package web

import (
	"net/http"
	"os"
	"strconv"
	"strings"

	"github.com/go-chi/chi/v5"

	"hearthforge/internal/avatar"
	"hearthforge/internal/highlight"
)

// immutableCache caches a response for one year. Both routes are safe to
// cache that long because their URLs carry a version or change only with the
// binary.
const immutableCache = "public, max-age=31536000, immutable"

// avatarRoutes serves user avatars and the generated syntax highlighting CSS.
func (s *Server) avatarRoutes(r chi.Router) {
	r.Get("/avatars/{id}", s.serveAvatar)
	// The literal path wins over the /assets/* static file handler in chi's
	// trie, so the order of registration does not matter.
	// TestCodeThemeBeatsStaticMount covers that.
	r.Get("/assets/code-theme.css", serveCodeTheme)
}

func (s *Server) serveAvatar(w http.ResponseWriter, r *http.Request) {
	name := strings.TrimSuffix(chi.URLParam(r, "id"), ".png")
	userID, err := strconv.ParseInt(name, 10, 64)
	if err != nil {
		http.Error(w, "Not found", http.StatusNotFound)
		return
	}
	// Without the version parameter the answer could be cached forever under
	// a URL that never changes, so refuse it.
	if !r.URL.Query().Has("v") {
		http.Error(w, "Not found", http.StatusNotFound)
		return
	}

	path := avatar.Path(s.Cfg.AvatarsDir(), userID)
	if _, err := os.Stat(path); err != nil {
		// Users created before avatars existed have no file yet.
		user, err := s.DB.UserByID(r.Context(), userID)
		if err != nil || user == nil {
			http.Error(w, "Not found", http.StatusNotFound)
			return
		}
		if err := avatar.SaveDefault(s.Cfg.AvatarsDir(), userID, user.Username); err != nil {
			http.Error(w, "Not found", http.StatusNotFound)
			return
		}
	}

	w.Header().Set("Content-Type", "image/png")
	w.Header().Set("Cache-Control", immutableCache)
	http.ServeFile(w, r, path)
}

func serveCodeTheme(w http.ResponseWriter, r *http.Request) {
	w.Header().Set("Content-Type", "text/css; charset=utf-8")
	w.Header().Set("Cache-Control", immutableCache)
	w.Write([]byte(highlight.CSS()))
}