1 files changed, 65 insertions, 0 deletions
diff --git a/modules/web/middleware/flash.go b/modules/web/middleware/flash.go
new file mode 100644
index 0000000..88da204
--- /dev/null
+++ b/modules/web/middleware/flash.go
@@ -0,0 +1,65 @@
+// Copyright 2020 The Gitea Authors. All rights reserved.
+// SPDX-License-Identifier: MIT
+
+package middleware
+
+import (
+	"fmt"
+	"html/template"
+	"net/url"
+)
+
+// Flash represents a one time data transfer between two requests.
+type Flash struct {
+	DataStore ContextDataStore
+	url.Values
+	ErrorMsg, WarningMsg, InfoMsg, SuccessMsg string
+}
+
+func (f *Flash) set(name, msg string, current ...bool) {
+	if f.Values == nil {
+		f.Values = make(map[string][]string)
+	}
+	showInCurrentPage := len(current) > 0 && current[0]
+	if showInCurrentPage {
+		// assign it to the context data, then the template can use ".Flash.XxxMsg" to render the message
+		f.DataStore.GetData()["Flash"] = f
+	} else {
+		// the message map will be saved into the cookie and be shown in next response (a new page response which decodes the cookie)
+		f.Set(name, msg)
+	}
+}
+
+func flashMsgStringOrHTML(msg any) string {
+	switch v := msg.(type) {
+	case string:
+		return v
+	case template.HTML:
+		return string(v)
+	}
+	panic(fmt.Sprintf("unknown type: %T", msg))
+}
+
+// Error sets error message
+func (f *Flash) Error(msg any, current ...bool) {
+	f.ErrorMsg = flashMsgStringOrHTML(msg)
+	f.set("error", f.ErrorMsg, current...)
+}
+
+// Warning sets warning message
+func (f *Flash) Warning(msg any, current ...bool) {
+	f.WarningMsg = flashMsgStringOrHTML(msg)
+	f.set("warning", f.WarningMsg, current...)
+}
+
+// Info sets info message
+func (f *Flash) Info(msg any, current ...bool) {
+	f.InfoMsg = flashMsgStringOrHTML(msg)
+	f.set("info", f.InfoMsg, current...)
+}
+
+// Success sets success message
+func (f *Flash) Success(msg any, current ...bool) {
+	f.SuccessMsg = flashMsgStringOrHTML(msg)
+	f.set("success", f.SuccessMsg, current...)
+}