/**
 * Copy text to clipboard
 * @param text - text to copy
 * @returns - whether copy is successful
 */
async function copyTextToClipboard(text: string): Promise<boolean> {
  // Try Clipboard API first
  if (navigator.clipboard?.writeText) {
    try {
      await navigator.clipboard.writeText(text);
      return true;
    } catch (err) {
      console.warn('Clipboard API failed:', err);
    }
  }

  // Fallback 1: execCommand (PC)
  try {
    const textarea = document.createElement('textarea');
    textarea.value = text;
    // Prevent scrolling
    textarea.style.position = 'fixed';
    textarea.style.opacity = '0';
    document.body.appendChild(textarea);

    // Special handling for iOS
    if (navigator.userAgent.match(/ipad|iphone/i)) {
      textarea.contentEditable = 'true';
      textarea.readOnly = false;

      const range = document.createRange();
      range.selectNodeContents(textarea);

      const selection = window.getSelection();
      if (selection) {
        selection.removeAllRanges();
        selection.addRange(range);
        textarea.setSelectionRange(0, 999999);
      }
    } else {
      textarea.select();
    }

    const result = document.execCommand('copy');
    document.body.removeChild(textarea);
    return result;
  } catch (err) {
    console.warn('execCommand failed:', err);
  }

  // Fallback 2: Prompt user to copy manually
  throw new Error('Failed to copy text to clipboard, please copy manually');
}

/**
 * exitFullscreen
 * @example
 * exitFullscreen();
 */
function exitFullScreen() {
  if (!document?.fullscreenElement && !(document as any)?.webkitFullscreenElement && !(document as any)?.mozFullScreenElement) {
    return;
  }
  const exitFullScreenDocument = document as Document & {
    mozCancelFullScreen(): Promise<void>;
    msExitFullscreen(): Promise<void>;
    webkitExitFullscreen(): Promise<void>;
  };
  if (exitFullScreenDocument?.exitFullscreen) {
    exitFullScreenDocument?.exitFullscreen();
  } else if (exitFullScreenDocument?.msExitFullscreen) {
    exitFullScreenDocument?.msExitFullscreen();
  } else if (exitFullScreenDocument?.mozCancelFullScreen) {
    exitFullScreenDocument?.mozCancelFullScreen();
  } else if (exitFullScreenDocument?.webkitExitFullscreen) {
    exitFullScreenDocument?.webkitExitFullscreen();
  }
}

/**
 * Deep merge multiple objects into a single object
 * @param args - Objects to be merged
 * @returns Merged object
 * @example
 * const obj1 = { a: 1, b: { c: 2 } };
 * const obj2 = { b: { d: 3 }, e: 4 };
 * const result = objectMerge(obj1, obj2);
 * // result: { a: 1, b: { c: 2, d: 3 }, e: 4 }
 */
function objectMerge(...args: any[]) {
  return args.reduce((acc, cur) => {
    Object.keys(cur).forEach((key) => {
      if (acc[key] && typeof acc[key] === 'object') {
        acc[key] = objectMerge(acc[key], cur[key]);
      } else {
        acc[key] = cur[key];
      }
    });
    return acc;
  }, {});
}

const _encoder = new TextEncoder();

/**
 * Truncate a string so its UTF-8 byte length does not exceed maxBytes.
 * Avoids splitting multi-byte characters mid-sequence.
 */
function truncateByBytes(str: string, maxBytes: number): string {
  if (_encoder.encode(str).length <= maxBytes) {
    return str;
  }
  let result = '';
  let bytes = 0;
  for (const char of str) {
    const charBytes = _encoder.encode(char).length;
    if (bytes + charBytes > maxBytes) {
      break;
    }
    result += char;
    bytes += charBytes;
  }
  return result;
}

export {
  copyTextToClipboard,
  exitFullScreen,
  objectMerge,
  truncateByBytes,
};