#!/usr/bin/env bash
# export-server-config.sh — seed ./server-config/ from /data/config inside the
# mc_data volume, so the compose bind mount `./server-config:/data/config` can
# take over without losing the mod configs the server already generated.
#
# WHY: a bind mount shadows whatever is under it. Mounting an empty host dir over
# /data/config hides every existing config file and each mod regenerates its
# defaults — silently reverting tuning. Run this ONCE, before the first boot with
# the mount in place.
#
# Cautious by design: refuses to run if the target already has content, if the
# volume can't be resolved unambiguously, or if the server is still running.
#
# Usage:
#   tooling/export-server-config.sh            # export, then chown to MC_UID:MC_GID
#   MC_UID=1002 MC_GID=1002 tooling/…          # oxps (host user oier = 1002)
set -euo pipefail

cd "$(dirname "$0")/.."   # repo root

[ -f .env ] && { set -a; . ./.env; set +a; }

TARGET="./server-config"
MC_UID="${MC_UID:-1000}"
MC_GID="${MC_GID:-1000}"

# ── resolve the mc_data volume ──────────────────────────────────────────────
# Compose prefixes the volume with the project name (defaults to the repo dir
# name), so never hardcode it — match and require exactly one.
mapfile -t VOLS < <(docker volume ls -q | grep -E '(^|_)mc_data$' || true)
if [ "${#VOLS[@]}" -eq 0 ]; then
  echo "FATAL: no mc_data volume found (docker volume ls). Nothing to export." >&2
  echo "       If this is a fresh host there is no config yet — create an empty" >&2
  echo "       $TARGET and let the server generate defaults into it." >&2
  exit 1
fi
if [ "${#VOLS[@]}" -gt 1 ]; then
  echo "FATAL: multiple mc_data volumes, refusing to guess:" >&2
  printf '  %s\n' "${VOLS[@]}" >&2
  exit 1
fi
VOL="${VOLS[0]}"

# ── refuse while the server is live (it rewrites config on shutdown) ────────
if [ -n "$(docker ps -q -f name='^minecraft$')" ]; then
  echo "FATAL: the minecraft container is running. Stop it first:" >&2
  echo "         docker compose stop minecraft" >&2
  exit 1
fi

# ── refuse to clobber an existing export ────────────────────────────────────
if [ -d "$TARGET" ] && [ -n "$(ls -A "$TARGET" 2>/dev/null)" ]; then
  echo "FATAL: $TARGET already has content — refusing to overwrite." >&2
  echo "       Move it aside if you really want a fresh export." >&2
  exit 1
fi
mkdir -p "$TARGET"

# ── copy out of the volume ──────────────────────────────────────────────────
echo "Exporting $VOL:/data/config -> $TARGET"
docker run --rm \
  -v "$VOL":/data:ro \
  -v "$PWD/$TARGET":/out \
  alpine sh -euc '
    if [ ! -d /data/config ]; then
      echo "FATAL: /data/config does not exist in the volume." >&2
      exit 1
    fi
    cp -a /data/config/. /out/
  '

# ── ownership: the server (uid 1000 under itzg) must be able to write ───────
docker run --rm -v "$PWD/$TARGET":/out \
  alpine chown -R "$MC_UID:$MC_GID" /out

COUNT=$(find "$TARGET" -type f | wc -l)
echo "Exported $COUNT files, owned by $MC_UID:$MC_GID."

if [ "$(id -u)" != "$MC_UID" ]; then
  echo
  echo "NOTE: your host uid ($(id -u)) != $MC_UID, so $TARGET is not yours to edit." >&2
  echo "      Either edit via sudo, or add group write and join the group." >&2
fi

echo
echo "Next: the compose bind mount ./server-config:/data/config now takes over."
echo "      docker compose up -d --force-recreate minecraft"