package commands

import (
	"crypto/ecdsa"
	"crypto/ed25519"
	"crypto/rand"
	"crypto/rsa"
	"crypto/x509"
	"fmt"
	"strings"
	"time"

	"github.com/spf13/cobra"

	"github.com/authelia/authelia/v4/internal/utils"
)

func newCryptoCmd() (cmd *cobra.Command) {
	cmd = &cobra.Command{
		Use:     cmdUseCrypto,
		Short:   cmdAutheliaCryptoShort,
		Long:    cmdAutheliaCryptoLong,
		Example: cmdAutheliaCryptoExample,
		Args:    cobra.NoArgs,

		DisableAutoGenTag: true,
	}

	cmd.AddCommand(
		newCryptoRandCmd(),
		newCryptoCertificateCmd(),
		newCryptoHashCmd(),
		newCryptoPairCmd(),
	)

	return cmd
}

func newCryptoRandCmd() (cmd *cobra.Command) {
	cmd = &cobra.Command{
		Use:     cmdUseRand,
		Short:   cmdAutheliaCryptoRandShort,
		Long:    cmdAutheliaCryptoRandLong,
		Example: cmdAutheliaCryptoRandExample,
		Args:    cobra.NoArgs,
		RunE: func(cmd *cobra.Command, args []string) (err error) {
			useCharSet, useCharacters := cmd.Flags().Changed(cmdFlagNameCharSet), cmd.Flags().Changed(cmdFlagNameCharacters)
			if useCharSet && useCharacters {
				return fmt.Errorf("flags '--%s' and '--%s' are mutually exclusive, only one may be specified", cmdFlagNameCharSet, cmdFlagNameCharacters)
			}

			var (
				charset string
				n       int
			)

			if n, err = cmd.Flags().GetInt(cmdFlagNameLength); err != nil {
				return err
			}

			if n < 1 {
				return fmt.Errorf("length must be at least 1")
			}

			switch {
			case useCharSet, !useCharSet && !useCharacters:
				var c string

				if c, err = cmd.Flags().GetString(cmdFlagNameCharSet); err != nil {
					return err
				}

				switch c {
				case "ascii":
					charset = utils.CharSetASCII
				case "alphanumeric":
					charset = utils.CharSetAlphaNumeric
				case "alphabetic":
					charset = utils.CharSetAlphabetic
				case "numeric-hex":
					charset = utils.CharSetNumericHex
				case "numeric":
					charset = utils.CharSetNumeric
				default:
					return fmt.Errorf("invalid charset '%s', must be one of 'ascii', 'alphanumeric', 'alphabetic', 'numeric', or 'numeric-hex'", c)
				}
			case useCharacters:
				if charset, err = cmd.Flags().GetString(cmdFlagNameCharacters); err != nil {
					return err
				}
			}

			fmt.Printf("Random Value: %s\n", utils.RandomString(n, charset, true))

			return nil
		},

		DisableAutoGenTag: true,
	}

	cmd.Flags().StringP(cmdFlagNameCharSet, "c", "alphanumeric", "Sets the charset for the output, options are 'ascii', 'alphanumeric', 'alphabetic', 'numeric', and 'numeric-hex'")
	cmd.Flags().String(cmdFlagNameCharacters, "", "Sets the explicit characters for the random output")
	cmd.Flags().IntP(cmdFlagNameLength, "n", 80, "Sets the length of the random output")

	return cmd
}

func newCryptoCertificateCmd() (cmd *cobra.Command) {
	cmd = &cobra.Command{
		Use:     cmdUseCertificate,
		Short:   cmdAutheliaCryptoCertificateShort,
		Long:    cmdAutheliaCryptoCertificateLong,
		Example: cmdAutheliaCryptoCertificateExample,
		Args:    cobra.NoArgs,

