feat(PROJ-17): Admin Dashboard Systemauslastung immer anzeigen

- Systemauslastungs-Sektion wird immer gerendert (nicht nur bei Erfolg) - Fehlermeldung wenn /api/admin/system/stats nicht erreichbar ist - Feature-Status auf In Review gesetzt Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
2026-03-14 11:43:19 +01:00
parent a893084a88
commit d360c9a5ba
68 changed files with 11938 additions and 435 deletions
@@ -0,0 +1,145 @@
+package storage
+
+import (
+	"crypto/sha256"
+	"errors"
+	"fmt"
+	"io/fs"
+	"os"
+	"path/filepath"
+	"time"
+)
+
+// Store is a file-based email storage using SHA256 for deduplication.
+type Store struct {
+	dir string
+}
+
+// StoreStats reports total mail count and size in bytes.
+type StoreStats struct {
+	TotalMails int64
+	TotalBytes int64
+}
+
+// New initialises the storage directory, creating required subdirectories.
+func New(dir string) (*Store, error) {
+	for _, sub := range []string{"store", "attachments", "meta"} {
+		if err := os.MkdirAll(filepath.Join(dir, sub), 0o755); err != nil {
+			return nil, fmt.Errorf("storage: mkdir %s: %w", sub, err)
+		}
+	}
+	return &Store{dir: dir}, nil
+}
+
+// Save writes raw email bytes to storage. The ID is the hex-encoded SHA256 of
+// the content. If the file already exists, Save is a no-op (deduplication).
+func (s *Store) Save(raw []byte, _ time.Time) (string, error) {
+	sum := sha256.Sum256(raw)
+	id := fmt.Sprintf("%x", sum[:]) // 64 hex chars
+
+	path := s.filePath(id)
+	if err := os.MkdirAll(filepath.Dir(path), 0o755); err != nil {
+		return "", fmt.Errorf("storage: mkdir shard: %w", err)
+	}
+
+	// If file already exists, dedup: return same id without error.
+	if _, err := os.Stat(path); err == nil {
+		return id, nil
+	}
+
+	if err := os.WriteFile(path, raw, 0o644); err != nil {
+		return "", fmt.Errorf("storage: write: %w", err)
+	}
+
+	return id, nil
+}
+
+// Load reads a stored email by its ID.
+func (s *Store) Load(id string) ([]byte, error) {
+	path := s.filePath(id)
+	data, err := os.ReadFile(path)
+	if err != nil {
+		if errors.Is(err, os.ErrNotExist) {
+			return nil, fmt.Errorf("storage: not found: %s", id)
+		}
+		return nil, fmt.Errorf("storage: read: %w", err)
+	}
+	return data, nil
+}
+
+// Delete removes a stored email by its ID.
+func (s *Store) Delete(id string) error {
+	path := s.filePath(id)
+	if err := os.Remove(path); err != nil {
+		if errors.Is(err, os.ErrNotExist) {
+			return fmt.Errorf("storage: not found: %s", id)
+		}
+		return fmt.Errorf("storage: delete: %w", err)
+	}
+	return nil
+}
+
+// Stats walks the store directory and returns aggregate statistics.
+func (s *Store) Stats() (*StoreStats, error) {
+	var stats StoreStats
+	err := filepath.WalkDir(filepath.Join(s.dir, "store"), func(_ string, d fs.DirEntry, err error) error {
+		if err != nil {
+			return err
+		}
+		if d.IsDir() {
+			return nil
+		}
+		info, err := d.Info()
+		if err != nil {
+			return err
+		}
+		stats.TotalMails++
+		stats.TotalBytes += info.Size()
+		return nil
+	})
+	if err != nil {
+		return nil, fmt.Errorf("storage: stats: %w", err)
+	}
+	return &stats, nil
+}
+
+// MailRef holds the ID and modification time of a stored mail.
+type MailRef struct {
+	ID      string
+	ModTime time.Time
+}
+
+// FirstAndLastMail walks the store and returns the oldest and newest mail by
+// file modification time. Returns nil for either if the store is empty.
+func (s *Store) FirstAndLastMail() (first, last *MailRef, err error) {
+	err = filepath.WalkDir(filepath.Join(s.dir, "store"), func(path string, d fs.DirEntry, werr error) error {
+		if werr != nil {
+			return werr
+		}
+		if d.IsDir() {
+			return nil
+		}
+		info, err := d.Info()
+		if err != nil {
+			return err
+		}
+		ref := &MailRef{ID: d.Name(), ModTime: info.ModTime()}
+		if first == nil || ref.ModTime.Before(first.ModTime) {
+			first = ref
+		}
+		if last == nil || ref.ModTime.After(last.ModTime) {
+			last = ref
+		}
+		return nil
+	})
+	if err != nil {
+		return nil, nil, fmt.Errorf("storage: first/last: %w", err)
+	}
+	return first, last, nil
+}
+
+// filePath returns the on-disk path for a given mail ID.
+// Uses 2-char prefix sharding: {dir}/store/{id[:2]}/{id}
+func (s *Store) filePath(id string) string {
+	return filepath.Join(s.dir, "store", id[:2], id)
+}