Merge pull request 'handler/swagger: initial import' (#169) from swagger into v3

Reviewed-on: #169

handler/swagger/swagger.go

@@ -0,0 +1,55 @@
+package swagger
+
+import (
+	"io/fs"
+	"net/http"
+
+	yamlcodec "go.unistack.org/micro-codec-yaml/v3"
+	rutil "go.unistack.org/micro/v3/util/reflect"
+)
+
+// Handler append to generated swagger data from dst map[string]interface{}
+var Handler = func(dst map[string]interface{}, fsys fs.FS) http.HandlerFunc {
+	c := yamlcodec.NewCodec()
+	return func(w http.ResponseWriter, r *http.Request) {
+		if r.Method != http.MethodGet {
+			w.WriteHeader(http.StatusNotFound)
+			return
+		}
+
+		path := r.URL.Path
+		if len(path) > 1 && path[0] == '/' {
+			path = path[1:]
+		}
+
+		buf, err := fs.ReadFile(fsys, path)
+		if err != nil {
+			w.WriteHeader(http.StatusInternalServerError)
+			_, _ = w.Write([]byte(err.Error()))
+			return
+		}
+
+		var src interface{}
+
+		if err = c.Unmarshal(buf, src); err != nil {
+			w.WriteHeader(http.StatusInternalServerError)
+			_, _ = w.Write([]byte(err.Error()))
+			return
+		}
+
+		if err = rutil.Merge(src, dst); err != nil {
+			w.WriteHeader(http.StatusInternalServerError)
+			_, _ = w.Write([]byte(err.Error()))
+			return
+		}
+
+		if buf, err = c.Marshal(src); err != nil {
+			w.WriteHeader(http.StatusInternalServerError)
+			_, _ = w.Write([]byte(err.Error()))
+			return
+		}
+
+		w.WriteHeader(http.StatusOK)
+		_, _ = w.Write(buf)
+	}
+}