#!/bin/sh

if [ $# -ne 1 ] || [ "$1" = "-h" ]; then
    cat<<EOF
Usage: ${0##*/} PKGBUILD

Convert an Arch Linux PKGBUILD to a universal standalone bash script. (The
infamous 'bash' is assumed because PKGBUILD are bash scripts.)  The resulting
script tries to resemble makepkg build process where it makes sense. There is no
dependency resolution because we cannot guess the package names of the target
system.

Differences with makepkg
* Parameters are not the same.
* The output may differ.
* The fakeroot environment lies directly in \$pkgdir, not in \$pkgdir/\$pkgname.

EOF
    exit
fi

if [ -z "$(command -v realpath)" ]; then
    echo "You need 'realpath'"
    exit
fi

if [ ! -f "$1" ]; then
    echo "$1 must be a PKGBUILD file."
    exit
fi

OUTPATH="$(realpath "$1")"
OUTPATH="${OUTPATH%/*}"
UBUILD="${OUTPATH}/UBUILD.sh"

if [ -f "$UBUILD" ]; then
    echo "$UBUILD already exists."
    exit
fi

echo '#!/bin/bash

if [ -z "$(command -v realpath)" ];then
    echo "You need 'realpath'."
    exit
fi
if [ -z "$(command -v wget)" ];then
    echo "You need 'wget'."
    exit
fi

################################################################################
' > "$UBUILD"

cat "$1" | sed -e 's|--prefix=/usr|--prefix=/usr/local|g' \
     -e 's|PREFIX=/usr|PREFIX=/usr/local|g' >> "$UBUILD"

cat  "$(realpath "$0").in" >> "$UBUILD"

chmod +x "$UBUILD"