function vrot -d 'Rotate a video with ffmpeg: metadata-only by default, re-encode with -r'
    argparse -n vrot 'h/help' 'r/reencode' 'a/angle=' 'p/preset=' -- $argv
    or return 2

    if set -q _flag_help
        __vrot_usage
        return 0
    end

    if test (count $argv) -lt 1
        __vrot_usage
        return 2
    end

    set -q _flag_angle; or set _flag_angle 90
    set -q _flag_preset; or set _flag_preset medium

    switch $_flag_angle
        case 90 180 270
        case '*'
            __vrot_error "angle must be 90, 180 or 270 (got '$_flag_angle')"
            return 2
    end

    __vrot_colors

    set -l want_reencode 0
    set -q _flag_reencode; and set want_reencode 1

    set -l rc 0
    for file in $argv
        if not test -f "$file"
            __vrot_error "no such file: '$file'"
            set rc 1
            continue
        end
        __vrot_one "$file" "$_flag_angle" "$_flag_preset" "$want_reencode"
        or set rc 1
    end
    return $rc
end

function __vrot_one
    set -l file $argv[1]
    set -l angle $argv[2]
    set -l preset $argv[3]
    set -l want_reencode $argv[4]

    set -l name (path basename "$file")
    set -l ext (path extension "$file")
    set -l out (path change-extension '' "$file")_rot$ext
    set -l outname (path basename "$out")

    __vrot_banner "$name  →  $outname"

    set -l lines (ffprobe -v error -select_streams v:0 \
        -show_entries stream=codec_name,width,height,r_frame_rate,nb_frames:format=duration,bit_rate \
        -of default=noprint_wrappers=1 "$file")

    set -l codec (string match 'codec_name=*' -- $lines | string replace 'codec_name=' '')[1]
    set -l width (string match 'width=*' -- $lines | string replace 'width=' '')[1]
    set -l height (string match 'height=*' -- $lines | string replace 'height=' '')[1]
    set -l fpsraw (string match 'r_frame_rate=*' -- $lines | string replace 'r_frame_rate=' '')[1]
    set -l frames (string match 'nb_frames=*' -- $lines | string replace 'nb_frames=' '')[1]
    set -l duration (string match 'duration=*' -- $lines | string replace 'duration=' '')[1]
    set -l bitrate (string match 'bit_rate=*' -- $lines | string replace 'bit_rate=' '')[1]

    set -l info "$width"x"$height"
    if test -n "$codec"
        set info "$info  "(string upper "$codec")
    end
    if test -n "$fpsraw"; and string match -rq '^[0-9]+/[0-9]+$' "$fpsraw"; and not string match -q '*/0' "$fpsraw"
        set info "$info  "(math -s 2 "$fpsraw")" fps"
    end
    if test -n "$duration"; and string match -rq '^[0-9.]+$' "$duration"
        set info "$info  "(__vrot_fmtsecs "$duration")
    end
    if test -n "$bitrate"; and string match -rq '^[0-9.]+$' "$bitrate"
        set info "$info  "(math -s 1 "$bitrate/1000000")" Mbit/s"
    end
    echo "$vrot_c_dim  $info$vrot_c_reset"

    if test "$file" = "$out"
        __vrot_error "output would overwrite input: '$out'"
        return 1
    end

    if test -e "$out"
        read -l -P "vrot: '$out' exists. Overwrite? [y/N] " ans
        if not string match -qi 'y' "$ans"
            echo "$vrot_c_dim  skipped: $out$vrot_c_reset"
            return 1
        end
        rm -f "$out"
    end

    if test "$want_reencode" -eq 1
        __vrot_reencode "$file" "$out" "$angle" "$preset" "$height" "$codec" "$duration" "$frames"
        return $status
    end

    echo "$vrot_c_dim  mode: metadata-only rotation (lossless, instant)$vrot_c_reset"
    ffmpeg -hide_banner -loglevel error -nostdin -i "$file" -map 0 -c copy -ignore_unknown \
        -movflags +faststart -metadata:s:v:0 rotate=$angle "$out"
    if test $status -eq 0
        __vrot_summary "$out"
        return 0
    end

