package rpm

import "compress/gzip"
import "context"
import "crypto/md5"
import "crypto/sha1"
import "crypto/sha256"
import "crypto/sha512"
import "crypto/tls"
import "bytes"
import "encoding/hex"
import "encoding/xml"
import "errors"
import "hash"
import "io"
import "io/fs"
import "net"
import "net/http"
import "net/url"
import "os"
import "path/filepath"
import "strconv"
import "strings"
import "sync"
import "time"

import "codit/internal/db"
import "codit/internal/models"
import "codit/internal/util"

type MirrorManager struct {
	store  *db.Store
	logger *util.Logger
	meta   *MetaManager
	stopCh chan struct{}
	cancelMu sync.Mutex
	cancelByKey map[string]context.CancelFunc
}

type repomdDoc struct {
	Data []repomdData `xml:"data"`
}

type repomdData struct {
	Type     string         `xml:"type,attr"`
	Location repomdLocation `xml:"location"`
}

type repomdLocation struct {
	Href string `xml:"href,attr"`
}

type primaryDoc struct {
	Packages []primaryPackage `xml:"package"`
}

type primaryPackage struct {
	Location primaryLocation `xml:"location"`
	Checksum primaryChecksum `xml:"checksum"`
	Time     primaryTime     `xml:"time"`
}

type primaryLocation struct {
	Href string `xml:"href,attr"`
}

type primaryChecksum struct {
	Type  string `xml:"type,attr"`
	Value string `xml:",chardata"`
}

type mirrorChecksum struct {
	Algo  string
	Value string
	BuildTime int64
	FileTime  int64
}

type primaryTime struct {
	File  string `xml:"file,attr"`
	Build string `xml:"build,attr"`
}

type mirrorHTTPConfig struct {
	BaseURL         string
	ConnectHost     string
	HostHeader      string
	TLSServerName   string
	TLSInsecure     bool
	DefaultHost     string
	DefaultServer   string
}

func NewMirrorManager(store *db.Store, logger *util.Logger, meta *MetaManager) *MirrorManager {
	var m *MirrorManager
	m = &MirrorManager{
		store:  store,
		logger: logger,
		meta:   meta,
		stopCh: make(chan struct{}),
		cancelByKey: make(map[string]context.CancelFunc),
	}
	return m
}

func (m *MirrorManager) CancelTask(repoID string, path string) bool {
	var key string
	var cancel context.CancelFunc
	if m == nil {
		return false
	}
	key = mirrorTaskKey(repoID, path)
	m.cancelMu.Lock()
	cancel = m.cancelByKey[key]
	m.cancelMu.Unlock()
	if cancel == nil {
		return false
	}
	cancel()
	return true
}

func (m *MirrorManager) Start() {
	var err error
	var tasks []models.RPMMirrorTask
	var i int
	if m == nil {
		return
	}
	err = m.store.ResetRunningRPMMirrorTasks()
	if err != nil && m.logger != nil {
		m.logger.Write("rpm-mirror", util.LOG_ERROR, "reset running tasks failed err=%v", err)
	}
	tasks, err = m.store.ListRPMMirrorPaths()
	if err == nil {
		for i = 0; i < len(tasks); i++ {
			_ = m.store.CleanupRPMMirrorRunsRetention(tasks[i].RepoID, tasks[i].MirrorPath, 200, 30)
		}
	}
	go m.loop()
}

func (m *MirrorManager) Stop() {
	if m == nil {
		return
	}
	close(m.stopCh)
}

func (m *MirrorManager) loop() {
	var ticker *time.Ticker
	ticker = time.NewTicker(10 * time.Second)
	defer ticker.Stop()
	m.runDue()
	for {
		select {
		case <-m.stopCh:
			return
		case <-ticker.C:
			m.runDue()
		}
	}
}

