Levyraati26_go/render.go

package main

import (
	"bytes"
	"embed"
	"html/template"
	"log/slog"
	"net/http"
	"net/url"
	"strconv"
	"time"
)

//go:embed templates static
var assetFS embed.FS

var funcs = template.FuncMap{
	"fidate": func(t time.Time) string { return t.Local().Format("2.1.2006 15:04") },
	"score":  func(f *float64) string { return strconv.FormatFloat(*f, 'f', 1, 64) },
	"value":  func(f float64) string { return strconv.FormatFloat(f, 'f', 1, 64) },
	// Lets one board partial be called with a title and a list, instead of two near-identical
	// partials per leaderboard.
	"dict": func(pairs ...any) map[string]any {
		m := map[string]any{}
		for i := 0; i+1 < len(pairs); i += 2 {
			m[pairs[i].(string)] = pairs[i+1]
		}
		return m
	},
}

// Each page is parsed with the layout into its own set, so two pages may both define "content".
var pages = map[string]*template.Template{}

func init() {
	entries, err := assetFS.ReadDir("templates")
	if err != nil {
		panic(err)
	}
	for _, e := range entries {
		if e.Name() == "layout.html" {
			continue
		}
		if e.IsDir() {
			continue
		}
		pages[e.Name()] = template.Must(template.New("layout.html").Funcs(funcs).
			ParseFS(assetFS, "templates/layout.html", "templates/partials/*.html", "templates/"+e.Name()))
	}
}

// page is everything the layout needs, plus whatever the page itself wants in Data.
type page struct {
	Title  string
	Member *member
	Admin  bool
	Flash  string
	Path   string
	Narrow bool // auth pages are a 420px column
	Queued int  // songs still owed a review, shown in the nav
	Data   any
}

func (a *app) render(w http.ResponseWriter, r *http.Request, status int, name string, p page) {
	t, ok := pages[name]
	if !ok {
		slog.Error("unknown template", "name", name)
		http.Error(w, "template", http.StatusInternalServerError)
		return
	}
	p.Member = memberFrom(r.Context())
	p.Path = r.URL.Path
	if p.Member != nil {
		// The queue is a worklist, so its size belongs in the nav.
		a.pool.QueryRow(r.Context(), `
			select count(*)::int from songs s
			 where s.submitted_by <> $1
			   and not exists (select 1 from reviews r
			                    where r.song_id = s.id and r.reviewer_id = $1)`,
			p.Member.ID).Scan(&p.Queued)
	}
	p.Flash = a.takeFlash(w, r)

	// Render to memory first: a template that fails halfway must not leave a half-written 200.
	var buf bytes.Buffer
	if err := t.ExecuteTemplate(&buf, "layout.html", p); err != nil {
		slog.Error("render", "name", name, "error", err)
		http.Error(w, "template", http.StatusInternalServerError)
		return
	}
	w.Header().Set("Content-Type", "text/html; charset=utf-8")
	w.WriteHeader(status)
	buf.WriteTo(w)
}

// Toasts are a cookie rendered server-side and cleared on read — no JS, no session storage.
func (a *app) flash(w http.ResponseWriter, msg string) {
	http.SetCookie(w, &http.Cookie{
		Name: "flash", Value: url.QueryEscape(msg), Path: "/",
		HttpOnly: true, Secure: a.cfg.secureCookies, SameSite: http.SameSiteLaxMode,
	})
}

func (a *app) takeFlash(w http.ResponseWriter, r *http.Request) string {
	c, err := r.Cookie("flash")
	if err != nil || c.Value == "" {
		return ""
	}
	http.SetCookie(w, &http.Cookie{
		Name: "flash", Value: "", Path: "/", MaxAge: -1,
		HttpOnly: true, Secure: a.cfg.secureCookies, SameSite: http.SameSiteLaxMode,
	})
	msg, err := url.QueryUnescape(c.Value)
	if err != nil {
		return ""
	}
	return msg
}