From d81757efd3f07ac9f2854f63aecab99cb397be17 Mon Sep 17 00:00:00 2001
From: "Gustavo L de Mello (Guz)" <contact@guz.one>
Date: Mon, 27 Jan 2025 09:51:39 -0300
Subject: [PATCH] feat(blogo,plugins): template error handler

---
 blogo/plugins/template_error_handler.go | 106 ++++++++++++++++++++++++
 1 file changed, 106 insertions(+)
 create mode 100644 blogo/plugins/template_error_handler.go

diff --git a/blogo/plugins/template_error_handler.go b/blogo/plugins/template_error_handler.go
new file mode 100644
index 0000000..639565b
--- /dev/null
+++ b/blogo/plugins/template_error_handler.go
@@ -0,0 +1,106 @@
+// Copyright 2025-present Gustavo "Guz" L. de Mello
+// Copyright 2025-present The Lored.dev Contributors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//	http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package plugins
+
+import (
+	"errors"
+	"html/template"
+	"io"
+	"log/slog"
+	"net/http"
+
+	"forge.capytal.company/loreddev/x/blogo/core"
+	"forge.capytal.company/loreddev/x/blogo/plugin"
+	"forge.capytal.company/loreddev/x/tinyssert"
+)
+
+const templateErrorHandlerName = "blogo-templateerrorhandler-errorhandler"
+
+func NewTemplateErrorHandler(
+	templt template.Template,
+	opts ...TemplateErrorHandlerOpts,
+) plugin.ErrorHandler {
+	opt := TemplateErrorHandlerOpts{}
+	if len(opts) > 0 {
+		opt = opts[0]
+	}
+
+	if opt.Assertions == nil {
+		opt.Assertions = tinyssert.NewDisabledAssertions()
+	}
+	if opt.Logger == nil {
+		opt.Logger = slog.New(slog.NewTextHandler(io.Discard, &slog.HandlerOptions{}))
+	}
+
+	return &templateErrorHandler{
+		templt: templt,
+
+		assert: opt.Assertions,
+		log:    opt.Logger,
+	}
+}
+
+type TemplateErrorHandlerOpts struct {
+	Assertions tinyssert.Assertions
+	Logger     *slog.Logger
+}
+
+type TemplateErrorHandlerInfo struct {
+	Path     string
+	Error    error
+	ErrorMsg string
+}
+
+type templateErrorHandler struct {
+	templt template.Template
+
+	assert tinyssert.Assertions
+	log    *slog.Logger
+}
+
+func (h *templateErrorHandler) Name() string {
+	return templateErrorHandlerName
+}
+
+func (h *templateErrorHandler) Handle(err error) (recovr any, handled bool) {
+	h.assert.NotNil(err, "Error should not be nil")
+	h.assert.NotNil(h.templt, "Template should not be nil")
+	h.assert.NotNil(h.log)
+
+	log := h.log.With(slog.String("err", err.Error()))
+
+	var serr core.ServeError
+	if !errors.As(err, &serr) {
+		log.Debug("Error is not a core.ServeError, ignoring error")
+		return nil, false
+	}
+
+	log.Debug("Handling error")
+
+	w, r := serr.Res, serr.Req
+
+	w.WriteHeader(http.StatusInternalServerError)
+	if err := h.templt.Execute(w, TemplateErrorHandlerInfo{
+		Path:     r.URL.Path,
+		Error:    serr.Err,
+		ErrorMsg: serr.Err.Error(),
+	}); err != nil {
+		log.Error("Failed to execute template and respond error")
+		return nil, false
+	}
+
+	return nil, true
+}