func (m *MirrorManager) runDue() {
	var tasks []models.RPMMirrorTask
	var started bool
	var now int64
	var i int
	var err error
	now = time.Now().UTC().Unix()
	tasks, err = m.store.ListDueRPMMirrorTasks(now, 8)
	if err != nil {
		if m.logger != nil {
			m.logger.Write("rpm-mirror", util.LOG_ERROR, "list due tasks failed err=%v", err)
		}
		return
	}
	for i = 0; i < len(tasks); i++ {
		started, err = m.store.TryStartRPMMirrorTask(tasks[i].RepoID, tasks[i].MirrorPath, now)
		if err != nil {
			if m.logger != nil {
				m.logger.Write("rpm-mirror", util.LOG_ERROR, "try start failed repo=%s path=%s err=%v", tasks[i].RepoID, tasks[i].MirrorPath, err)
			}
			continue
		}
		if !started {
			continue
		}
		m.syncOne(tasks[i])
	}
}

func (m *MirrorManager) syncOne(task models.RPMMirrorTask) {
	var localRoot string
	var cfg mirrorHTTPConfig
	var client *http.Client
	var repomdData []byte
	var revision string
	var primaryHref string
	var primaryData []byte
	var expected map[string]mirrorChecksum
	var duplicateCount int
	var runID string
	var startedAt int64
	var total int64
	var done int64
	var failed int64
	var deleted int64
	var changed int64
	var err error
	var syncCtx context.Context
	var syncCancel context.CancelFunc
	var canceled bool
	var key string
	localRoot = filepath.Join(task.RepoPath, filepath.FromSlash(task.MirrorPath))
	startedAt = time.Now().UTC().Unix()
	syncCtx, syncCancel = context.WithCancel(context.Background())
	key = mirrorTaskKey(task.RepoID, task.MirrorPath)
	m.cancelMu.Lock()
	m.cancelByKey[key] = syncCancel
	m.cancelMu.Unlock()
	defer func() {
		m.cancelMu.Lock()
		delete(m.cancelByKey, key)
		m.cancelMu.Unlock()
		syncCancel()
	}()
	runID, err = m.store.CreateRPMMirrorRun(task.RepoID, task.MirrorPath, startedAt)
	if err != nil {
		_ = m.store.FinishRPMMirrorTask(task.RepoID, task.MirrorPath, false, "", err.Error())
		return
	}
	cfg, err = buildMirrorHTTPConfig(task)
	if err != nil {
		if m.logger != nil {
			m.logger.Write("rpm-mirror", util.LOG_ERROR, "sync failed repo=%s path=%s step=start err=%v", task.RepoID, task.MirrorPath, err)
		}
		_ = m.store.FinishRPMMirrorTask(task.RepoID, task.MirrorPath, false, "", err.Error())
		_ = m.store.FinishRPMMirrorRun(runID, time.Now().UTC().Unix(), "failed", "start", 0, 0, 0, 0, "", err.Error())
		return
	}
	client = buildMirrorHTTPClient(cfg)
	if m.logger != nil {
		m.logger.Write("rpm-mirror", util.LOG_INFO, "sync start repo=%s path=%s remote=%s", task.RepoID, task.MirrorPath, task.RemoteURL)
	}
	_ = m.store.UpdateRPMMirrorTaskProgress(task.RepoID, task.MirrorPath, "fetch_repodata", 0, 0, 0, 0)
	repomdData, err = mirrorFetch(syncCtx, client, cfg, "repodata/repomd.xml")
	if err != nil {
		if m.logger != nil {
			m.logger.Write("rpm-mirror", util.LOG_ERROR, "sync failed repo=%s path=%s step=fetch_repodata err=%v", task.RepoID, task.MirrorPath, err)
		}
		_ = m.store.FinishRPMMirrorTask(task.RepoID, task.MirrorPath, false, "", err.Error())
		_ = m.store.FinishRPMMirrorRun(runID, time.Now().UTC().Unix(), "failed", "fetch_repodata", 0, 0, 0, 0, "", err.Error())
		return
	}
	revision = sha256HexBytes(repomdData)
	if !task.Dirty && task.LastSyncedRevision != "" && task.LastSyncedRevision == revision {
		if m.meta != nil {
			ensureRepodata(task, localRoot, m.meta, m.logger)
		}
		if m.logger != nil {
			m.logger.Write("rpm-mirror", util.LOG_INFO, "sync done repo=%s path=%s status=no_change revision=%s", task.RepoID, task.MirrorPath, revision)
		}
		_ = m.store.FinishRPMMirrorTask(task.RepoID, task.MirrorPath, true, revision, "")
		_ = m.store.FinishRPMMirrorRun(runID, time.Now().UTC().Unix(), "success", "no_change", 0, 0, 0, 0, revision, "")
		return
	}
	primaryHref, err = parseRepomdPrimaryHref(repomdData)
	if err != nil {
		if m.logger != nil {
			m.logger.Write("rpm-mirror", util.LOG_ERROR, "sync failed repo=%s path=%s step=parse_repodata err=%v", task.RepoID, task.MirrorPath, err)
		}
		_ = m.store.FinishRPMMirrorTask(task.RepoID, task.MirrorPath, false, "", err.Error())
