move upstream into own package

html/error.go

@@ -0,0 +1,23 @@
+package html
+
+import (
+	"bytes"
+	"github.com/valyala/fasthttp"
+	"strconv"
+)
+
+// ReturnErrorPage sets the response status code and writes NotFoundPage to the response body, with "%status" replaced
+// with the provided status code.
+func ReturnErrorPage(ctx *fasthttp.RequestCtx, code int) {
+	ctx.Response.SetStatusCode(code)
+	ctx.Response.Header.SetContentType("text/html; charset=utf-8")
+	message := fasthttp.StatusMessage(code)
+	if code == fasthttp.StatusMisdirectedRequest {
+		message += " - domain not specified in <code>.domains</code> file"
+	}
+	if code == fasthttp.StatusFailedDependency {
+		message += " - target repo/branch doesn't exist or is private"
+	}
+	// TODO: use template engine?
+	ctx.Response.SetBody(bytes.ReplaceAll(NotFoundPage, []byte("%status"), []byte(strconv.Itoa(code)+" "+message)))
+}