alps/renderer.go
2020-01-20 22:06:47 +01:00

178 lines
4 KiB
Go

package koushin
import (
"fmt"
"html/template"
"io"
"io/ioutil"
"os"
"github.com/labstack/echo/v4"
)
const themesDir = "themes"
// GlobalRenderData contains data available in all templates.
type GlobalRenderData struct {
Path string
LoggedIn bool
// if logged in
Username string
// TODO: list of mailboxes
// additional plugin-specific data
Extra map[string]interface{}
}
// BaseRenderData is the base type for templates. It should be extended with
// additional template-specific fields:
//
// type MyRenderData struct {
// BaseRenderData
// // add additional fields here
// }
type BaseRenderData struct {
GlobalData GlobalRenderData
// additional plugin-specific data
Extra map[string]interface{}
}
// Global implements RenderData.
func (brd *BaseRenderData) Global() *GlobalRenderData {
return &brd.GlobalData
}
// RenderData is implemented by template data structs. It can be used to inject
// additional data to all templates.
type RenderData interface {
// GlobalData returns a pointer to the global render data.
Global() *GlobalRenderData
}
// NewBaseRenderData initializes a new BaseRenderData.
//
// It can be used by routes to pre-fill the base data:
//
// type MyRenderData struct {
// BaseRenderData
// // add additional fields here
// }
//
// data := &MyRenderData{
// BaseRenderData: *koushin.NewBaseRenderData(ctx),
// // other fields...
// }
func NewBaseRenderData(ctx *Context) *BaseRenderData {
global := GlobalRenderData{Extra: make(map[string]interface{})}
if ctx.Session != nil {
global.LoggedIn = true
global.Username = ctx.Session.username
}
global.Path = ctx.Request().URL.String()
return &BaseRenderData{
GlobalData: global,
Extra: make(map[string]interface{}),
}
}
type renderer struct {
logger echo.Logger
defaultTheme string
base *template.Template
themes map[string]*template.Template
}
func (r *renderer) Render(w io.Writer, name string, data interface{}, ectx echo.Context) error {
// ectx is the raw *echo.context, not our own *Context
ctx := ectx.Get("context").(*Context)
var renderData RenderData
if data == nil {
renderData = &struct{ BaseRenderData }{*NewBaseRenderData(ctx)}
} else {
var ok bool
renderData, ok = data.(RenderData)
if !ok {
return fmt.Errorf("data passed to template %q doesn't implement RenderData", name)
}
}
for _, plugin := range ctx.Server.plugins {
if err := plugin.Inject(ctx, name, renderData); err != nil {
return fmt.Errorf("failed to run plugin %q: %v", plugin.Name(), err)
}
}
// TODO: per-user theme selection
t := r.base
if r.defaultTheme != "" {
t = r.themes[r.defaultTheme]
}
return t.ExecuteTemplate(w, name, data)
}
func loadTheme(name string, base *template.Template) (*template.Template, error) {
theme, err := base.Clone()
if err != nil {
return nil, err
}
theme, err = theme.ParseGlob(themesDir + "/" + name + "/*.html")
if err != nil {
return nil, err
}
return theme, nil
}
func (r *renderer) Load(plugins []Plugin) error {
base := template.New("")
for _, p := range plugins {
if err := p.LoadTemplate(base); err != nil {
return fmt.Errorf("failed to load template for plugin %q: %v", p.Name(), err)
}
}
themes := make(map[string]*template.Template)
files, err := ioutil.ReadDir(themesDir)
if err != nil && !os.IsNotExist(err) {
return err
}
for _, fi := range files {
if !fi.IsDir() {
continue
}
r.logger.Printf("Loading theme %q", fi.Name())
var err error
if themes[fi.Name()], err = loadTheme(fi.Name(), base); err != nil {
return fmt.Errorf("failed to load theme %q: %v", fi.Name(), err)
}
}
if r.defaultTheme != "" {
if _, ok := themes[r.defaultTheme]; !ok {
return fmt.Errorf("failed to find default theme %q", r.defaultTheme)
}
}
r.base = base
r.themes = themes
return nil
}
func newRenderer(logger echo.Logger, defaultTheme string) *renderer {
return &renderer{
logger: logger,
defaultTheme: defaultTheme,
}
}