		_ = m.store.FinishRPMMirrorRun(runID, time.Now().UTC().Unix(), "failed", "fetch_repodata", 0, 0, 0, 0, "", err.Error())
		return
	}
	_ = m.store.UpdateRPMMirrorTaskProgress(task.RepoID, task.MirrorPath, "fetch_primary", 0, 0, 0, 0)
	primaryData, err = mirrorFetch(syncCtx, client, cfg, primaryHref)
	if err != nil {
		if m.logger != nil {
			m.logger.Write("rpm-mirror", util.LOG_ERROR, "sync failed repo=%s path=%s step=fetch_primary err=%v", task.RepoID, task.MirrorPath, err)
		}
		_ = m.store.FinishRPMMirrorTask(task.RepoID, task.MirrorPath, false, "", err.Error())
		_ = m.store.FinishRPMMirrorRun(runID, time.Now().UTC().Unix(), "failed", "fetch_primary", 0, 0, 0, 0, "", err.Error())
		return
	}
	if strings.HasSuffix(strings.ToLower(primaryHref), ".gz") {
		primaryData, err = gunzipBytes(primaryData)
		if err != nil {
			if m.logger != nil {
				m.logger.Write("rpm-mirror", util.LOG_ERROR, "sync failed repo=%s path=%s step=decode_primary err=%v", task.RepoID, task.MirrorPath, err)
			}
			_ = m.store.FinishRPMMirrorTask(task.RepoID, task.MirrorPath, false, "", err.Error())
			_ = m.store.FinishRPMMirrorRun(runID, time.Now().UTC().Unix(), "failed", "fetch_primary", 0, 0, 0, 0, "", err.Error())
			return
		}
	}
	expected, duplicateCount, err = parsePrimaryPackages(primaryData)
	if err != nil {
		if m.logger != nil {
			m.logger.Write("rpm-mirror", util.LOG_ERROR, "sync failed repo=%s path=%s step=parse_primary err=%v", task.RepoID, task.MirrorPath, err)
		}
		_ = m.store.FinishRPMMirrorTask(task.RepoID, task.MirrorPath, false, "", err.Error())
		_ = m.store.FinishRPMMirrorRun(runID, time.Now().UTC().Unix(), "failed", "fetch_primary", 0, 0, 0, 0, "", err.Error())
		return
	}
	if m.logger != nil {
		m.logger.Write("rpm-mirror", util.LOG_INFO, "primary parsed repo=%s path=%s primary_href=%s packages=%d", task.RepoID, task.MirrorPath, primaryHref, len(expected))
		if duplicateCount > 0 {
			m.logger.Write("rpm-mirror", util.LOG_WARN, "primary has duplicate package paths repo=%s path=%s primary_href=%s duplicates=%d", task.RepoID, task.MirrorPath, primaryHref, duplicateCount)
		}
	}
	total, done, failed, deleted, changed, err = m.applyMirror(syncCtx, task, localRoot, client, cfg, expected)
	if err != nil {
		canceled = errors.Is(err, context.Canceled)
		if m.logger != nil {
			if canceled {
				m.logger.Write("rpm-mirror", util.LOG_WARN, "sync canceled repo=%s path=%s step=apply total=%d done=%d failed=%d deleted=%d err=%v", task.RepoID, task.MirrorPath, total, done, failed, deleted, err)
			} else {
				m.logger.Write("rpm-mirror", util.LOG_ERROR, "sync failed repo=%s path=%s step=apply total=%d done=%d failed=%d deleted=%d err=%v", task.RepoID, task.MirrorPath, total, done, failed, deleted, err)
			}
		}
		if canceled {
			_ = m.store.FinishRPMMirrorTask(task.RepoID, task.MirrorPath, false, "", "sync canceled by user")
			_ = m.store.FinishRPMMirrorRun(runID, time.Now().UTC().Unix(), "failed", "canceled", total, done, failed, deleted, "", "sync canceled by user")
		} else {
			_ = m.store.FinishRPMMirrorTask(task.RepoID, task.MirrorPath, false, "", err.Error())
			_ = m.store.FinishRPMMirrorRun(runID, time.Now().UTC().Unix(), "failed", "apply", total, done, failed, deleted, "", err.Error())
		}
		return
	}
	if m.meta != nil && changed > 0 {
		if m.logger != nil {
			m.logger.Write("rpm-mirror", util.LOG_INFO, "repodata schedule repo=%s path=%s reason=sync_changed changed=%d", task.RepoID, task.MirrorPath, changed)
		}
		m.meta.Schedule(localRoot)
	}
	_ = m.store.FinishRPMMirrorTask(task.RepoID, task.MirrorPath, true, revision, "")
	_ = m.store.FinishRPMMirrorRun(runID, time.Now().UTC().Unix(), "success", "done", total, done, failed, deleted, revision, "")
	_ = m.store.CleanupRPMMirrorRunsRetention(task.RepoID, task.MirrorPath, 200, 30)
	if m.logger != nil {
		m.logger.Write("rpm-mirror", util.LOG_INFO, "sync done repo=%s path=%s status=success total=%d done=%d failed=%d deleted=%d revision=%s", task.RepoID, task.MirrorPath, total, done, failed, deleted, revision)
	}
}

