/
templates.go
166 lines (135 loc) · 3.36 KB
/
templates.go
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package main
import (
"bytes"
"errors"
"fmt"
"html/template"
"io/fs"
"path"
"strings"
"sync"
)
var gRenderPool = sync.Pool{
New: func() any {
return bytes.NewBuffer(make([]byte, 0, 4096))
},
}
type Templates struct {
Base *template.Template
Home *template.Template
LogIn *template.Template
LogOut *template.Template
Board *template.Template
Topic *template.Template
Thread *template.Template
}
func Render(t *template.Template, data *DataModel) ([]byte, error) {
buf := gRenderPool.Get().(*bytes.Buffer)
defer func() {
buf.Reset()
gRenderPool.Put(buf)
}()
if err := t.Execute(buf, data); err != nil {
return nil, err
}
shared := buf.Bytes()
result := make([]byte, len(shared))
copy(result, shared)
return result, nil
}
func (templates *Templates) Load(fsys fs.FS) error {
*templates = Templates{}
baseTemplate, err := createBaseTemplate(fsys)
if err != nil {
return err
}
homeTemplate, err := createTemplate(baseTemplate, fsys, "home.tmpl")
if err != nil {
return err
}
logInTemplate, err := createTemplate(baseTemplate, fsys, "login.tmpl")
if err != nil {
return err
}
logOutTemplate, err := createTemplate(baseTemplate, fsys, "logout.tmpl")
if err != nil {
return err
}
boardTemplate, err := createTemplate(baseTemplate, fsys, "board.tmpl")
if err != nil {
return err
}
topicTemplate, err := createTemplate(baseTemplate, fsys, "topic.tmpl")
if err != nil {
return err
}
threadTemplate, err := createTemplate(baseTemplate, fsys, "thread.tmpl")
if err != nil {
return err
}
*templates = Templates{
Base: baseTemplate,
Home: homeTemplate,
LogIn: logInTemplate,
LogOut: logOutTemplate,
Board: boardTemplate,
Topic: topicTemplate,
Thread: threadTemplate,
}
return nil
}
func createBaseTemplate(fsys fs.FS) (*template.Template, error) {
t := template.New("root")
t.Option("missingkey=error")
t.Funcs(kFuncMap)
if err := mergeTemplateIncludes(t, gBuiltInFS); err != nil {
return nil, fmt.Errorf("built-in template: %w", err)
}
if fsys != nil {
if err := mergeTemplateIncludes(t, fsys); err != nil {
return nil, err
}
}
return t, nil
}
func createTemplate(baseTemplate *template.Template, fsys fs.FS, pathName string) (*template.Template, error) {
pathName = path.Join("templates", pathName)
t, err := baseTemplate.Clone()
if err != nil {
panic(err)
}
err = mergeTemplate(t, gBuiltInFS, pathName)
if err != nil {
return nil, fmt.Errorf("built-in template: %w", err)
}
if fsys != nil {
err = mergeTemplate(t, fsys, pathName)
if err != nil && !errors.Is(err, fs.ErrNotExist) {
return nil, err
}
}
return t, nil
}
func mergeTemplateIncludes(t *template.Template, fsys fs.FS) error {
return fs.WalkDir(fsys, ".", func(pathName string, d fs.DirEntry, err error) error {
if err != nil {
return err
}
if !d.IsDir() && strings.HasPrefix(pathName, "templates/include/") && strings.HasSuffix(pathName, ".tmpl") {
return mergeTemplate(t, fsys, pathName)
}
return nil
})
}
func mergeTemplate(t *template.Template, fsys fs.FS, pathName string) error {
raw, err := fs.ReadFile(fsys, pathName)
if err != nil {
return fmt.Errorf("%q: failed to read file: %w", pathName, err)
}
_, err = t.Parse(string(raw))
if err != nil {
return fmt.Errorf("%q: failed to parse file as Go HTML template: %w", pathName, err)
}
return nil
}
var kFuncMap = template.FuncMap(nil)