#!/bin/bash

set -euo pipefail

echo "=== 通用 Linux 初始化脚本 ==="

# 确保为 root
if [ "$EUID" -ne 0 ]; then
    echo "请以 root 用户运行此脚本。" >&2
    exit 1
fi

# 检测系统信息
get_os_info() {
    if [ -f /etc/os-release ]; then
        . /etc/os-release
        DISTRO_ID=$ID
        DISTRO_NAME=$NAME
        DISTRO_VERSION=$VERSION_ID
    else
        echo "无法识别系统类型。" >&2
        exit 1
    fi
}

# 设置 DNS
set_dns() {
    echo "设置 DNS..."
    rm -f /etc/resolv.conf
    cat > /etc/resolv.conf <<EOF
nameserver 114.114.114.114
nameserver 223.5.5.5
EOF
    if command -v chattr &>/dev/null; then
        chattr +i /etc/resolv.conf || echo "警告: 无法锁定 resolv.conf"
    fi
}

# 设置时区和时间同步
set_timezone_and_time() {
    echo "设置时区为 Asia/Shanghai..."
    timedatectl set-timezone Asia/Shanghai 2>/dev/null || ln -sf /usr/share/zoneinfo/Asia/Shanghai /etc/localtime

    echo "安装 ntpdate..."
    $INSTALL_CMD ntpdate -y
    echo "正在同步时间..."
    ntpdate ntp.aliyun.com || echo "时间同步失败，请检查网络连接"
}

# 设置清华源
set_mirrors() {
    echo "更换软件源为清华镜像..."

    case "$DISTRO_ID" in
        debian|ubuntu|raspbian)
            CODENAME=$(lsb_release -cs 2>/dev/null || echo "stable")
            cat > /etc/apt/sources.list <<EOF
deb https://mirrors.tuna.tsinghua.edu.cn/${DISTRO_ID}/ ${CODENAME} main contrib non-free non-free-firmware
deb https://mirrors.tuna.tsinghua.edu.cn/${DISTRO_ID}/ ${CODENAME}-updates main contrib non-free non-free-firmware
deb https://mirrors.tuna.tsinghua.edu.cn/${DISTRO_ID}/ ${CODENAME}-backports main contrib non-free non-free-firmware
deb https://mirrors.tuna.tsinghua.edu.cn/${DISTRO_ID}-security ${CODENAME}-security main contrib non-free non-free-firmware
EOF
            apt update -y
            ;;

        centos|rhel|almalinux|rocky)
            if [ -f /etc/yum.repos.d/CentOS-Base.repo ]; then
                cp /etc/yum.repos.d/CentOS-Base.repo /etc/yum.repos.d/CentOS-Base.repo.bak
            fi
            # shellcheck disable=SC2046
            curl -o /etc/yum.repos.d/CentOS-Base.repo https://mirrors.tuna.tsinghua.edu.cn/help/centos/?date=$(date +%Y%m%d)
            yum clean all && yum makecache
            ;;

        fedora)
            dnf install -y dnf-plugins-core
            sed -i 's|^metalink=|#metalink=|g' /etc/yum.repos.d/fedora*.repo
            sed -i 's|^#baseurl=http.*|baseurl=https://mirrors.tuna.tsinghua.edu.cn/fedora/linux/releases/$releasever/Everything/$basearch/os/|g' /etc/yum.repos.d/fedora.repo
            dnf makecache
            ;;

        *)
            echo "不支持的系统: $DISTRO_NAME"
            exit 1
            ;;
    esac
}

# 主程序
get_os_info

echo "检测到系统: $DISTRO_NAME $DISTRO_VERSION"

# 判断使用哪个包管理器
if command -v apt &>/dev/null; then
    INSTALL_CMD="apt install -y"
    apt update -y
elif command -v dnf &>/dev/null; then
    INSTALL_CMD="dnf install -y"
    dnf makecache
elif command -v yum &>/dev/null; then
    INSTALL_CMD="yum install -y"
    yum makecache
else
    echo "不支持的包管理器。" >&2
    exit 1
fi

# 安装通用工具
$INSTALL_CMD curl wget lsb-release || true

# 执行配置步骤
set_mirrors
set_dns
set_timezone_and_time

echo "=== 初始化完成！系统已优化 ==="