func (m *MirrorManager) applyMirror(ctx context.Context, task models.RPMMirrorTask, localRoot string, client *http.Client, cfg mirrorHTTPConfig, expected map[string]mirrorChecksum) (int64, int64, int64, int64, int64, error) {
	var local map[string]bool
	var total int64
	var done int64
	var failed int64
	var deleted int64
	var changed int64
	var path string
	var checksum mirrorChecksum
	var fullPath string
	var localSum string
	var needDownload bool
	var err error
	local, err = listLocalRPMs(localRoot)
	if err != nil {
		return 0, 0, 0, 0, 0, err
	}
	total = int64(len(expected))
	_ = m.store.UpdateRPMMirrorTaskProgress(task.RepoID, task.MirrorPath, "apply", total, 0, 0, 0)
	for path = range local {
		select {
		case <-ctx.Done():
			return total, done, failed, deleted, changed, ctx.Err()
		default:
		}
		if expected[path].Value != "" {
			continue
		}
		if m.logger != nil {
			m.logger.Write("rpm-mirror", util.LOG_DEBUG, "delete local stale repo=%s path=%s file=%s", task.RepoID, task.MirrorPath, path)
		}
		err = os.Remove(filepath.Join(localRoot, filepath.FromSlash(path)))
		if err == nil || os.IsNotExist(err) {
			deleted = deleted + 1
			changed = changed + 1
		} else {
			if m.logger != nil {
				m.logger.Write("rpm-mirror", util.LOG_WARN, "delete local stale failed repo=%s path=%s file=%s err=%v", task.RepoID, task.MirrorPath, path, err)
			}
		}
	}
	for path, checksum = range expected {
		select {
		case <-ctx.Done():
			return total, done, failed, deleted, changed, ctx.Err()
		default:
		}
		fullPath = filepath.Join(localRoot, filepath.FromSlash(path))
		needDownload = true
		_, err = os.Stat(fullPath)
		if err == nil {
			localSum, err = fileHexByAlgo(fullPath, checksum.Algo)
			if err == nil && (checksum.Value == "" || strings.EqualFold(localSum, checksum.Value)) {
				needDownload = false
			}
		}
		if needDownload {
			if m.logger != nil {
				m.logger.Write("rpm-mirror", util.LOG_DEBUG, "download start repo=%s path=%s file=%s checksum_type=%s checksum=%s", task.RepoID, task.MirrorPath, path, checksum.Algo, checksum.Value)
			}
			err = mirrorDownload(ctx, client, cfg, path, fullPath, checksum.Algo, checksum.Value)
			if err != nil {
				failed = failed + 1
				if m.logger != nil {
					m.logger.Write("rpm-mirror", util.LOG_WARN, "download failed repo=%s path=%s file=%s err=%v", task.RepoID, task.MirrorPath, path, err)
				}
				_ = m.store.UpdateRPMMirrorTaskProgress(task.RepoID, task.MirrorPath, "apply", total, done, failed, deleted)
				continue
			}
			changed = changed + 1
			if m.logger != nil {
				m.logger.Write("rpm-mirror", util.LOG_DEBUG, "download done repo=%s path=%s file=%s", task.RepoID, task.MirrorPath, path)
			}
		} else {
			if m.logger != nil {
				m.logger.Write("rpm-mirror", util.LOG_DEBUG, "download skip repo=%s path=%s file=%s reason=up-to-date", task.RepoID, task.MirrorPath, path)
			}
		}
		done = done + 1
		_ = m.store.UpdateRPMMirrorTaskProgress(task.RepoID, task.MirrorPath, "apply", total, done, failed, deleted)
	}
	if failed > 0 {
		return total, done, failed, deleted, changed, errors.New("some mirror files failed to sync")
	}
	return total, done, failed, deleted, changed, nil
}

