#!/bin/sh
# Author: Pali Rohár
# Licence: GPLv3

if test -z "$1"; then
    echo "Usage: $0 file.deb"
    exit 1
fi

if test ! -f "$1"; then
    echo "File $1 not exists"
    exit 1
fi

if test -d "__tmp"; then
    echo "Temporary directory __tmp exists"
    exit 1
fi

mkdir -p __tmp
if test "$?" != "0"; then
    echo "Cannot create temporary directory __tmp"
    exit 1
fi

echo "Unpacking..."
dpkg -x "$1" __tmp/deb
dpkg -e "$1" __tmp/deb/DEBIAN

cd __tmp || exit 1

source="$(sed -n 's/^Source:\s*\(.*\)$/\1/p' deb/DEBIAN/control | head -1)"
package="$(sed -n 's/^Package:\s*\(.*\)$/\1/p' deb/DEBIAN/control | head -1)"
version="$(sed -n 's/^Version:\s*\(.*\)$/\1/p' deb/DEBIAN/control | head -1)"
maintainer="$(sed -n 's/^Maintainer:\s*\(.*\)$/\1/p' deb/DEBIAN/control | head -1)"

if test -z "$source"; then
    source="$package"
fi

if test -z "$maintainer"; then
    if test -z "$USER"; then USER=user; fi
    if test -z "$HOSTNAME"; then HOSTNAME="$(hostname)"; fi
    if test -z "$HOSTNAME"; then HOSTNAME=localhost; fi
    if test -z "$DEBEMAIL"; then DEBEMAIL="$USER@$HOSTNAME"; fi
    if test -z "$DEBFULLNAME"; then DEBFULLNAME="$USER"; fi
    maintainer="$DEBFULLNAME <$DEBEMAIL>"
fi

mkdir "$source-$version" || exit 1
mv deb "$source-$version/" || exit 1
cd "$source-$version" || exit 1

#### debian ####

echo "Creating debian"
mkdir debian || exit 1

#### debian/changelog ####

echo "Generating debian/changelog"

have_changelog=0
upstream_changelog=0

for file in changelog.Debian.gz changelog.Debian changelog.gz changelog; do
    for file in $(find deb/usr/share/doc/ -name $file -type f); do
        if test ! -f "$file"; then continue; fi
        if echo "$file" | grep -q '\.gz$'; then
            gunzip -c "$file" > debian/changelog
            if test "$?" != "0"; then continue; fi
        else
            cp "$file" debian/changelog
        fi
        touch -r "$file" debian/changelog
        rm -f "$file"
        have_changelog=1
        break
    done
    if echo "$file" | grep -q Debian; then upstream_changelog=1; fi
    if test "$have_changelog" = "1"; then break; fi
done

if test "$have_changelog" != "1"; then

    time="@$(find deb -type f -exec stat --format '%Y' {} \; | sort -nr | cut -d: -f2- | head -1)"
    if test -z "$time"; then time="now"; fi
    date="$(date -R -d $time)"
    cat > debian/changelog << EOF
$source ($version) unstable; urgency=low

  * Initial release

 -- $maintainer  $date
EOF

fi

have_changelog=0
if test "$upstream_changelog" = "1"; then
    for file in changelog.gz changelog; do
        for file in $(find deb/usr/share/doc/ -name $file -type f); do
            if test ! -f "$file"; then continue; fi
            if echo "$file" | grep -q '\.gz$'; then
                mv "$file" changelog.gz
                gunzip changelog.gz
            else
                mv "$file" changelog
            fi
            rm -f "$file"
            have_changelog=1
            changelog=" changelog"
            break
        done
        if test "$have_changelog" = "1"; then break; fi
    done
fi

#### debian/copyright ####

file="$(find deb/usr/share/doc/ -name copyright -type f | head -1)"
if test ! -z "$file"; then
    cp "$file" debian/copyright
    touch -r "$file" debian/copyright
    rm -f "$file"
fi

#### debian/compat ####

echo "Generating debian/compat"

echo 5 > debian/compat

#### debian/rules ####

echo "Generating debian/rules"

cat > debian/rules << EOF
#!/usr/bin/make -f
# -*- makefile -*-

build:

clean:
    dh_testdir
    dh_clean

binary:
    dh_testdir
    dh_testroot
    dh_clean -k
    mkdir -p debian/$package
    cp -ra files/* debian/$package
    dh_installdocs -p$package
    dh_installchangelogs -p$package$changelog
    dh_compress
    dh_fixperms
    dh_strip
    dh_makeshlibs
    dh_shlibdeps
    dh_installdeb
    dh_gencontrol
    dh_md5sums
    dh_builddeb

.PHONY: build clean binary
EOF

chmod +x debian/rules

#### debian/control ####

echo "Generating debian/control..."

cat > debian/control << EOF
Source: $source
Maintainer: $maintainer
Build-Depends: debhelper (>= 5)

EOF
cat deb/DEBIAN/control | grep -v '^Version:' | grep -v '^Installed-Size:' | grep -v '^Maintainer:' >> debian/control

#### debian pre/post scripts ####

echo "Adding debian scripts..."

mv deb/DEBIAN/pre* debian/ 2>/dev/null
mv deb/DEBIAN/post* debian/ 2>/dev/null

#### docs ####

echo "Adding debian docs..."

for file in $(ls deb/usr/share/doc/$package/ 2>/dev/null); do
    if test ! -f "deb/usr/share/doc/$package/$file"; then continue; fi
    mv "deb/usr/share/doc/$package/$file" "$file"
    if echo "$file" | grep -q '\.gz$'; then
        gunzip "$file"
        file="${file%%.gz}"
    fi
    echo "$file" >> "debian/$package.docs"
done

if test -z "$(ls -A deb/usr/share/doc/$package/ 2>/dev/null)"; then
    rmdir "deb/usr/share/doc/$package" 2>/dev/null
    if test -z "$(ls -A deb/usr/share/doc/ 2>/dev/null)"; then
        rmdir deb/usr/share/doc 2>/dev/null
        if test -z "$(ls -A deb/usr/share/ 2>/dev/null)"; then
            rmdir deb/usr/share 2>/dev/null
            if test -z "$(ls -A deb/usr/ 2>/dev/null)"; then
                rmdir deb/usr 2>/dev/null
            fi
        fi
    fi
fi

#### files ####

echo "Adding files..."

rm -rf deb/DEBIAN
mv deb files

#### build dsc package ####

echo "Building source package..."

dpkg-buildpackage -S -sa -us -uc

cd ..
mv *.dsc ../
mv *.tar.gz ../

#### remove __tmp ####

echo "Cleaning..."

cd .. && rm -rf __tmp

echo "Done."