web_hgdjc_server/app/service/videoser/vtt.go

package videoser

import (
	"bufio"
	"bytes"
	"fmt"
	"io"
	http2 "net/http"
	"strings"
	"videoweb/app/appg"
	"videoweb/app/service/configser"
	"videoweb/pub/common"
	"videoweb/pub/common/enum/redisconst"
	"videoweb/pub/common/errors"
	"videoweb/pub/common/http"
	"videoweb/pub/common/log"
	"videoweb/pub/common/m3u8"
	"videoweb/pub/common/srvdef"
	"videoweb/pub/common/utils"
	"videoweb/pub/redis"
	"videoweb/pub/storage/proxy"

	"github.com/gin-gonic/gin"
)

func GetVTTEx(ctx *gin.Context) {
	fn := func(c *gin.Context) (contentLength int64, contentType string, reader io.Reader, extraHeaders map[string]string, err error) {
		vttName := ctx.Param("key")
		var req m3u8.Req
		if err = ctx.BindQuery(&req); err != nil {
			return
		}

		req.Name = vttName
		cfg := configser.GetConfigInfo()
		cdnDomain := cfg.ImgCdn
		originDomain := appg.Conf.OrigDomain

		buff, err := TransformVttEx(req.Name, cdnDomain, originDomain)
		if err != nil {
			return
		}
		contentType = "application/vnd.apple.mpegurl"
		reader = bytes.NewReader(buff)
		contentLength = int64(len(buff))
		extraHeaders = map[string]string{}
		return
	}
	contentLength, contentType, reader, extraHeaders, err := fn(ctx)
	if err != nil {
		common.ServerJSON(ctx, srvdef.DownloadM3u8File, err)
		return
	}
	ctx.DataFromReader(http2.StatusOK, contentLength, contentType, reader, extraHeaders)
}

func TransformVttEx(name, cdnDomain, originDomain string) (buff []byte, err error) {
	if name == "" {
		err = errors.MakeWithMsg(errors.M3u8FileName, "m3u8 file name is empty")
		return
	}
	if cdnDomain == "" || originDomain == "" {
		err = errors.MakeWithMsg(errors.DomainErr, "cdnDomain or origDomain is empty")
		return
	}
	// 处理媒资库 桶1(v1) 桶2(v2) 桶3（v3）
	mediaVerson := proxy.AppendsMediaS3Version(name)
	if len(mediaVerson) > 0 {
		name = mediaVerson + name
	}

	// 原始vtt
	srcReader, err := readFromRedis(name, originDomain)
	if err != nil {
		return
	}

	raw, err := io.ReadAll(srcReader)
	if err != nil {
		return nil, errors.MakeWithMsg(errors.M3u8Read, "read vtt reader fail: "+err.Error())
	}
	// 替换为cdn路径
	newData := rewriteVttWithCDN(raw, cdnDomain)
	reader := bytes.NewReader(newData)
	buff, err = io.ReadAll(reader)
	if err != nil {
		return nil, errors.MakeWithMsg(errors.M3u8Read, "read vtt fail: "+err.Error())
	}
	return
}

// 从redis缓存中读取
func readFromRedis(name, domain string) (reader io.Reader, err error) {
	vttKey := redisconst.MediaM3U8Key(name)
	data, err := redis.GetBytes(vttKey)
	if err == nil && len(data) > 0 {
		reader = bytes.NewReader(data)
		return
	}
	requestUrl := utils.JoinUrlPath(domain, name)
	resp, err := http.GetLargeFile(requestUrl, nil)
	if err != nil {
		fmt.Println("requestUrl111", requestUrl)
		return
	}
	fmt.Println("requestUrl", requestUrl, resp.StatusCode)
	if resp.StatusCode != 200 {
		msg := fmt.Sprintf("read vtt fail, url: %s, status code %d", requestUrl, resp.StatusCode)
		err = errors.MakeWithMsg(errors.M3u8Read, msg)
		return
	}
	if err := redis.Set(vttKey, resp.Data,
		redisconst.MediaM3U8CacheExpire); err != nil {
		log.Info("vtt:readFromRedis redis set err", log.E(err))
	}
	reader = bytes.NewReader(resp.Data)
	return
}

// rewriteVttWithCDN 将 vtt 内 "path#xywh=..." 的 path 改为 cdnDomain/path
func rewriteVttWithCDN(vttData []byte, cdnDomain string) []byte {
	cdnDomain = strings.TrimSpace(cdnDomain)
	cdnDomain = strings.TrimRight(cdnDomain, "/")

	var out bytes.Buffer
	scanner := bufio.NewScanner(bytes.NewReader(vttData))

	for scanner.Scan() {
		line := scanner.Text()
		trim := strings.TrimSpace(line)

		// 只处理缩略图行：xxx#xywh=...
		if strings.Contains(trim, "#xywh=") {
			parts := strings.SplitN(trim, "#xywh=", 2)
			if len(parts) == 2 {
				p := strings.TrimSpace(parts[0]) // 原路径
				xywh := parts[1]

				// 已经是绝对URL则不改
				if strings.HasPrefix(p, "http://") || strings.HasPrefix(p, "https://") {
					out.WriteString(p + "#xywh=" + xywh + "\n")
					continue
				}

				// 处理相对路径，确保只有一个 /
				p = strings.TrimLeft(p, "/")
				newPath := cdnDomain + "/" + p
				out.WriteString(newPath + "#xywh=" + xywh + "\n")
				continue
			}
		}

		out.WriteString(line + "\n")
	}

	// scanner.Err()
	return out.Bytes()
}