/
net.go
333 lines (293 loc) · 9.07 KB
/
net.go
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package main
import (
"bufio"
"bytes"
"errors"
"fmt"
"image"
"image/jpeg"
"image/png"
"io"
"net/http"
"strconv"
"strings"
"time"
)
var client = http.Client{Timeout: 120 * time.Second}
// TODO: cancel response body readings for unfinished tracks
// will solve a lot of problems
// TODO: maybe it is a good idea to check domain everytime, just in case?
func download(link string, mobile bool, checkDomain bool) (io.ReadCloser, string) {
window.sendEvent(newDebugMessage(link))
request, err := http.NewRequest("GET", link, nil)
if err != nil {
window.sendEvent(newErrorMessage(err))
return nil, ""
}
// pretend that we are Chrome on Win10
request.Header.Set("User-Agent", "Mozilla/5.0 (Macintosh; Intel Mac OS X 12_0_1) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/95.0.4638.69 Safari/537.36")
// set mobile view, html weights a bit less than desktop version
if mobile {
request.Header.Set("Cookie", "mvp=p")
}
response, err := client.Do(request)
if err != nil {
// https requests fail here because reasons (real certificate
// is replacced by expired generic one), only relevant for
// images at the moment
// basically try http instead of https, and don't report error
if strings.Contains(link, "https://") {
window.sendEvent(newDebugMessage(err.Error() + "; trying over http://"))
return download(strings.Replace(link, "https://", "http://", 1),
mobile, checkDomain)
}
window.sendEvent(newErrorMessage(err))
return nil, ""
}
window.sendEvent(newDebugMessage(response.Status))
// not all artists are hosted on bandname.bandcamp.com,
// deal with aliases by reading canonical names from response
if checkDomain {
if !strings.Contains(response.Header.Get("Link"),
"bandcamp.com") {
window.sendEvent(newErrorMessage(errors.New("response came not from bandcamp.com")))
window.sendEvent(newDebugMessage(fmt.Sprint(response)))
response.Body.Close()
return nil, ""
}
}
return response.Body, response.Header.Get("content-type")
}
func processMediaPage(link string) {
defer wg.Done()
window.sendEvent(newMessage("fetching media page..."))
reader, _ := download(link, false, true)
if reader == nil {
window.sendEvent(newItem(nil))
return
}
defer reader.Close()
window.sendEvent(newMessage("parsing..."))
scanner := bufio.NewScanner(reader)
// NOTE: might fail here
// 64k is not enough for all pages apparently
// failed on a page with 43 tracks
var buffer []byte
scanner.Buffer(buffer, 131072)
var metaDataJSON string
var mediaDataJSON string
var err error
var isAlbum bool
// TODO: expects only album/track pages and artist page with pinned item
// if artist page is discography, will try to parse it as album/track
// doesn't crash, but doesn't need to get there in the first place
// NOTE: 5ccc945faa4b3243c4ab9f71ec53ed0c9a5c7df7 - absolutely zero idea
// what was here before and why, probably there was a reason for that
for scanner.Scan() {
line := scanner.Text()
if strings.Contains(line, "og:type") {
if strings.Contains(line, "album") {
isAlbum = true
}
} else if strings.Contains(line, "application/ld+json") {
scanner.Scan()
metaDataJSON = scanner.Text()
} else if prefix := `data-tralbum="`; strings.Contains(line, prefix) {
mediaDataJSON, err = extractJSON(prefix, line, `"`)
}
}
if err != nil {
window.sendEvent(newErrorMessage(err))
return
}
if metaDataJSON != "" || mediaDataJSON != "" {
if !isAlbum {
window.sendEvent(newMessage("found track data"))
} else {
window.sendEvent(newMessage("found album data"))
}
metadata, err := parseTrAlbumJSON(metaDataJSON, mediaDataJSON, isAlbum)
if err == nil {
window.sendEvent(newItem(metadata))
} else {
window.sendEvent(newErrorMessage(err))
}
} else {
window.sendEvent(newErrorMessage(errors.New("unexpected page format")))
}
}
func downloadMedia(link string, track int) {
defer wg.Done()
var err error
key := getTruncatedURL(link)
// TODO: move this check to upper level?
if _, ok := cache.get(key); ok {
window.sendEvent(newTrackDownloaded(key))
window.sendEvent(newMessage(fmt.Sprintf("playing track %d from cache",
track+1)))
return
}
window.sendEvent(newMessage(fmt.Sprintf("fetching track %d...", track+1)))
// NOTE: media location suggests that there is always only mp3 files on server
// for now ignore type of media
reader, _ := download(link, false, false)
if reader == nil {
return // error should be reported on other end already
}
defer reader.Close()
window.sendEvent(newMessage(fmt.Sprintf("downloading track %d...", track+1)))
body, err := io.ReadAll(reader)
if err != nil {
window.sendEvent(newErrorMessage(err))
return
}
cache.set(getTruncatedURL(link), body)
window.sendEvent(newTrackDownloaded(key))
window.sendEvent(newMessage(fmt.Sprintf("track %d downloaded", track+1)))
}
func downloadCover(link string) {
defer wg.Done()
window.sendEvent(newDebugMessage("fetching album cover..."))
