# Reverse proxy + TLS edge for «Контракт-чек».
# Variables ${NGINX_SERVER_NAME} are expanded by the nginx Docker entrypoint
# from files in /etc/nginx/templates/*.template. Mount this directory:
#
#   ./deploy/nginx/templates:/etc/nginx/templates:ro
#
# Do not run `nginx -t` directly on this .template file; render it first with
# envsubst or start the container.

# ── Dynamic upstream resolution ─────────────────────────────────────────────
# In Docker Compose the `api` hostname must be re-resolved when the API
# container is recreated (it gets a new IP). By default nginx resolves an
# upstream hostname once at startup and caches it forever, so after a deploy the
# edge proxy would keep trying the old API IP. Using a variable with
# proxy_pass forces nginx to re-resolve `api` against Docker's embedded DNS
# every `valid=` interval.
#
# 127.0.0.11 is Docker's internal resolver (available inside containers).
# If it is unreachable, increase `valid=` or set an explicit resolver address.
resolver 127.0.0.11 valid=10s;

# ── Logging ─────────────────────────────────────────────────────────────────
log_format contract_check '$remote_addr - $remote_user [$time_local] "$request" '
                            '$status $body_bytes_sent "$http_referer" '
                            '"$http_user_agent" "$http_x_forwarded_for" '
                            'rt=$request_time cid=$http_x_correlation_id';

access_log  /var/log/nginx/access.log  contract_check;

# Body limit: contracts may be large PDFs/DOCX (default 50 MiB).
client_max_body_size 50M;

# ── HTTP → HTTPS redirect (certbot handles LE challenge inline) ───────────────
server {
    listen 80;
    listen [::]:80;
    server_name ${NGINX_SERVER_NAME};

    location /.well-known/acme-challenge/ {
        root /var/www/certbot;
    }

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

# ── HTTPS server ──────────────────────────────────────────────────────────────
server {
    listen 443 ssl;
    listen [::]:443 ssl;
    http2 on;
    server_name ${NGINX_SERVER_NAME};

    ssl_certificate     /etc/letsencrypt/live/${NGINX_SERVER_NAME}/fullchain.pem;
    ssl_certificate_key /etc/letsencrypt/live/${NGINX_SERVER_NAME}/privkey.pem;

    ssl_protocols       TLSv1.2 TLSv1.3;
    ssl_ciphers         ECDHE-ECDSA-AES128-GCM-SHA256:ECDHE-RSA-AES128-GCM-SHA256:ECDHE-ECDSA-AES256-GCM-SHA384:ECDHE-RSA-AES256-GCM-SHA384;
    ssl_prefer_server_ciphers on;
    ssl_session_cache shared:SSL:10m;
    ssl_session_timeout 1d;

    # Security headers
    add_header X-Frame-Options           "SAMEORIGIN" always;
    add_header X-Content-Type-Options    "nosniff" always;
    add_header Referrer-Policy           "strict-origin-when-cross-origin" always;

    # Public endpoints: health, metrics, B2B API, auth, document analysis.
    # /metrics is intentionally exposed here for external Prometheus scrape;
    # lock it down at the firewall (or remove this block if metrics must stay
    # private and are scraped by an in-compose Prometheus).
    location ~ ^/(healthz|readyz|metrics|api/|admin/|docs|openapi.json) {
        # Variable forces dynamic DNS resolution for `api`.
        set $api http://api:8000;
        proxy_pass $api;
        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 X-Forwarded-Host  $host;
        proxy_set_header X-Forwarded-Port  $server_port;
        proxy_set_header X-Correlation-Id  $http_x_correlation_id;

        proxy_connect_timeout 10s;
        proxy_send_timeout    30s;
        proxy_read_timeout    120s;
        proxy_buffering       off;
    }

    # Webhook endpoint for future payment providers (ЮKassa, etc.).
    # Kept separate so it's easy to add IP allow-listing or extra logging.
    location /webhook/ {
        # Variable forces dynamic DNS resolution for `api`.
        set $api http://api:8000;
        proxy_pass $api/api/v1/webhooks/;
        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_connect_timeout 10s;
        proxy_send_timeout    30s;
        proxy_read_timeout    60s;
    }

    # Grafana / Loki: exposed under /grafana so everything lives on one domain.
    # In production restrict access here or via firewall (basic auth / VPN / SSO).
    location /grafana/ {
        # Variable forces dynamic DNS resolution for `grafana`.
        set $grafana http://grafana:3000;
        proxy_pass $grafana;
        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 X-Forwarded-Host  $host;
        proxy_set_header X-Correlation-Id  $http_x_correlation_id;

        # Grafana needs the subpath so it can build correct links/redirects.
        proxy_set_header X-Forwarded-Prefix /grafana;

        proxy_connect_timeout 10s;
        proxy_send_timeout    30s;
        proxy_read_timeout    60s;
        proxy_buffering       off;
    }

    # Static web SPA (future). Placeholder: serve pre-built static assets.
    # location / {
    #     root /usr/share/nginx/html;
    #     try_files $uri $uri/ /index.html;
    # }

    # Default: 404. Remove this when the static web SPA is enabled above.
    location / {
        return 404;
    }

    location /stub_status {
        stub_status on;
        allow 10.0.0.0/8;
        allow 172.16.0.0/12;
        allow 192.168.0.0/16;
        allow 127.0.0.1;
        deny all;
    }
}