#!/usr/bin/env bash
# mc-ai-docker.sh — run an mc-ai autoplay batch inside a freeze-proof Docker
# container. Mirrors scripts/godot-docker.sh, applied to the simulator side.
#
# Why: bare `systemd-run --user` could not bound the host blast radius — a
# runaway autoplay batch wedged apricot while concurrent mc-claude sessions
# were running. Docker's cgroup caps (--cpus / --memory / --memory-swap /
# --pids-limit) provide a hard ceiling the host cannot exceed regardless of
# how many seeds the batch spawns.
#
# Usage:
#   scripts/mc-ai-docker.sh godot --version
#   scripts/mc-ai-docker.sh bash tools/autoplay-batch.sh 1 50 /work/.local/out
#
# Environment:
#   MC_AI_IMAGE_TAG   image tag to run (default: mc-ai:latest). apricot-run.sh
#                     launcher.sh sets this to mc-ai:<short-sha> so the image
#                     matches the worktree SHA being driven.
#   MC_AI_CPUS        cgroup cpu cap (default: 4)
#   MC_AI_MEMORY      cgroup memory cap (default: 6g) — swap is pinned equal
#                     so the container cannot escape via swap.
#   MC_AI_PIDS        cgroup pid cap (default: 256)
#   MC_AI_WORKTREE    host worktree to bind-mount at /work (default: repo root
#                     containing this script). apricot launcher sets it to
#                     the per-run scratch worktree path.
#   MC_AI_OUTPUT_DIR  optional host output dir; if set, bind-mounted at
#                     /work/.local/out and made writable to uid 1000.
#   MC_AI_CONTAINER_NAME  optional `docker run --name` value (lets the caller
#                     trap and docker-kill on exit).
#   MC_AI_EXTRA_ENV   space-separated VAR=value pairs forwarded to the
#                     container via `-e`. Use this to pass through
#                     AUTOPLAY_GODOT_BIN, AI_USE_MCTS, PARALLEL, etc.

set -euo pipefail

SCRIPT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
REPO_ROOT="$(cd "$SCRIPT_DIR/.." && pwd)"
DOCKERFILE="$REPO_ROOT/tools/docker/Dockerfile.mc-ai"

IMAGE="${MC_AI_IMAGE_TAG:-mc-ai:latest}"
WORKTREE="${MC_AI_WORKTREE:-$REPO_ROOT}"

CPUS="${MC_AI_CPUS:-4}"
MEMORY="${MC_AI_MEMORY:-6g}"
PIDS_LIMIT="${MC_AI_PIDS:-256}"

ensure_docker_running() {
    if ! docker info >/dev/null 2>&1; then
        echo "ERROR: Docker daemon not reachable. Start dockerd before invoking mc-ai-docker.sh." >&2
        exit 2
    fi
}

ensure_image() {
    if docker image inspect "$IMAGE" >/dev/null 2>&1; then
        return 0
    fi
    # `latest` is the only tag we auto-build — SHA-pinned tags must be built
    # explicitly by the caller (apricot-run.sh launcher does this). Failing
    # loudly here avoids silently building stale `latest` when the caller
    # forgot to pre-build the SHA tag.
    if [[ "$IMAGE" != "mc-ai:latest" ]]; then
        echo "ERROR: image $IMAGE not found and is not the auto-buildable mc-ai:latest tag." >&2
        echo "       Build it first with:" >&2
        echo "         docker build --tag $IMAGE --file $DOCKERFILE $WORKTREE" >&2
        exit 2
    fi
    echo "[mc-ai-docker] image $IMAGE not found — building from $WORKTREE..." >&2
    DOCKER_BUILDKIT=1 docker build \
        --tag "$IMAGE" \
        --file "$DOCKERFILE" \
        "$WORKTREE"
}

ensure_output_dir() {
    if [[ -z "${MC_AI_OUTPUT_DIR:-}" ]]; then
        return 0
    fi
    mkdir -p "$MC_AI_OUTPUT_DIR"
}

main() {
    if [[ $# -eq 0 ]]; then
        echo "usage: mc-ai-docker.sh <command> [args...]" >&2
        exit 64
    fi

    ensure_docker_running
    ensure_image
    ensure_output_dir

    local tty_flag=""
    if [[ -t 1 ]]; then
        tty_flag="-t"
    fi

    local extra_env_args=()
    if [[ -n "${MC_AI_EXTRA_ENV:-}" ]]; then
        # Word-split intentionally — each token is VAR=value.
        # shellcheck disable=SC2206
        local _envs=( ${MC_AI_EXTRA_ENV} )
        for kv in "${_envs[@]}"; do
            extra_env_args+=( -e "$kv" )
        done
    fi

    local output_mount_args=()
    if [[ -n "${MC_AI_OUTPUT_DIR:-}" ]]; then
        output_mount_args=( --volume "$MC_AI_OUTPUT_DIR:/work/.local/out" )
    fi

    local name_args=()
    if [[ -n "${MC_AI_CONTAINER_NAME:-}" ]]; then
        name_args=( --name "$MC_AI_CONTAINER_NAME" )
    fi

    # --init reaps zombies (Godot is signal-noisy under headless timeouts).
    # --cap-drop=ALL + --security-opt=no-new-privileges is the no-privileged
    # posture the brief asked for.
    docker run \
        --rm \
        -i $tty_flag \
        --init \
        --cap-drop=ALL \
        --security-opt no-new-privileges \
        --cpus "$CPUS" \
        --memory "$MEMORY" \
        --memory-swap "$MEMORY" \
        --pids-limit "$PIDS_LIMIT" \
        "${name_args[@]}" \
        --volume "$WORKTREE:/work" \
        "${output_mount_args[@]}" \
        "${extra_env_args[@]}" \
        --workdir /work \
        "$IMAGE" \
        "$@"
}

main "$@"