improved error page handling by tapping into Echo and its middleware

errors.go

@@ -10,7 +10,12 @@
 package main
 
 import (
+	"fmt"
+	"net/http"
+
 	"git.erbosoft.com/amy/amsterdam/ui"
+	"github.com/labstack/echo/v4"
+	log "github.com/sirupsen/logrus"
 )
 
 /* NotImplPage is used for all TODO links, to show that something hasn't yet been implemented.
@@ -27,3 +32,39 @@ func NotImplPage(ctxt ui.AmContext) (string, any, error) {
 	ctxt.VarMap().Set("path", ctxt.URLPath())
 	return "framed_template", "notimpl.jet", nil
 }
+
+/* AmErrorHandler handles all the mundane HTTP errors generated by the Echo engine.
+ * Parameters:
+ *     err - The error to be handled.
+ *     c - The Echo context error is being handled on.
+ */
+func AmErrorHandler(err error, c echo.Context) {
+	if c.Response().Committed {
+		return
+	}
+
+	errCode := http.StatusInternalServerError
+	if he, ok := err.(*echo.HTTPError); ok {
+		errCode = he.Code
+	}
+
+	amctxt := ui.AmContextFromEchoContext(c)
+	if amctxt == nil {
+		var qerr error
+		amctxt, qerr = ui.AmCreateContext(c)
+		if qerr != nil {
+			log.Errorf("failed to create AmContext in error handler: %v", qerr)
+			c.String(errCode, fmt.Sprintf("error %d: %v", errCode, err))
+			return
+		}
+	}
+	amctxt.SetLeftMenu("top")
+	amctxt.SetRC(errCode)
+	amctxt.VarMap().Set("error", err.Error())
+	// TODO: come up with a way to shift templates and titles for different error codes
+	amctxt.VarMap().Set("amsterdam_pageTitle", "Amsterdam Internal Server Error")
+	cerr := ui.AmSendPageData(c, amctxt, "framed_template", "error.jet")
+	if cerr != nil {
+		log.Errorf("Error rendering error %d (%v): %v", errCode, err, cerr)
+	}
+}