feat: add HTTP HEAD method support (#1135)

backend/internal/middleware/head_middleware.go

@@ -0,0 +1,40 @@
+package middleware
+
+import (
+	"net/http"
+	"strconv"
+
+	"github.com/gin-gonic/gin"
+)
+
+type IsHeadRequestCtxKey struct{}
+
+type headWriter struct {
+	gin.ResponseWriter
+	size int
+}
+
+func (w *headWriter) Write(b []byte) (int, error) {
+	w.size += len(b)
+	return w.size, nil
+}
+
+func HeadMiddleware() gin.HandlerFunc {
+	return func(c *gin.Context) {
+		// Only process if it's a HEAD request
+		if c.Request.Context().Value(IsHeadRequestCtxKey{}) != true {
+			c.Next()
+			return
+		}
+
+		// Replace the ResponseWriter with our headWriter to swallow the body
+		hw := &headWriter{ResponseWriter: c.Writer}
+		c.Writer = hw
+
+		c.Next()
+
+		c.Writer.Header().Set("Content-Length", strconv.Itoa(hw.size))
+		c.Request.Method = http.MethodHead
+
+	}
+}