vcl 4.1;

# Backend definition - points to our PHP/Apache container
backend default {
    .host = "app";
    .port = "80";
    .connect_timeout = 60s;
    .first_byte_timeout = 60s;
    .between_bytes_timeout = 60s;
}


# Called at the beginning of a request
sub vcl_recv {
    # Remove port from Host header for proper backend routing
    if (req.http.Host) {
        set req.http.Host = regsub(req.http.Host, ":[0-9]+", "");
    }

    # Handle image requests
    if (req.url ~ "\.(jpg|jpeg|png|gif|webp|svg|ico)$") {
        # Cache images aggressively
        set req.http.Cache-Control = "public, max-age=2592000";
        return (hash);
    }

    # Handle API image proxy requests
    if (req.url ~ "^/api/image\.php") {
        # Cache external images through our proxy
        return (hash);
    }

    # Handle CSS and JS files
    if (req.url ~ "\.(css|js)$") {
        return (hash);
    }

    # Don't cache POST, PUT, DELETE requests
    if (req.method != "GET" && req.method != "HEAD") {
        return (pass);
    }

    # Don't cache requests with cookies (except for images)
    if (req.http.Cookie && req.url !~ "\.(jpg|jpeg|png|gif|webp|svg|ico|css|js)$") {
        return (pass);
    }

    # Remove tracking parameters
    if (req.url ~ "\?") {
        set req.url = regsub(req.url, "\?.*", "");
    }

    return (hash);
}

# Called after a cache lookup
sub vcl_hit {
    # Add cache hit header for debugging
    set req.http.X-Cache = "HIT";
    return (deliver);
}

# Called after a cache miss
sub vcl_miss {
    set req.http.X-Cache = "MISS";
    return (fetch);
}

# Called before sending response to client
sub vcl_deliver {
    # Add cache status header
    if (req.http.X-Cache) {
        set resp.http.X-Cache = req.http.X-Cache;
    }

    # Add CORS headers for images
    if (req.url ~ "\.(jpg|jpeg|png|gif|webp|svg|ico)$") {
        set resp.http.Access-Control-Allow-Origin = "*";
    }

    # Remove server identification
    unset resp.http.Server;
    unset resp.http.X-Powered-By;
    unset resp.http.X-Varnish;

    return (deliver);
}

# Called after fetching from backend
sub vcl_backend_response {
    # Cache images for 30 days
    if (bereq.url ~ "\.(jpg|jpeg|png|gif|webp|svg|ico)$") {
        set beresp.ttl = 30d;
        set beresp.http.Cache-Control = "public, max-age=2592000";
        set beresp.http.Expires = beresp.http.Date + 30d;
        
        # Don't cache if backend says not to
        if (beresp.http.Cache-Control ~ "no-cache") {
            set beresp.ttl = 0s;
        }
    }

    # Cache CSS and JS for 7 days
    if (bereq.url ~ "\.(css|js)$") {
        set beresp.ttl = 7d;
        set beresp.http.Cache-Control = "public, max-age=604800";
    }

    # Cache API image proxy for 1 day
    if (bereq.url ~ "^/api/image\.php") {
        set beresp.ttl = 1d;
        set beresp.http.Cache-Control = "public, max-age=86400";
    }

    # Don't cache if there's an error
    if (beresp.status >= 400) {
        set beresp.ttl = 0s;
        set beresp.uncacheable = true;
    }

    # Enable compression
    if (beresp.http.Content-Type ~ "text|application|image/svg") {
        set beresp.do_gzip = true;
    }

    return (deliver);
}

# Called when there's an error
sub vcl_backend_error {
    set beresp.http.Content-Type = "text/html; charset=utf-8";
    set beresp.status = 503;
    synthetic( {"<!DOCTYPE html>
<html>
<head>
    <title>Service Unavailable</title>
    <style>
        body { font-family: Arial, sans-serif; text-align: center; padding: 50px; }
        h1 { color: #666; }
    </style>
</head>
<body>
    <h1>Service Temporarily Unavailable</h1>
    <p>Please try again in a few moments.</p>
</body>
</html>"} );
    return (deliver);
}