#!/bin/bash
# Electric Cherry host installer. Downloaded release integrity is checked before
# execution. Existing Docker data and unrelated containers are never changed.
set -euo pipefail
umask 077

controller=''
enrollment_token=''
data_dir='/var/lib/electric-cherry'
reenroll=''
while [ "$#" -gt 0 ]; do
    case "$1" in
        --controller) controller="${2:?Missing controller URL}"; shift 2 ;;
        --token) enrollment_token="${2:?Missing enrollment token}"; shift 2 ;;
        --data-dir) data_dir="${2:?Missing data directory}"; shift 2 ;;
        --reenroll) reenroll='--force-enroll'; shift ;;
        *) echo "Unknown installer option" >&2; exit 2 ;;
    esac
done
[ "$(id -u)" = 0 ] || { echo 'Run the installer as root.' >&2; exit 1; }
case "$controller" in https://*) ;; *) echo '--controller must be an HTTPS URL.' >&2; exit 2 ;; esac
[ -n "$enrollment_token" ] || { echo '--token is required.' >&2; exit 2; }
case "$data_dir" in /*) ;; *) echo '--data-dir must be absolute.' >&2; exit 2 ;; esac
case "$data_dir" in *[!a-zA-Z0-9/_.-]*|*/../*|*/./*|*/..|*/.|*//*|*/) echo 'Choose a canonical, dedicated data directory.' >&2; exit 2 ;; esac
[ ! -L "$data_dir" ] || { echo 'Data directory must not be a symlink.' >&2; exit 2; }
. /etc/os-release
[ "${ID:-}" = debian ] || { echo 'Supported platform: Debian 12 or 13.' >&2; exit 1; }
case "${VERSION_ID:-}" in 12|13) ;; *) echo 'Supported platform: Debian 12 or 13.' >&2; exit 1 ;; esac
[ "$(dpkg --print-architecture)" = amd64 ] || { echo 'Supported architecture: amd64.' >&2; exit 1; }
command -v systemctl >/dev/null || { echo 'systemd is required.' >&2; exit 1; }

export DEBIAN_FRONTEND=noninteractive
apt-get update -qq
apt-get install -y --no-install-recommends ca-certificates curl python3
python3 - "$controller" "$data_dir" /etc/electric-cherry/agent.json <<'PY'
# INSTALLATION_PREFLIGHT: this runs before touching managed directories or services.
import json, pathlib, re, stat, sys

controller, raw_root, config_name = sys.argv[1:]
root = pathlib.Path(raw_root)
config = pathlib.Path(config_name)
reserved = {
    '/', '/bin', '/boot', '/dev', '/etc', '/home', '/lib', '/lib64',
    '/media', '/mnt', '/opt', '/proc', '/root', '/run', '/sbin', '/srv',
    '/sys', '/tmp', '/usr', '/usr/local', '/usr/local/bin', '/usr/local/lib',
    '/usr/local/libexec', '/var', '/var/cache', '/var/lib', '/var/log', '/var/tmp',
}
if (not re.fullmatch(r'/[A-Za-z0-9/_.-]+', raw_root)
        or str(root) != raw_root or any(part in ('.', '..') for part in raw_root.split('/')[1:])
        or len(root.parts) < 3 or raw_root in reserved or config.parent == root or config.parent in root.parents):
    raise SystemExit('Choose a canonical, dedicated data directory outside the agent configuration directory.')
installed_paths = [config,
    pathlib.Path('/usr/local/libexec/electric-cherry-agent.py'),
    pathlib.Path('/usr/local/libexec/electric-cherry-uninstall.py'),
    pathlib.Path('/etc/systemd/system/electric-cherry-agent.service'),
    pathlib.Path('/etc/systemd/system/electric-cherry-uninstall.service')]
if any(root == path or root in path.parents for path in installed_paths):
    raise SystemExit('Choose a dedicated data directory outside the agent executable and service directories.')

def trusted_directories(path):
    for current in [*reversed(path.parents), path]:
        try:
            info = current.lstat()
        except FileNotFoundError:
            continue
        if not stat.S_ISDIR(info.st_mode) or info.st_uid != 0 or info.st_mode & 0o022:
            raise SystemExit('Installation directories and their parents must be root-owned, not symlinks, and not writable by other users.')

