server {
    listen 80;
    server_name localhost;
    root /usr/share/nginx/html;
    index index.html;

    add_header X-Content-Type-Options "nosniff" always;
    add_header X-Frame-Options "SAMEORIGIN" always;
    add_header Referrer-Policy "strict-origin-when-cross-origin" always;
    add_header Permissions-Policy "camera=(), microphone=(), geolocation=()" always;

    # Docker-Embedded DNS: Hostname »backend« bei Container-Neustarts neu auflösen
    # — verringert sporadische 502, wenn sich nur die Backend-Container-IP geändert hat.
    resolver 127.0.0.11 valid=10s ipv6=off;

    # Uploads (Übungsmedien, Medienarchiv-Bulk) — Limit muss >= größte Einzeldatei und
    # bei multipart ggf. Summe mehrerer Dateien sein (Backend praxis: bis 1024 MB Admin).
    client_max_body_size 1024m;

    # Medienbibliothek (React /media) — vor location ^~ /media/: sonst liefert ein Reload
    # auf /media/ den FastAPI StaticFiles-Mount unter /media und der Browser zeigt {"detail":"Not Found"}.
    location = /media {
        add_header Content-Security-Policy "default-src 'self'; base-uri 'self'; form-action 'self'; frame-ancestors 'self'; object-src 'none'; script-src 'self'; style-src 'self' 'unsafe-inline'; img-src 'self' data: blob: https:; font-src 'self' data:; connect-src 'self'; media-src 'self' blob: data:; worker-src 'self' blob:; manifest-src 'self';" always;
        try_files /index.html =404;
    }
    location = /media/ {
        add_header Content-Security-Policy "default-src 'self'; base-uri 'self'; form-action 'self'; frame-ancestors 'self'; object-src 'none'; script-src 'self'; style-src 'self' 'unsafe-inline'; img-src 'self' data: blob: https:; font-src 'self' data:; connect-src 'self'; media-src 'self' blob: data:; worker-src 'self' blob:; manifest-src 'self';" always;
        try_files /index.html =404;
    }

    location ^~ /api/ {
        set $docker_backend_svc backend;
        proxy_pass http://$docker_backend_svc:8000$request_uri;
        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 60s;
        proxy_send_timeout 300s;
        proxy_read_timeout 300s;
    }

    location ^~ /media/ {
        # Auslieferung Übungsdateien erfolgt geschützt über /api/exercises/.../media/.../file (?ssetoken).
        # Optional: Backend mit ALLOW_PUBLIC_MEDIA_STATIC=1 → wieder /media/ ohne Auth.
        set $docker_backend_svc backend;
        proxy_pass http://$docker_backend_svc:8000$request_uri;
        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;
    }

    location = /health {
        set $hc_upstream backend;
        proxy_pass http://$hc_upstream:8000/health;
        proxy_http_version 1.1;
        proxy_set_header Host $host;
    }

    location / {
        # Document-CSP für SPA/PWA — React nutzt häufig inline-styles; Mediendateien & API sind same-origin (Proxy).
        # Bei separater API-Origin: connect-src hier erweitern oder nginx-Envsubst nutzen.
        add_header Content-Security-Policy "default-src 'self'; base-uri 'self'; form-action 'self'; frame-ancestors 'self'; object-src 'none'; script-src 'self'; style-src 'self' 'unsafe-inline'; img-src 'self' data: blob: https:; font-src 'self' data:; connect-src 'self'; media-src 'self' blob: data:; worker-src 'self' blob:; manifest-src 'self';" always;
        try_files $uri $uri/ /index.html;
    }

    # Cache static assets
    location ~* \.(js|css|png|jpg|jpeg|gif|ico|svg)$ {
        expires 1y;
        add_header Cache-Control "public, immutable";
    }
}
