# ---------------------------------------------------------------------------
# 班级小助手 · Nginx 反向代理样例（HTTPS + WebSocket）
#
# 作用：把 https://class.example.com 反向代理到本机 4000 端口的服务端，
#      同时处理 WebSocket 升级、真实 IP 透传、静态资源缓存与安全响应头。
#
# 使用：
#   1) 把本文件放到 /etc/nginx/conf.d/classhelper.conf（或 sites-available 并做软链）
#   2) 修改 server_name 与证书路径
#   3) nginx -t && systemctl reload nginx
#   4) 服务端 .env 中设置 TRUST_PROXY=1（否则限流按代理 IP 统计）
#      以及 CORS_ORIGIN=https://class.example.com
# ---------------------------------------------------------------------------

# 上游：本机运行的服务端（Windows 安装包 / Docker / 手动启动均适用）
upstream classhelper_backend {
    server 127.0.0.1:4000;
    keepalive 32;
}

# HTTP -> HTTPS 跳转
server {
    listen 80;
    listen [::]:80;
    server_name class.example.com;

    # Let's Encrypt 校验目录（如使用 certbot --webroot）
    location /.well-known/acme-challenge/ {
        root /var/www/certbot;
    }

    location / {
        return 301 https://$host$request_uri;
    }
}

server {
    listen 443 ssl;
    listen [::]:443 ssl;
    http2 on;
    server_name class.example.com;

    # ---------------------------------------------------------------- 证书
    ssl_certificate     /etc/nginx/certs/class.example.com.crt;
    ssl_certificate_key /etc/nginx/certs/class.example.com.key;
    ssl_protocols       TLSv1.2 TLSv1.3;
    ssl_ciphers         HIGH:!aNULL:!MD5;
    ssl_session_cache   shared:SSL:10m;
    ssl_session_timeout 1d;

    # ---------------------------------------------------------------- 基础
    client_max_body_size 8m;
    charset utf-8;
    access_log /var/log/nginx/classhelper.access.log;
    error_log  /var/log/nginx/classhelper.error.log warn;

    # 安全响应头（应用层已用 helmet 设置，这里作为兜底）
    add_header X-Content-Type-Options nosniff always;
    add_header X-Frame-Options SAMEORIGIN always;
    add_header Referrer-Policy no-referrer always;
    add_header Strict-Transport-Security "max-age=15552000; includeSubDomains" always;

    # gzip（静态资源与接口响应）
    gzip on;
    gzip_comp_level 5;
    gzip_min_length 1024;
    gzip_types text/plain text/css application/json application/javascript application/manifest+json image/svg+xml;

    # ---------------------------------------------------------------- WebSocket（Socket.IO）
    location /socket.io/ {
        proxy_pass http://classhelper_backend;
        proxy_http_version 1.1;
        proxy_set_header Upgrade $http_upgrade;
        proxy_set_header Connection "upgrade";
        proxy_set_header Host $host;
        proxy_set_header X-Real-IP $remote_addr;
        proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
        proxy_set_header X-Forwarded-Proto $scheme;
        proxy_read_timeout 3600s;
        proxy_send_timeout 3600s;
        proxy_buffering off;
    }

    # ---------------------------------------------------------------- 静态资源（带哈希，长缓存）
    location /assets/ {
        proxy_pass http://classhelper_backend;
        proxy_set_header Host $host;
        proxy_set_header X-Forwarded-Proto $scheme;
        expires 1y;
        add_header Cache-Control "public, immutable";
        access_log off;
    }

    # ---------------------------------------------------------------- 接口与页面
    location / {
        proxy_pass http://classhelper_backend;
        proxy_http_version 1.1;
        proxy_set_header Host $host;
        proxy_set_header X-Real-IP $remote_addr;
        proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
        proxy_set_header X-Forwarded-Proto $scheme;
        proxy_set_header Connection "";
        proxy_read_timeout 120s;
        proxy_connect_timeout 10s;
    }
}