reader, format := download(link, false, false)
if reader == nil {
window.sendEvent(newCoverDownloaded(nil, ""))
return
}
defer reader.Close()
window.sendEvent(newDebugMessage("downloading album cover..."))
var img image.Image
var err error
switch format {
case "image/jpeg":
img, err = jpeg.Decode(reader)
// in case there is png somewhere for whatever reason
case "image/png":
img, err = png.Decode(reader)
default:
img, err = nil, errors.New("unexpected image format")
}
if err != nil {
window.sendEvent(newErrorMessage(err))
window.sendEvent(newCoverDownloaded(nil, ""))
return
}
window.sendEvent(newDebugMessage("album cover downloaded"))
window.sendEvent(newCoverDownloaded(img, link))
}
func processTagPage(args arguments) {
defer wg.Done()
window.sendEvent(newMessage("fetching tag search page..."))
sbuilder := strings.Builder{}
defer sbuilder.Reset()
fmt.Fprint(&sbuilder, "https://bandcamp.com/tag/", args.tags[0], "?tab=all_releases")
if len(args.tags) > 1 {
fmt.Fprint(&sbuilder, "&t=")
for i := 1; i < len(args.tags); i++ {
if i == 1 {
fmt.Fprint(&sbuilder, args.tags[i])
continue
}
fmt.Fprint(&sbuilder, "%2C", args.tags[i])
}
}
var inHighlights bool
if args.sort != "" && args.sort != "highlights" {
fmt.Fprint(&sbuilder, "&s=", args.sort)
} else if args.sort == "highlights" {
inHighlights = true
}
if args.format != "" {
fmt.Fprint(&sbuilder, "&f=", args.format)
}
reader, _ := download(sbuilder.String(), false, true)
if reader == nil {
return
}
defer reader.Close()
window.sendEvent(newMessage("parsing..."))
scanner := bufio.NewScanner(reader)
var dataBlobJSON string
// NOTE: might fail here
// 64k is not enough for these pages
// buffer with size 1048576 reads json with 178 items
var buffer []byte
var err error
scanner.Buffer(buffer, 1048576)
for scanner.Scan() {
line := scanner.Text()
if prefix := `data-blob="`; strings.Contains(line, prefix) {
dataBlobJSON, err = extractJSON(prefix, line, `"`)
break
}
}
if err != nil {
window.sendEvent(newErrorMessage(err))
return
}
window.sendEvent(newMessage("found data"))
results, err := parseTagSearchJSON(dataBlobJSON, inHighlights)
if err != nil {
window.sendEvent(newErrorMessage(err))
return
}
if results == nil || len(results.Items) == 0 {
window.sendEvent(newMessage("nothing was found"))
return
}
window.sendEvent(newTagSearch(results))
}
func extractJSON(prefix, line, suffix string) (string, error) {
start := strings.Index(line, prefix)
start += len(prefix)
end := strings.Index(line[start:], suffix)
end += start
if start == -1 || end == -1 || end < start {
return "", errors.New("unexpected page format")
}
replacer := strings.NewReplacer(`"`, `"`, `&`, `&`, `'`, `'`)
return replacer.Replace(line[start:end]), nil
}
// cache key = media url without any parameters
func getTruncatedURL(link string) string {
if strings.Contains(link, "?") {
index := strings.Index(link, "?")
return link[:index]
} else {
return ""
}
}
func getAdditionalResults(result *Result) {
defer wg.Done()
window.sendEvent(newMessage("pulling additional results..."))
jsonString := "{\"filters\":" + result.filters + ",\"page\":" +
strconv.Itoa(result.page) + "}"
buffer := bytes.NewBuffer([]byte(jsonString))
request, err := http.NewRequest("POST",
"https://bandcamp.com/api/hub/2/dig_deeper", buffer)
if err != nil {
window.sendEvent(newAdditionalTagSearch(nil))
window.sendEvent(newErrorMessage(err))
return
}
// pretend that we are Chrome on Win10
request.Header.Set("User-Agent", "Mozilla/5.0 (Macintosh; Intel Mac OS X 12_0_1) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/95.0.4638.69 Safari/537.36")
response, err := client.Do(request)
if err != nil {
window.sendEvent(newAdditionalTagSearch(nil))
window.sendEvent(newErrorMessage(err))
return
}
body, err := io.ReadAll(response.Body)
if err != nil {
window.sendEvent(newAdditionalTagSearch(nil))
window.sendEvent(newErrorMessage(err))
return
}
additionalResult, err := extractResults(body)
if err != nil {
window.sendEvent(newAdditionalTagSearch(nil))
window.sendEvent(newErrorMessage(err))
return
}
window.sendEvent(newAdditionalTagSearch(additionalResult))
}