package config

import (
	"context"
	"crypto/sha256"
	"crypto/tls"
	"crypto/x509"
	"fmt"
	"slices"
	"time"

	"forge.cadoles.com/arcad/arcast/pkg/network"
	"forge.cadoles.com/arcad/arcast/pkg/selfsigned"
	"github.com/pkg/errors"
	"gitlab.com/wpetit/goweb/logger"
)

func GenerateSelfSignedCert(ctx context.Context, filename string, conf *Config) error {
	if !conf.HTTPS.SelfSigned.Enabled {
		return nil
	}

	if conf.HTTPS.Cert != nil && conf.HTTPS.Key != nil {
		return nil
	}

	rawCert, rawKey, err := selfsigned.NewLANKeyPair()
	if err != nil {
		return errors.Wrap(err, "could not generate self signed x509 key pair")
	}

	conf.HTTPS.Cert = rawCert
	conf.HTTPS.Key = rawKey

	networkFingerprint, err := getNetworkFingerprint()
	if err != nil {
		return errors.Wrap(err, "could not retrieve network fingerprint")
	}

	conf.HTTPS.SelfSigned.NetworkFingerprint = networkFingerprint

	return nil
}

func RenewExpiredSelfSignedCert(ctx context.Context, filename string, conf *Config) error {
	if !conf.HTTPS.SelfSigned.Enabled {
		return nil
	}

	if conf.HTTPS.Cert == nil || conf.HTTPS.Key == nil {
		if err := GenerateSelfSignedCert(ctx, filename, conf); err != nil {
			return errors.WithStack(err)
		}
	}

	cert, err := tls.X509KeyPair(conf.HTTPS.Cert, conf.HTTPS.Key)
	if err != nil {
		return errors.Wrap(err, "could not parse x509 cert/key pair")
	}

	leaf, err := x509.ParseCertificate(cert.Certificate[0])
	if err != nil {
		logger.Error(ctx, "could not parse x509 certificate, regenerating one", logger.CapturedE(errors.WithStack(err)))

		if err := GenerateSelfSignedCert(ctx, filename, conf); err != nil {
			return errors.WithStack(err)
		}
	}

	// Check that self-signed certificate is still valid
	if time.Now().Before(leaf.NotAfter) {
		return nil
	}

	logger.Warn(ctx, "self-signed certificate has expired, regenerating one", logger.CapturedE(errors.WithStack(err)))

	if err := GenerateSelfSignedCert(ctx, filename, conf); err != nil {
		return errors.WithStack(err)
	}

	return nil
}

func getNetworkFingerprint() (string, error) {
	ips, err := network.GetLANIPv4Addrs()
	if err != nil {
		return "", errors.WithStack(err)
	}

	slices.Sort(ips)

	hash := sha256.New()
	for _, ip := range ips {
		if _, err := hash.Write([]byte(ip)); err != nil {
			return "", errors.WithStack(err)
		}
	}

	return fmt.Sprintf("%x", hash.Sum(nil)), nil
}