#!/bin/bash

set -e

usage() {
    echo "usage: dcp-init [-sh] [-C key=val] [-d REPODIR] PACKAGE [(PATCH|-m)...]"
    echo "       PATCH ::= [-p LEVEL] [-bB BRANCH] FILE"
    echo "       -b creates a new branch at the current patch"
    echo "       -B creates a new branch at the upstream sources"
    echo "       -m merges the current branch into the master branch"
}

rungit() {
    (
	cd "$td"
	git "$@"
    ) || false
}

getaptsrc() {
    mkdir "$td/apt-tmp"
    (cd "$td/apt-tmp"; apt-get source "$1") || false
    
    sdir=
    for f in "$td/apt-tmp"/*; do
	if [ -d "$f" ]; then
	    if [ -z "$sdir" ]; then
		sdir="$f"
	    else
		echo "dcp-init: got more than one directory from apt-get; cannot continue" >&2
		exit 1
	    fi
	fi
    done
    if [ -z "$sdir" ]; then
	echo "dcp-init: could not find any source directory" >&2
	exit 1
    fi
    mv "$sdir" "$td/src"
    rm -rf "$td/apt-tmp"

    rungit add src
}

initrepo() {
    rungit init
    mkdir "$td/control"
    touch "$td/control/conf"
    rungit add control
    rungit commit -q -m "Initial repo"
    rungit tag empty
}

initbase() {
    mkdir "$td/control/build.d"
    mkdir "$td/control/update.d"
    cat >"$td/control/functions" <<EOF
readconf() {
    if [ -r "\$HOME/.dcp-build-conf" ]; then
        while read key val; do
            export "CONF_\$key"="\$val"
        done <"\$HOME/.dcp-build-conf"
    fi
    if [ -r "/etc/dcp-conf" ]; then
        while read key val; do
            export "CONF_\$key"="\$val"
        done <"/etc/dcp-conf"
    fi
    while read key val; do
        export "CONF_\$key"="\$val"
    done <control/conf
}

rungit() {
    (cd repo; git "\$@") || false
}

logchange() {
    tag="\${CONF_VERTAG:-dcp}"
    ver="\$(dpkg-parsechangelog -lrepo/src/debian/changelog | sed -n 's/^Version: \(.*\)$/\1/p')"
    [ -n "\$ver" ]
    maint="\$CONF_MAINTAINER"
    if [ -z "\$maint" ]; then
        maint="\$(id -un) <\$(id -un)@\$(hostname -f)>"
    fi
    cat - repo/src/debian/changelog >repo/src/debian/changelog.new <<ENDCL
\${CONF_APTPKG} (\${ver}+\${tag}1) unstable; urgency=low
  
  * Remerged changes in DCP

 -- \${maint}  \$(date -R)
ENDCL
    mv -f repo/src/debian/changelog.new repo/src/debian/changelog
}
EOF
    cat >"$td/control/build" <<EOF
#!/bin/sh

set -e

. control/functions
readconf

for file in control/build.d/*; do
    if [ -x "\$file" ]; then "\$file"; fi
done
EOF
    chmod 755 "$td/control/build"
    cat >"$td/control/update" <<EOF
#!/bin/sh

set -e

. control/functions
readconf

updated=n
for branch in repo/.git/refs/heads/*; do
    branch="\${branch##*/}"
    if [ -x "control/update.d/\$branch" ]; then
        rungit checkout "\$branch"
        lastrev="\$(rungit rev-parse HEAD)"
        "control/update.d/\$branch"
        newrev="\$(rungit rev-parse HEAD)"
        rungit checkout master
        if [ "\$newrev" != "\$lastrev" ]; then
            rungit merge -n "\$branch"
            updated=y
        fi
    fi
done

if [ "\$updated" = y ]; then
    for file in control/update.d/post-*; do
        if [ -x "\$file" ]; then "\$file"; fi
    done
fi
EOF
    chmod 755 "$td/control/update"
    rungit add control
}

