#!/usr/bin/env bash
set -Eeuo pipefail

SCRIPT_DIR="$(cd -- "$(dirname -- "${BASH_SOURCE[0]}")" && pwd)"
INSTALL_ROOT="${PT_INSTALL_ROOT:-$SCRIPT_DIR}"
SERVER_NAME="${PT_SERVER:-${1:-}}"
RUNTIME_BASE_DIR="${PT_RUNTIME_DIR:-$INSTALL_ROOT/.pt-panel-runtime}"
DOWNLOAD_DIR="$RUNTIME_BASE_DIR/downloads"

JAVA_BIN="${JAVA_BIN:-java}"
JAVA_ARGS="${PT_JAVA_ARGS:--Xms1G -Xmx2G}"
SERVER_JAR_OVERRIDE="${PT_SERVER_JAR:-}"
FORCE_UPDATE="${PT_FORCE_UPDATE:-0}"
DRY_RUN="${PT_DRY_RUN:-0}"
SKIP_HASH_CHECK="${PT_SKIP_HASH_CHECK:-0}"
AUTO_EULA="${PT_AUTO_EULA:-TRUE}"

PACK_DIR=""
MODS_DIR=""
STAMP_FILE=""
MOD_STATE_FILE=""

log() {
  printf '[pt-panel] %s\n' "$*"
}

fail() {
  printf '[pt-panel] ERROR: %s\n' "$*" >&2
  exit 1
}

need_cmd() {
  command -v "$1" >/dev/null 2>&1 || fail "缺少命令: $1"
}

fetch() {
  local url="$1"
  local dest="$2"

  if command -v curl >/dev/null 2>&1; then
    curl -fL --retry 3 --retry-delay 2 -o "$dest" "$url"
  elif command -v wget >/dev/null 2>&1; then
    wget -O "$dest" "$url"
  else
    fail "缺少 curl 或 wget，无法下载文件"
  fi
}

fetch_to_stdout() {
  local url="$1"

  if command -v curl >/dev/null 2>&1; then
    curl -fL --retry 3 --retry-delay 2 "$url"
  elif command -v wget >/dev/null 2>&1; then
    wget -O - "$url"
  else
    fail "缺少 curl 或 wget，无法下载文件"
  fi
}

trim_quotes() {
  local value="$1"
  value="${value#\"}"
  value="${value%\"}"
  printf '%s' "$value"
}

toml_value() {
  local key="$1"
  local file="$2"
  local line

  line="$(grep -E "^${key}[[:space:]]*=" "$file" | head -n 1 || true)"
  [ -n "$line" ] || return 1
  line="${line#*=}"
  line="${line#${line%%[![:space:]]*}}"
  trim_quotes "$line"
}

hash_cmd_for() {
  case "$1" in
    sha512) echo sha512sum ;;
    sha256) echo sha256sum ;;
    sha1) echo sha1sum ;;
    md5) echo md5sum ;;
    *) return 1 ;;
  esac
}

verify_hash() {
  local file="$1"
  local expected="$2"
  local format="$3"
  local cmd actual

  [ "$SKIP_HASH_CHECK" = "1" ] && return 0

  cmd="$(hash_cmd_for "$format" || true)"
  [ -n "$cmd" ] || return 0
  command -v "$cmd" >/dev/null 2>&1 || return 0

  actual="$($cmd "$file" | awk '{print $1}')"
  [ "$actual" = "$expected" ]
}

list_available_servers() {
  find "$SCRIPT_DIR" -mindepth 1 -maxdepth 1 -type d -name 'server-*' -exec basename {} \; | sort
}

select_server() {
  local available count first

  if [ -n "$SERVER_NAME" ]; then
    PACK_DIR="$SCRIPT_DIR/$SERVER_NAME"
    [ -f "$PACK_DIR/pack.toml" ] || fail "指定的服务端不存在: $SERVER_NAME"
    return 0
  fi

  available="$(list_available_servers || true)"
  count="$(printf '%s\n' "$available" | sed '/^$/d' | wc -l | awk '{print $1}')"

  if [ "$count" = "1" ]; then
    first="$(printf '%s\n' "$available" | sed -n '1p')"
    SERVER_NAME="$first"
    PACK_DIR="$SCRIPT_DIR/$SERVER_NAME"
    return 0
  fi

  if [ "$count" = "0" ]; then
    fail "仓库中没有找到任何 server-* 服务端目录"
  fi

  printf '[pt-panel] 可选服务端：\n%s\n' "$(printf '%s\n' "$available" | sed 's/^/  - /')" >&2
  fail "检测到多个服务端，请通过 PT_SERVER=<目录名> 或第一个参数指定，例如：PT_SERVER=server-01-random-block bash start.sh"
}

