mlblive/cmd/subscribe.go

/*
Copyright © 2024 filifa

This program is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.

This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
GNU General Public License for more details.

You should have received a copy of the GNU General Public License
along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
package cmd

import (
	"encoding/json"
	"fmt"
	"log"
	"strconv"
	"time"

	"github.com/gorilla/websocket"
	"github.com/spf13/cobra"
	"scm.dairydemon.net/filifa/mlblive/cmd/internal/statsapi"
)

var gamePk int

func patch(feedResp []byte, gamePk, ts, updateId string) ([]byte, error) {
	diffPatchResp, err := statsapi.RequestDiffPatch(gamePk, ts, updateId)
	if err != nil {
		return feedResp, err
	}

	patches, err := diffPatchResp.ExtractPatches()
	if err != nil {
		return feedResp, err
	}

	for _, patch := range patches {
		feedResp, err = patch.Apply(feedResp)
		if err != nil {
			return feedResp, err
		}
	}

	return feedResp, err
}

func newWebsocket(gamePk string) (*statsapi.GamedayWebsocket, <-chan error, error) {
	ws, err := statsapi.NewGamedayWebsocket(gamePk)
	if err != nil {
		return nil, nil, err
	}

	ch := make(chan error)
	go ws.KeepAlive(10*time.Second, ch)

	return ws, ch, err
}

func handleUnexpectedClose(gamePk string) (*statsapi.GamedayWebsocket, []byte, error) {
	ws, _, err := newWebsocket(gamePk)
	if err != nil {
		return nil, nil, err
	}

	feedResp, err := statsapi.RequestFeed(gamePk)
	return ws, feedResp, err
}

func updateFeed(ws *statsapi.GamedayWebsocket, feedResp []byte, gamePk string) ([]byte, error) {
	var feed statsapi.Feed
	err := json.Unmarshal(feedResp, &feed)
	if err != nil {
		return nil, err
	}
	ts := feed.MetaData.TimeStamp

	var p statsapi.Push
	err = ws.ReadJSON(&p)
	if websocket.IsUnexpectedCloseError(err, statsapi.GameFinalCode, statsapi.GameUnavailableCode) {
		log.Println(err)

		newWs, feedResp, err := handleUnexpectedClose(gamePk)
		if err != nil {
			return feedResp, err
		}
		*ws = *newWs
		return feedResp, err
	} else if err != nil {
		return nil, err
	}

	feedResp, err = patch(feedResp, gamePk, ts, p.UpdateId)
	if err != nil {
		feedResp, err = statsapi.RequestFeed(gamePk)
	}
	return feedResp, err
}

func subscribe(cmd *cobra.Command, args []string) {
	pkStr := strconv.Itoa(gamePk)
	ws, _, err := newWebsocket(pkStr)
	if err != nil {
		log.Fatal(err)
	}
	defer ws.Close()

	feedResp, err := statsapi.RequestFeed(pkStr)
	if err != nil {
		log.Fatal(err)
	}

	for {
		fmt.Println(string(feedResp))

		feedResp, err = updateFeed(ws, feedResp, pkStr)
		if err != nil {
			log.Fatal(err)
		}
	}
}

// subscribeCmd represents the subscribe command
var subscribeCmd = &cobra.Command{
	Use:   "subscribe -g [gamePk]",
	Short: "Output live game data",
	Long: `Output live game data.

Establish a websocket connection with ws.statsapi.mlb.com and output JSON with
live updates of a game.`,
	Args: cobra.NoArgs,
	Run:  subscribe,
}

func init() {
	rootCmd.AddCommand(subscribeCmd)

	// Here you will define your flags and configuration settings.

	// Cobra supports Persistent Flags which will work for this command
	// and all subcommands, e.g.:
	// subscribeCmd.PersistentFlags().String("foo", "", "A help for foo")

	// Cobra supports local flags which will only run when this command
	// is called directly, e.g.:
	subscribeCmd.Flags().IntVarP(&gamePk, "gamePk", "g", 0, "game PK")
	subscribeCmd.MarkFlagRequired("gamePk")
}