feat: implementar webapp app_compartir con visor universal, auth y purga 24h para guest

internal/storage/storage.go

@@ -0,0 +1,121 @@
+package storage
+
+import (
+	"crypto/rand"
+	"io"
+	"mime"
+	"net/http"
+	"os"
+	"path/filepath"
+	"regexp"
+	"strings"
+)
+
+const slugChars = "23456789abcdefghjkmnpqrstuvwxyzABCDEFGHJKLMNPQRSTUVWXYZ"
+
+var safeFilenameRegex = regexp.MustCompile(`[^a-zA-Z0-9._-]+`)
+
+func GenerateSlug(length int) string {
+	b := make([]byte, length)
+	if _, err := rand.Read(b); err != nil {
+		return "x" + strings.ToLower(slugChars[:length-1])
+	}
+	charsLen := byte(len(slugChars))
+	for i := 0; i < length; i++ {
+		b[i] = slugChars[b[i]%charsLen]
+	}
+	return string(b)
+}
+
+func SanitizeFilename(name string) string {
+	base := filepath.Base(name)
+	sanitized := safeFilenameRegex.ReplaceAllString(base, "_")
+	if len(sanitized) > 100 {
+		ext := filepath.Ext(sanitized)
+		sanitized = sanitized[:100-len(ext)] + ext
+	}
+	if sanitized == "" || sanitized == "." {
+		sanitized = "archivo.bin"
+	}
+	return sanitized
+}
+
+func DetectMimeType(filename string, reader io.ReadSeeker) string {
+	ext := strings.ToLower(filepath.Ext(filename))
+	if m := mime.TypeByExtension(ext); m != "" {
+		return m
+	}
+
+	// Sniff first 512 bytes
+	if reader != nil {
+		buf := make([]byte, 512)
+		n, err := reader.Read(buf)
+		_, _ = reader.Seek(0, io.SeekStart)
+		if err == nil && n > 0 {
+			detected := http.DetectContentType(buf[:n])
+			if detected != "application/octet-stream" {
+				return detected
+			}
+		}
+	}
+
+	// Known fallback extensions
+	switch ext {
+	case ".pdf":
+		return "application/pdf"
+	case ".mp4":
+		return "video/mp4"
+	case ".webm":
+		return "video/webm"
+	case ".mp3":
+		return "audio/mpeg"
+	case ".wav":
+		return "audio/wav"
+	case ".ogg":
+		return "audio/ogg"
+	case ".png":
+		return "image/png"
+	case ".jpg", ".jpeg":
+		return "image/jpeg"
+	case ".gif":
+		return "image/gif"
+	case ".webp":
+		return "image/webp"
+	case ".svg":
+		return "image/svg+xml"
+	case ".txt", ".log", ".env":
+		return "text/plain; charset=utf-8"
+	case ".json":
+		return "application/json"
+	case ".js":
+		return "application/javascript"
+	case ".go", ".py", ".rs", ".java", ".c", ".cpp", ".sh", ".sql", ".html", ".css", ".md":
+		return "text/plain; charset=utf-8"
+	default:
+		return "application/octet-stream"
+	}
+}
+
+func SaveFile(uploadDir, slug, originalFilename string, src io.Reader) (string, int64, error) {
+	if err := os.MkdirAll(uploadDir, 0755); err != nil {
+		return "", 0, err
+	}
+
+	safeName := SanitizeFilename(originalFilename)
+	storedFilename := slug + "_" + safeName
+	destPath := filepath.Join(uploadDir, storedFilename)
+
+	dest, err := os.Create(destPath)
+	if err != nil {
+		return "", 0, err
+	}
+	defer dest.Close()
+
+	written, err := io.Copy(dest, src)
+	if err != nil {
+		_ = os.Remove(destPath)
+		return "", 0, err
+	}
+
+	return storedFilename, written, nil
+}