ensure_dirs() {
  mkdir -p "$INSTALL_ROOT" "$RUNTIME_BASE_DIR" "$DOWNLOAD_DIR"
  MODS_DIR="${PT_MODS_DIR:-$INSTALL_ROOT/mods}"
  mkdir -p "$MODS_DIR"
}

prepare_server_paths() {
  local safe_server_name
  safe_server_name="$(printf '%s' "$SERVER_NAME" | tr '/' '_')"
  STAMP_FILE="$RUNTIME_BASE_DIR/fabric-install-${safe_server_name}.stamp"
  MOD_STATE_FILE="$RUNTIME_BASE_DIR/mods-${safe_server_name}.txt"
}

load_pack_versions() {
  [ -f "$PACK_DIR/pack.toml" ] || fail "找不到 $PACK_DIR/pack.toml，请确认服务端 pack 存在"

  MINECRAFT_VERSION="$(toml_value 'minecraft' "$PACK_DIR/pack.toml")"
  FABRIC_LOADER_VERSION="$(toml_value 'fabric' "$PACK_DIR/pack.toml")"

  [ -n "$MINECRAFT_VERSION" ] || fail "无法从 $PACK_DIR/pack.toml 读取 minecraft 版本"
  [ -n "$FABRIC_LOADER_VERSION" ] || fail "无法从 $PACK_DIR/pack.toml 读取 fabric 版本"
}

load_latest_fabric_installer_version() {
  local meta version
  meta="$(fetch_to_stdout 'https://meta.fabricmc.net/v2/versions/installer')"
  version="$(printf '%s\n' "$meta" | grep '"version"' | head -n 1 | sed 's/.*"version": *"\([^"]*\)".*/\1/')"
  [ -n "$version" ] || fail "无法获取最新 Fabric installer 版本"
  printf '%s' "$version"
}

install_fabric_server() {
  local installer_version installer_jar wanted_stamp current_stamp

  installer_version="$(load_latest_fabric_installer_version)"
  installer_jar="$DOWNLOAD_DIR/fabric-installer-${installer_version}.jar"
  wanted_stamp="server=$SERVER_NAME mc=$MINECRAFT_VERSION loader=$FABRIC_LOADER_VERSION installer=$installer_version"
  current_stamp="$(cat "$STAMP_FILE" 2>/dev/null || true)"

  if [ "$FORCE_UPDATE" != "1" ] && [ -f "$INSTALL_ROOT/fabric-server-launch.jar" ] && [ "$wanted_stamp" = "$current_stamp" ]; then
    log "Fabric 服务端已就绪，跳过重复安装"
    return 0
  fi

  log "准备安装 Fabric 服务端：$SERVER_NAME (Minecraft $MINECRAFT_VERSION / Loader $FABRIC_LOADER_VERSION)"
  fetch "https://maven.fabricmc.net/net/fabricmc/fabric-installer/${installer_version}/fabric-installer-${installer_version}.jar" "$installer_jar"

  if [ "$DRY_RUN" = "1" ]; then
    log "DRY RUN: 跳过执行 Fabric installer"
    return 0
  fi

  (
    cd "$INSTALL_ROOT"
    "$JAVA_BIN" -jar "$installer_jar" server -mcversion "$MINECRAFT_VERSION" -loader "$FABRIC_LOADER_VERSION" -downloadMinecraft
  )
  printf '%s\n' "$wanted_stamp" > "$STAMP_FILE"
}

cleanup_stale_mods() {
  local current_file stale_name

  [ -f "$MOD_STATE_FILE" ] || return 0

  while IFS= read -r stale_name; do
    [ -n "$stale_name" ] || continue
    current_file="$MODS_DIR/$stale_name"
    if [ ! -f "$RUNTIME_BASE_DIR/current-mods.txt" ] || ! grep -Fxq "$stale_name" "$RUNTIME_BASE_DIR/current-mods.txt"; then
      if [ -f "$current_file" ]; then
        log "移除旧模组: $stale_name"
        [ "$DRY_RUN" = "1" ] || rm -f "$current_file"
      fi
    fi
  done < "$MOD_STATE_FILE"
}

sync_mods() {
  local meta file_name url hash_format hash dest tmp
  local tmp_state_file="$RUNTIME_BASE_DIR/current-mods.txt"

