#!/bin/bash
# ============================================================
# 生产服务器初始化脚本
# 
# 功能:
#   - 系统更新
#   - Docker 安装
#   - 防火墙配置 (ufw)
#   - SSH 加固
#   - 用户创建
#   - 目录结构创建
#
# 用法: sudo ./server-setup.sh
# ============================================================
set -euo pipefail

# ==================== 配置 ====================
DEPLOY_USER="${DEPLOY_USER:-deploy}"
APP_DIR="${APP_DIR:-/opt/water-management}"
BACKUP_DIR="${BACKUP_DIR:-/opt/water-management/backups}"
LOG_DIR="${LOG_DIR:-/opt/water-management/logs}"

# ==================== 函数 ====================

log() {
    echo "[$(date '+%Y-%m-%d %H:%M:%S')] $1"
}

check_root() {
    if [ "$(id -u)" -ne 0 ]; then
        log "❌ 请以 root 用户或 sudo 执行此脚本"
        exit 1
    fi
}

# ==================== 系统更新 ====================
update_system() {
    log "📦 更新系统包..."
    
    if command -v apt-get &>/dev/null; then
        apt-get update -y
        apt-get upgrade -y
        apt-get install -y \
            curl \
            wget \
            git \
            unzip \
            software-properties-common \
            apt-transport-https \
            ca-certificates \
            gnupg \
            lsb-release \
            htop \
            iotop \
            jq \
            openssl \
            fail2ban \
            ufw
    elif command -v yum &>/dev/null; then
        yum update -y
        yum install -y \
            curl \
            wget \
            git \
            unzip \
            yum-utils \
            htop \
            iotop \
            jq \
            openssl \
            fail2ban \
            firewalld
    else
        log "⚠️ 未知的包管理器，请手动安装依赖"
    fi
    
    log "✅ 系统更新完成"
}

# ==================== Docker 安装 ====================
install_docker() {
    if command -v docker &>/dev/null; then
        log "✅ Docker 已安装: $(docker --version)"
        return 0
    fi
    
    log "🐳 安装 Docker..."
    
    # 使用官方安装脚本
    curl -fsSL https://get.docker.com | sh
    
    # 启动 Docker
    systemctl enable docker
    systemctl start docker
    
    # 配置 Docker 镜像加速（中国大陆）
    mkdir -p /etc/docker
    cat > /etc/docker/daemon.json <<EOF
{
    "registry-mirrors": [
        "https://docker.mirrors.ustc.edu.cn",
        "https://hub-mirror.c.163.com"
    ],
    "log-driver": "json-file",
    "log-opts": {
        "max-size": "50m",
        "max-file": "3"
    },
    "storage-driver": "overlay2",
    "live-restore": true,
    "default-ulimits": {
        "nofile": {
            "Name": "nofile",
            "Hard": 65535,
            "Soft": 65535
        }
    }
}
EOF
    
    systemctl restart docker
    
    # 安装 Docker Compose
    COMPOSE_VERSION=$(curl -s https://api.github.com/repos/docker/compose/releases/latest | grep -oP '"tag_name": "\K(.*)(?=")')
    curl -L "https://github.com/docker/compose/releases/download/${COMPOSE_VERSION}/docker-compose-$(uname -s)-$(uname -m)" \
        -o /usr/local/bin/docker-compose
    chmod +x /usr/local/bin/docker-compose
    ln -sf /usr/local/bin/docker-compose /usr/bin/docker-compose
    
    log "✅ Docker 安装完成: $(docker --version)"
    log "✅ Docker Compose 安装完成: $(docker-compose --version)"
}

# ==================== 防火墙配置 ====================
setup_firewall() {
    log "🔥 配置防火墙..."
    
    if command -v ufw &>/dev/null; then
        # Ubuntu/Debian - UFW
        ufw default deny incoming
        ufw default allow outgoing
        
