this client is not enrolled
func (c *Client) CheckEnrollment() error {
	err := c.Init()
	if err != nil {
		return err
	}
	keyFileExists := util.FileExists(c.keyFile)
	certFileExists := util.FileExists(c.certFile)
	if keyFileExists && certFileExists {
		return nil
	}
	// If key file does not exist, but certFile does, key file is probably
	// stored by bccsp, so check to see if this is the case
	if certFileExists {
		_, _, _, err := util.GetSignerFromCertFile(c.certFile, c.csp)
		if err == nil {
			// Yes, the key is stored by BCCSP
			return nil
		}
	}
	return errors.New("Enrollment information does not exist. Please execute enroll command first. Example: fabric-ca-client enroll -u http://user:userpw@serverAddr:serverPort")
}

// NormalizeURL normalizes a URL (from cfssl)
func NormalizeURL(addr string) (*url.URL, error) {
	addr = strings.TrimSpace(addr)
	u, err := url.Parse(addr)
	if err != nil {
		return nil, err
	}
	if u.Opaque != "" {
		u.Host = net.JoinHostPort(u.Scheme, u.Opaque)
		u.Opaque = ""
	} else if u.Path != "" && !strings.Contains(u.Path, ":") {
		u.Host = net.JoinHostPort(u.Path, util.GetServerPort())
		u.Path = ""
	} else if u.Scheme == "" {
		u.Host = u.Path
		u.Path = ""
	}
	if u.Scheme != "https" {
		u.Scheme = "http"
	}
	_, port, err := net.SplitHostPort(u.Host)
	if err != nil {
		_, port, err = net.SplitHostPort(u.Host + ":" + util.GetServerPort())
		if err != nil {
			return nil, err
		}
	}
	if port != "" {
		_, err = strconv.Atoi(port)
		if err != nil {
			return nil, err
		}
	}
	return u, nil
}