#!/bin/sh

#initializing..

help_text () {
        while IFS= read -r line; do
	    printf "%s\n" "$line"
	done <<-EOF
	Usage:
	    ${0##*/} [ -o <filename> ] [ -r | -f | -n <no. of connections>] [ <m3u8_link> ]
	    ${0##*/} -h
	
	Options:
	    -h show helptext
	    -o filename (default : video)
	    -r select highest resolution automatically
	    -n set maximum number of connections (default : 36)
	    -f skip ffmpeg file conversion (used to enable the video file to run on any video player)
	    -s subtitles url (will be saved as same name as the video file)
	EOF
}

download(){
	printf "" > $failed
	for i in $1; do 
	    curl --max-time 30 -s "${relative_url}$(printf "%s" "$data" | sed -n "${i}p")" > "$tmpdir/$(printf "%05d" "$i").ts" && printf "\033[2K\r\033[1;32m ✓ $i / $range done" || printf "$i\n" >> $failed &
	    jobs -p > "$jobdir"
	    while [ "$(cat "$jobdir" | wc -l)" -ge $n ];do jobs > "$jobdir";sleep 0.05;done
	done
	wait
}

n=36 #no. of parallel download or connections
file="video" #default filename
tmpdir="${XDG_CACHE_HOME:-$HOME/.cache}/hls-temp"
jobdir="${XDG_CACHE_HOME:-$HOME/.cache}/hls-jobs"
failed="${XDG_CACHE_HOME:-$HOME/.cache}/hls-fail"

while getopts 'o:rfhn:s:' OPT; do
        case $OPT in
                o)	file=$OPTARG ;;
                n)	n=$OPTARG ;;
                f)	skip_ffmpeg=1;;
                r)	skip_res=1;;
		s)	subs=$OPTARG;;
                *|h)
                        help_text
                        exit 0
                        ;;
	esac
done
shift $((OPTIND - 1))

[ -z "$*" ] && printf "\033[1;34mEnter link >\033[0m " && read -r link || link=$* 
trap "killall curl;rm -rdf $tmpdir $jobdir;exit 0" INT HUP
printf "\033[2K\r\033[1;36mFetching resolutions.."
m3u8_data=$(curl -s "$link")
res_list=$(printf "%s" "$m3u8_data" | sed -nE 's_.*RESOLUTION=.*x([^,]*).*_\1_p')
if [ -n "$res_list" ];then
        highest_res=$(printf "$res_list" | sort -nr | head -1)
        [ -z "$skip_res" ] && printf "\033[2K\r\033[1;33mRESOLUTIONS >>\n\033[0m$res_list\n\033[1;34mType ur preferred resolution (default: $highest_res) > " && read -r sel_res || printf "\033[2K\r\033[1;36mSelecting highest resolution.."
        [ -z "$sel_res" ] && sel_res=$highest_res
        unset highest_res res_list
        url=$(printf "%s" "$m3u8_data" | sed -n "/x$sel_res/{n;p;}" | tr -d '\r')
    #check whether the m3u8_data contains uri that starts from http
        printf "%s" "$m3u8_data" | grep -q "http" || relative_url=$(printf "%s" "$link" | sed 's_[^/]*$__')
        printf "\033[2K\r\033[1;36mFetching Metadata.."
	url="${relative_url}$url"
        resp="$(curl -s "$url")"
else
	url=$link
        resp=$m3u8_data
fi
[ -d "$tmpdir" ] || mkdir -p "$tmpdir"
#extract key uri and iv uri from encrypted stream if exists..
key_uri="$(printf "%s" "$resp" | sed -nE 's/^#EXT-X-KEY.*URI="([^"]*)"/\1/p')"
[ -z "$key_uri" ] || iv_uri="$(printf "%s" "$resp" | sed -nE 's/^#EXT-X-IV.*URI="([^"]*)"/\1/p')"
data="$(printf "%s" "$resp" | sed '/#/d')"
printf "%s" "$data" | grep -q "http" && relative_url='' || relative_url=$(printf "%s" "$url" | sed 's_[^/]*$__')
range=$(printf "%s\n" "$data" | wc -l)

#for encrypted stream only
if [ -n "$key_uri" ];then
	#extract key from uri..
	key=$(curl -s "$key_uri" | od -A n -t x1 | tr -d ' |\n')
	#iv from uri
	[ -z "$iv_uri" ] && iv=$(openssl rand -hex 16) || iv=$(curl -s "$iv_uri" | od -A n -t x1 | tr -d ' |\n')
fi

printf "\033[2K\r\033[1;35mpieces : $range\n\033[1;33mDownloading.."
#downloading .ts data asynchronously
download "$(seq $range)"
#redownloading failed pieces
download "$(cat $failed)"
#downloading subtitles if uri passed using -s option
[ -z "$subs" ] || curl -s "$subs" -o "$file.srt" &

#concatenating all .ts file in one file..
if [ -n "$key_uri" ];then
    #decrypting while concatenating..
    printf "\033[2K\r\033[1;36m Decrypting and Concatenating pieces into single file.."
    for i in "$tmpdir"/*;do
	openssl aes-128-cbc -d -K "$key" -iv "$iv" -nopad >> "$file.ts" < "$i"
    done
else
    printf "\033[2K\r\033[1;36m Concatenating pieces into single file.."
    cat "$tmpdir"/* >> "$file.ts"
fi

rm -rdf $tmpdir $jobdir $failed
#conversion of allts file to mp4 video using ffmpeg..
if [ -z "$skip_ffmpeg" ];then
    printf "\033[2K\r\033[1;36mEncoding file to mp4 video..\n\033[0m"
    ffmpeg -i "$file.ts" -loglevel error -stats -c copy "$file.mp4"
else
    mv "$file.ts" "$file.mp4"
fi

#cleanup..
rm -f "$file".ts
printf "\033[2K\r\033[1;36m Done!!"