From 3eaf1b921d8320270c448a1d721f0628617a9542 Mon Sep 17 00:00:00 2001
From: Justin Hawkins <justin@hawkins.id.au>
Date: Fri, 24 Sep 2021 15:35:54 +0930
Subject: [PATCH] Add an option to use a youtube-dl fork, and change the
 command line arguments.

---
 README.md | 47 +++++++++++++++++++++++++++++++++++++++++------
 main.go   | 37 +++++++++++++++++++++++++++++++------
 2 files changed, 72 insertions(+), 12 deletions(-)

diff --git a/README.md b/README.md
index 9697efe..88c8816 100644
--- a/README.md
+++ b/README.md
@@ -25,20 +25,55 @@ Binaries are available at https://github.com/tardisx/gropple/releases
 With no arguments, it will listen on port 6283 and use an address of 'http://localhost:6283'.
 
 The address must be specified so that the bookmarklet can refer to the correct
-host when it is not running on your local machine. You may also need to specify
+host if it is not running on your local machine. You may also need to specify
 a different address if you are running it behind a proxy server or similar.
 
 ## Using
 
-Bring up `http://localhost:6283` (or your chosen address) in your browser. You should see a link to the bookmarklet at the top of the screen, and the list of downloads (currently empty).
+Bring up `http://localhost:6283` (or your chosen address) in your browser. You 
+should see a link to the bookmarklet at the top of the screen, and the list of
+downloads (currently empty).
 
-Drag the bookmarklet to your favourites bar, or otherwise bookmark it as you see fit.
+Drag the bookmarklet to your favourites bar, or otherwise bookmark it as you 
+see fit.
 
-Whenever you are on a page with a video you would like to download, simply click the bookmarklet.
+Whenever you are on a page with a video you would like to download, simply 
+click the bookmarklet.
 
-A popup window will appear, the download will start on the your gropple server and the status will be shown in the window.
+A popup window will appear, the download will start on the your gropple server 
+and the status will be shown in the window.
 
-You may close this window at any time without stopping the download, the status of all downloads is available on the index page.
+You may close this window at any time without stopping the download, the status 
+of all downloads is available on the index page.
+
+## Using an alternative downloader
+
+The default downloader is youtube-dl. It is possible to use a different downloader 
+via the `-dl-cmd` command line option.
+
+While `gropple` will use your `PATH` to find the executable, you may also want 
+to specify a full path instead.o
+
+So, for instance, to use `youtube-dlc` instead of `youtube-dl` and specify the 
+full path:
+
+`gropple -dl-cmd /home/username/bin/youtube-dlc`
+
+Note that this is only the path to the executable. If you need to change the 
+command arguments, see below.
+
+## Changing the youtube-dl arguments
+
+The default arguments passed to `youtube-dl` are:
+
+* `--newline` (needed to allow gropple to properly parse the output)
+* `--write-info-json` (optional, but provides information on the download in the corresponding .json file)
+* `-f` and `bestvideo[ext=mp4]+bestaudio[ext=m4a]/best[ext=mp4]/best` (choose the type of video `youtube-dl` will download)
+
+These are customisable on the command line for `gropple`. For example, to duplicate these default options, you would 
+do:
+
+`gropple -dl-args '--newline' -dl-args '--write-info-json' -dl-args '-f' -dl-args 'bestvideo[ext=mp4]+bestaudio[ext=m4a]/best[ext=mp4]/best`
 
 ## TODO
 
diff --git a/main.go b/main.go
index 46f38fb..4bdfdf5 100644
--- a/main.go
+++ b/main.go
@@ -39,18 +39,45 @@ var downloadPath = "./"
 
 var address string
 
+var dlCmd = "youtube-dl"
+
+type args []string
+
+var dlArgs = args{}
+var defaultArgs = args{
+	"--write-info-json",
+	"-f", "bestvideo[ext=mp4]+bestaudio[ext=m4a]/best[ext=mp4]/best",
+	"--newline",
+}
+
 const currentVersion = "v0.02"
 
 //go:embed web
 var webFS embed.FS
 
+func (i *args) Set(value string) error {
+	*i = append(*i, strings.TrimSpace(value))
+	return nil
+}
+
+func (i *args) String() string {
+	return fmt.Sprintf("%v", i)
+}
+
 func main() {
 	var port int
 	flag.IntVar(&port, "port", 6283, "port to listen on")
 	flag.StringVar(&address, "address", "http://localhost:6283", "address for the service")
 	flag.StringVar(&downloadPath, "path", "", "path for downloaded files - defaults to current directory")
+	flag.StringVar(&dlCmd, "dl-cmd", "youtube-dl", "downloader to use")
+	flag.Var(&dlArgs, "dl-args", "arguments to the downloader")
+
 	flag.Parse()
 
+	if len(dlArgs) == 0 {
+		dlArgs = defaultArgs
+	}
+
 	r := mux.NewRouter()
 	r.HandleFunc("/", HomeHandler)
 	r.HandleFunc("/fetch", FetchHandler)
@@ -164,13 +191,11 @@ func FetchHandler(w http.ResponseWriter, r *http.Request) {
 }
 
 func queue(dl *download) {
+	cmdSlice := []string{}
+	cmdSlice = append(cmdSlice, dlArgs...)
+	cmdSlice = append(cmdSlice, dl.Url)
 
-	cmd := exec.Command(
-		"youtube-dl",
-		"--write-info-json",
-		"-f", "bestvideo[ext=mp4]+bestaudio[ext=m4a]/best[ext=mp4]/best",
-		"--newline", dl.Url,
-	)
+	cmd := exec.Command(dlCmd, cmdSlice...)
 	cmd.Dir = downloadPath
 
 	stdout, err := cmd.StdoutPipe()