package certs

import (
	"context"
	"crypto/ecdsa"
	"crypto/elliptic"
	"crypto/rand"
	"crypto/x509"
	"encoding/pem"
	"fmt"
	"os"
	"path/filepath"
	"debtik/internal/logging"
	"strings"
	"time"
)

func (cm *CertManager) renewCandidates(now time.Time) []LetsEncryptRequest {
	cm.mu.RLock()
	defer cm.mu.RUnlock()
	var requests []LetsEncryptRequest
	for _, cert := range cm.certs {
		if cert.Type == TypeACME && cert.ValidTo.Before(now.Add(30*24*time.Hour)) {
			req := LetsEncryptRequest{Name: cert.Name, Domain: cert.CommonName, Comment: cert.Comment, Staging: strings.Contains(cert.Issuer, "Staging")}
			if cert.ACMERequest != nil {
				req = *cert.ACMERequest
			}
			if req.Domain == "" {
				continue
			}
			req.renew = true
			requests = append(requests, req)
		}
	}
	return requests
}
func (cm *CertManager) RenewDue(ctx context.Context) {
	cm.renewMu.Lock()
	defer cm.renewMu.Unlock()
	for _, request := range cm.renewCandidates(time.Now()) {
		if ctx.Err() != nil {
			return
		}
		attemptCtx, cancel := context.WithTimeout(ctx, 5*time.Minute)
		_, err := cm.IssueLetsEncrypt(attemptCtx, request)
		cancel()
		cm.mu.Lock()
		if cert := cm.certs[strings.ToLower(request.Name)]; cert != nil {
			cert.LastRenewAttempt = time.Now()
			cert.RenewalError = ""
			if err != nil {
				cert.RenewalError = err.Error()
			}
			if saveErr := cm.saveLocked(); saveErr != nil {
				logging.Log("certs,error", "Failed to persist renewal result: %v", saveErr)
			}
		}
		cm.mu.Unlock()
		if err != nil {
			logging.Log("certs,error", "Certificate %s renewal failed: %v", request.Name, err)
		} else {
			logging.Log("certs,info", "Certificate %s renewed", request.Name)
		}
	}
}
func (cm *CertManager) RunRenewal(ctx context.Context) {
	// Allow the HTTP challenge listener to become available first.
	timer := time.NewTimer(5 * time.Minute)
	defer timer.Stop()
	for {
		select {
		case <-ctx.Done():
			return
		case <-timer.C:
			cm.RenewDue(ctx)
			timer.Reset(12 * time.Hour)
		}
	}
}

func (cm *CertManager) acmeAccountKey(staging bool) (*ecdsa.PrivateKey, error) {
	cm.accountMu.Lock()
	defer cm.accountMu.Unlock()
	name := "acme-account-production.key"
	if staging {
		name = "acme-account-staging.key"
	}
	path := filepath.Join(cm.dir, name)
	data, err := os.ReadFile(path)
	if err == nil {
		block, _ := pem.Decode(data)
		if block == nil {
			return nil, fmt.Errorf("invalid ACME account key")
		}
		return x509.ParseECPrivateKey(block.Bytes)
	}
	if !os.IsNotExist(err) {
		return nil, err
	}
	key, err := ecdsa.GenerateKey(elliptic.P256(), rand.Reader)
	if err != nil {
		return nil, err
	}
	if err = savePrivateKeyPEM(path, key); err != nil {
		return nil, err
	}
	return key, nil
}