        # SSH
        ufw allow 22/tcp comment "SSH"
        ufw limit 22/tcp
        
        # HTTP/HTTPS
        ufw allow 80/tcp comment "HTTP"
        ufw allow 443/tcp comment "HTTPS"
        
        # MQTT (物联网设备接入)
        ufw allow 1883/tcp comment "MQTT"
        
        # 内部服务端口（仅允许内网访问，按实际 IP 段调整）
        # ufw allow from 10.0.0.0/8 to any port 8080
        # ufw allow from 10.0.0.0/8 to any port 8848
        
        ufw --force enable
        log "✅ UFW 防火墙已启用"
        
    elif command -v firewall-cmd &>/dev/null; then
        # CentOS/RHEL - firewalld
        systemctl enable firewalld
        systemctl start firewalld
        
        firewall-cmd --permanent --add-service=ssh
        firewall-cmd --permanent --add-service=http
        firewall-cmd --permanent --add-service=https
        firewall-cmd --permanent --add-port=1883/tcp
        firewall-cmd --reload
        
        log "✅ firewalld 防火墙已配置"
    fi
}

# ==================== SSH 加固 ====================
harden_ssh() {
    log "🔒 SSH 加固..."
    
    local sshd_config="/etc/ssh/sshd_config"
    
    # 备份原配置
    cp "$sshd_config" "${sshd_config}.bak.$(date +%Y%m%d)"
    
    # 禁用 root 密码登录
    sed -i 's/^#*PermitRootLogin.*/PermitRootLogin prohibit-password/' "$sshd_config"
    
    # 禁用空密码
    sed -i 's/^#*PermitEmptyPasswords.*/PermitEmptyPasswords no/' "$sshd_config"
    
    # 启用公钥认证
    sed -i 's/^#*PubkeyAuthentication.*/PubkeyAuthentication yes/' "$sshd_config"
    
    # 禁用密码登录（确保已配置公钥后启用）
    # sed -i 's/^#*PasswordAuthentication.*/PasswordAuthentication no/' "$sshd_config"
    
    # 限制最大认证尝试
    sed -i 's/^#*MaxAuthTries.*/MaxAuthTries 3/' "$sshd_config"
    
    # 客户端存活检测
    sed -i 's/^#*ClientAliveInterval.*/ClientAliveInterval 300/' "$sshd_config"
    sed -i 's/^#*ClientAliveCountMax.*/ClientAliveCountMax 2/' "$sshd_config"
    
    systemctl restart sshd
    
    log "✅ SSH 加固完成"
}

# ==================== Fail2Ban 配置 ====================
setup_fail2ban() {
    log "🛡️ 配置 Fail2Ban..."
    
    cat > /etc/fail2ban/jail.local <<EOF
[DEFAULT]
bantime = 3600
findtime = 600
maxretry = 5
backend = systemd

[sshd]
enabled = true
port = ssh
filter = sshd
logpath = /var/log/auth.log
maxretry = 3
bantime = 86400
EOF
    
    systemctl enable fail2ban
    systemctl restart fail2ban
    
    log "✅ Fail2Ban 已配置"
}

# ==================== 创建部署用户 ====================
create_deploy_user() {
    log "👤 创建部署用户: ${DEPLOY_USER}"
    
    if id "$DEPLOY_USER" &>/dev/null; then
        log "✅ 用户已存在: ${DEPLOY_USER}"
    else
        useradd -m -s /bin/bash "$DEPLOY_USER"
        usermod -aG docker "$DEPLOY_USER"
        log "✅ 用户已创建: ${DEPLOY_USER}"
    fi
    
    # 配置 sudo 权限（免密码执行 docker 命令）
    cat > "/etc/sudoers.d/${DEPLOY_USER}" <<EOF
${DEPLOY_USER} ALL=(ALL) NOPASSWD: /usr/bin/docker, /usr/bin/docker-compose, /usr/local/bin/docker-compose
EOF
    chmod 440 "/etc/sudoers.d/${DEPLOY_USER}"
    