    echo "$vrot_c_warn  ↷ dropping unsupported data/attachment tracks, retrying…$vrot_c_reset"
    rm -f "$out"
    ffmpeg -hide_banner -loglevel error -nostdin -i "$file" -map 0 -map '-0:d' -map '-0:t' \
        -c copy -movflags +faststart -metadata:s:v:0 rotate=$angle "$out"
    if test $status -eq 0
        __vrot_summary "$out"
        return 0
    end

    echo "$vrot_c_warn  ↷ metadata rotation unsupported here, re-encoding instead…$vrot_c_reset"
    rm -f "$out"
    __vrot_reencode "$file" "$out" "$angle" "$preset" "$height" "$codec" "$duration" "$frames"
end

function __vrot_reencode
    set -l file $argv[1]
    set -l out $argv[2]
    set -l angle $argv[3]
    set -l preset $argv[4]
    set -l height $argv[5]
    set -l codec $argv[6]
    set -l duration $argv[7]
    set -l frames $argv[8]

    test -n "$height"; or set height 1080

    set -l enc libx264
    switch "$codec"
        case 'hevc*' 'h265*' 'h266*'
            set enc libx265
    end

    set -l crf 20
    set -l maxrate 20M
    set -l bufsize 40M
    if test $height -ge 2160
        set crf 22; set maxrate 40M; set bufsize 80M
    else if test $height -ge 1440
        set crf 21; set maxrate 30M; set bufsize 60M
    else if test $height -ge 1080
        set crf 20; set maxrate 20M; set bufsize 40M
    else if test $height -ge 720
        set crf 19; set maxrate 10M; set bufsize 20M
    else
        set crf 18; set maxrate 6M; set bufsize 12M
    end

    set -l vf 'transpose=1'
    switch $angle
        case 180
            set vf 'transpose=1,transpose=1'
        case 270
            set vf 'transpose=2'
    end

    set -l faststart
    switch (string lower (path extension "$out"))
        case '.mp4' '.mov' '.m4v'
            set faststart '-movflags' '+faststart'
    end

    echo "$vrot_c_dim  mode: re-encode ($enc · crf $crf · cap $maxrate)$vrot_c_reset"

    set -l total_frames ''
    string match -rq '^\d+$' "$frames"; and test "$frames" -gt 0; and set total_frames $frames

    set -l out_t ''
    set -l frame 0
    set -l fps_txt ''
    set -l bitrate_txt ''
    set -l speed_txt ''

    ffmpeg -hide_banner -loglevel error -nostdin -progress pipe:1 -i "$file" \
        -map 0:v -map '0:a?' -map '0:s?' -ignore_unknown -vf "$vf" -c:v $enc -crf $crf \
        -maxrate $maxrate -bufsize $bufsize -preset $preset -c:a copy -c:s copy \
        $faststart "$out" | while read -l line
            switch "$line"
                case 'frame=*'
                    set frame (string replace 'frame=' '' -- "$line")
                case 'fps=*'
                    set fps_txt (string replace 'fps=' '' -- "$line")"fps"
                case 'bitrate=*'
                    set bitrate_txt (string replace 'bitrate=' '' -- "$line")
                    if string match -q '*kbits/s' "$bitrate_txt"
                        set bitrate_txt (math -s 1 (string replace 'kbits/s' '' -- "$bitrate_txt") / 1000)"Mbit/s"
                    else if string match -q '*Mbits/s' "$bitrate_txt"
                        set bitrate_txt (string replace 'Mbits/s' 'Mbit/s' -- "$bitrate_txt")
                    end
case 'out_time=*'
                    set -l t (string replace 'out_time=' '' -- "$line")
                    set -l parts (string split ':' -- "$t")
                    if test (count $parts) -eq 3; and string match -rq '^\d+$' "$parts[1]"; and string match -rq '^\d+$' "$parts[2]"; and string match -rq '^[\d.]+$' "$parts[3]"
                        set out_t (math "$parts[1]*3600+$parts[2]*60+$parts[3]")
                    end
                case 'speed=*'
                    set speed_txt (string replace 'speed=' '' -- "$line")
            end
            if isatty stdout
                printf '\r\033[K'
                set -l pct '--.-%'
                set -l eta_txt ''
                set -l bar (string repeat -n 24 '░')
                set -l frac ''
                if test -n "$total_frames"; and string match -rq '^\d+$' "$frame"; and test "$total_frames" -gt 0
                    set frac (math "min(1, $frame/$total_frames)")
                else if test -n "$out_t"; and string match -rq '^[0-9.]+$' "$duration"; and not string match -rq '^0+(\.0*)?$' "$duration"
                    set frac (math "min(1, $out_t/$duration)")
                end
                if test -n "$frac"
                    set -l filled (math "floor($frac*24)")
                    set -l bar (string repeat -n $filled '█')
                    set bar "$bar"(string repeat -n (math "24-$filled") '░')
                    set pct (math -s 1 "$frac*100")%
                    set -l sp (string replace -r '[xX]$' '' -- "$speed_txt")
                    if test -n "$sp"; and string match -rq '^[0-9.]+$' "$sp"; and not string match -rq '^0+(\.0*)?$' "$sp"; and test -n "$out_t"; and string match -rq '^[0-9.]+$'
"$duration"
                        set eta_txt "  ETA "(__vrot_fmtsecs (math "($duration - $out_t)/$sp"))
                    end
                end
                set -l frame_txt $frame
                if test -n "$total_frames"
                    set frame_txt "$frame/$total_frames"
                end
                echo -n "  $vrot_c_ok$bar$vrot_c_reset  $pct  frame=$frame_txt  $fps_txt  $bitrate_txt  $speed_txt$eta_txt"
            end
        end
    set -l ff_status $pipestatus[1]
    printf '\n'

