1 files changed, 103 insertions, 0 deletions
diff --git a/internal/modules/middleware.go b/internal/modules/middleware.go
new file mode 100644
index 0000000..6159573
--- /dev/null
+++ b/internal/modules/middleware.go
@@ -0,0 +1,103 @@
+package modules
+
+import (
+	"net/http"
+	"strings"
+)
+
+// ModuleMiddleware handles Go module requests directly or passes to next handler
+func ModuleMiddleware(moduleHandler http.Handler, next http.Handler) http.Handler {
+	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		if isModuleRequest(r) {
+			moduleHandler.ServeHTTP(w, r)
+			return
+		}
+		next.ServeHTTP(w, r)
+	})
+}
+
+// isModuleRequest checks if the request is for Go module endpoints
+func isModuleRequest(r *http.Request) bool {
+	// Check for go-import meta tag requests
+	if r.URL.Query().Get("go-get") == "1" {
+		return true
+	}
+
+	// Check for Go module proxy endpoints
+	return isModuleProxyPath(r.URL.Path)
+}
+
+// isModuleProxyPath checks if the path matches Go module proxy endpoints
+func isModuleProxyPath(path string) bool {
+	// Module proxy endpoints:
+	// /{module}/@v/list
+	// /{module}/@v/{version}.info
+	// /{module}/@v/{version}.mod
+	// /{module}/@v/{version}.zip
+	// /{module}/@latest
+
+	// Check for @latest endpoint
+	if strings.HasSuffix(path, "/@latest") {
+		return true
+	}
+
+	// Check for @v/ endpoints
+	if !strings.Contains(path, "/@v/") {
+		return false
+	}
+
+	// Valid @v/ endpoint suffixes
+	suffixes := []string{"/list", ".info", ".mod", ".zip"}
+	for _, suffix := range suffixes {
+		if strings.HasSuffix(path, suffix) {
+			return true
+		}
+	}
+
+	return false
+}
+
+// ExtractModulePath extracts the module path from a request URL
+func ExtractModulePath(path string) string {
+	// Remove leading slash
+	path = strings.TrimPrefix(path, "/")
+
+	// For proxy endpoints, extract module path before /@v/ or /@latest
+	if idx := strings.Index(path, "/@v/"); idx != -1 {
+		return path[:idx]
+	}
+
+	if strings.HasSuffix(path, "/@latest") {
+		return strings.TrimSuffix(path, "/@latest")
+	}
+
+	// Remove trailing slash for clean module paths
+	return strings.TrimSuffix(path, "/")
+}
+
+// ExtractVersion extracts the version from a module proxy request
+func ExtractVersion(path string) string {
+	if !strings.Contains(path, "/@v/") {
+		return ""
+	}
+
+	// Extract version from /@v/{version}.{suffix}
+	parts := strings.Split(path, "/@v/")
+	if len(parts) != 2 {
+		return ""
+	}
+
+	versionPart := parts[1]
+
+	// Special case for /list endpoint
+	if versionPart == "list" {
+		return ""
+	}
+
+	// Remove suffix (.info, .mod, .zip)
+	if idx := strings.LastIndex(versionPart, "."); idx != -1 {
+		return versionPart[:idx]
+	}
+
+	return versionPart
+}