apijson/parsechannel.go

   1 package apijson
   2
   3 import (
   4         "github.com/valyala/fastjson"
   5         "errors"
   6         "strings"
   7         "net/http"
   8         "io/ioutil"
   9         "fmt"
  10 )
  11
  12 var MissingData = errors.New("missing data")
  13 var ServerError = errors.New("server error")
  14
  15 func ParseChannelVideoURLs(res *http.Response) ([]string, error) {
  16         if res.StatusCode != 200 {
  17                 return nil, fmt.Errorf("HTTP error: %s", res.Request.URL.String())
  18         }
  19
  20         // Download response
  21         defer res.Body.Close()
  22         buf, err := ioutil.ReadAll(res.Body)
  23         if err != nil { return nil, err }
  24
  25         // Parse JSON
  26         var p fastjson.Parser
  27         rootObj, err := p.ParseBytes(buf)
  28         if err != nil { return nil, err }
  29
  30         // Root as array
  31         root, err := rootObj.Array()
  32         if err != nil { return nil, err }
  33
  34         // Find response container
  35         var container *fastjson.Value
  36         for _, item := range root {
  37                 if item.Exists("response") {
  38                         container = item
  39                         break
  40                 }
  41         }
  42         if container == nil { return nil, MissingData }
  43
  44         // Get error obj
  45         errorExists := container.Exists(
  46                 "response",
  47                 "responseContext",
  48                 "errors",
  49                 "error",
  50         )
  51         if errorExists { return nil, ServerError }
  52
  53         // Get items from grid
  54         itemsObj := container.Get(
  55                 "response",
  56                 "continuationContents",
  57                 "gridContinuation",
  58                 "items",
  59         )
  60         if itemsObj == nil { return nil, MissingData }
  61
  62         // Items as array
  63         items, err := itemsObj.Array()
  64         if err != nil { return nil, err }
  65
  66         urls := make([]string, 0)
  67
  68         // Enumerate
  69         for _, item := range items {
  70                 // Find URL
  71                 urlObj := item.Get(
  72                         "gridVideoRenderer",
  73                         "navigationEndpoint",
  74                         "commandMetadata",
  75                         "webCommandMetadata",
  76                         "url",
  77                 )
  78                 if urlObj == nil { return nil, MissingData }
  79
  80                 // URL as string
  81                 urlBytes, err := urlObj.StringBytes()
  82                 if err != nil { return nil, err }
  83                 url := string(urlBytes)
  84
  85                 if strings.HasPrefix(url, "/watch?v") {
  86                         urls = append(urls, "https://www.youtube.com" + url)
  87                 }
  88         }
  89         return urls, nil
  90 }