server {
    listen 80;
    listen [::]:80;
    server_name localhost;
    # Point root to the frontend directory where static assets reside inside the container
    root /var/www/html;
    index index.html;
    
    # Enable detailed error logging
    error_log /var/log/nginx/error.log debug;
    access_log /var/log/nginx/access.log;
    
    # Global settings
    gzip on;
    gzip_types text/plain text/css application/javascript application/json;
    client_max_body_size __NGINX_MAX_BODY_SIZE_CONFIG_VALUE__; # Configurable global limit
    
    # Add CORS headers globally
    add_header 'Access-Control-Allow-Origin' '*';
    add_header 'Access-Control-Allow-Methods' 'GET, POST, OPTIONS, PUT, DELETE';
    add_header 'Access-Control-Allow-Headers' 'DNT,User-Agent,X-Requested-With,If-Modified-Since,Cache-Control,Content-Type,Range,Authorization';
    
    # MIME types - fixed duplicate js entry
    types {
        text/html                             html htm shtml;
        text/css                              css;
        application/javascript                js;
        image/png                             png;
        image/jpeg                            jpg jpeg;
        image/gif                             gif;
        image/svg+xml                         svg svgz;
        application/pdf                       pdf;
        image/x-icon                          ico;
        application/json                      json;
        application/manifest+json             webmanifest manifest;
    }
    
    # Specific location for locales JSON files
    location /locales/ {
        alias /var/www/html/locales/;
        try_files $uri =404;
        add_header Content-Type "application/json; charset=utf-8";
        add_header Cache-Control "no-cache, no-store, must-revalidate";
        expires -1;
    }
    
    # API requests - proxy to backend (fixed upstream host)
    # Using ^~ to ensure this prefix match takes precedence over regex extension matches
    location ^~ /api/ {
        proxy_pass http://127.0.0.1:5000; # Removed trailing slash to pass /api/ prefix
        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;
        client_max_body_size __NGINX_MAX_BODY_SIZE_CONFIG_VALUE__; # Configurable limit for API location
        
        # Pass Authorization header to backend
        proxy_set_header Authorization $http_authorization;
        
        # Enhanced proxy settings for file handling
        proxy_buffering off; # Disable buffering for file downloads to prevent content-length mismatches
        proxy_request_buffering off; # Disable request buffering for uploads
        proxy_read_timeout 300s; # Increased timeout for large file transfers
        proxy_connect_timeout 30s;
        proxy_send_timeout 300s;
        
        # Prevent proxy from modifying response headers that could cause issues
        proxy_set_header Connection "";
        proxy_http_version 1.1;
        
        # Add debug headers to see what's happening
        add_header X-Debug-Message "API request proxied to backend" always;
        
        # CORS for API
        add_header 'Access-Control-Allow-Origin' '*' always;
        add_header 'Access-Control-Allow-Methods' 'GET, POST, OPTIONS, PUT, DELETE' always;
        add_header 'Access-Control-Allow-Headers' 'DNT,User-Agent,X-Requested-With,If-Modified-Since,Cache-Control,Content-Type,Range,Authorization' always;
        
        # CORS preflight
        if ($request_method = 'OPTIONS') {
            add_header 'Access-Control-Allow-Origin' '*' always;
            add_header 'Access-Control-Allow-Methods' 'GET, POST, OPTIONS, PUT, DELETE' always;
            add_header 'Access-Control-Allow-Headers' 'DNT,User-Agent,X-Requested-With,If-Modified-Since,Cache-Control,Content-Type,Range,Authorization' always;
            add_header 'Access-Control-Max-Age' 1728000 always;
            add_header 'Content-Type' 'text/plain charset=UTF-8' always;
            add_header 'Content-Length' 0 always;
            return 204;
        }
    }
    
    # Uploads - serve files from uploads directory
    location /uploads/ {
        return 403 "Access forbidden";
    }
    
    # HTML files - ensure proper content type
    location ~ \.html$ {
        add_header Content-Type "text/html; charset=utf-8";
        add_header Cache-Control "no-cache, no-store, must-revalidate";
    }
    
    # Favicon - specific handling
    location = /favicon.ico {
        log_not_found off;
        access_log off;
        try_files $uri =404;
        expires 7d;
        add_header Cache-Control "public, max-age=604800";
    }
    
    # Service Worker - no cache to ensure updates
    location = /sw.js {
        try_files $uri =404;
        add_header Cache-Control "no-cache, no-store, must-revalidate";
        expires -1;
    }

    # Static assets (CSS, JS, images)
    location ~* \.(css|js|jpg|jpeg|png|gif|ico|svg)$ {
        try_files $uri =404;
        expires 7d;
        add_header Cache-Control "public, max-age=604800";
    }
    
    # Test uploads path
    location = /test-uploads {
        add_header Content-Type text/plain;
        return 200 "Uploads directory exists: $document_root\n";
    }

    # Specific handling for manifest.json
    location = /manifest.json {
        alias /var/www/html/manifest.json; # Serve from this specific path
        # The global types block should set the correct Content-Type
        # (application/manifest+json for 'manifest' extension)
        # If not found by alias, it will result in a 404, which is correct.
        # No need for try_files here if alias is used and file must exist.
        # If you want to be explicit about 404 if alias target doesn't exist:
        # if (!-f /var/www/html/manifest.json) { return 404; }
        # However, alias itself should handle this.
        # Add caching headers if desired, e.g.:
        # expires 1d;
        # add_header Cache-Control "public, must-revalidate";
    }
    
    # Default location
    location / {
        try_files $uri $uri/ /index.html;
    }
}