bgrab.go

package main

import (
	"crypto/md5"
	"encoding/json"
	"errors"
	"fmt"
	"io"
	"log"
	"regexp"
	"sort"
	"strings"

	"github.com/PuerkitoBio/goquery"
	"github.com/parnurzeal/gorequest"
)

type DocId struct {
	CID string
	AID string
}

const (
	APP_KEY  = "6f90a59ac58a4123"
	APP_SEC  = "0bfd84cc3940035173f35e6777508326"
	BASE_URL = "https://interface.bilibili.com/playurl"
)

func signParam(param map[string]string) {
	param["appkey"] = APP_KEY

	keys := make([]string, len(param))

	i := 0
	for k, _ := range param {
		keys[i] = k
		i++
	}

	sort.Strings(keys)

	data := ""
	for _, v := range keys {
		if data != "" {
			data += "&"
		}
		data += v + "=" + param[v]
	}
	data += APP_SEC
	param["sign"] = fmt.Sprintf("%x", md5.Sum([]byte(data)))
}

func parseId(id string) (*DocId, error) {
	url := fmt.Sprintf("http://www.bilibili.com/video/av%s", id)
	doc, err := goquery.NewDocument(url)

	if err != nil {
		return nil, err
	}

	sel := doc.Find(".scontent>script")
	if sel != nil {
		script := sel.Text()
		regex := regexp.MustCompile("cid=(\\d+)&aid=(\\d+)&pre_ad=.*")

		result := regex.FindStringSubmatch(script)
		if result == nil {
			return nil, errors.New("ID not found")
		}

		var id DocId
		id.CID = result[1]
		id.AID = result[2]

		return &id, nil
	} else {
		return nil, errors.New("ID not found")
	}
}

func GrabVideoUrl(aid string) (string, error) {
	id, err := parseId(aid)

	if err != nil {
		return "", err
	}

	var param map[string]string = make(map[string]string)
	param["cid"] = id.CID
	param["otype"] = "json"
	param["type"] = "mp4"
	param["quality"] = "3"

	signParam(param)

	data := ""
	for k, v := range param {
		if data != "" {
			data += "&"
		}
		data += k + "=" + v
	}

	url := fmt.Sprintf("%s?%s", BASE_URL, data)
	request := gorequest.New()
	_, body, errs := request.Get(url).End()

	if errs != nil && len(errs) > 0 {
		return "", errs[0]
	}

	//log.Println(body)
	dec := json.NewDecoder(strings.NewReader(body))
	video_url := ""
	for {
		t, err := dec.Token()
		if err == io.EOF {
			break
		}

		if err != nil {
			return "", err
		}
		//fmt.Printf("%T: %v", t, t)
		if t == "url" {
			t, err := dec.Token()
			if err != nil {
				return "", err
			}
			video_url = fmt.Sprintf("%v", t)
		}

		//fmt.Printf("\n")
	}

	return video_url, nil
}

func main() {
	//url := "http://www.bilibili.com/video/av6467776/"
	url, _ := GrabVideoUrl("6467776")
	log.Println(url)
}