package main

import (
	"crypto/tls"
	"crypto/x509"
	"encoding/pem"
	"fmt"
	"io/ioutil"
	"net/http"
	"os"
	"os/user"
	"path/filepath"
	"runtime"
	"strconv"
	"strings"
	"time"

	"github.com/docopt/docopt-go"
	"github.com/go-ini/ini"
	"github.com/tidwall/gjson"
)

const errMsg string = "[ERR]"
const infoMsg string = "[INFO]"

var (
	appVersion                string
	buildTime                 string
	CertBase                  string
	KeyBase                   string
	GroupName                 string
	GroupID                   int
	RedisBaseURL              string
	VaultBaseURL              string
	VaultURL                  string
	RedisCertURL              string
	RedisCAURL                string
	RedisFullChainURL         string
	certificateDestination    string
	fullchainDestination      string
	keyDestination            string
	caDestination             string
	Type                      string
	tmpCertificateDestination string
	tmpFullchainDestination   string
	tmpCaDestination          string
	tmpKeyDestination         string
	certTmpDir                string
	key                       *x509.Certificate
	cert                      *x509.Certificate
)

// app clean and exit
func appExit(status int) {
	if runtime.GOOS == "windows" {
		certTmpDir = "C:\\tmp\\acme-downloader\\"
	} else {
		certTmpDir = "/tmp/acme-downloader"
	}
	err := os.RemoveAll(certTmpDir)
	if err != nil {
		fmt.Printf("%v could not delete temporary directory: %v\n", errMsg, err)
	}
	os.Exit(status)
}

// check certificates
func checkCertificates(dnsname string, certificate string, fullchain string, ca string, key string, days int, fail bool) bool {

	Seconds := days * 86400
	daysNumber := time.Now().Local().Add(time.Second * time.Duration(Seconds))

	certPEM, err := ioutil.ReadFile(certificate)
	if err != nil {
		if fail == true {
			fmt.Printf("%v %v\n", errMsg, err)
			appExit(255)
		} else {
			return false
		}
	}

	certFullchainPEM, err := ioutil.ReadFile(fullchain)
	if err != nil {
		if fail == true {
			fmt.Printf("%v %v\n", errMsg, err)
			appExit(255)
		} else {
			return false
		}
	}

	rootPEM, err := ioutil.ReadFile(ca)
	if err != nil {
		if fail == true {
			fmt.Printf("%v %v\n", errMsg, err)
			appExit(255)
		} else {
			return false
		}
	}

	roots := x509.NewCertPool()
	ok := roots.AppendCertsFromPEM([]byte(rootPEM))
	if !ok {
		if fail == true {
			fmt.Printf("%v failed to parse root certificate\n", errMsg)
			appExit(255)
		} else {
			return false
		}
	}

	block, _ := pem.Decode([]byte(certPEM))
	if block == nil {
		if fail == true {
			fmt.Printf("%v failed to parse certificate PEM\n", errMsg)
			appExit(255)
		} else {
			return false
		}
	}

	cert, err := x509.ParseCertificate(block.Bytes)
	if err != nil {
		if fail == true {
			fmt.Printf("%v failed to parse certificate %v\n", errMsg, err)
			appExit(255)
		} else {
			return false
		}
	}

	fullchainBlock, _ := pem.Decode([]byte(certFullchainPEM))
	if fullchainBlock == nil {
		if fail == true {
			fmt.Printf("%v failed to parse certificate PEM\n", errMsg)
			appExit(255)
		} else {
			return false
		}
	}
	fullchainCert, fullchainErr := x509.ParseCertificate(fullchainBlock.Bytes)
	if fullchainErr != nil {
		if fail == true {
			fmt.Printf("%v failed to parse certificate %v\n", errMsg, fullchainErr)
			appExit(255)
		} else {
			return false
		}
	}

	opts := x509.VerifyOptions{
		Roots:         roots,
		DNSName:       dnsname,
		CurrentTime:   daysNumber,
		Intermediates: x509.NewCertPool(),
	}

	if _, err := cert.Verify(opts); err != nil {
		if fail == true {
			fmt.Printf("%v failed to parse certificate %v\n", errMsg, err.Error())
			appExit(255)
		} else {
			return false
		}
	}
	if _, fullchainErr := fullchainCert.Verify(opts); fullchainErr != nil {
		if fail == true {
			fmt.Printf("%v failed to parse certificate %v\n", errMsg, err.Error())
		} else {
			return false
		}
	}
	return true
}

