Rename template.go to renderer.go

1 files changed, 178 insertions, 0 deletions

diff --git a/renderer.go b/renderer.go
new file mode 100644
index 0000000..b229d34
--- /dev/null
+++ b/renderer.go
@@ -0,0 +1,178 @@
+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 '%v' 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 '%v': %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 '%v': %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 '%v'", fi.Name())
+		var err error
+		if themes[fi.Name()], err = loadTheme(fi.Name(), base); err != nil {
+			return fmt.Errorf("failed to load theme '%v': %v", fi.Name(), err)
+		}
+	}
+
+	if r.defaultTheme != "" {
+		if _, ok := themes[r.defaultTheme]; !ok {
+			return fmt.Errorf("failed to find default theme '%v'", r.defaultTheme)
+		}
+	}
+
+	r.base = base
+	r.themes = themes
+	return nil
+}
+
+func newRenderer(logger echo.Logger, defaultTheme string) *renderer {
+	return &renderer{
+		logger:       logger,
+		defaultTheme: defaultTheme,
+	}
+}