package centrifugo

import (
	"bytes"
	"encoding/json"
	"net/http"

	"git.golem15.com/golem15/summercms/modules/bouncer"
	"git.golem15.com/golem15/summercms/modules/lighthouse"
)

type errorBody struct {
	Error string `json:"error"`
}

type tokenBody struct {
	Token string `json:"token"`
}

// TokenHandler issues the connection token of the signed-in user. It must
// be mounted behind a user guard (the UserAuth surface).
//
//   - no principal, or no user for it: 401 {"error":"Unauthorized"}
//   - no token secret: 503 with the WinterCMS not-configured error body
//   - otherwise 200 {"token":"…"} (see TokenIssuer.ForUser)
func TokenHandler(svc *lighthouse.Service, issuer *TokenIssuer) http.HandlerFunc {
	return func(w http.ResponseWriter, r *http.Request) {
		p, ok := bouncer.User(r.Context())
		if !ok || p == nil || p.ID == 0 {
			writeJSON(w, http.StatusUnauthorized, errorBody{Error: "Unauthorized"})
			return
		}
		u, found, err := svc.User(r.Context(), p.ID)
		if err != nil || !found {
			writeJSON(w, http.StatusUnauthorized, errorBody{Error: "Unauthorized"})
			return
		}
		if !issuer.Configured() {
			writeJSON(w, http.StatusServiceUnavailable, errorBody{Error: "WebSocket not configured"})
			return
		}
		tok, err := issuer.ForUser(u)
		if err != nil {
			svc.Logger().Error("realtime: token signing failed", "error", err)
			writeJSON(w, http.StatusInternalServerError, errorBody{Error: "Internal server error"})
			return
		}
		writeJSON(w, http.StatusOK, tokenBody{Token: tok})
	}
}

// writeJSON writes v with no trailing newline and no HTML escaping, plus the
// Content-Type and Cache-Control headers of a Laravel JSON response.
func writeJSON(w http.ResponseWriter, status int, v any) {
	var buf bytes.Buffer
	enc := json.NewEncoder(&buf)
	enc.SetEscapeHTML(false)
	if err := enc.Encode(v); err != nil {
		w.WriteHeader(http.StatusInternalServerError)
		return
	}
	h := w.Header()
	h.Set("Content-Type", "application/json")
	h.Set("Cache-Control", "no-cache, private")
	w.WriteHeader(status)
	_, _ = w.Write(bytes.TrimSuffix(buf.Bytes(), []byte("\n")))
}