dialog(1)/Xdialog(1) prototype for new bsdinstall distfetch

#!/bin/sh
# Copyright (c)2013 Devin Teske. All rights reserved.
increment=1   # How much to increment % each time (must be even divisor of 100)
sleep_sec=    # Time to sleep in-between increments
pbar_size=17  # How big is the mini-progressbar?
txt_size=28   # Maximum width for labels (file names)
files="base.txz dict.txz doc.txz games.txz ports.txz" # Files to fake-fetch
### Rest below shouldn't need editing ###
if [ "$1" = "-X" ]; then
    DIALOG=Xdialog USE_XDIALOG=1 USE_DIALOG= USE_COLOR=
else
    DIALOG=dialog USE_DIALOG=1
    : ${USE_COLOR=1}
fi
spin="/-\|"
pct_lsize=$(( ( $pbar_size - 4 ) / 2 ))
pct_rsize=$pct_lsize
[ $(( $pct_lsize * 2 + 4 )) -ne $pbar_size ] &&
    pct_rsize=$(( $pct_rsize + 1 ))
dun_lsize=$pct_lsize dun_rsize=$pct_rsize
pen_lsize=$(( ( $pbar_size - 7 ) / 2 ))
pen_rsize=$pen_lsize
[ $(( $pen_lsize * 2 + 7 )) -ne $pbar_size ] &&
    pen_rsize=$(( $pen_rsize + 1 ))
n=
nfiles=$( set -- $files; echo $# )
HEIGHT=$(( $nfiles + 4 + 5 )) WIDTH=$(( $txt_size + $pbar_size + 9 ))
[ "$USE_XDIALOG" ] && HEIGHT=$(( $HEIGHT + $HEIGHT / 4 ))
while [ ${n:-0} -lt $nfiles ]; do
    n=$(( ${n:-0} + 1 ))
    pct=
    while [ ${pct:-0} -lt 100 ]; do # ... incrementing 1% each sub-loop
        [ "$sleep_sec" ] && sleep $sleep_sec
        pct=$(( ${pct:--$increment} + $increment ))
        #
        # Create the progress bar
        #
        if [ "$USE_XDIALOG" ]; then
            pbar=$( printf "%${pct_lsize}s%3u%%%%%${pct_rsize}s" \
                           "" $pct "" )
        else
            pbar=$( printf "%${pct_lsize}s%3u%%%${pct_rsize}s" \
                           "" $pct "" )
        fi
        if [ "$USE_DIALOG" ]; then
            # Calculate the fill-width of the progress bar
            width=$(( $pct * $pbar_size / 100 ))
            # Round up based on one-tenth of a percent
            [ $(( $pct * $pbar_size % 100 )) -gt 50 ] &&
                width=$(( $width + 1 ))
            #
            # Make a copy of the pbar and split the copy into two
            # halves (we'll insert the ANSI delimiter in between)
            #
            lpbar="$pbar" rpbar="$pbar"
            rwidth=$(( $pbar_size - $width ))
            while [ ${#lpbar} -gt $width ]
            do lpbar="${lpbar%?}"; done
            while [ ${#rpbar} -gt $rwidth ]
            do rpbar="${rpbar#?}"; done
            #
            # Finalize the mini progress bar
            #
            pbar=
            [ "$USE_COLOR" ] && pbar="$pbar\Zb\Zr\Z4"
            pbar="$pbar$lpbar"
            [ "$USE_COLOR" ] && pbar="$pbar\ZR"
            pbar="$pbar$rpbar"
            [ "$USE_COLOR" ] && pbar="$pbar\Zn"
        fi
        #
        # Build the prompt text
        #
        p=1 prompt=
        for f in $files; do
            flabel="$f"
            while [ ${#flabel} -gt $txt_size ]; do
                flabel="${flabel%?}"
            done
            if [ ${#flabel} -ne ${#f} ]; then
                while [ ${#flabel} -gt $(( $txt_size - 3 )) ]
                do flabel="${flabel%?}"; done
                flabel="$flabel..."
            fi
            if [ $n -eq $p -a $pct -ne 100 ]; then
                # This is the file we're processing right now
                while [ ${#flabel} -gt $(( $txt_size - 3 )) ]
                do flabel="${flabel%?}"; done
                spin_char=$( echo "$spin" | sed -e "
                    s/.\{0,$(( $pct % ${#spin} ))\}\(.\).*/\1/
                    ${USE_XDIALOG:+s/\\\\/\\\\&/g}
                " )
                prompt="$prompt$(
                    printf "%s%-${txt_size}s%s %s" \
                           "${USE_COLOR:+\Zb}" \
                           "${flabel%...}..." \
                           "${USE_COLOR:+\ZB}" \
                           "$spin_char"
                )"
            else
                prompt="$prompt$(
                    printf "%-${txt_size}s %s" \
                           "$flabel" " "
                )"
            fi
            if [ $p -eq $n -a $pct -ne 100 ]; then
                prompt="$prompt [$pbar]\n"
            elif [ $p -gt $n ]; then
                prompt="$prompt [$(
                    printf "%${pen_lsize}s" ""
                )Pending$(
                    printf "%${pen_rsize}s" ""
                )]\n"
            else
                prompt="$prompt [$(
                    printf "%s%${dun_lsize}s" \
                           "${USE_COLOR:+\Zb\Zr\Z2}" ""
                )Done$(
                    printf "%${dun_rsize}s%s" "" \
                           "${USE_COLOR:+\Zn}"
                )]\n"
            fi
            p=$(( $p + 1 ))
        done
        #
        # Add trailing information
        #
        prompt="$prompt\nFetching distribution files...\n"
        prompt="$prompt\n  ${USE_COLOR:+\Zb}Overall Progress:"
        [ "$USE_COLOR" ] && prompt="$prompt\Zn"
        #
        # Xdialog(1) requires newlines to be:
        # (a) escaped and (b) on a line by themselves.
        #
        [ "$USE_XDIALOG" ] &&
            prompt=$( echo "$prompt" | sed -e 's/\\n/&\\&&/g' )
        #
        # Calculate total overall progress
        #
        opct=$(( ( 100 * $n - 100 + $pct ) / $nfiles ))
        # Round up based on one-tenth of a percent
        [ $(( (100*$n - 100 + $pct) * 10 / $nfiles % 100 )) -gt 50 ] &&
            opct=$(( $opct + 1 ))

        if [ "$USE_XDIALOG" ]; then
            printf "XXX\n$prompt\nXXX\n%u\n" $opct
        else
            printf "XXX\n%s\nXXX\n%u\n" "$prompt" $opct
        fi
    done
done | env ${USE_XDIALOG:+XDIALOG_HIGH_DIALOG_COMPAT=1} $DIALOG \
    --title 'Fetching Distribution' \
    --backtitle 'FreeBSD Installer' \
    ${USE_COLOR:+--colors} ${USE_XDIALOG:+--left} \
    --gauge "" $HEIGHT $WIDTH