    if test $ff_status -ne 0
        __vrot_error "encoding failed (ffmpeg exited $ff_status)"
        return 1
    end
    __vrot_summary "$out"
end

function __vrot_summary
    set -l out $argv[1]
    set -l size ''
    if command -q numfmt
        set size (numfmt --to=iec --suffix=B -- (stat -c %s -- "$out") 2>/dev/null)
    else
        set size (du -h -- "$out" | string replace -r '\t.*' '')
    end
    set -l dims (ffprobe -v error -select_streams v:0 \
        -show_entries stream=width,height -of default=noprint_wrappers=1:nokey=1 "$out" \
        | string match -r '^\d+$' | string join '×')
    set -l extra ''
    if test -n "$dims"
        set extra " · $dims"
    end
    echo "$vrot_c_ok  ✔ $out$vrot_c_dim  ($size$extra)$vrot_c_reset"
end

function __vrot_banner
    set -l title $argv[1]
    echo "$vrot_c_dim"(string repeat -n 58 '─')"$vrot_c_reset"
    echo "$vrot_c_hi  $title$vrot_c_reset"
end

function __vrot_colors
    set -q vrot_colors_set; and return 0
    set -g vrot_colors_set 1
    if isatty stdout
        set -g vrot_c_hi (set_color brwhite --bold)
        set -g vrot_c_dim (set_color brblack)
        set -g vrot_c_ok (set_color brgreen)
        set -g vrot_c_warn (set_color bryellow)
        set -g vrot_c_err (set_color brred)
        set -g vrot_c_reset (set_color normal)
    else
        for c in hi dim ok warn err reset
            set -g vrot_c_$c ''
        end
    end
end

function __vrot_fmtsecs
    set -l s (math "max(0, round($argv[1]))")
    set -l h (math "floor($s/3600)")
    set -l m (math "floor($s%3600/60)")
    set -l sec (math "$s%60")
    if test $h -gt 0
        printf '%02d:%02d:%02d' $h $m $sec
    else
        printf '%02d:%02d' $m $sec
    end
end

function __vrot_error
    echo "$vrot_c_err""vrot: "$argv"$vrot_c_reset" >&2
end

function __vrot_usage
    echo 'usage: vrot [options] <video> [<video> ...]'
    echo
    echo 'Rotates one or more videos and writes <name>_rot.<ext> next to each.'
    echo
    echo 'Default mode is metadata-only rotation: lossless and instant. Works for'
    echo 'MP4/MOV/M4V (including GoPro files; unsupported data/timecode tracks are'
    echo 'dropped automatically). If the container cannot carry the flag, vrot'
    echo 'falls back to re-encoding, with a live progress bar. Players that'
    echo 'ignore rotation flags need -r.'
    echo
    echo 'options:'
    echo '  -a, --angle <90|180|270>  clockwise angle (default 90)'
    echo '  -r, --reencode            rotate pixels by re-encoding'
    echo '  -p, --preset <name>       x264/x265 preset (default medium)'
    echo '  -h, --help                show this help'
end