#!/usr/bin/env zsh
# compat: -ash -bash -dash +zsh

rs() { ### @-
    ### record screen. does not record audio.
    ### currently only works on Windows (gdigrab).
    ### i'm sure there's something equivalent for Linux.
    ###
    ### **TODO:** consider renaming because rs(1) already exists.

    local o_overwrite= o_rate=30 o_duration=0
    local o_x=0 o_y=0 o_w=1920 o_h=1080
    local o_filename="output.mp4"
    local opt=

    while getopts -- 'yr:t:o:s:h' opt; do
        case $opt in
        y)  o_overwrite='-y';;
        r)  o_rate=$OPTARG;;
        t)  o_duration=$OPTARG;;
        o)  o_x=${OPTARG%%,*}
            o_y=${${OPTARG#*,}%%,*};;
        s)  o_w=${OPTARG%%,*}
            o_h=${${OPTARG#*,}%%,*};;
        ?)  local fd=0
            [ $opt = h ] && fd=0 || fd=2
            echo -E "usage: $0 [-r framerate] [-t duration] [-o x,y] [-s w,h] [filename]" >&$fd
            [ $opt = h ]
            return
        esac
    done

    shift $((OPTIND-1))

    if [ "$#" -gt 0 ]; then
        o_filename="$1"
        shift
        if [ "$#" -gt 0 ]; then
            echo -E "too many arguments"
            return 1
        fi
    fi

    local extless="${o_filename%.*}"
    local ext="${o_filename##*.}"

    # TODO: handle extensionless case (-f mp4) or something?

    local duration=()
    if [ "$o_duration" -gt 0 ]; then
        duration=(-t $o_duration)
    fi

    # TODO: try -qp 0 with fullscreen (instead of -crf 17)

    ffmpeg -hide_banner -loglevel warning \
        -rtbufsize 100M -f gdigrab \
        -framerate "$o_rate" \
        -offset_x "$o_x" -offset_y "$o_y" \
        -video_size "$o_w"x"$o_h" \
        -draw_mouse 0 -i desktop \
        -c:v libx264 -preset superfast -crf 17 \
        -me_method 1 -partitions i4x4 -x264opts no-cabac \
        -r "$o_rate" ${duration[@]} \
        $o_overwrite "$o_filename" || return

    ffmpeg -hide_banner -loglevel warning \
        -i "$o_filename" \
        -sn -dn -metadata = -map_chapters -1 -movflags +faststart \
        -crf 22 -maxrate 3840k -bufsize 4800k \
        -c:v libx264 -pix_fmt yuv420p -profile:v high -preset slow -threads 0 \
        $o_overwrite "$extless.enc.$ext" || return
}

[ -n "${preload+-}" ] || rs "$@"