func buildMirrorHTTPConfig(task models.RPMMirrorTask) (mirrorHTTPConfig, error) {
	var cfg mirrorHTTPConfig
	var u *url.URL
	var err error
	cfg = mirrorHTTPConfig{
		BaseURL:       strings.TrimRight(strings.TrimSpace(task.RemoteURL), "/"),
		ConnectHost:   strings.TrimSpace(task.ConnectHost),
		HostHeader:    strings.TrimSpace(task.HostHeader),
		TLSServerName: strings.TrimSpace(task.TLSServerName),
		TLSInsecure:   task.TLSInsecureSkipVerify,
	}
	if cfg.BaseURL == "" {
		return cfg, errors.New("remote url is empty")
	}
	u, err = url.Parse(cfg.BaseURL)
	if err != nil {
		return cfg, err
	}
	cfg.DefaultHost = u.Host
	cfg.DefaultServer = u.Hostname()
	if cfg.DefaultHost == "" {
		return cfg, errors.New("remote url host is empty")
	}
	return cfg, nil
}

func buildMirrorHTTPClient(cfg mirrorHTTPConfig) *http.Client {
	var transport *http.Transport
	transport = &http.Transport{
		Proxy: http.ProxyFromEnvironment,
		TLSClientConfig: &tls.Config{
			InsecureSkipVerify: cfg.TLSInsecure,
			ServerName:         effectiveServerName(cfg),
		},
	}
	if cfg.ConnectHost != "" {
		transport.DialContext = func(ctx context.Context, network string, addr string) (net.Conn, error) {
			var d net.Dialer
			_ = addr
			return d.DialContext(ctx, network, cfg.ConnectHost)
		}
	}
	return &http.Client{
		Transport: transport,
		Timeout:   60 * time.Second,
	}
}

func effectiveHostHeader(cfg mirrorHTTPConfig) string {
	if strings.TrimSpace(cfg.HostHeader) != "" {
		return strings.TrimSpace(cfg.HostHeader)
	}
	return cfg.DefaultHost
}