		DisableAutoGenTag: true,
	}

	cmd.AddCommand(
		newCryptoCertificateSubCmd(cmdUseRSA),
		newCryptoCertificateSubCmd(cmdUseECDSA),
		newCryptoCertificateSubCmd(cmdUseEd25519),
	)

	return cmd
}

func newCryptoCertificateSubCmd(use string) (cmd *cobra.Command) {
	useFmt := fmtCryptoCertificateUse(use)

	cmd = &cobra.Command{
		Use:     use,
		Short:   fmt.Sprintf(fmtCmdAutheliaCryptoCertificateSubShort, useFmt),
		Long:    fmt.Sprintf(fmtCmdAutheliaCryptoCertificateSubLong, useFmt, useFmt),
		Example: fmt.Sprintf(fmtCmdAutheliaCryptoCertificateSubExample, use),
		Args:    cobra.NoArgs,

		DisableAutoGenTag: true,
	}

	cmd.AddCommand(newCryptoGenerateCmd(cmdUseCertificate, use), newCryptoCertificateRequestCmd(use))

	return cmd
}

func newCryptoCertificateRequestCmd(algorithm string) (cmd *cobra.Command) {
	cmd = &cobra.Command{
		Use:  cmdUseRequest,
		Args: cobra.NoArgs,
		RunE: cryptoCertificateRequestRunE,

		DisableAutoGenTag: true,
	}

	cmdFlagsCryptoPrivateKey(cmd)
	cmdFlagsCryptoCertificateCommon(cmd)
	cmdFlagsCryptoCertificateRequest(cmd)

	algorithmFmt := fmtCryptoCertificateUse(algorithm)

	cmd.Short = fmt.Sprintf(fmtCmdAutheliaCryptoCertificateGenerateRequestShort, algorithmFmt, cryptoCertCSROut)
	cmd.Long = fmt.Sprintf(fmtCmdAutheliaCryptoCertificateGenerateRequestLong, algorithmFmt, cryptoCertCSROut, algorithmFmt, cryptoCertCSROut)

	switch algorithm {
	case cmdUseRSA:
		cmd.Example = cmdAutheliaCryptoCertificateRSARequestExample

		cmdFlagsCryptoPrivateKeyRSA(cmd)
	case cmdUseECDSA:
		cmd.Example = cmdAutheliaCryptoCertificateECDSARequestExample

		cmdFlagsCryptoPrivateKeyECDSA(cmd)
	case cmdUseEd25519:
		cmd.Example = cmdAutheliaCryptoCertificateEd25519RequestExample

		cmdFlagsCryptoPrivateKeyEd25519(cmd)
	}

	return cmd
}

func newCryptoPairCmd() (cmd *cobra.Command) {
	cmd = &cobra.Command{
		Use:     cmdUsePair,
		Short:   cmdAutheliaCryptoPairShort,
		Long:    cmdAutheliaCryptoPairLong,
		Example: cmdAutheliaCryptoPairExample,
		Args:    cobra.NoArgs,

		DisableAutoGenTag: true,
	}

	cmd.AddCommand(
		newCryptoPairSubCmd(cmdUseRSA),
		newCryptoPairSubCmd(cmdUseECDSA),
		newCryptoPairSubCmd(cmdUseEd25519),
	)

	return cmd
}

func newCryptoPairSubCmd(use string) (cmd *cobra.Command) {
	var (
		example, useFmt string
	)

	useFmt = fmtCryptoCertificateUse(use)

	switch use {
	case cmdUseRSA:
		example = cmdAutheliaCryptoPairRSAExample
	case cmdUseECDSA:
		example = cmdAutheliaCryptoPairECDSAExample
	case cmdUseEd25519:
		example = cmdAutheliaCryptoPairEd25519Example
	}

	cmd = &cobra.Command{
		Use:     use,
		Short:   fmt.Sprintf(cmdAutheliaCryptoPairSubShort, useFmt),
		Long:    fmt.Sprintf(cmdAutheliaCryptoPairSubLong, useFmt, useFmt),
		Example: example,
		Args:    cobra.NoArgs,
		RunE:    cryptoGenerateRunE,