  : > "$tmp_state_file"

  shopt -s nullglob
  local files=("$PACK_DIR"/mods/*.pw.toml)
  shopt -u nullglob

  [ "${#files[@]}" -gt 0 ] || fail "在 $PACK_DIR/mods 下没有找到任何 .pw.toml 模组定义"

  for meta in "${files[@]}"; do
    file_name="$(toml_value 'filename' "$meta")"
    url="$(toml_value 'url' "$meta")"
    hash_format="$(toml_value 'hash-format' "$meta" || true)"
    hash="$(toml_value 'hash' "$meta" || true)"

    [ -n "$file_name" ] || fail "无法读取 $meta 中的 filename"
    [ -n "$url" ] || fail "无法读取 $meta 中的 download.url"

    printf '%s\n' "$file_name" >> "$tmp_state_file"
    dest="$MODS_DIR/$file_name"

    if [ "$FORCE_UPDATE" != "1" ] && [ -f "$dest" ]; then
      if [ -n "$hash_format" ] && [ -n "$hash" ]; then
        if verify_hash "$dest" "$hash" "$hash_format"; then
          log "模组已存在且校验通过: $file_name"
          continue
        fi
        log "模组校验失败，重新下载: $file_name"
      else
        log "模组已存在，跳过下载: $file_name"
        continue
      fi
    else
      log "下载模组: $file_name"
    fi

    if [ "$DRY_RUN" = "1" ]; then
      log "DRY RUN: 跳过下载 $url"
      continue
    fi

    tmp="$dest.part"
    fetch "$url" "$tmp"

    if [ -n "$hash_format" ] && [ -n "$hash" ] && ! verify_hash "$tmp" "$hash" "$hash_format"; then
      rm -f "$tmp"
      fail "模组校验失败: $file_name"
    fi

    mv "$tmp" "$dest"
  done

  cleanup_stale_mods
  [ "$DRY_RUN" = "1" ] || mv "$tmp_state_file" "$MOD_STATE_FILE"
}

write_eula() {
  if [ "$AUTO_EULA" = "TRUE" ] || [ "$AUTO_EULA" = "true" ] || [ "$AUTO_EULA" = "1" ]; then
    printf 'eula=true\n' > "$INSTALL_ROOT/eula.txt"
    log "已写入 eula.txt"
  else
    log "已跳过自动写入 EULA（PT_AUTO_EULA=$AUTO_EULA）"
  fi
}

find_server_jar() {
  if [ -n "$SERVER_JAR_OVERRIDE" ]; then
    printf '%s' "$SERVER_JAR_OVERRIDE"
    return 0
  fi

  if [ -f "$INSTALL_ROOT/fabric-server-launch.jar" ]; then
    printf '%s' "$INSTALL_ROOT/fabric-server-launch.jar"
    return 0
  fi

  local candidate
  candidate="$(find "$INSTALL_ROOT" -maxdepth 1 -type f \( -name 'fabric-server-launch.jar' -o -name 'fabric-server-*.jar' -o -name 'server.jar' \) | sort | head -n 1 || true)"
  [ -n "$candidate" ] || return 1
  printf '%s' "$candidate"
}

start_server() {
  local server_jar
  server_jar="$(find_server_jar || true)"

  if [ "$DRY_RUN" = "1" ]; then
    if [ -n "$server_jar" ]; then
      log "使用服务端文件: $server_jar"
    else
      log "DRY RUN: 当前尚未生成服务端 jar；正式运行时会先执行 Fabric installer"
    fi
    log "安装目录: $INSTALL_ROOT"
    log "启动参数: $JAVA_ARGS"
    log "DRY RUN: 跳过实际启动"
    return 0
  fi

  [ -n "$server_jar" ] || fail "找不到可启动的服务端 jar，请检查 Fabric 安装是否成功"

  log "使用服务端: $SERVER_NAME"
  log "使用服务端文件: $server_jar"
  log "安装目录: $INSTALL_ROOT"
  log "启动参数: $JAVA_ARGS"

  cd "$INSTALL_ROOT"
  exec "$JAVA_BIN" $JAVA_ARGS -jar "$server_jar" nogui
}

main() {
  need_cmd "$JAVA_BIN"
  need_cmd grep
  need_cmd sed
  need_cmd awk
  need_cmd find

  select_server
  ensure_dirs
  prepare_server_paths
  load_pack_versions

  log "脚本目录: $SCRIPT_DIR"
  log "安装目录: $INSTALL_ROOT"
  log "选择服务端: $SERVER_NAME"
  log "Pack 目录: $PACK_DIR"
  log "Minecraft 版本: $MINECRAFT_VERSION"
  log "Fabric Loader 版本: $FABRIC_LOADER_VERSION"

  install_fabric_server
  sync_mods
  write_eula
  start_server
}

main "$@"