Add file upload to website and integrate into chat

backend/handlers/handle_message_upload.go

@@ -0,0 +1,63 @@
+package handlers
+
+import (
+	"crypto/rand"
+	"encoding/hex"
+	"net/http"
+	"os"
+	"path/filepath"
+	"strings"
+
+	"github.com/gin-gonic/gin"
+)
+
+var allowedExtensions = map[string]bool{
+	".jpg": true, ".jpeg": true, ".png": true, ".gif": true, ".webp": true,
+	".mp4": true, ".webm": true, ".mp3": true, ".ogg": true,
+	".pdf": true, ".txt": true,
+}
+
+func (store *Store) UploadMessageFile(ctx *gin.Context) {
+	file, err := ctx.FormFile("file")
+	if err != nil {
+		ctx.JSON(http.StatusBadRequest, gin.H{"error": "file is required"})
+		return
+	}
+
+	const maxSize = 10 << 20 // 10MB
+	if file.Size > maxSize {
+		ctx.JSON(http.StatusBadRequest, gin.H{"error": "file too large"})
+		return
+	}
+
+	ext := strings.ToLower(filepath.Ext(file.Filename))
+	if !allowedExtensions[ext] {
+		ctx.JSON(http.StatusBadRequest, gin.H{"error": "file type not allowed"})
+		return
+	}
+
+	b := make([]byte, 16)
+	if _, err := rand.Read(b); err != nil {
+		ctx.JSON(http.StatusInternalServerError, gin.H{"error": "failed to generate filename"})
+		return
+	}
+	filename := hex.EncodeToString(b) + ext
+
+	uploadDir := "/backend/uploads"
+	if err := os.MkdirAll(uploadDir, 0755); err != nil {
+		ctx.JSON(http.StatusInternalServerError, gin.H{"error": "failed to create upload directory"})
+		return
+	}
+
+	dest := filepath.Join(uploadDir, filename)
+	if err := ctx.SaveUploadedFile(file, dest); err != nil {
+		ctx.JSON(http.StatusInternalServerError, gin.H{"error": "failed to save file"})
+		return
+	}
+	if err := os.Chmod(dest, 0644); err != nil {
+		ctx.JSON(http.StatusInternalServerError, gin.H{"error": "failed to set file permissions"})
+		return
+	}
+
+	ctx.JSON(http.StatusOK, gin.H{"url": "/uploads/" + filename})
+}