// Copyright (c) 2016-present Mattermost, Inc. All Rights Reserved.
// See License.txt for license information.

package app

import (
	l4g "github.com/alecthomas/log4go"

	"net/http"

	"github.com/mattermost/mattermost-server/model"
	"github.com/mattermost/mattermost-server/utils"
)

type webSocketHandler interface {
	ServeWebSocket(*WebConn, *model.WebSocketRequest)
}

type WebSocketRouter struct {
	handlers map[string]webSocketHandler
}

func NewWebSocketRouter() *WebSocketRouter {
	router := &WebSocketRouter{}
	router.handlers = make(map[string]webSocketHandler)
	return router
}

func (wr *WebSocketRouter) Handle(action string, handler webSocketHandler) {
	wr.handlers[action] = handler
}

func (wr *WebSocketRouter) ServeWebSocket(conn *WebConn, r *model.WebSocketRequest) {
	if r.Action == "" {
		err := model.NewAppError("ServeWebSocket", "api.web_socket_router.no_action.app_error", nil, "", http.StatusBadRequest)
		ReturnWebSocketError(conn, r, err)
		return
	}

	if r.Seq <= 0 {
		err := model.NewAppError("ServeWebSocket", "api.web_socket_router.bad_seq.app_error", nil, "", http.StatusBadRequest)
		ReturnWebSocketError(conn, r, err)
		return
	}

	if r.Action == model.WEBSOCKET_AUTHENTICATION_CHALLENGE {
		if conn.GetSessionToken() != "" {
			return
		}

		token, ok := r.Data["token"].(string)
		if !ok {
			conn.WebSocket.Close()
			return
		}

		session, err := Global().GetSession(token)

		if err != nil {
			conn.WebSocket.Close()
		} else {
			go func() {
				Global().SetStatusOnline(session.UserId, session.Id, false)
				Global().UpdateLastActivityAtIfNeeded(*session)
			}()

			conn.SetSession(session)
			conn.SetSessionToken(session.Token)
			conn.UserId = session.UserId

			HubRegister(conn)

			resp := model.NewWebSocketResponse(model.STATUS_OK, r.Seq, nil)
			conn.Send <- resp
		}

		return
	}

	if !conn.IsAuthenticated() {
		err := model.NewAppError("ServeWebSocket", "api.web_socket_router.not_authenticated.app_error", nil, "", http.StatusUnauthorized)
		ReturnWebSocketError(conn, r, err)
		return
	}

	var handler webSocketHandler
	if h, ok := wr.handlers[r.Action]; !ok {
		err := model.NewAppError("ServeWebSocket", "api.web_socket_router.bad_action.app_error", nil, "", http.StatusInternalServerError)
		ReturnWebSocketError(conn, r, err)
		return
	} else {
		handler = h
	}

	handler.ServeWebSocket(conn, r)
}

func ReturnWebSocketError(conn *WebConn, r *model.WebSocketRequest, err *model.AppError) {
	l4g.Error(utils.T("api.web_socket_router.log.error"), r.Seq, conn.UserId, err.SystemMessage(utils.T), err.DetailedError)

	err.DetailedError = ""
	errorResp := model.NewWebSocketError(r.Seq, err)

	conn.Send <- errorResp
}