#!/bin/bash -e

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

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

function compress() {(
    local nb total dir newdir file
    cd "$DIR"

    dir="$PWD"
    total="$(printf '%s\n' * | wc -l)"
    newdir="${PWD%/*}/$(basename "$dir")_1080p"
    mkdir -p "$newdir"
    for file in *; do
        "${IDENTIFY[@]}" "$file" 2> /dev/null >&2 \
            && "${CONVERT[@]}" -resize x1080 "$file" "$newdir/$file" &
        wait_queue
        nb="$(printf '%s\n' "$newdir"/* | wc -l)"
        echo "$((nb * 100 / total))"
    done
)}

IDENTIFY=(identify)
CONVERT=(convert)
if command -v gm > /dev/null; then
    IDENTIFY=(gm "${IDENTIFY[@]}")
    CONVERT=(gm "${CONVERT[@]}")
fi

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

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

for DIR in "$@"; do
    compress | zenity --progress --title="$DIR"
done