package qq_obv11

// This file implements the server role of the OneBot v11 WebSocket channel:
// the adapter listens on a TCP port and accepts inbound OneBot (反向) client
// connections, validates any configured access token, and upgrades each HTTP
// request to a WebSocket session.

import (
	"context"
	"errors"
	"fmt"
	"net"
	"net/http"
	"strings"
)

// connectServer starts the HTTP listener in server mode. It returns once the
// listener is bound; the session becomes live when a OneBot client connects.
func (a *Adapter) connectServer(ctx context.Context) error {
	if a.cfg.ListenAddr == "" {
		return errors.New("qq-obv11: server mode requires listenAddr")
	}
	mux := http.NewServeMux()
	mux.HandleFunc("/", a.wsHandler)

	ln, err := net.Listen("tcp", a.cfg.ListenAddr)
	if err != nil {
		return fmt.Errorf("qq-obv11: listen %s: %w", a.cfg.ListenAddr, err)
	}

	a.mu.Lock()
	a.ln = ln
	a.srv = &http.Server{Handler: mux}
	a.mu.Unlock()

	go func() {
		if serveErr := a.srv.Serve(ln); serveErr != nil && serveErr != http.ErrServerClosed {
			a.log.Warn("websocket server stopped", "err", serveErr)
		}
	}()
	a.log.Info("websocket server listening (server mode)", "addr", ln.Addr().String())
	return nil
}

// wsHandler is the HTTP handler that upgrades one inbound OneBot client
// connection to a WebSocket session.
func (a *Adapter) wsHandler(w http.ResponseWriter, r *http.Request) {
	if a.cfg.AccessToken != "" && !a.checkAuth(r) {
		http.Error(w, "Forbidden: invalid access_token", http.StatusForbidden)
		return
	}
	conn, err := upgradeWS(w, r)
	if err != nil {
		a.log.Warn("websocket upgrade failed", "err", err)
		return
	}
	a.setConn(conn)
	a.log.Info("onebot client connected (server mode)", "remote", r.RemoteAddr)
}

// checkAuth validates the access token carried by an upgrade request. OneBot
// implementations pass it either as an access_token query parameter or as an
// Authorization: Bearer header.
func (a *Adapter) checkAuth(r *http.Request) bool {
	if got := r.URL.Query().Get("access_token"); got != "" {
		return got == a.cfg.AccessToken
	}
	auth := r.Header.Get("Authorization")
	if strings.HasPrefix(auth, "Bearer ") {
		return strings.TrimPrefix(auth, "Bearer ") == a.cfg.AccessToken
	}
	return false
}