#!/usr/bin/env bash
# Github: https://github.com/Karmenzind/dotfiles-and-scripts/tree/master/others/aria2
# a script to manage aria2

# -----------------------------------------------------------------------------
# /* custom variables */

# url to fetch bt-tracker list
# if your have no idea what it is
# see http://www.senra.me/solutions-to-aria2-bt-metalink-download-slowly/
# trackerlist_url="https://raw.githubusercontent.com/ngosang/trackerslist/master/trackers_best_ip.txt"
trackerlist_url="https://raw.githubusercontent.com/ngosang/trackerslist/master/trackers_all_ip.txt"

if command -v proxychains >/dev/null && [[ ${USE_PROXYCHAINS_FIRST:=false} == "true" ]]; then
    use_pc=true
else
    use_pc=false
fi
# command -v proxychains && [[ ${USE_PROXYCHAINS_FIRST:=false} == "true" ]] && trackerlist_url="proxychains $"

# update frequency
update_interval_hours=4

# to save your trackerlist
# no need to change
config_dir=${HOME}/.config/aria2 # trackerlist
conffile=${config_dir}/aria2.conf
conffileworking=${conffile}.lock

# parse from configuration
eval log_path=$(sed -n 's/^log=//p' $conffile)
# log_path=${log_path/\$\{HOME\}/$HOME}

eval download_dir=$(sed -n 's/^dir=//p' $conffile)
# echo $download_dir

# TODO(k): <2020-12-29>
local_dir=${HOME}/.local/aria2
dat_file=${local_dir}/session.dat

# open a web manage page while running this script
web_url='http://aria2c.com/'
browser=$(which chromium)

# move log file to specific dir when restart
history_dir=${HOME}/Downloads/aria2/logs

# init dirs and files
init_files() {
    ! [[ -d "$config_dir" ]] && mkdir -p $config_dir && echo "Created $config_dir"
    ! [[ -d "$download_dir" ]] && mkdir -p $download_dir && echo "Created $download_dir"

    if ! [[ "$log_path" == "-" ]]; then
        if [[ -n "$log_path" ]]; then
            local log_dir=$(dirname $log_path)
            ! [[ -d "$log_dir" ]] && mkdir -p $log_dir
            ! [[ -e "$log_path" ]] && touch $log_path
        fi
    fi

    ! [[ -d "$local_dir" ]] && mkdir -p $local_dir && echo "Created $local_dir"
    ! [[ -e "$dat_file" ]] && touch $dat_file

    ! [[ -d "$history_dir" ]] && mkdir -p $history_dir && echo "Created $history_dir"
}

# -----------------------------------------------------------------------------

cut_off='--------------------------------------------'
save_trackerlist_path=${config_dir}/trackerlist
trackers=$(cat $save_trackerlist_path)

help() {
    echo $cut_off
    cat <<EOF
This is a script to manage your aria2.

Usage:
    $0 [OPTION]

Options:
    start [params]      Start your aria2c and update bt-tracker list if conformed
                        *params: aria2c running paramters. See aria2c's man page
    restart [params]    
    stop        

    update              Force-update bt-tracker list and restart service
    log                 Output appended log as the file grows
    status              Check running status

    web                 Open web ui
    rotate              Backup log files

    ...(to be continued)


Feedback:
    github: Karmenzind
    email: valesail@gmail.com

EOF
}

install_service_if_not_exists() {
    [[ -n "$(systemctl --user list-unit-files | grep aria2cd)" ]] && return
    echo "Installing service..."
    mkdir -p ~/.config/systemd/user
    cat >~/.config/systemd/user/aria2cd.service <<EOF
[Unit]
Description=Aria2 Daemon

[Service]
Type=forking
ExecStart=/usr/bin/aria2c --conf-path=${conffileworking}

[Install]
WantedBy=default.target
EOF
    systemctl --user enable aria2cd
}

status_service() {
    echo "Current status:"
    systemctl --no-pager --user status aria2cd
}

start_service() {
    systemctl --user start aria2cd
}

restart_service() {
    systemctl --user restart aria2cd
}

stop_service() {
    systemctl --user stop aria2cd
}

try_exec() {
    which $1 >/dev/null 2>&1
    (($? == 0)) && $@
}

confirm_configration() {
    ! [[ -e $conffileworking ]] && cp $conffile $conffileworking
}

stop() {
    stop_service
}

status() {
    status_service
    log
}

restart() {
    install_service_if_not_exists
    update_config
    restart_service
    status_service
}

start() {
    install_service_if_not_exists
    update_config
    if is_running; then
        echo "Service has been already started."
    else
        start_service
    fi
    status_service
}

log() {
    if [[ "$log_path" == "-" ]]; then
        journalctl --user -fu aria2cd.service
    else
        echo -e '\nLOG:'
        tail $log_path $1
    fi
}

# return 1: need update
internal_update_condition() {
    if [[ ! -e $save_trackerlist_path ]]; then
        return 0
    else
        last_modify=$(stat $save_trackerlist_path | grep -i Modify)
        last_modify_stamp=$(date +%s -d "${last_modify#*:}")
        now_ts=$(date +%s)
        time_dist=$(($now_ts - $last_modify_stamp))
        echo "It's been $time_dist sec since last update."
        interval_second=$(($update_interval_hours * 3600))
        if (($time_dist < $interval_second)); then
            echo -e "Last updated at $last_modify.\nNo need to update."
        else
            return 0
        fi
    fi
    return 1
}

process_raw_trackerlist() {
    python -c "
import sys 
urls = (_.strip() for _ in sys.stdin if _.strip())
result = ','.join(urls)
print(result)
"
}

update_bt_tracker() {
    echo "Feching tracker-list from $trackerlist_url ..."

    echo "[use proxychains: ${use_pc}]"

    if [[ "${use_pc}" == "true" ]]; then
        trackers=$(proxychains curl $trackerlist_url | process_raw_trackerlist)
    else
        trackers=$(curl $trackerlist_url | process_raw_trackerlist)
    fi

    if (($? == 0)) && [[ -n $trackers ]]; then
        echo -e '\nGot new tracker-list:'
        echo $trackers | tee $save_trackerlist_path
    else
        echo -e '\nFailed to get new tracker-list'
    fi
}

rotate_log() {
    if (($save_history)) && [[ -e $log_path ]]; then
        mkdir -p $history_dir
        mv -v $log_path "${history_dir}/until_$(date +%s).log"
    fi
}

update_config() {
    if [[ "$1" == "-f" ]] || [[ -z ${trackers} ]] || internal_update_condition; then
        update_bt_tracker
    fi
    # if [[ "$1" == "-f" ]] || ! [[ -e ${conffileworking} ]] ; then
    [[ -e ${conffileworking} ]] && mv -v $conffileworking ${conffileworking}.backup
    cp $conffile $conffileworking
    if [[ -n ${trackers} ]]; then
        sed -i 's/^bt-tracker=/# \0/' $conffileworking
        echo "bt-tracker=$trackers" >>$conffileworking
        echo "Using trackers: $trackers"
    fi
    echo "Recreated locked configuration file."
    # fi

}

update() {
    update_config -f
    restart
}

is_running() {
    systemctl --user is-active aria2cd
}

open_browser() {
    try_exec $browser 'http://aria2c.com/'
}

# main
# --------------------------------------------
# clear
try_exec figlet aria2
init_files

case $1 in
start) start ;;
stop) stop ;;
restart) restart ;;
status) status ;;
update) update ;;
log) log -f ;;
web) open_browser ;;
*) help ;;
esac

echo -e $cut_off
echo -e '\nDONE :)'