# -----------------------------------------------------------------------------
# Serves the SPA and proxies /api to the Django container.
#
# Putting both behind one origin means the browser never issues a cross-origin
# request, so no CORS pre-flight, no third-party cookie rules, and the API can
# keep its allow-list empty in production.
#
# Every location includes security-headers.conf rather than relying on a
# server-level declaration - see the comment in that file for why inheritance
# cannot be trusted here.  Proxied locations additionally include
# proxy-backend.conf, which forwards the client details and drops the
# duplicate security headers Django emits.
# -----------------------------------------------------------------------------

# The SPA's policy: no inline script, nothing loaded off-origin.  The bundle is
# fully self-hosted, so this can stay strict.  ('unsafe-inline' for styles is
# still required by the inline style attributes React emits.)
map $host $spa_csp {
    default "default-src 'self'; script-src 'self'; style-src 'self' 'unsafe-inline'; img-src 'self' data:; connect-src 'self'; font-src 'self'; frame-ancestors 'none'; base-uri 'self'; form-action 'self'";
}

server {
    listen 8080;
    server_name _;

    root /usr/share/nginx/html;
    index index.html;

    server_tokens off;
    client_max_body_size 2m;

    gzip on;
    gzip_types text/css application/javascript application/json image/svg+xml;
    gzip_min_length 1024;

    location = /healthz {
        access_log off;
        include /etc/nginx/conf.d/security-headers.conf;
        add_header Content-Type text/plain;
        return 200 'ok';
    }

    # Hashed assets never change under the same name - cache them hard.
    location /assets/ {
        include /etc/nginx/conf.d/security-headers.conf;
        add_header Content-Security-Policy $spa_csp always;
        expires 1y;
        add_header Cache-Control "public, immutable";
        try_files $uri =404;
    }

    # --- API documentation ---------------------------------------------------
    # Swagger UI and ReDoc bootstrap themselves from an inline <script> block
    # that drf-spectacular generates, which the SPA's "script-src 'self'"
    # blocks - the page loads but renders blank.  Rather than punching
    # 'unsafe-inline' into the policy the SPA runs under, the exemption is
    # confined to these three documentation paths: they render no user data and
    # no user input, they load nothing off-origin (drf-spectacular-sidecar
    # serves the bundles from /static/, not a CDN), and in production they are
    # not routed at all - SERVE_API_DOCS defaults to false there.
    location ~ ^/api/(docs|redoc|schema)/ {
        include /etc/nginx/conf.d/security-headers.conf;
        add_header Content-Security-Policy "default-src 'self'; script-src 'self' 'unsafe-inline'; style-src 'self' 'unsafe-inline'; img-src 'self' data:; connect-src 'self'; font-src 'self'; frame-ancestors 'none'; base-uri 'self'; form-action 'self'" always;

        include /etc/nginx/conf.d/proxy-backend.conf;
        proxy_pass http://backend:8000;
    }

    location /api/ {
        include /etc/nginx/conf.d/security-headers.conf;
        add_header Content-Security-Policy $spa_csp always;

        include /etc/nginx/conf.d/proxy-backend.conf;
        proxy_pass http://backend:8000;
    }

    # Django admin and static files share the backend origin.
    location ~ ^/(admin|static)/ {
        include /etc/nginx/conf.d/security-headers.conf;
        add_header Content-Security-Policy $spa_csp always;

        include /etc/nginx/conf.d/proxy-backend.conf;
        proxy_pass http://backend:8000;
    }

    # Client-side routing: unknown paths fall back to the SPA shell.
    location / {
        include /etc/nginx/conf.d/security-headers.conf;
        add_header Content-Security-Policy $spa_csp always;
        add_header Cache-Control "no-cache";
        try_files $uri $uri/ /index.html;
    }
}