#!/bin/sh
# shellcheck disable=SC2086

# truepng - POSIX-compliant shell script to help running TruePNG through Wine
#
# Written in 2016-2017 by Daniel Bermond < yahoo.com: danielbermond >
#
# To the extent possible under law, the author(s) have dedicated all
# copyright  and related and neighboring rights to this software to the
# public domain worldwide. This software is distributed without any
# warranty.
#
# You should have received a copy of the CC0 Public Domain Dedication
# along with this software. If not, see
# <http://creativecommons.org/publicdomain/zero/1.0/>.

truepng_dir='/usr/share/truepng'
truepng_file='TruePNG.exe'

# cd_error function: print a message indicating a failed cd command and exit
# arguments: $1 - the directory that failed to cd into
# return value: none
# return code (status): not relevant, will exit the program
cd_error() {
    printf '%s\n' "error: could not cd into '${1%/}/' directory" >&2
    exit 1
}

# enable some options if the executing shell is zsh
if [ -n "$ZSH_VERSION" ] 
then
    command -v setopt >/dev/null 2>&1 ||
    {
        printf '%s\n' 'script appears to be running in zsh but setopt was not found';
        exit 1;
    }
    setopt SH_WORD_SPLIT # enable variable word splitting
fi

# check if requirements are installed (wine and TruePNG.exe)
command -v wine >/dev/null 2>&1 ||
{
    printf '%s\n' 'error: wine not found'      >&2;
    printf '%s\n' '       please install wine' >&2;
    exit 1;
}
test -f "${truepng_dir}/${truepng_file}" ||
{
    printf '%s\n' "error: '${truepng_file}' not found"         >&2;
    printf '%s\n' "       please copy it to '${truepng_dir}/'" >&2;
    exit 1;
}

# Parse command line arguments and build a string with options
# and PNG files to be passed to TruePNG. We cannot simply pass
# the untouched command line arguments to TruePNG because it's
# necessary to map paths for wine.
for arg in "$@"
do
    # test if command line argument is a valid file
    if [ -f "$arg" ] 
    then
        # map path for wine using default WINEPREFIX
        fullpath="$(printf '%s' "$(cd "$(dirname "$arg")" || cd_error "$(dirname "$arg")"; pwd)/$(basename "$arg")")"
        pngfiles="${pngfiles} ${HOME}/.wine/dosdevices/z:${fullpath}
"
    else
        # if not a valid file, just store it (should be an option)
        truepng_opts="${truepng_opts} ${arg}"
    fi
done

# delete the first character of strings (a blank character)
     pngfiles="$(printf '%s' "$pngfiles"     | sed 's/.//')"
 truepng_opts="$(printf '%s' "$truepng_opts" | sed 's/.//')"

# execute TruePNG through wine
cd "$truepng_dir" || cd_error "$truepng_dir"
IFS='
'
wine ./"$truepng_file" $truepng_opts $pngfiles