// check if the private key matches the publick key
func checkPrivkey(privkey string, pubkey string, fail bool) bool {
	_, errFileExist := os.Stat(privkey)
	if os.IsNotExist(errFileExist) {
		fmt.Printf("%v could not access the private key %v\n", errMsg, privkey)
		appExit(255)
	}
	_, err := tls.LoadX509KeyPair(pubkey, privkey)
	if fail == true {
		if err != nil {
			fmt.Printf("%v the private key %v does not match the the public certificate %v\n", errMsg, privkey, pubkey)
			appExit(255)
		} else {
			return false
		}
	}
	return true
}

// get redis key
func GetRedisKey(redisurl string, redistoken string) string {
	client := &http.Client{}
	req, err := http.NewRequest("GET", redisurl, nil)
	if err != nil {
		fmt.Printf("%v Fail to read %v: %v\n", errMsg, redisurl, err)
		appExit(255)
	}
	req.SetBasicAuth("redis", redistoken)
	resp, err := client.Do(req)
	body, err := ioutil.ReadAll(resp.Body)
	if resp.StatusCode < 200 || resp.StatusCode > 299 {
		fmt.Printf("%v Fail to fetch %v\n", errMsg, redisurl)
		appExit(255)
	}
	defer resp.Body.Close()
	if err != nil {
		fmt.Printf("%v Fail to read %v: %v\n", errMsg, redisurl, err)
		appExit(255)
	}
	return fmt.Sprintf(string(body))
}

// get Vault key
func GetVaultKey(vaulturl string, vaulttoken string) string {
	vaultClient := &http.Client{}
	req, err := http.NewRequest("GET", vaulturl, nil)
	if err != nil {
		fmt.Printf("%v Fail to read %v: %v\n", errMsg, vaulturl, err)
		appExit(255)
	}
	req.Header.Add("X-vault-token", vaulttoken)
	resp, err := vaultClient.Do(req)
	body, err := ioutil.ReadAll(resp.Body)
	if resp.StatusCode < 200 || resp.StatusCode > 299 {
		fmt.Printf("%v Fail to fetch %v\n", errMsg, vaulturl)
		appExit(255)
	}
	defer resp.Body.Close()
	if err != nil {
		fmt.Printf("%v Fail to read %v: %v\n", errMsg, vaulturl, err)
		appExit(255)
	}
	return gjson.Get(string(body), "data.value").String()
}

// create directory structure and write certificate to file
func WriteToFile(content string, destination string, filemode os.FileMode) {
	baseDir := filepath.Dir(destination)
	if _, err := os.Stat(baseDir); os.IsNotExist(err) {
		os.MkdirAll(baseDir, 0755)
	}

	file, err := os.OpenFile(destination, os.O_WRONLY|os.O_CREATE, filemode)
	if err != nil {
		fmt.Printf("%v %v cannot be created\n", errMsg, destination)
		appExit(255)
	}

	fmt.Fprintf(file, "%v\n", content)
	file.Close()
}

// move temp file to destination
func moveFile(source string, destination string, groupid int, filemode os.FileMode, dirmode os.FileMode) {
	baseDir := filepath.Dir(destination)
	if _, err := os.Stat(baseDir); os.IsNotExist(err) {
		os.MkdirAll(baseDir, 0755)
	}
	err := os.Rename(source, destination)
	if err != nil {
		fmt.Printf("%v Fail to install %v: %v\n", errMsg, destination, err)
		appExit(255)
	}
	if runtime.GOOS != "windows" {
		err = os.Chown(destination, 0, groupid)
		if err != nil {
			fmt.Printf("%v Changing file owner to %v", errMsg, groupid)
			appExit(255)
		}
	}
	fmt.Printf("%v installed: %v\n", infoMsg, destination)
}

// ReadOSRelease from /etc/os-release
func ReadOSRelease(configfile string) map[string]string {
	ConfigParams := make(map[string]string)
	cfg, err := ini.Load(configfile)
	if err != nil {
		ConfigParams["ID"] = "unknown"
	} else {
		ConfigParams["ID"] = cfg.Section("").Key("ID").String()
	}

