server {
    listen 80;
    server_name localhost;

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

    # Gzip compression
    gzip on;
    gzip_types text/plain text/css application/json application/javascript text/xml application/xml application/xml+rss text/javascript;

    # Enhanced Security headers.
    # This config only ever runs inside the frontend image, i.e. for self-hosted
    # deployments - app.chattermate.chat serves the SPA from its own reverse proxy
    # and never routes here, so its CSP is set there and is unaffected by this file.
    # The CSP is repeated in every location block below because an add_header inside
    # a location cancels the inherited ones - change one, change all five.
    add_header X-Frame-Options "DENY" always;
    add_header X-XSS-Protection "1; mode=block" always;
    add_header X-Content-Type-Options "nosniff" always;
    add_header Strict-Transport-Security "max-age=31536000; includeSubDomains" always;
    add_header Content-Security-Policy "frame-ancestors 'none'; default-src 'self'; script-src 'self' 'unsafe-inline' 'unsafe-eval' https://cdn.shopify.com https://connect.facebook.net; style-src 'self' 'unsafe-inline' https://fonts.googleapis.com https://cdn.shopify.com; font-src 'self' data: https://fonts.gstatic.com https://cdn.shopify.com; img-src 'self' data: blob: http: https:; connect-src 'self' https: http: ws: wss: blob:; frame-src 'self' http://localhost:* https:; worker-src 'self' blob:;" always;
    add_header Referrer-Policy "strict-origin-when-cross-origin" always;
    add_header Permissions-Policy "geolocation=(), microphone=(), camera=()" always;

    location / {
        try_files $uri $uri/ /index.html;
    }

    # PWA control files must never be long-cached: a stale sw.js pins every
    # installed client to an old build, and config.js is runtime-substituted
    # per environment. (Exact locations win over the regex cache block below;
    # add_header in a location cancels inherited headers, so re-add security.)
    location = /sw.js {
        add_header Cache-Control "no-cache" always;
        add_header Service-Worker-Allowed "/" always;
        add_header X-Frame-Options "DENY" always;
        add_header X-XSS-Protection "1; mode=block" always;
        add_header X-Content-Type-Options "nosniff" always;
        add_header Strict-Transport-Security "max-age=31536000; includeSubDomains" always;
        add_header Content-Security-Policy "frame-ancestors 'none'; default-src 'self'; script-src 'self' 'unsafe-inline' 'unsafe-eval' https://cdn.shopify.com https://connect.facebook.net; style-src 'self' 'unsafe-inline' https://fonts.googleapis.com https://cdn.shopify.com; font-src 'self' data: https://fonts.gstatic.com https://cdn.shopify.com; img-src 'self' data: blob: http: https:; connect-src 'self' https: http: ws: wss: blob:; frame-src 'self' http://localhost:* https:; worker-src 'self' blob:;" always;
        add_header Referrer-Policy "strict-origin-when-cross-origin" always;
        add_header Permissions-Policy "geolocation=(), microphone=(), camera=()" always;
    }

    location = /config.js {
        add_header Cache-Control "no-cache" always;
        add_header X-Frame-Options "DENY" always;
        add_header X-XSS-Protection "1; mode=block" always;
        add_header X-Content-Type-Options "nosniff" always;
        add_header Strict-Transport-Security "max-age=31536000; includeSubDomains" always;
        add_header Content-Security-Policy "frame-ancestors 'none'; default-src 'self'; script-src 'self' 'unsafe-inline' 'unsafe-eval' https://cdn.shopify.com https://connect.facebook.net; style-src 'self' 'unsafe-inline' https://fonts.googleapis.com https://cdn.shopify.com; font-src 'self' data: https://fonts.gstatic.com https://cdn.shopify.com; img-src 'self' data: blob: http: https:; connect-src 'self' https: http: ws: wss: blob:; frame-src 'self' http://localhost:* https:; worker-src 'self' blob:;" always;
        add_header Referrer-Policy "strict-origin-when-cross-origin" always;
        add_header Permissions-Policy "geolocation=(), microphone=(), camera=()" always;
    }

    location = /manifest.webmanifest {
        default_type application/manifest+json;
        add_header Cache-Control "no-cache" always;
        add_header X-Frame-Options "DENY" always;
        add_header X-XSS-Protection "1; mode=block" always;
        add_header X-Content-Type-Options "nosniff" always;
        add_header Strict-Transport-Security "max-age=31536000; includeSubDomains" always;
        add_header Content-Security-Policy "frame-ancestors 'none'; default-src 'self'; script-src 'self' 'unsafe-inline' 'unsafe-eval' https://cdn.shopify.com https://connect.facebook.net; style-src 'self' 'unsafe-inline' https://fonts.googleapis.com https://cdn.shopify.com; font-src 'self' data: https://fonts.gstatic.com https://cdn.shopify.com; img-src 'self' data: blob: http: https:; connect-src 'self' https: http: ws: wss: blob:; frame-src 'self' http://localhost:* https:; worker-src 'self' blob:;" always;
        add_header Referrer-Policy "strict-origin-when-cross-origin" always;
        add_header Permissions-Policy "geolocation=(), microphone=(), camera=()" always;
    }

    # Cache static assets
    location ~* \.(js|css|png|jpg|jpeg|gif|ico|svg)$ {
        expires 30d;
        add_header Cache-Control "public, no-transform";
        
        # Ensure security headers are also sent for static assets
        add_header X-Frame-Options "DENY" always;
        add_header X-XSS-Protection "1; mode=block" always;
        add_header X-Content-Type-Options "nosniff" always;
        add_header Strict-Transport-Security "max-age=31536000; includeSubDomains" always;
        add_header Content-Security-Policy "frame-ancestors 'none'; default-src 'self'; script-src 'self' 'unsafe-inline' 'unsafe-eval' https://cdn.shopify.com https://connect.facebook.net; style-src 'self' 'unsafe-inline' https://fonts.googleapis.com https://cdn.shopify.com; font-src 'self' data: https://fonts.gstatic.com https://cdn.shopify.com; img-src 'self' data: blob: http: https:; connect-src 'self' https: http: ws: wss: blob:; frame-src 'self' http://localhost:* https:; worker-src 'self' blob:;" always;
        add_header Referrer-Policy "strict-origin-when-cross-origin" always;
        add_header Permissions-Policy "geolocation=(), microphone=(), camera=()" always;
    }

    # API proxy
    location /api/ {
        proxy_pass http://backend:8000/;
        proxy_http_version 1.1;
        proxy_set_header Upgrade $http_upgrade;
        proxy_set_header Connection 'upgrade';
        proxy_set_header Host $host;
        # Forward the real client IP so per-IP rate limiting keys on the client,
        # not this proxy container. Overwrites any client-supplied X-Real-IP.
        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_cache_bypass $http_upgrade;
    }
}