// Package omni connects managed WebSocket sessions to a GoOmni application.
package omni

import (
	"errors"

	"git.yuntuo.hk/k2safe/go-omni/app"
	"git.yuntuo.hk/k2safe/go-omni/config"
	"git.yuntuo.hk/k2safe/go-omni/httpx"
	"git.yuntuo.hk/k2safe/go-omni/ws"
)

// Handler preserves the HTTP middleware chain and records the actual upgrade
// status. The server owns all session callbacks after this handler returns.
// Register Server.Stop/Drain on App or svc Runtime before accepting connections.
func Handler(server *ws.Server, handlers ws.Handlers) httpx.Handler {
	if server == nil {
		panic("ws/omni: nil server")
	}
	return func(c *httpx.Context) error {
		_, err := server.Accept(c.Raw(), c.Request(), handlers)
		if err == nil {
			c.MarkUpgraded()
		}
		// Accept has already written any handshake failure response.
		return nil
	}
}

// Mount registers a GET endpoint and its shutdown barriers on a standalone App.
// Use Handler with svc.OnStop/OnDrain when the service Runtime owns dependencies.
// Mount once per Server. Configure the App before calling it.
func Mount(a *app.App, path string, server *ws.Server, handlers ws.Handlers) error {
	if a == nil || server == nil {
		return errors.New("ws/omni: app and server required")
	}
	if a.Config().Transport != config.TransportNetHTTP && a.Config().Transport != "" {
		return ws.ErrUnsupportedTransport
	}
	a.GET(path, Handler(server, handlers))
	a.OnStop("ws:"+path, server.Stop)
	a.OnDrain("ws:"+path, server.Drain)
	return nil
}