	return ConfigParams
}

func main() {

	OSInfo := ReadOSRelease("/etc/os-release")
	OSRelease := OSInfo["ID"]
	if OSRelease == "centos" || OSRelease == "rhel" {
		CertBase = "/etc/pki/tls/certs"
		KeyBase = "/etc/pki/tls/private"
		GroupName = "root"
	} else if OSRelease == "ubuntu" || OSRelease == "debian" {
		CertBase = "/etc/ssl/certs"
		KeyBase = "/etc/ssl/private"
		GroupName = "ssl-cert"
	} else if OSRelease == "arch" {
		CertBase = "/etc/ssl/certs"
		KeyBase = "/etc/ssl/private"
		GroupName = "root"
	} else if OSRelease == "unknown" {
		if runtime.GOOS == "windows" {
			CertBase = "C:\\ACME\\certificates"
			KeyBase = "C:\\ACME\\private"
			GroupName = "root"
		} else {
			CertBase = "/etc/acme/certs"
			KeyBase = "/etc/acme/private"
			GroupName = "root"
		}
	}

	usage := fmt.Sprintf(`ACME Downloader:
  - fetches and stores a given Certificate, Full Chain, CA and Private Key

Usage:
  acme-downloader --redis-token=REDISTOKEN --vault-token=VAULTTOKEN --cert-name=CERTNAME --team-name=TEAMNAME [--silent] [--days=DAYS] [--type=TYPE] [--cert-destination=CERTDESTINATION] [--fullchain-destination=FULLCHAINDESTINATION] [--key-destination=KEYDESTINATION] [--ca-destination=CADESTINATION] [--wildcard]
  acme-downloader -h | --help
  acme-downloader -v | --version
  acme-downloader -b | --build

Options:
  -h --help                                     Show this screen
  -v --version                                  Print version information and exit
  -b --build                                    Print version and build information and exit
  --redis-token=REDISTOKEN                      Redis access token
  --vault-token=VAULTTOKEN                      Vault access token
  --cert-name=CERTNAME                          Certificate name
  --team-name=TEAMNAME                          Team name: swd, it, ne, ti...
  --days=DAYS                                   Days before expiration [default: 30]
  --type=TYPE                                   Type, EV or OV [default: EV]
  --cert-destination=CERTDESTINATION            Cert Destination [default: %v/<cert-name>.crt]
  --fullchain-destination=FULLCHAINDESTINATION  Full Chain Destination[default: %v/<cert-name>_fullchain.crt]
  --key-destination=KEYDESTINATION              Key Destination [default: %v/<cert-name>.key]
  --ca-destination=CADESTINATION                CA Destination [default: %v/COMODO_<type>.crt]
  --wildcard                                    The certificate type is wildcard
`, CertBase, CertBase, KeyBase, CertBase)

	arguments, _ := docopt.Parse(usage, nil, true, appVersion, false)

	if arguments["--build"] == true {
		fmt.Printf("acme-downloader version: %v, built on: %v\n", appVersion, buildTime)
		appExit(0)
	}

	if runtime.GOOS == "windows" {
		tmpCertificateDestination = "C:\\tmp\\acme-downloader\\cert\\amce_cert.pem"
		tmpFullchainDestination = "C:\\tmp\\acme-downloader\\cert\\amce_fullchain.pem"
		tmpCaDestination = "C:\\tmp\\acme-downloader\\cert\\amce_ca.pem"
		tmpKeyDestination = "C:\\tmp\\acme-downloader\\key\\amce_key.pem"
		GroupID = 0 // just a fake one
	} else {
		tmpCertificateDestination = "/tmp/acme-downloader/cert/amce_cert.pem"
		tmpFullchainDestination = "/tmp/acme-downloader/cert/amce_fullchain.pem"
		tmpCaDestination = "/tmp/acme-downloader/cert/amce_ca.pem"
		tmpKeyDestination = "/tmp/acme-downloader/key/amce_key.pem"
		group, groupErr := user.LookupGroup(GroupName)
		if groupErr != nil {
			fmt.Printf("%v Fail looking up %v user user info\n", errMsg, GroupName)
			appExit(255)
		}
		GroupID, _ = strconv.Atoi(group.Gid)
	}