initapt() {
    cat >"$td/control/build.d/99dpkg" <<EOF
#!/bin/bash

set -e

cmd=(dpkg-buildpackage -b -rfakeroot)
if [ -n "\$CONF_MAINTAINER" ]; then
    cmd=("\${cmd[@]}" "-m\$CONF_MAINTAINER")
fi
if [ -n "\$CONF_GPGKEY" ]; then
    cmd=("\${cmd[@]}" "-k\$CONF_GPGKEY")
fi
(cd repo/src; "\${cmd[@]}") || false
mv repo/*.deb output/
EOF
    chmod 755 "$td/control/build.d/99dpkg"
    rungit add control/build.d/99dpkg
    cat >"$td/control/update.d/upstream" <<EOF
#!/bin/sh

set -e

. control/functions

cd repo
dcp-update-apt "\$CONF_APTPKG"
EOF
    chmod 755 "$td/control/update.d/upstream"
    rungit add control/update.d/upstream
    cat >"$td/control/update.d/post-logchange" <<EOF
#!/bin/sh

set -e
. control/functions

logchange
rungit add src/debian/changelog
rungit commit -q -m "Added changelog entry"

EOF
    echo "APTPKG $pkg" >>"$td/control/conf"
    rungit add control/conf
}

defdir=/srv/dcp
repodir=
confopts=()
shared=n

while [ "${1:0:1}" = - ]; do
    opt="${1:1}"
    shift
    if [ "$opt" = d ]; then
	repodir="$1"
	shift
    elif [ "$opt" = h ]; then
	usage
	exit 0
    elif [ "$opt" = s ]; then
	shared=y
    elif [ "$opt" = C ]; then
	confopts=("${confopts[@]}" "$1")
	shift
    else
	echo "dcp-init: unknown option '$opt'" >&2
	exit 1
    fi
done

if [ $# -lt 1 ]; then
    usage >&2
    exit 1
fi
pkg="$1"
shift
if [ -z "$repodir" ]; then repodir="$pkg"; fi
if [[ "$repodir" != */* ]]; then
    repodir="$defdir/${repodir}.git"
fi

td="$(mktemp -d "/tmp/dcp-XXXXXX")"
initrepo

initbase
rungit commit -q -m "Base control files"

if [ "${#confopts[@]}" -gt 0 ]; then
    for opt in "${confopts[@]}"; do
	key="${opt%%=*}"
	val="${opt#*=}"
	echo "$key $val" >>"$td/control/conf"
    done
    rungit add control/conf
    rungit commit -q -m "Custom configuration file"
fi

rungit checkout -q -b upstream empty
getaptsrc "$pkg"
rungit commit -q -m "Initial upstream import"
rungit checkout master
rungit merge -n upstream

initapt
rungit commit -q -m "APT control files"

initvals() {
    level=0
}
initvals
curbranch=master
while [ $# -gt 0 ]; do
    arg="$1"
    shift
    if [ "${arg:0:1}" = - ]; then
	if [ "$arg" = -p ]; then
	    level="$1"
	    shift
	elif [ "$arg" = -b ]; then
	    curbranch="$1"
	    shift
	    rungit checkout -q -b "$curbranch"
	elif [ "$arg" = -B ]; then
	    curbranch="$1"
	    shift
	    rungit checkout -q -b "$curbranch" upstream
	elif [ "$arg" = -m ]; then
	    rungit checkout -q master
	    rungit merge -n "$curbranch"
	else
	    echo "dcp-init: unknown patch option '$arg'" >&2
	    exit 1
	fi
    else
	(
	    if [[ "$arg" == *.gz ]]; then
		zcat "$arg"
	    else
		cat "$arg"
	    fi
	) | patch -d "$td/src" -p"$level"
	rungit add src
	rungit commit -q -m "Applied $(basename "$arg")"
	initvals
    fi
done

git clone -q --bare "$td" "$repodir"
if [ "$shared" = y ]; then
    chmod -R g+w "$repodir"
    td="$repodir" rungit config core.sharedrepository 1
fi

rm -rf "$td"