    # 创建 SSH 目录
    local user_home
    user_home=$(eval echo "~${DEPLOY_USER}")
    mkdir -p "${user_home}/.ssh"
    chmod 700 "${user_home}/.ssh"
    chown -R "${DEPLOY_USER}:${DEPLOY_USER}" "${user_home}/.ssh"
    
    log "✅ 部署用户配置完成"
    log "⚠️  请将公钥添加到 ${user_home}/.ssh/authorized_keys"
}

# ==================== 创建目录结构 ====================
create_directories() {
    log "📁 创建应用目录结构..."
    
    mkdir -p "${APP_DIR}"
    mkdir -p "${APP_DIR}/config"
    mkdir -p "${APP_DIR}/config/postgres"
    mkdir -p "${APP_DIR}/config/nginx"
    mkdir -p "${APP_DIR}/config/certs"
    mkdir -p "${BACKUP_DIR}/daily"
    mkdir -p "${BACKUP_DIR}/weekly"
    mkdir -p "${BACKUP_DIR}/monthly"
    mkdir -p "${LOG_DIR}"
    
    chown -R "${DEPLOY_USER}:${DEPLOY_USER}" "${APP_DIR}"
    
    log "✅ 目录结构创建完成"
}

# ==================== 内核优化 ====================
optimize_kernel() {
    log "⚙️ 内核参数优化..."
    
    cat > /etc/sysctl.d/99-water-management.conf <<EOF
# TCP 优化
net.core.somaxconn = 65535
net.ipv4.tcp_max_syn_backlog = 65535
net.ipv4.tcp_syncookies = 1
net.ipv4.tcp_tw_reuse = 1
net.ipv4.ip_local_port_range = 1024 65535

# 文件描述符
fs.file-max = 655350
fs.inotify.max_user_watches = 524288

# 内存优化
vm.swappiness = 10
vm.dirty_ratio = 15
vm.dirty_background_ratio = 5

# 网络优化
net.ipv4.tcp_keepalive_time = 600
net.ipv4.tcp_keepalive_intvl = 30
net.ipv4.tcp_keepalive_probes = 3
EOF
    
    sysctl -p /etc/sysctl.d/99-water-management.conf
    
    # 文件描述符限制
    cat > /etc/security/limits.d/99-water-management.conf <<EOF
* soft nofile 65535
* hard nofile 65535
* soft nproc 65535
* hard nproc 65535
${DEPLOY_USER} soft nofile 65535
${DEPLOY_USER} hard nofile 65535
EOF
    
    log "✅ 内核优化完成"
}

# ==================== 配置定时任务 ====================
setup_cron() {
    log "⏰ 配置定时任务..."
    
    local cron_file="/etc/cron.d/water-management"
    
    cat > "$cron_file" <<EOF
# 数据库备份 - 每天凌晨 2 点
0 2 * * * ${DEPLOY_USER} ${APP_DIR}/deploy/production/backup/backup-db.sh >> ${LOG_DIR}/backup.log 2>&1

# 证书续期 - 每天凌晨 3 点
0 3 * * * root ${APP_DIR}/deploy/production/nginx/certbot-renew.sh >> ${LOG_DIR}/certbot-renew.log 2>&1

# 日志清理 - 每天凌晨 4 点
0 4 * * * ${DEPLOY_USER} find ${LOG_DIR} -name "*.log" -mtime +30 -delete 2>/dev/null || true

# 磁盘监控 - 每小时
0 * * * * ${DEPLOY_USER} df -h | awk 'NR>1 && +\$5>90 {print "⚠️ 磁盘告警: "\$0}' | mail -s "磁盘告警" root 2>/dev/null || true
EOF
    
    chmod 644 "$cron_file"
    
    log "✅ 定时任务配置完成"
}

# ==================== 主流程 ====================

log "========================================="
log " 生产服务器初始化"
log "========================================="

check_root
update_system
install_docker
setup_firewall
harden_ssh
setup_fail2ban
create_deploy_user
create_directories
optimize_kernel
setup_cron

log "========================================="
log " ✅ 服务器初始化完成!"
log "========================================="
log ""
log "后续步骤:"
log "1. 将 SSH 公钥添加到 /home/${DEPLOY_USER}/.ssh/authorized_keys"
log "2. 配置 .env 环境变量文件: ${APP_DIR}/.env"
log "3. 配置域名 DNS 解析"
log "4. 申请 Let's Encrypt 证书"
log "5. 部署应用: docker compose -f docker-compose.yml -f deploy/production/docker-compose.override.yml up -d"
log "6. 启动监控栈: docker compose -f deploy/production/monitoring/docker-compose.monitoring.yml up -d"
log "7. 启动日志栈: docker compose -f deploy/production/logging/docker-compose.logging.yml up -d"
log ""