func effectiveServerName(cfg mirrorHTTPConfig) string {
	var host string
	if strings.TrimSpace(cfg.TLSServerName) != "" {
		return strings.TrimSpace(cfg.TLSServerName)
	}
	host = strings.TrimSpace(cfg.HostHeader)
	if host != "" {
		if strings.Contains(host, ":") {
			return strings.Split(host, ":")[0]
		}
		return host
	}
	return cfg.DefaultServer
}

func mirrorFetch(ctx context.Context, client *http.Client, cfg mirrorHTTPConfig, rel string) ([]byte, error) {
	var fullURL string
	var req *http.Request
	var res *http.Response
	var body []byte
	var err error
	fullURL = joinRemoteURL(cfg.BaseURL, rel)
	req, err = http.NewRequestWithContext(ctx, http.MethodGet, fullURL, nil)
	if err != nil {
		return nil, err
	}
	req.Host = effectiveHostHeader(cfg)
	res, err = client.Do(req)
	if err != nil {
		return nil, err
	}
	defer res.Body.Close()
	if res.StatusCode < 200 || res.StatusCode >= 300 {
		return nil, errors.New("upstream request failed: " + res.Status)
	}
	body, err = io.ReadAll(res.Body)
	if err != nil {
		return nil, err
	}
	return body, nil
}

func mirrorDownload(ctx context.Context, client *http.Client, cfg mirrorHTTPConfig, rel string, dstPath string, checksumType string, checksum string) error {
	var fullURL string
	var req *http.Request
	var res *http.Response
	var tempPath string
	var out *os.File
	var hash hashWriter
	var copied int64
	var actualSum string
	var contentType string
	var finalURL string
	var err error
	err = os.MkdirAll(filepath.Dir(dstPath), 0o755)
	if err != nil {
		return err
	}
	fullURL = joinRemoteURL(cfg.BaseURL, rel)
	req, err = http.NewRequestWithContext(ctx, http.MethodGet, fullURL, nil)
	if err != nil {
		return err
	}
	req.Host = effectiveHostHeader(cfg)
	res, err = client.Do(req)
	if err != nil {
		return err
	}
	defer res.Body.Close()
	if res.StatusCode < 200 || res.StatusCode >= 300 {
		return errors.New("upstream request failed: " + res.Status)
	}
	contentType = strings.TrimSpace(res.Header.Get("Content-Type"))
	finalURL = ""
	if res.Request != nil && res.Request.URL != nil {
		finalURL = res.Request.URL.String()
	}
	tempPath = dstPath + ".mirror.tmp"
	out, err = os.Create(tempPath)
	if err != nil {
		return err
	}
	defer out.Close()
	hash, err = newHashWriter(checksumType)
	if err != nil {
		_ = os.Remove(tempPath)
		return err
	}
	copied, err = io.Copy(io.MultiWriter(out, hash), res.Body)
	_ = copied
	if err != nil {
		_ = os.Remove(tempPath)
		return err
	}
	err = out.Close()
	if err != nil {
		_ = os.Remove(tempPath)
		return err
	}
	if strings.TrimSpace(checksum) != "" {
		actualSum = hash.Sum()
		if !strings.EqualFold(actualSum, strings.TrimSpace(checksum)) {
			_ = os.Remove(tempPath)
			return errors.New(
				"download checksum mismatch for " + rel +
					" type=" + normalizeChecksumAlgo(checksumType) +
					" expected=" + strings.TrimSpace(checksum) +
					" actual=" + actualSum +
					" bytes=" + int64ToString(copied) +
					" content_type=" + contentType +
					" url=" + finalURL)
		}
	}
	err = os.Rename(tempPath, dstPath)
	if err != nil {
		_ = os.Remove(tempPath)
		return err
	}
	return nil
}

