// Package brand serves the suite's app icons from Go, so a page can link
// any sibling app's icon (the app switcher) without vendoring the file.
// The artwork itself is brand/svg/, generated by generate.mjs; see README.md.
package brand

import (
	"embed"
	"net/http"
	"strings"
)

//go:embed svg/*.svg
var svgFS embed.FS

// Prefix is the URL path Handler serves under.
const Prefix = "/static/estilo/brand/"

// files maps a public slug to its master. "meet" is Calls' name before
// the rename, kept so a page still linking it gets the right icon.
var files = map[string]string{
	"oficina":  "oficina.svg",
	"docs":     "docs.svg",
	"sheets":   "sheets.svg",
	"slides":   "slides.svg",
	"calendar": "calendar.svg",
	"calls":    "calls.svg",
	"meet":     "calls.svg",
	"memoria":  "memoria.svg",
	"fichas":   "fichas.svg",
	"mail":     "mail.svg",
	"files":    "files.svg",
}

// SVG returns the icon for slug, or nil for an unknown slug.
func SVG(slug string) []byte {
	name, ok := files[slug]
	if !ok {
		return nil
	}
	body, err := svgFS.ReadFile("svg/" + name)
	if err != nil {
		return nil
	}
	return body
}

// Path is the URL Handler serves slug's icon at.
func Path(slug string) string { return Prefix + slug + ".svg" }

// Handler serves GET and HEAD for Prefix + "<slug>.svg". Mount it at
// Prefix. Anything else is 404; the icons are public artwork and need no
// session.
func Handler() http.Handler {
	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		slug, ok := strings.CutSuffix(strings.TrimPrefix(r.URL.Path, Prefix), ".svg")
		body := SVG(slug)
		if !ok || body == nil || !strings.HasPrefix(r.URL.Path, Prefix) {
			http.NotFound(w, r)
			return
		}
		if r.Method != http.MethodGet && r.Method != http.MethodHead {
			w.Header().Set("Allow", "GET, HEAD")
			http.Error(w, http.StatusText(http.StatusMethodNotAllowed), http.StatusMethodNotAllowed)
			return
		}
		w.Header().Set("Content-Type", "image/svg+xml")
		w.Header().Set("Cache-Control", "public, max-age=86400")
		w.Header().Set("X-Content-Type-Options", "nosniff")
		if r.Method == http.MethodHead {
			return
		}
		_, _ = w.Write(body)
	})
}