		DisableAutoGenTag: true,
	}

	cmd.AddCommand(newCryptoGenerateCmd(cmdUsePair, use))

	return cmd
}

func newCryptoGenerateCmd(category, algorithm string) (cmd *cobra.Command) {
	cmd = &cobra.Command{
		Use:  cmdUseGenerate,
		Args: cobra.NoArgs,
		RunE: cryptoGenerateRunE,

		DisableAutoGenTag: true,
	}

	cmdFlagsCryptoPrivateKey(cmd)

	algorithmFmt := fmtCryptoCertificateUse(algorithm)

	switch category {
	case cmdUseCertificate:
		cmdFlagsCryptoCertificateCommon(cmd)
		cmdFlagsCryptoCertificateGenerate(cmd)

		cmd.Short = fmt.Sprintf(fmtCmdAutheliaCryptoCertificateGenerateRequestShort, algorithmFmt, cryptoCertPubCertOut)
		cmd.Long = fmt.Sprintf(fmtCmdAutheliaCryptoCertificateGenerateRequestLong, algorithmFmt, cryptoCertPubCertOut, algorithmFmt, cryptoCertPubCertOut)

		switch algorithm {
		case cmdUseRSA:
			cmd.Example = cmdAutheliaCryptoCertificateRSAGenerateExample

			cmdFlagsCryptoPrivateKeyRSA(cmd)
		case cmdUseECDSA:
			cmd.Example = cmdAutheliaCryptoCertificateECDSAGenerateExample

			cmdFlagsCryptoPrivateKeyECDSA(cmd)
		case cmdUseEd25519:
			cmd.Example = cmdAutheliaCryptoCertificateEd25519GenerateExample

			cmdFlagsCryptoPrivateKeyEd25519(cmd)
		}
	case cmdUsePair:
		cmdFlagsCryptoPairGenerate(cmd)

		cmd.Short = fmt.Sprintf(fmtCmdAutheliaCryptoPairGenerateShort, algorithmFmt)
		cmd.Long = fmt.Sprintf(fmtCmdAutheliaCryptoPairGenerateLong, algorithmFmt, algorithmFmt)

		switch algorithm {
		case cmdUseRSA:
			cmd.Example = cmdAutheliaCryptoPairRSAGenerateExample

			cmdFlagsCryptoPrivateKeyRSA(cmd)
		case cmdUseECDSA:
			cmd.Example = cmdAutheliaCryptoPairECDSAGenerateExample

			cmdFlagsCryptoPrivateKeyECDSA(cmd)
		case cmdUseEd25519:
			cmd.Example = cmdAutheliaCryptoPairEd25519GenerateExample

			cmdFlagsCryptoPrivateKeyEd25519(cmd)
		}
	}

	return cmd
}

func cryptoGenerateRunE(cmd *cobra.Command, args []string) (err error) {
	var (
		privateKey any
	)

	if privateKey, err = cryptoGenPrivateKeyFromCmd(cmd); err != nil {
		return err
	}

	if cmd.Parent().Parent().Use == cmdUseCertificate {
		return cryptoCertificateGenerateRunE(cmd, args, privateKey)
	}

	return cryptoPairGenerateRunE(cmd, args, privateKey)
}

func cryptoCertificateRequestRunE(cmd *cobra.Command, _ []string) (err error) {
	var (
		privateKey any
	)

	if privateKey, err = cryptoGenPrivateKeyFromCmd(cmd); err != nil {
		return err
	}

	var (
		template                *x509.CertificateRequest
		csr                     []byte
		privateKeyPath, csrPath string
	)

	if template, err = cryptoGetCSRFromCmd(cmd); err != nil {
		return err
	}

	b := strings.Builder{}

	b.WriteString("Generating Certificate Request\n\n")