func joinRemoteURL(base string, rel string) string {
	var baseURL *url.URL
	var relURL *url.URL
	var cleanRel string
	var err error
	cleanRel = strings.ReplaceAll(rel, "\\", "/")
	baseURL, err = url.Parse(strings.TrimSpace(base))
	if err != nil || baseURL == nil {
		cleanRel = strings.TrimLeft(cleanRel, "/")
		return strings.TrimRight(base, "/") + "/" + cleanRel
	}
	// Treat base as a directory root for repository-relative href resolution.
	if !strings.HasSuffix(baseURL.Path, "/") {
		baseURL.Path = baseURL.Path + "/"
	}
	relURL, err = url.Parse(strings.TrimSpace(cleanRel))
	if err != nil || relURL == nil {
		cleanRel = strings.TrimLeft(cleanRel, "/")
		return strings.TrimRight(base, "/") + "/" + cleanRel
	}
	return baseURL.ResolveReference(relURL).String()
}

func parseRepomdPrimaryHref(data []byte) (string, error) {
	var doc repomdDoc
	var i int
	var href string
	var err error
	err = xml.Unmarshal(data, &doc)
	if err != nil {
		return "", err
	}
	for i = 0; i < len(doc.Data); i++ {
		if strings.EqualFold(strings.TrimSpace(doc.Data[i].Type), "primary") {
			href = strings.TrimSpace(doc.Data[i].Location.Href)
			if href != "" {
				return href, nil
			}
		}
	}
	return "", errors.New("primary metadata not found in repomd")
}

func parsePrimaryPackages(data []byte) (map[string]mirrorChecksum, int, error) {
	var doc primaryDoc
	var out map[string]mirrorChecksum
	var i int
	var path string
	var checksum string
	var checksumType string
	var fileTime int64
	var buildTime int64
	var existing mirrorChecksum
	var ok bool
	var duplicates int
	var err error
	err = xml.Unmarshal(data, &doc)
	if err != nil {
		return nil, 0, err
	}
	out = make(map[string]mirrorChecksum)
	for i = 0; i < len(doc.Packages); i++ {
		path = strings.TrimSpace(doc.Packages[i].Location.Href)
		if path == "" {
			continue
		}
		if !strings.HasSuffix(strings.ToLower(path), ".rpm") {
			continue
		}
		checksum = strings.TrimSpace(doc.Packages[i].Checksum.Value)
		checksumType = strings.TrimSpace(doc.Packages[i].Checksum.Type)
		fileTime = parseTimeAttr(doc.Packages[i].Time.File)
		buildTime = parseTimeAttr(doc.Packages[i].Time.Build)
		if existing, ok = out[path]; ok {
			duplicates = duplicates + 1
			if !shouldReplaceDuplicate(existing, buildTime, fileTime, checksum) {
				continue
			}
		}
		out[path] = mirrorChecksum{
			Algo:  normalizeChecksumAlgo(checksumType),
			Value: strings.ToLower(checksum),
			BuildTime: buildTime,
			FileTime: fileTime,
		}
	}
	return out, duplicates, nil
}

func listLocalRPMs(root string) (map[string]bool, error) {
	var out map[string]bool
	var err error
	out = make(map[string]bool)
	err = filepath.WalkDir(root, func(path string, d fs.DirEntry, walkErr error) error {
		var rel string
		if walkErr != nil {
			return walkErr
		}
		if d == nil {
			return nil
		}
		if d.IsDir() {
			if strings.EqualFold(d.Name(), "repodata") {
				return filepath.SkipDir
			}
			return nil
		}
		if !strings.HasSuffix(strings.ToLower(d.Name()), ".rpm") {
			return nil
		}
		rel, err = filepath.Rel(root, path)
		if err != nil {
			return err
		}
		out[filepath.ToSlash(rel)] = true
		return nil
	})
	if err != nil {
		return nil, err
	}
	return out, nil
}

func sha256HexBytes(data []byte) string {
	var sum [32]byte
	sum = sha256.Sum256(data)
	return hex.EncodeToString(sum[:])
}

