package host

import (
	"bytes"
	"strings"
)

// ReloadScript is the JavaScript code injected into HTML pages for hot reload.
const ReloadScript = `<script>
(function() {
    var wsUrl = 'ws://' + window.location.host + '/__livereload';
    var ws;
    var reconnectAttempts = 0;
    var maxReconnectDelay = 5000;

    function connect() {
        ws = new WebSocket(wsUrl);
        
        ws.onopen = function() {
            console.log('[iris] Hot reload connected');
            reconnectAttempts = 0;
        };
        
        ws.onmessage = function(event) {
            if (event.data === 'reload') {
                console.log('[iris] Reloading...');
                window.location.reload();
            }
        };
        
        ws.onclose = function() {
            var delay = Math.min(1000 * Math.pow(2, reconnectAttempts), maxReconnectDelay);
            reconnectAttempts++;
            console.log('[iris] Connection lost. Reconnecting in ' + delay + 'ms...');
            setTimeout(connect, delay);
        };
        
        ws.onerror = function() {
            ws.close();
        };
    }

    connect();
})();
</script>`

// InjectReloadScript injects the live reload script into HTML content.
// The script is inserted just before the closing </body> tag.
func InjectReloadScript(html []byte) []byte {
	// Try to inject before </body>
	bodyEnd := bytes.LastIndex(html, []byte("</body>"))
	if bodyEnd != -1 {
		result := make([]byte, 0, len(html)+len(ReloadScript))
		result = append(result, html[:bodyEnd]...)
		result = append(result, []byte(ReloadScript)...)
		result = append(result, html[bodyEnd:]...)
		return result
	}

	// Try to inject before </html>
	htmlEnd := bytes.LastIndex(html, []byte("</html>"))
	if htmlEnd != -1 {
		result := make([]byte, 0, len(html)+len(ReloadScript))
		result = append(result, html[:htmlEnd]...)
		result = append(result, []byte(ReloadScript)...)
		result = append(result, html[htmlEnd:]...)
		return result
	}

	// Append at the end as fallback
	result := make([]byte, 0, len(html)+len(ReloadScript))
	result = append(result, html...)
	result = append(result, []byte(ReloadScript)...)
	return result
}

// IsHTMLContent checks if the content type indicates HTML.
func IsHTMLContent(contentType string) bool {
	return strings.Contains(contentType, "text/html")
}