def trusted_json(path):
    info = path.lstat()
    if not stat.S_ISREG(info.st_mode) or info.st_uid != 0 or info.st_mode & 0o022:
        raise SystemExit('Existing installation metadata must be regular, root-owned files that other users cannot modify.')
    value = json.loads(path.read_text())
    if not isinstance(value, dict):
        raise SystemExit('Existing installation metadata is invalid.')
    return value

trusted_directories(root)
trusted_directories(config.parent)
mountinfo = pathlib.Path('/proc/1/mountinfo')
if mountinfo.exists():
    for line in mountinfo.read_text().splitlines():
        fields = line.split()
        if len(fields) < 5:
            continue
        mount = re.sub(r'\\([0-7]{3})', lambda match: chr(int(match[1], 8)), fields[4])
        if mount == raw_root or mount.startswith(raw_root + '/'):
            raise SystemExit('Use a dedicated subdirectory of the mounted disk, with no filesystems mounted inside it, so host deletion can remove the entire data directory.')
request = config.with_name('decommission.json')
if request.exists() or request.is_symlink():
    raise SystemExit('Host deletion is in progress. Finish or repair that deletion before installing again.')
saved = None
if config.exists() or config.is_symlink():
    saved = trusted_json(config)
    if saved.get('controller', '').rstrip('/') != controller.rstrip('/') or saved.get('root') != raw_root:
        raise SystemExit('Existing enrollment uses a different controller or data directory. Preserve the existing installation and migrate it explicitly.')
    if not saved.get('hostId') or not saved.get('credential'):
        raise SystemExit('Existing enrollment is incomplete. Repair its credentials before upgrading.')
marker = root / '.electric-cherry.json'
if marker.exists() or marker.is_symlink():
    owned = trusted_json(marker)
    if not saved or owned != {'version': 1, 'root': raw_root, 'hostId': saved['hostId'], 'controller': controller.rstrip('/')}:
        raise SystemExit('Data directory ownership does not match this enrollment. Preserve it and migrate explicitly.')
elif root.exists() and any(root.iterdir()):
    # Upgrade installations predating ownership markers only when the entire
    # root has the known layout. Never adopt a directory of unrelated files.
    if not saved or any(path.name not in {'agent', 'instances', 'libraries'} for path in root.iterdir()):
        raise SystemExit('The data directory contains files not owned by this installation. Choose an empty, dedicated directory.')
for directory in ('agent', 'instances', 'libraries'):
    trusted_directories(root / directory)
PY
if ! command -v docker >/dev/null; then
    if [ -e /var/lib/docker ] || [ -e /etc/docker/daemon.json ]; then
        echo 'Existing Docker data/configuration detected without a Docker CLI. Repair Docker, then rerun.' >&2
        exit 1
    fi
    apt-get install -y --no-install-recommends docker.io
    systemctl enable --now docker
fi
docker info >/dev/null 2>&1 || { echo 'Docker is installed but unavailable. Start or repair it, then rerun.' >&2; exit 1; }
install -d -m 0755 "$data_dir" "$data_dir/libraries" "$data_dir/instances"
install -d -m 0700 "$data_dir/agent" /etc/electric-cherry
available_kb=$(df -Pk "$data_dir" | awk 'NR==2 {print $4}')
[ "$available_kb" -ge 1048576 ] || { echo 'At least 1 GiB of available game storage is required.' >&2; exit 1; }
temporary_dir=$(mktemp -d)
trap 'rm -rf "$temporary_dir"' EXIT
controller="${controller%/}"
curl --proto '=https' --tlsv1.2 --fail --silent --show-error "$controller/api/agent/release/manifest.json" -o "$temporary_dir/manifest.json"
curl --proto '=https' --tlsv1.2 --fail --silent --show-error "$controller/api/agent/release/ec-agent.py" -o "$temporary_dir/ec-agent.py"
python3 - "$temporary_dir/manifest.json" "$temporary_dir/ec-agent.py" <<'PY'
import hashlib, json, pathlib, sys
manifest = json.loads(pathlib.Path(sys.argv[1]).read_text())
actual = hashlib.sha256(pathlib.Path(sys.argv[2]).read_bytes()).hexdigest()
if actual != manifest.get('sha256'):
    raise SystemExit('Agent release checksum verification failed.')
if manifest.get('platform') != 'debian-amd64' or manifest.get('protocolVersion') != 1:
    raise SystemExit('Unsupported agent release manifest.')
PY
# Stop only the agent while replacing its own executable/journal owner. Existing
# game containers keep running under Docker throughout installation and updates.
if systemctl cat electric-cherry-agent.service >/dev/null 2>&1; then
    systemctl stop electric-cherry-agent.service
fi
install -m 0755 "$temporary_dir/ec-agent.py" /usr/local/libexec/electric-cherry-agent.py 2>/dev/null || {
    install -d -m 0755 /usr/local/libexec
    install -m 0755 "$temporary_dir/ec-agent.py" /usr/local/libexec/electric-cherry-agent.py
}
# A separate worker survives stopping/removing the agent service. Its only
# entry point is a fixed, authenticated deletion request prepared by the agent.
install -m 0755 "$temporary_dir/ec-agent.py" /usr/local/libexec/electric-cherry-uninstall.py
printf '%s' "$enrollment_token" > "$temporary_dir/enrollment-token"
unset enrollment_token
python3 /usr/local/libexec/electric-cherry-agent.py --enroll --controller "$controller" --root "$data_dir" --token-file "$temporary_dir/enrollment-token" ${reenroll:+"$reenroll"}
python3 - "$data_dir" /etc/electric-cherry/agent.json <<'PY'
# INSTALLATION_OWNERSHIP: bind deletion authority to this exact enrollment/root.
import json, os, pathlib, sys, uuid
root = pathlib.Path(sys.argv[1])
config = json.loads(pathlib.Path(sys.argv[2]).read_text())
if config.get('root') != str(root) or not config.get('hostId') or not config.get('controller'):
    raise SystemExit('Enrollment did not establish ownership of this data directory.')
marker = root / '.electric-cherry.json'
temporary = root / ('.electric-cherry.' + uuid.uuid4().hex + '.tmp')
try:
    with temporary.open('x') as stream:
        os.chmod(temporary, 0o600)
        json.dump({'version': 1, 'root': str(root), 'hostId': config['hostId'], 'controller': config['controller'].rstrip('/')}, stream)
        stream.flush()
        os.fsync(stream.fileno())
    os.replace(temporary, marker)
    directory_fd = os.open(root, os.O_RDONLY | os.O_DIRECTORY)
    try:
        os.fsync(directory_fd)
    finally:
        os.close(directory_fd)
finally:
    temporary.unlink(missing_ok=True)
PY
cat > /etc/systemd/system/electric-cherry-agent.service <<EOF
[Unit]
Description=Electric Cherry Host Agent
After=network-online.target docker.service
Wants=network-online.target
Requires=docker.service