func fileHexByAlgo(path string, algo string) (string, error) {
	var file *os.File
	var hash hashWriter
	var copied int64
	var err error
	file, err = os.Open(path)
	if err != nil {
		return "", err
	}
	defer file.Close()
	hash, err = newHashWriter(algo)
	if err != nil {
		return "", err
	}
	copied, err = io.Copy(hash, file)
	_ = copied
	if err != nil {
		return "", err
	}
	return hash.Sum(), nil
}

func gunzipBytes(data []byte) ([]byte, error) {
	var reader *gzip.Reader
	var input *bytes.Reader
	var out []byte
	var err error
	input = bytes.NewReader(data)
	reader, err = gzip.NewReader(input)
	if err != nil {
		return nil, err
	}
	defer reader.Close()
	out, err = io.ReadAll(reader)
	if err != nil {
		return nil, err
	}
	return out, nil
}

type hashWriter interface {
	io.Writer
	Sum() string
}

type shaWriter struct {
	h hash.Hash
}

func newHashWriter(algo string) (hashWriter, error) {
	var w *shaWriter
	var normalized string
	var h hash.Hash
	normalized = normalizeChecksumAlgo(algo)
	switch normalized {
	case "", "sha256":
		h = sha256.New()
	case "sha", "sha1":
		h = sha1.New()
	case "sha224":
		h = sha256.New224()
	case "sha384":
		h = sha512.New384()
	case "sha512":
		h = sha512.New()
	case "md5":
		h = md5.New()
	default:
		return nil, errors.New("unsupported checksum type: " + normalized)
	}
	w = &shaWriter{h: h}
	return w, nil
}

func (w *shaWriter) Write(p []byte) (int, error) {
	return w.h.Write(p)
}

func (w *shaWriter) Sum() string {
	var raw []byte
	raw = w.h.Sum(nil)
	return hex.EncodeToString(raw)
}

func normalizeChecksumAlgo(algo string) string {
	var out string
	out = strings.ToLower(strings.TrimSpace(algo))
	out = strings.ReplaceAll(out, "-", "")
	out = strings.ReplaceAll(out, "_", "")
	if out == "sha1" {
		return "sha1"
	}
	if out == "sha" {
		return "sha"
	}
	if out == "sha224" {
		return "sha224"
	}
	if out == "sha256" {
		return "sha256"
	}
	if out == "sha384" {
		return "sha384"
	}
	if out == "sha512" {
		return "sha512"
	}
	if out == "md5" {
		return "md5"
	}
	return out
}

func int64ToString(v int64) string {
	return strconv.FormatInt(v, 10)
}

func mirrorTaskKey(repoID string, path string) string {
	return repoID + "\x00" + path
}

func ensureRepodata(task models.RPMMirrorTask, localRoot string, meta *MetaManager, logger *util.Logger) {
	var repomdPath string
	var statErr error
	repomdPath = filepath.Join(localRoot, "repodata", "repomd.xml")
	_, statErr = os.Stat(repomdPath)
	if statErr == nil {
		return
	}
	if logger != nil {
		logger.Write("rpm-mirror", util.LOG_INFO, "repodata schedule repo=%s path=%s reason=missing repomd=%s", task.RepoID, task.MirrorPath, repomdPath)
	}
	meta.Schedule(localRoot)
}

func parseTimeAttr(value string) int64 {
	var trimmed string
	var parsed int64
	var err error
	trimmed = strings.TrimSpace(value)
	if trimmed == "" {
		return 0
	}
	parsed, err = strconv.ParseInt(trimmed, 10, 64)
	if err != nil {
		return 0
	}
	return parsed
}

func shouldReplaceDuplicate(existing mirrorChecksum, newBuildTime int64, newFileTime int64, newChecksum string) bool {
	var existingChecksum string
	if newBuildTime > existing.BuildTime {
		return true
	}
	if newBuildTime < existing.BuildTime {
		return false
	}
	if newFileTime > existing.FileTime {
		return true
	}
	if newFileTime < existing.FileTime {
		return false
	}
	existingChecksum = strings.TrimSpace(existing.Value)
	if existingChecksum == "" && strings.TrimSpace(newChecksum) != "" {
		return true
	}
	return false
}