#!/bin/bash

# 2025, 2026, writen mostly by chatgpt, rewriten to get compression percentage by chatgpt.

# toALAC with concurrency
# usage: toALAC *.wav

trap "echo -e '\nAborted by user.'; kill 0" INT

if [ $# -eq 0 ]; then
    echo "Usage: toALAC *.wav"
    exit 1
fi

MAX_JOBS=4
jobcount=0

total_in=0
total_out=0

# calculate total input size
for f in "$@"; do
    [ -f "$f" ] && (( total_in += $(stat -c%s "$f") ))
done

for f in "$@"; do
    [ -f "$f" ] || { echo "Skipping: $f (not a file)"; continue; }
    base="${f%.*}"
    out="${base}.alac.m4a"
    echo "Encoding: $f -> $out"

    (
        ffmpeg -y -hide_banner -loglevel quiet -i "$f" -c:a alac "$out"

        # add output size safely after encoding finishes
        if [ -f "$out" ]; then
            size=$(stat -c%s "$out")
            echo "$size" >> /tmp/alac_sizes.$$
        fi
    ) &

    ((jobcount++))
    if (( jobcount % MAX_JOBS == 0 )); then
        wait -n
    fi
done

wait

# sum output sizes
if [ -f /tmp/alac_sizes.$$ ]; then
    while read -r s; do
        (( total_out += s ))
    done < /tmp/alac_sizes.$$
    rm -f /tmp/alac_sizes.$$
fi

# compute compression
if (( total_in > 0 )); then
    ratio=$(awk -v tin="$total_in" -v tout="$total_out" \
        'BEGIN { if (tin > 0) printf "%.2f", (tout/tin) * 100; else print "0.00" }')
else
    ratio="0.00"
fi

echo "All encodes finished. Final size is ${ratio}% of original"