#!/bin/sh

# references:
# https://blog.csdn.net/qq_41730930/article/details/79327757
# https://blog.csdn.net/u011112876/article/details/89634505
# https://github.com/pystardust/ytfzf

homepage_url='https://node.kg.qq.com/cgi/fcgi-bin/kg_ugc_get_homepage'
music_url='https://node.kg.qq.com/cgi/fcgi-bin/fcg_get_play_url'
# num seems only 8 and 15 works
num=15
tmp_file="$(mktemp)"

get_json () {
	curl -s -G --data-urlencode type=get_uinfo -d outCharset=utf-8 -d start="$1" -d num=$num -d share_uid="$uid" "$homepage_url" | sed 's/.*({\(.*\)}).*/{\1}/'
}

# concurrent file append with less than 4096 bytes will be atomic on arch linux ext4
# so need to process json data before append to the file, to append less than 4096 bytes for each process
# another appraoch is to use a loop to write to several files each corresponding to one process
# https://stackoverflow.com/questions/1154446/is-file-append-atomic-in-unix
# https://unix.stackexchange.com/questions/458653/parallel-processes-appending-outputs-to-an-array-in-a-bash-script
process_json() {
	jq -r '.data.ugclist[]|"'"$music_url"'?shareid=\(.shareid)\n out=\(.title)_\(.time).m4a"' >> "$tmp_file"
}

while getopts u: opt; do
	case $opt in
		u) uid="$OPTARG";;
		\?) exit 1;;
	esac
done
# for lan lan, uid=649b9e82272a348b
# for cheng ruan, uid=64949d822c25328c
[ -z "$uid" ] && echo 'error: must provide share_uid
ex: curlkg -u 649b9e82272a348b ./' >&2 && exit 1 
shift $((OPTIND-1))
download_dir="${1:-"$PWD"}"
[ -d "$download_dir" ] || mkdir -p "$download_dir"

first_json="$(get_json 1)"
ugc_total_count=$(echo "$first_json" | jq '.data.ugc_total_count')
echo "$first_json" | process_json
# can also use while loop with i=$((i+1))
# the calculation considers both ugc_total_count%num==0 and ugc_total_count%num>0
for i in $(seq 2 $(((ugc_total_count+num-1)/num))); do
	get_json "$i" | process_json &
done

wait
aria2c -d "$download_dir" --auto-file-renaming=false --console-log-level=warn -i "$tmp_file"
rm "$tmp_file"