	b.WriteString("Subject:\n")
	b.WriteString(fmt.Sprintf("\tCommon Name: %s, Organization: %s, Organizational Unit: %s\n", template.Subject.CommonName, template.Subject.Organization, template.Subject.OrganizationalUnit))
	b.WriteString(fmt.Sprintf("\tCountry: %v, Province: %v, Street Address: %v, Postal Code: %v, Locality: %v\n\n", template.Subject.Country, template.Subject.Province, template.Subject.StreetAddress, template.Subject.PostalCode, template.Subject.Locality))

	b.WriteString("Properties:\n")

	b.WriteString(fmt.Sprintf("\tSignature Algorithm: %s, Public Key Algorithm: %s", template.SignatureAlgorithm, template.PublicKeyAlgorithm))

	switch k := privateKey.(type) {
	case *rsa.PrivateKey:
		b.WriteString(fmt.Sprintf(", Bits: %d", k.N.BitLen()))
	case *ecdsa.PrivateKey:
		b.WriteString(fmt.Sprintf(", Elliptic Curve: %s", k.Curve.Params().Name))
	}

	b.WriteString(fmt.Sprintf("\n\tSubject Alternative Names: %s\n\n", strings.Join(cryptoSANsToString(template.DNSNames, template.IPAddresses), ", ")))

	if privateKeyPath, csrPath, err = cryptoGetWritePathsFromCmd(cmd); err != nil {
		return err
	}

	b.WriteString("Output Paths:\n")
	b.WriteString(fmt.Sprintf("\tPrivate Key: %s\n", privateKeyPath))
	b.WriteString(fmt.Sprintf("\tCertificate Request: %s\n\n", csrPath))

	fmt.Print(b.String())

	b.Reset()

	if csr, err = x509.CreateCertificateRequest(rand.Reader, template, privateKey); err != nil {
		return fmt.Errorf("failed to create certificate request: %w", err)
	}

	if privateKeyPath, csrPath, err = cryptoGetWritePathsFromCmd(cmd); err != nil {
		return err
	}

	if err = utils.WriteKeyToPEM(privateKey, privateKeyPath, false); err != nil {
		return err
	}

	if err = utils.WriteCertificateBytesToPEM(csr, csrPath, true); err != nil {
		return err
	}

	return nil
}

func cryptoCertificateGenerateRunE(cmd *cobra.Command, _ []string, privateKey any) (err error) {
	var (
		template, caCertificate, parent       *x509.Certificate
		publicKey, caPrivateKey, signatureKey any
	)

	if publicKey = utils.PublicKeyFromPrivateKey(privateKey); publicKey == nil {
		return fmt.Errorf("failed to obtain public key from private key")
	}

	if caPrivateKey, caCertificate, err = cryptoGetCAFromCmd(cmd); err != nil {
		return err
	}

	signatureKey = privateKey

	if caPrivateKey != nil {
		signatureKey = caPrivateKey
	}

	if template, err = cryptoGetCertificateFromCmd(cmd); err != nil {
		return err
	}

	b := strings.Builder{}

	b.WriteString("Generating Certificate\n\n")

	b.WriteString(fmt.Sprintf("\tSerial: %x\n\n", template.SerialNumber))

	switch caCertificate {
	case nil:
		parent = template

		b.WriteString("Signed By:\n\tSelf-Signed\n")
	default:
		parent = caCertificate

		b.WriteString(fmt.Sprintf("Signed By:\n\t%s\n", caCertificate.Subject.CommonName))
		b.WriteString(fmt.Sprintf("\tSerial: %x, Expires: %s\n", caCertificate.SerialNumber, caCertificate.NotAfter.Format(time.RFC3339)))
	}

	b.WriteString("\nSubject:\n")
	b.WriteString(fmt.Sprintf("\tCommon Name: %s, Organization: %s, Organizational Unit: %s\n", template.Subject.CommonName, template.Subject.Organization, template.Subject.OrganizationalUnit))
	b.WriteString(fmt.Sprintf("\tCountry: %v, Province: %v, Street Address: %v, Postal Code: %v, Locality: %v\n\n", template.Subject.Country, template.Subject.Province, template.Subject.StreetAddress, template.Subject.PostalCode, template.Subject.Locality))

