// ============================================================================
// Channel URL Parser Utility
// Parses various URL formats and usernames to extract channel username
// ============================================================================

export function parseChannelInput(input: string): string | null {
  if (!input || typeof input !== "string") return null;

  let cleaned = input.trim();

  // Remove @ prefix if present
  cleaned = cleaned.replace(/^@/, "");

  // Patterns for different URL formats
  const patterns: RegExp[] = [
    /telemetr\.me\/content\/([a-zA-Z0-9_]+)/, // telemetr.me/content/rian_ru
    /telemetr\.me\/([a-zA-Z0-9_]+)/, // telemetr.me/rian_ru (alternative)
    /t\.me\/([a-zA-Z0-9_]+)/, // t.me/rian_ru or https://t.me/rian_ru
    /tgstat\.ru\/channel\/@?([a-zA-Z0-9_]+)/, // tgstat.ru/channel/@rian_ru or tgstat.ru/channel/rian_ru
    /tg\.me\/([a-zA-Z0-9_]+)/, // tg.me/rian_ru
  ];

  for (const pattern of patterns) {
    const match = cleaned.match(pattern);
    if (match && match[1]) {
      return match[1];
    }
  }

  // If it's just a plain username (alphanumeric + underscore)
  if (/^[a-zA-Z0-9_]+$/.test(cleaned)) {
    return cleaned;
  }

  return null;
}

// Check if input is a valid channel identifier
export function isValidChannelInput(input: string): boolean {
  return parseChannelInput(input) !== null;
}

// Get platform hint from URL (for analytics links)
export function getChannelAnalyticsUrls(username: string): {
  telemetr: string;
  tgstat: string;
} {
  const cleanUsername = username.replace(/^@/, "");
  return {
    telemetr: `https://telemetr.me/channel/${cleanUsername}`,
    tgstat: `https://tgstat.ru/channel/@${cleanUsername}`,
  };
}