#!/bin/bash -e

THREADS="$(nproc --all)"
THREADS="$((THREADS / 2))"

function wait_queue() {
    for job in $(jobs -p | awk "FNR>=$THREADS"); do
        wait "$job"
    done
}

if [ -z "$1" ]; then
    set "$(zenity --file-selection --multiple --directory --separator='
')" > /dev/null
fi

if [ -z "$1" ]; then
    exit 1
fi

for DIR in "$@"; do
    cd "$DIR"
    DIR="$PWD"
    NEWDIR="${PWD%/*}/$(basename "$DIR")_1080p"
    mkdir -p "$NEWDIR"
    for FILE in *; do
        wait_queue
        identify "$FILE" 2> /dev/null >&2 \
            && convert -resize x1080 "$FILE" "$NEWDIR/$FILE" &
    done
done

wait_queue
zenity --info --text="Done"