[Service]
Type=simple
ExecStart=/usr/bin/python3 /usr/local/libexec/electric-cherry-agent.py --config /etc/electric-cherry/agent.json
Restart=on-failure
RestartSec=5
TimeoutStopSec=30
UMask=0077
NoNewPrivileges=true
ProtectSystem=strict
ProtectHome=true
PrivateTmp=true
ReadWritePaths=$data_dir /etc/electric-cherry

[Install]
WantedBy=multi-user.target
EOF
cat > /etc/systemd/system/electric-cherry-uninstall.service <<'EOF'
[Unit]
Description=Remove an Electric Cherry Host Installation
After=network-online.target docker.service
Wants=network-online.target

[Service]
Type=oneshot
ExecStart=/usr/bin/python3 /usr/local/libexec/electric-cherry-uninstall.py --uninstall /etc/electric-cherry/decommission.json
Restart=on-failure
RestartSec=15
TimeoutStartSec=0
UMask=0077

[Install]
WantedBy=multi-user.target
EOF
systemctl daemon-reload
systemctl enable electric-cherry-agent
systemctl restart electric-cherry-agent
systemctl is-active --quiet electric-cherry-agent || { echo 'Agent service did not start. Inspect journalctl -u electric-cherry-agent.' >&2; exit 1; }
echo 'Electric Cherry host agent installed and enrolled. Host readiness is shown in Hosts.'