package cert

import (
	"crypto/x509"
	"crypto/x509/pkix"
	"encoding/pem"
	"errors"
	"math/big"
	"net"
	"os"
	"time"
)

func GenerateCsr(country, province, city, org, orgUnit, name string, dnsName []string, start, end time.Time, isCa bool, maxPathLenZero bool, maxPathLen int) *x509.Certificate {
	var trueDNS []string
	var trueIp []net.IP
	for _, v := range dnsName {
		ip := net.ParseIP(v)
		if ip == nil {
			trueDNS = append(trueDNS, v)
			continue
		}
		trueIp = append(trueIp, ip)
	}
	ku := x509.KeyUsageDigitalSignature | x509.KeyUsageKeyEncipherment
	eku := x509.ExtKeyUsageServerAuth
	if isCa {
		ku = x509.KeyUsageCertSign | x509.KeyUsageCRLSign | x509.KeyUsageKeyEncipherment | x509.KeyUsageKeyAgreement | x509.KeyUsageDigitalSignature
		eku = x509.ExtKeyUsageAny
	}
	return &x509.Certificate{
		Version:      3,
		SerialNumber: big.NewInt(time.Now().Unix()),
		Subject: pkix.Name{
			Country:            s2s(country),
			Province:           s2s(province),
			Locality:           s2s(city),
			Organization:       s2s((org)),
			OrganizationalUnit: s2s(orgUnit),
			CommonName:         name,
		},
		DNSNames:              trueDNS,
		IPAddresses:           trueIp,
		NotBefore:             start,
		NotAfter:              end,
		BasicConstraintsValid: true,
		IsCA:                  isCa,
		MaxPathLen:            maxPathLen,
		MaxPathLenZero:        maxPathLenZero,
		KeyUsage:              ku,
		ExtKeyUsage:           []x509.ExtKeyUsage{eku},
	}
}

func outputCsr(csr *x509.Certificate) []byte {
	return pem.EncodeToMemory(&pem.Block{
		Type:  "CERTIFICATE REQUEST",
		Bytes: csr.Raw,
	})
}

func s2s(str string) []string {
	if len(str) == 0 {
		return nil
	}
	return []string{str}
}

func LoadCsr(csrPath string) (*x509.Certificate, error) {
	csrBytes, err := os.ReadFile(csrPath)
	if err != nil {
		return nil, err
	}
	block, _ := pem.Decode(csrBytes)
	if block == nil || block.Type != "CERTIFICATE REQUEST" {
		return nil, errors.New("Failed to decode PEM block containing the certificate")
	}
	cert, err := x509.ParseCertificate(block.Bytes)
	if err != nil {
		return nil, err
	}
	return cert, nil
}