#!/bin/bash

# this is simply my recommended encoding method.
# do not take this as a holy grail.

usage() {
    echo "unrecognized arguments, please retry"
    echo "encode -i input_file [-p] output_file"
    echo -e "\t-p print the command instead of executing [optional]"
    return 0 
}

encode() {
    ENCODE_FILE="/tmp/encode.sh"

    echo ffmpeg -i \""$INPUT"\" -map 0 $(unmap_streams "$INPUT") \
        -af '"aformat=channel_layouts=7.1|5.1|stereo|mono"' -c:a libopus $(get_bitrate_audio "$INPUT") \
        -c:s copy -c:V libsvtav1 -pix_fmt yuv420p10le -crf 25 -preset 3 -g 240 \
        -svtav1-params \"tune=0:enable-overlays=1:scd=1:enable-hdr=1:fast-decode=1:enable-variance-boost=1\" \
        \""$OUTPUT"\" "&& mkvpropedit \"$OUTPUT\" --add-track-statistics-tags " > "$ENCODE_FILE"
    
        if [[ "$PRINT_OUT" == "true" ]];
        then
            cat "$ENCODE_FILE"
        else
            bash "$ENCODE_FILE"
        fi
}

unmap_streams(){
    INPUT="$1"
    UNMAP_FILTER="jpeg|png"
    UNMAP_STREAMS=$(ffprobe "$INPUT" 2>&1 | grep "Stream" | grep -Ei "$UNMAP_FILTER" | cut -d':' -f2 | tr '\n' ' ')
    UNMAP_CMD=""
    for UNMAP_STREAM in $UNMAP_STREAMS; do
        UNMAP_CMD+="-map -0:$UNMAP_STREAM "
    done
    echo "$UNMAP_CMD"
}

get_bitrate_audio() {
    BITRATE_CMD=""
    NUM_AUDIO_STREAMS=$(ffprobe -v error -select_streams a -show_entries stream=index -of csv=p=0 "$INPUT" | wc -l)
    for ((i = 0; i < NUM_AUDIO_STREAMS; i++)); do
        NUM_CHANNELS=$(ffprobe -v error -select_streams "a:$i" -show_entries stream=channels -of default=noprint_wrappers=1:nokey=1 "$INPUT")
        BITRATE=$((NUM_CHANNELS * 64))
        BITRATE_CMD+="-b:a:$i ${BITRATE}k "
    done
    echo "$BITRATE_CMD"
}


OPTS='i:p'
NUM_OPTS=$(echo $OPTS | tr ':' '\n' | wc -l)
PRINT_OUT="false"
MIN_OPT=2
MAX_OPT=4
test "$#" -lt $MIN_OPT && usage && exit 1
test "$#" -gt $MAX_OPT && usage && exit 1
while getopts "$OPTS" flag; do
    case "${flag}" in
        i)
            INPUT="${OPTARG}"
            ;;
        p)
            PRINT_OUT="true"
            ;;
        *)
            usage
            exit 1
            ;;        
    esac
done

# allow optional output filename
if [[ "$#" -eq $MAX_OPT ]]; then
    OUTPUT="${@: -1}"
elif [[ 
    ("$PRINT_OUT" == "true") &&
    ( "$#" -eq 3) 
    ]]; then
    OUTPUT="${HOME}/av1_${INPUT}"
elif [[ "$#" -eq 2 ]]; then
    OUTPUT="${HOME}/av1_${INPUT}"
else
    OUTPUT="${@: -1}"
fi

echo
echo "INPUT: $INPUT, PRINT_OUT: $PRINT_OUT, OUTPUT: $OUTPUT"
echo

encode