#!/usr/bin/env bash
# Assemble a dependency-free Debian package from a prebuilt static tsunagi
# binary, using only dpkg-deb (no cargo-deb, no nfpm). The binary is statically
# linked, so the package declares no Depends and runs on any Debian/Ubuntu.
#
# Usage: build-deb.sh <binary> <deb_arch> <version> <output.deb>
#   <binary>   path to the built tsunagi executable
#   <deb_arch> Debian architecture: amd64 or arm64
#   <version>  package version (the tag without its leading v)
#   <output>   path to write the .deb to
set -euo pipefail

binary="$1"
arch="$2"
version="$3"
output="$4"

here="$(cd "$(dirname "$0")" && pwd)"
root="$(mktemp -d)"
trap 'rm -rf "$root"' EXIT

# Payload. Debian installs to /usr/bin (not /usr/local), so the service's
# ExecStart is rewritten to match; the source unit targets /usr/local/bin for
# the tarball installer.
install -D -m 0755 "$binary" "$root/usr/bin/tsunagi"

mkdir -p "$root/lib/systemd/system"
sed 's#/usr/local/bin/tsunagi#/usr/bin/tsunagi#' \
    "$here/../linux/tsunagi.service" > "$root/lib/systemd/system/tsunagi.service"
chmod 0644 "$root/lib/systemd/system/tsunagi.service"

install -D -m 0644 "$here/../linux/50-tsunagi-resolved.rules" \
    "$root/usr/share/polkit-1/rules.d/50-tsunagi-resolved.rules"
install -D -m 0644 "$here/../../README.md" "$root/usr/share/doc/tsunagi/README.md"
install -D -m 0644 "$here/../linux/README.md" "$root/usr/share/doc/tsunagi/INSTALL.md"

mkdir -p "$root/DEBIAN"

cat > "$root/DEBIAN/control" <<CTRL
Package: tsunagi
Version: ${version}
Architecture: ${arch}
Maintainer: AB <ab@hexor.cy>
Section: net
Priority: optional
Homepage: https://github.com/Ultradesu/tsunagi
Description: Serverless private mesh networking agent
 tsunagi forms small private mesh IP networks between peers, with NAT
 traversal and no central server. This package installs a static,
 dependency-free binary, a systemd service that runs the agent as a dedicated
 unprivileged "tsunagi" user with only CAP_NET_ADMIN and CAP_NET_BIND_SERVICE,
 and a polkit rule for the local DNS resolver.
CTRL

# The dedicated system user the service runs as. It is in the "tsunagi" group,
# which the polkit rule grants the resolve1 actions. systemd creates the state,
# cache and runtime directories for it on first start.
cat > "$root/DEBIAN/postinst" <<'POSTINST'
#!/bin/sh
set -e
if ! getent group tsunagi >/dev/null 2>&1; then
    addgroup --system tsunagi >/dev/null 2>&1 || true
fi
if ! getent passwd tsunagi >/dev/null 2>&1; then
    adduser --system --ingroup tsunagi --home /var/lib/tsunagi --no-create-home \
        --gecos "tsunagi agent" --disabled-login tsunagi >/dev/null 2>&1 || true
fi
if [ -d /run/systemd/system ]; then
    systemctl daemon-reload >/dev/null 2>&1 || true
fi
exit 0
POSTINST

cat > "$root/DEBIAN/prerm" <<'PRERM'
#!/bin/sh
set -e
if [ "$1" = remove ] || [ "$1" = purge ]; then
    if [ -d /run/systemd/system ]; then
        systemctl disable --now tsunagi.service >/dev/null 2>&1 || true
    fi
fi
exit 0
PRERM

cat > "$root/DEBIAN/postrm" <<'POSTRM'
#!/bin/sh
set -e
if [ -d /run/systemd/system ]; then
    systemctl daemon-reload >/dev/null 2>&1 || true
fi
exit 0
POSTRM

chmod 0755 "$root/DEBIAN/postinst" "$root/DEBIAN/prerm" "$root/DEBIAN/postrm"

# --root-owner-group writes the payload as root:root without needing fakeroot.
dpkg-deb --root-owner-group --build "$root" "$output"
echo "built $output"