Refactor template render (#36438)

modules/templates/mail.go

@@ -0,0 +1,195 @@
+// Copyright 2022 The Gitea Authors. All rights reserved.
+// SPDX-License-Identifier: MIT
+
+package templates
+
+import (
+	"html/template"
+	"io"
+	"regexp"
+	"slices"
+	"strings"
+	"sync"
+	texttmpl "text/template"
+
+	"code.gitea.io/gitea/modules/graceful"
+	"code.gitea.io/gitea/modules/log"
+	"code.gitea.io/gitea/modules/setting"
+	"code.gitea.io/gitea/modules/util"
+)
+
+type MailRender struct {
+	TemplateNames []string
+	BodyTemplates struct {
+		HasTemplate     func(name string) bool
+		ExecuteTemplate func(w io.Writer, name string, data any) error
+	}
+
+	// FIXME: MAIL-TEMPLATE-SUBJECT: only "issue" related messages support using subject from templates
+	// It is an incomplete implementation from "Use templates for issue e-mail subject and body" https://github.com/go-gitea/gitea/pull/8329
+	SubjectTemplates *texttmpl.Template
+
+	tmplRenderer *tmplRender
+
+	mockedBodyTemplates map[string]*template.Template
+}
+
+// mailSubjectTextFuncMap returns functions for injecting to text templates, it's only used for mail subject
+func mailSubjectTextFuncMap() texttmpl.FuncMap {
+	return texttmpl.FuncMap{
+		"dict": dict,
+		"Eval": evalTokens,
+
+		"EllipsisString": util.EllipsisDisplayString,
+		"AppName": func() string {
+			return setting.AppName
+		},
+		"AppDomain": func() string { // documented in mail-templates.md
+			return setting.Domain
+		},
+	}
+}
+
+var mailSubjectSplit = regexp.MustCompile(`(?m)^-{3,}\s*$`)
+
+func newMailRenderer() (*MailRender, error) {
+	subjectTemplates := texttmpl.New("")
+	subjectTemplates.Funcs(mailSubjectTextFuncMap())
+
+	renderer := &MailRender{
+		SubjectTemplates: subjectTemplates,
+	}
+
+	assetFS := AssetFS()
+
+	renderer.tmplRenderer = &tmplRender{
+		collectTemplateNames: func() ([]string, error) {
+			names, err := assetFS.ListAllFiles(".", true)
+			if err != nil {
+				return nil, err
+			}
+			names = slices.DeleteFunc(names, func(file string) bool {
+				return !strings.HasPrefix(file, "mail/") || !strings.HasSuffix(file, ".tmpl")
+			})
+			for i, name := range names {
+				names[i] = strings.TrimSuffix(strings.TrimPrefix(name, "mail/"), ".tmpl")
+			}
+			renderer.TemplateNames = names
+			return names, nil
+		},
+		readTemplateContent: func(name string) ([]byte, error) {
+			content, err := assetFS.ReadFile("mail/" + name + ".tmpl")
+			if err != nil {
+				return nil, err
+			}
+			var subjectContent []byte
+			bodyContent := content
+			loc := mailSubjectSplit.FindIndex(content)
+			if loc != nil {
+				subjectContent, bodyContent = content[0:loc[0]], content[loc[1]:]
+			}
+			_, err = renderer.SubjectTemplates.New(name).Parse(string(subjectContent))
+			if err != nil {
+				return nil, err
+			}
+			return bodyContent, nil
+		},
+	}
+
+	renderer.BodyTemplates.HasTemplate = func(name string) bool {
+		if renderer.mockedBodyTemplates[name] != nil {
+			return true
+		}
+		return renderer.tmplRenderer.Templates().HasTemplate(name)
+	}
+
+	staticFuncMap := NewFuncMap()
+	renderer.BodyTemplates.ExecuteTemplate = func(w io.Writer, name string, data any) error {
+		if t, ok := renderer.mockedBodyTemplates[name]; ok {
+			return t.Execute(w, data)
+		}
+		t, err := renderer.tmplRenderer.Templates().Executor(name, staticFuncMap)
+		if err != nil {
+			return err
+		}
+		return t.Execute(w, data)
+	}
+
+	err := renderer.tmplRenderer.recompileTemplates(staticFuncMap)
+	if err != nil {
+		return nil, err
+	}
+	return renderer, nil
+}
+
+func (r *MailRender) MockTemplate(name, subject, body string) func() {
+	if r.mockedBodyTemplates == nil {
+		r.mockedBodyTemplates = make(map[string]*template.Template)
+	}
+	oldSubject := r.SubjectTemplates
+	r.SubjectTemplates, _ = r.SubjectTemplates.Clone()
+	texttmpl.Must(r.SubjectTemplates.New(name).Parse(subject))
+
+	oldBody, hasOldBody := r.mockedBodyTemplates[name]
+	mockFuncMap := NewFuncMap()
+	r.mockedBodyTemplates[name] = template.Must(template.New(name).Funcs(mockFuncMap).Parse(body))
+	return func() {
+		r.SubjectTemplates = oldSubject
+		if hasOldBody {
+			r.mockedBodyTemplates[name] = oldBody
+		} else {
+			delete(r.mockedBodyTemplates, name)
+		}
+	}
+}
+
+var (
+	globalMailRenderer   *MailRender
+	globalMailRendererMu sync.RWMutex
+)
+
+func MailRendererReload() error {
+	globalMailRendererMu.Lock()
+	defer globalMailRendererMu.Unlock()
+	r, err := newMailRenderer()
+	if err != nil {
+		return err
+	}
+	globalMailRenderer = r
+	return nil
+}
+
+func MailRenderer() *MailRender {
+	globalMailRendererMu.RLock()
+	r := globalMailRenderer
+	globalMailRendererMu.RUnlock()
+	if r != nil {
+		return r
+	}
+
+	globalMailRendererMu.Lock()
+	defer globalMailRendererMu.Unlock()
+	if globalMailRenderer != nil {
+		return globalMailRenderer
+	}
+
+	var err error
+	globalMailRenderer, err = newMailRenderer()
+	if err != nil {
+		log.Fatal("Failed to initialize mail renderer: %v", err)
+	}
+
+	if !setting.IsProd {
+		go AssetFS().WatchLocalChanges(graceful.GetManager().ShutdownContext(), func() {
+			globalMailRendererMu.Lock()
+			defer globalMailRendererMu.Unlock()
+			r, err := newMailRenderer()
+			if err != nil {
+				log.Error("Mail template error: %v", err)
+				return
+			}
+			globalMailRenderer = r
+		})
+	}
+	return globalMailRenderer
+}