	b.WriteString("Properties:\n")
	b.WriteString(fmt.Sprintf("\tNot Before: %s, Not After: %s\n", template.NotBefore.Format(time.RFC3339), template.NotAfter.Format(time.RFC3339)))

	b.WriteString(fmt.Sprintf("\tCA: %v, CSR: %v, Signature Algorithm: %s, Public Key Algorithm: %s", template.IsCA, false, template.SignatureAlgorithm, template.PublicKeyAlgorithm))

	switch k := privateKey.(type) {
	case *rsa.PrivateKey:
		b.WriteString(fmt.Sprintf(", Bits: %d", k.N.BitLen()))
	case *ecdsa.PrivateKey:
		b.WriteString(fmt.Sprintf(", Elliptic Curve: %s", k.Curve.Params().Name))
	}

	b.WriteString(fmt.Sprintf("\n\tSubject Alternative Names: %s\n\n", strings.Join(cryptoSANsToString(template.DNSNames, template.IPAddresses), ", ")))

	var (
		privateKeyPath, certificatePath string
		certificate                     []byte
	)

	if privateKeyPath, certificatePath, err = cryptoGetWritePathsFromCmd(cmd); err != nil {
		return err
	}

	b.WriteString("Output Paths:\n")
	b.WriteString(fmt.Sprintf("\tPrivate Key: %s\n", privateKeyPath))
	b.WriteString(fmt.Sprintf("\tCertificate: %s\n\n", certificatePath))

	fmt.Print(b.String())

	b.Reset()

	if certificate, err = x509.CreateCertificate(rand.Reader, template, parent, publicKey, signatureKey); err != nil {
		return fmt.Errorf("failed to create certificate: %w", err)
	}

	if err = utils.WriteKeyToPEM(privateKey, privateKeyPath, false); err != nil {
		return err
	}

	if err = utils.WriteCertificateBytesToPEM(certificate, certificatePath, false); err != nil {
		return err
	}

	return nil
}

func cryptoPairGenerateRunE(cmd *cobra.Command, _ []string, privateKey any) (err error) {
	var (
		privateKeyPath, publicKeyPath string
		pkcs8                         bool
	)

	if pkcs8, err = cmd.Flags().GetBool(cmdFlagNamePKCS8); err != nil {
		return err
	}

	if privateKeyPath, publicKeyPath, err = cryptoGetWritePathsFromCmd(cmd); err != nil {
		return err
	}

	b := strings.Builder{}

	b.WriteString("Generating key pair\n\n")

	switch k := privateKey.(type) {
	case *rsa.PrivateKey:
		b.WriteString(fmt.Sprintf("\tAlgorithm: RSA-%d %d bits\n\n", k.Size(), k.N.BitLen()))
	case *ecdsa.PrivateKey:
		b.WriteString(fmt.Sprintf("\tAlgorithm: ECDSA Curve %s\n\n", k.Curve.Params().Name))
	case ed25519.PrivateKey:
		b.WriteString("\tAlgorithm: Ed25519\n\n")
	}

	b.WriteString("Output Paths:\n")
	b.WriteString(fmt.Sprintf("\tPrivate Key: %s\n", privateKeyPath))
	b.WriteString(fmt.Sprintf("\tPublic Key: %s\n\n", publicKeyPath))

	fmt.Print(b.String())

	b.Reset()

	if err = utils.WriteKeyToPEM(privateKey, privateKeyPath, pkcs8); err != nil {
		return err
	}

	var publicKey any

	if publicKey = utils.PublicKeyFromPrivateKey(privateKey); publicKey == nil {
		return fmt.Errorf("failed to obtain public key from private key")
	}

	if err = utils.WriteKeyToPEM(publicKey, publicKeyPath, pkcs8); err != nil {
		return err
	}

	return nil
}