#!/bin/bash

set -euo pipefail

SCRIPT_DIR=$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)
PROJECT_ROOT=$(dirname "$SCRIPT_DIR")

usage() {
    cat <<'USAGE'
Usage: update/debug.sh [--keep] [arch|ubuntu] [-- update-args...]

Spins up a temporary VM-like container, mounts the repository, and runs the update
script with UPDATE_DEBUG=1. Requires podman (preferred) or docker with systemd
support. Pass --keep to leave the container running for inspection. Any arguments
after -- are forwarded to update/update.sh.
USAGE
}

KEEP_CONTAINER=0
DISTRO=""
FORWARDED_ARGS=()

while (( $# )); do
    case "$1" in
        --keep)
            KEEP_CONTAINER=1
            shift
            ;;
        arch|ubuntu)
            DISTRO="$1"
            shift
            ;;
        --)
            shift
            FORWARDED_ARGS=("$@")
            break
            ;;
        -h|--help)
            usage
            exit 0
            ;;
        *)
            usage
            exit 1
            ;;
    esac
done

if [[ -z "$DISTRO" ]]; then
    DISTRO="ubuntu"
fi

case "$DISTRO" in
    arch)
        IMAGE="docker.io/archlinux:latest"
        INIT_PATH="/usr/lib/systemd/systemd"
        PREPARE_CMD='pacman -Syyu --noconfirm sudo git base-devel';
        ;;
    ubuntu)
        IMAGE="docker.io/library/ubuntu:24.04"
        INIT_PATH="/sbin/init"
        PREPARE_CMD='apt-get update && DEBIAN_FRONTEND=noninteractive apt-get install -y sudo git'
        ;;
    *)
        usage
        exit 1
        ;;
 esac

if command -v podman >/dev/null 2>&1; then
    RUNTIME="podman"
    MOUNT_OPTS=":Z"
elif command -v docker >/dev/null 2>&1; then
    RUNTIME="docker"
    MOUNT_OPTS=""
else
    echo "[!] Neither podman nor docker found in PATH." >&2
    exit 1
fi

CONTAINER_NAME="linuxbox-update-debug-${DISTRO}-$$"

cleanup() {
    if (( KEEP_CONTAINER )); then
        echo "[i] Keeping container ${CONTAINER_NAME} running for inspection." >&2
        return
    fi
    if "$RUNTIME" ps -a --format '{{.Names}}' 2>/dev/null | grep -qx "$CONTAINER_NAME"; then
        "$RUNTIME" rm -f "$CONTAINER_NAME" >/dev/null 2>&1 || true
    fi
}
trap cleanup EXIT

start_container() {
    if [[ "$RUNTIME" == "podman" ]]; then
        "$RUNTIME" run -d --name "$CONTAINER_NAME" --privileged \
            --tmpfs /tmp --tmpfs /run \
            -v /sys/fs/cgroup:/sys/fs/cgroup:ro \
            -v "$PROJECT_ROOT:/workspace${MOUNT_OPTS}" \
            -w /workspace "$IMAGE" "$INIT_PATH" >/dev/null
    else
        "$RUNTIME" run -d --name "$CONTAINER_NAME" --privileged --cgroupns=host \
            --tmpfs /tmp --tmpfs /run \
            -v /sys/fs/cgroup:/sys/fs/cgroup:ro \
            -v "$PROJECT_ROOT:/workspace" \
            -w /workspace "$IMAGE" "$INIT_PATH" >/dev/null
    fi
}

wait_for_systemd() {
    local attempts=0
    while (( attempts < 30 )); do
        local status
        status=$("$RUNTIME" exec "$CONTAINER_NAME" systemctl is-system-running 2>/dev/null || true)
        case "$status" in
            running|degraded)
                return 0
                ;;
        esac
        sleep 1
        ((attempts++))
    done
    echo "[!] systemd did not reach running state inside container (last status: $status)." >&2
}

bootstrap_container() {
    if [[ "$DISTRO" == "ubuntu" ]]; then
        "$RUNTIME" exec "$CONTAINER_NAME" bash -lc "export DEBIAN_FRONTEND=noninteractive; $PREPARE_CMD"
        "$RUNTIME" exec "$CONTAINER_NAME" bash -lc "useradd -m debugger || true"
        "$RUNTIME" exec "$CONTAINER_NAME" bash -lc "echo 'debugger ALL=(ALL) NOPASSWD:ALL' >/etc/sudoers.d/debugger && chmod 0440 /etc/sudoers.d/debugger"
    else
        "$RUNTIME" exec "$CONTAINER_NAME" bash -lc "$PREPARE_CMD"
        "$RUNTIME" exec "$CONTAINER_NAME" bash -lc "useradd -m debugger || true"
        "$RUNTIME" exec "$CONTAINER_NAME" bash -lc "echo 'debugger ALL=(ALL) NOPASSWD:ALL' >/etc/sudoers.d/debugger && chmod 0440 /etc/sudoers.d/debugger"
    fi
    "$RUNTIME" exec "$CONTAINER_NAME" bash -lc "chown -R debugger:debugger /workspace"
}

run_update() {
    local update_cmd
    printf -v update_cmd 'UPDATE_DEBUG=1 ./update/update.sh %q' "$DISTRO"
    for arg in "${FORWARDED_ARGS[@]}"; do
        printf -v update_cmd '%s %q' "$update_cmd" "$arg"
    done
    "$RUNTIME" exec "$CONTAINER_NAME" bash -lc "su - debugger -c \"cd /workspace && $update_cmd\""
}

start_container
wait_for_systemd
bootstrap_container
run_update

echo "[✓] Debug run completed." >&2