ytcfg.go

package main

import (
	"bytes"
	"encoding/json"
	"fmt"

	"golang.org/x/net/html"
)

var ytcfgStart = []byte("ytcfg.set(")

// TODO: If necessary, grab dataSyncIds as well
// Will be needed if SessionIndex is not available
type YTCFG struct {
	DelegatedSessionId        string `json:"DELEGATED_SESSION_ID"`
	IdToken                   string `json:"ID_TOKEN"`
	Hl                        string `json:"HL"`
	InnertubeApiKey           string `json:"INNERTUBE_API_KEY"`
	InnertubeClientName       string `json:"INNERTUBE_CLIENT_NAME"`
	InnertubeClientVersion    string `json:"INNERTUBE_CLIENT_VERSION"`
	InnertubeCtxClientName    int    `json:"INNERTUBE_CONTEXT_CLIENT_NAME"`
	InnertubeCtxClientVersion string `json:"INNERTUBE_CONTEXT_CLIENT_VERSION"`
	SessionIndex              string `json:"SESSION_INDEX"`
	VisitorData               string `json:"VISITOR_DATA"`
}

// Search the given HTML for the ytcfg object
func GetYTCFGFromHtml(data []byte) []byte {
	var objData []byte
	reader := bytes.NewReader(data)
	tokenizer := html.NewTokenizer(reader)
	isScript := false

	for {
		tt := tokenizer.Next()
		switch tt {
		case html.ErrorToken:
			return objData
		case html.TextToken:
			if isScript {
				data := tokenizer.Text()
				setStart := bytes.Index(data, ytcfgStart)
				if setStart < 0 {
					continue
				}

				// Maybe add a LogTrace in the future for stuff like this
				//LogDebug("Found script element with ytcfg data in watch page.")
				objStart := bytes.Index(data[setStart:], []byte("{")) + setStart
				objEnd := bytes.Index(data[objStart:], []byte("});")) + 1 + objStart

				if objEnd > objStart {
					objData = data[objStart:objEnd]
				}

				if len(objData) > 0 {
					return objData
				}
			}
		case html.StartTagToken:
			tn, _ := tokenizer.TagName()
			if string(tn) == "script" {
				isScript = true
			} else {
				isScript = false
			}
		}
	}
}

func GetDefaultYTCFG() *YTCFG {
	return &YTCFG{
		InnertubeApiKey:           "AIzaSyAO_FJ2SlqU8Q4STEHLGCilw_Y9_11qcW8",
		InnertubeClientName:       "WEB",
		InnertubeClientVersion:    "2.20241119.01.01",
		InnertubeCtxClientName:    1,
		InnertubeCtxClientVersion: "2.20241119.01.01",
	}
}

func (di *DownloadInfo) GetYTCFG(videoHtml []byte) error {
	ytcfg := GetDefaultYTCFG()
	di.Ytcfg = ytcfg

	if len(videoHtml) == 0 {
		return fmt.Errorf("unable to retrieve data from video page")
	}

	prData := GetYTCFGFromHtml(videoHtml)
	if len(prData) == 0 {
		return fmt.Errorf("unable to retrieve ytcfg data from watch page")
	}

	err := json.Unmarshal(prData, di.Ytcfg)
	if err != nil {
		return err
	}

	return nil
}