Switch to discordgo upstream again (#1759)

* Switch to upstream discordgo again

* Fix discord api changes

vendor/github.com/bwmarrin/discordgo/util.go

@@ -0,0 +1,110 @@
+package discordgo
+
+import (
+	"bytes"
+	"encoding/json"
+	"fmt"
+	"io"
+	"mime/multipart"
+	"net/textproto"
+	"strconv"
+	"strings"
+	"time"
+)
+
+// SnowflakeTimestamp returns the creation time of a Snowflake ID relative to the creation of Discord.
+func SnowflakeTimestamp(ID string) (t time.Time, err error) {
+	i, err := strconv.ParseInt(ID, 10, 64)
+	if err != nil {
+		return
+	}
+	timestamp := (i >> 22) + 1420070400000
+	t = time.Unix(0, timestamp*1000000)
+	return
+}
+
+// MultipartBodyWithJSON returns the contentType and body for a discord request
+// data  : The object to encode for payload_json in the multipart request
+// files : Files to include in the request
+func MultipartBodyWithJSON(data interface{}, files []*File) (requestContentType string, requestBody []byte, err error) {
+	body := &bytes.Buffer{}
+	bodywriter := multipart.NewWriter(body)
+
+	payload, err := json.Marshal(data)
+	if err != nil {
+		return
+	}
+
+	var p io.Writer
+
+	h := make(textproto.MIMEHeader)
+	h.Set("Content-Disposition", `form-data; name="payload_json"`)
+	h.Set("Content-Type", "application/json")
+
+	p, err = bodywriter.CreatePart(h)
+	if err != nil {
+		return
+	}
+
+	if _, err = p.Write(payload); err != nil {
+		return
+	}
+
+	for i, file := range files {
+		h := make(textproto.MIMEHeader)
+		h.Set("Content-Disposition", fmt.Sprintf(`form-data; name="file%d"; filename="%s"`, i, quoteEscaper.Replace(file.Name)))
+		contentType := file.ContentType
+		if contentType == "" {
+			contentType = "application/octet-stream"
+		}
+		h.Set("Content-Type", contentType)
+
+		p, err = bodywriter.CreatePart(h)
+		if err != nil {
+			return
+		}
+
+		if _, err = io.Copy(p, file.Reader); err != nil {
+			return
+		}
+	}
+
+	err = bodywriter.Close()
+	if err != nil {
+		return
+	}
+
+	return bodywriter.FormDataContentType(), body.Bytes(), nil
+}
+
+func avatarURL(avatarHash, defaultAvatarURL, staticAvatarURL, animatedAvatarURL, size string) string {
+	var URL string
+	if avatarHash == "" {
+		URL = defaultAvatarURL
+	} else if strings.HasPrefix(avatarHash, "a_") {
+		URL = animatedAvatarURL
+	} else {
+		URL = staticAvatarURL
+	}
+
+	if size != "" {
+		return URL + "?size=" + size
+	}
+	return URL
+}
+
+func bannerURL(bannerHash, staticBannerURL, animatedBannerURL, size string) string {
+	var URL string
+	if bannerHash == "" {
+		return ""
+	} else if strings.HasPrefix(bannerHash, "a_") {
+		URL = animatedBannerURL
+	} else {
+		URL = staticBannerURL
+	}
+
+	if size != "" {
+		return URL + "?size=" + size
+	}
+	return URL
+}