	VaultToken := arguments["--vault-token"].(string)
	CertName := arguments["--cert-name"].(string)
	CertNameUnderscored := strings.Replace(CertName, ".", "_", -1)
	TeamName := arguments["--team-name"].(string)
	RedisToken := arguments["--redis-token"].(string)
	Type = arguments["--type"].(string)
	DayString := arguments["--days"].(string)
	Days, daysErr := strconv.Atoi(DayString)
	if daysErr != nil {
		fmt.Printf("%v Days mut be an integer\n", errMsg)
		appExit(255)
	}
	RedisBaseURL = "https://redis.geant.org/GET"
	VaultBaseURL = "https://vault.geant.org/v1"
	if arguments["--wildcard"] == true {
		VaultURL = fmt.Sprintf("%v/%v/common/vault_sectigo_ov_wildcard_%v_key", VaultBaseURL, TeamName, CertNameUnderscored)
		RedisCertURL = fmt.Sprintf("%v/%v:common:redis_sectigo_ov_%v_pem.txt", RedisBaseURL, TeamName, CertNameUnderscored)
		RedisCAURL = fmt.Sprintf("%v/%v:common:redis_sectigo_ov_%v_chain_pem.txt", RedisBaseURL, TeamName, CertNameUnderscored)
		RedisFullChainURL = fmt.Sprintf("%v/%v:common:redis_sectigo_ov_%v_fullchain_pem.txt", RedisBaseURL, TeamName, CertNameUnderscored)
	} else {
		VaultURL = fmt.Sprintf("%v/%v/%v/vault_%v_key", VaultBaseURL, TeamName, CertName, CertNameUnderscored)
		RedisCertURL = fmt.Sprintf("%v/%v:%v:redis_%v_pem.txt", RedisBaseURL, TeamName, CertName, CertNameUnderscored)
		RedisCAURL = fmt.Sprintf("%v/%v:%v:redis_%v_chain_pem.txt", RedisBaseURL, TeamName, CertName, CertNameUnderscored)
		RedisFullChainURL = fmt.Sprintf("%v/%v:%v:redis_%v_fullchain_pem.txt", RedisBaseURL, TeamName, CertName, CertNameUnderscored)
	}

	if arguments["--cert-destination"] == fmt.Sprintf(filepath.Join(CertBase, "<cert-name>.crt")) {
		certificateDestination = fmt.Sprintf(filepath.Join(CertBase, fmt.Sprintf("%v.crt", CertName)))
	} else {
		certificateDestination = arguments["--cert-destination"].(string)
	}
	if arguments["--fullchain-destination"] == fmt.Sprintf(filepath.Join(CertBase, "<cert-name>_fullchain.crt")) {
		fullchainDestination = fmt.Sprintf(filepath.Join(CertBase, fmt.Sprintf("%v_fullchain.crt", CertName)))
	} else {
		fullchainDestination = arguments["--fullchain-destination"].(string)
	}
	if arguments["--ca-destination"] == fmt.Sprintf(filepath.Join(CertBase, "COMODO_<type>.crt")) {
		caDestination = fmt.Sprintf(filepath.Join(CertBase, fmt.Sprintf("COMODO_%v.crt", Type)))
	} else {
		caDestination = arguments["--ca-destination"].(string)
	}
	if arguments["--key-destination"] == fmt.Sprintf(filepath.Join(KeyBase, "<cert-name>.key")) {
		keyDestination = fmt.Sprintf(filepath.Join(KeyBase, fmt.Sprintf("%v.key", CertName)))
	} else {
		keyDestination = arguments["--key-destination"].(string)
	}

	// check if there is a certificate installed and it is valid
	existingCert := checkCertificates(CertName, certificateDestination, fullchainDestination, caDestination, keyDestination, Days, false)
	existingKey := checkPrivkey(keyDestination, certificateDestination, false)
	if existingCert == true && existingKey == true {
		fmt.Printf("%v the certificate is still valid\n", infoMsg)
		appExit(0)
	}
	certificate := GetRedisKey(RedisCertURL, RedisToken)
	ca := GetRedisKey(RedisCAURL, RedisToken)
	fullChain := GetRedisKey(RedisFullChainURL, RedisToken)
	privKey := GetVaultKey(VaultURL, VaultToken)

	// download and test certificates on a temporary location
	WriteToFile(certificate, tmpCertificateDestination, 0644)
	WriteToFile(fullChain, tmpFullchainDestination, 0644)
	WriteToFile(ca, tmpCaDestination, 0644)
	WriteToFile(privKey, tmpKeyDestination, 0640)

	checkCertificates(CertName, tmpCertificateDestination, tmpFullchainDestination, tmpCaDestination, tmpKeyDestination, Days, true)
	checkPrivkey(tmpKeyDestination, tmpCertificateDestination, true)

	// move certificates in place
	moveFile(tmpCertificateDestination, certificateDestination, GroupID, 0644, 0755)
	moveFile(tmpFullchainDestination, fullchainDestination, GroupID, 0644, 0755)
	moveFile(tmpCaDestination, caDestination, GroupID, 0644, 0755)
	moveFile(tmpKeyDestination, keyDestination, GroupID, 0640, 0750)

	// Exit 64: it means that the certificate was replaced and the
	// application can be reloaded to make use of the new certificate
	appExit(64)

}