// Copyright 2026 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

/**
 * @file This file includes DOM helpers and page-evaluated serialization helpers
 * used by AI assistance that require DOM types. They are isolated in a separate
 * target so DOM types do not leak into the rest of models/ai_assistance.
 */

import * as Platform from '../../core/platform/platform.js';

export interface GetErrorStackOutput {
  message: string;
  stack?: string;
}

/* istanbul ignore next */
export function getErrorStackOnThePage(this: Error): GetErrorStackOutput {
  // Using this.stack causes side effect checks to throw.
  return {stack: '', message: this.message};
}

/* istanbul ignore next */
export function stringifyObjectOnThePage(this: unknown): string {
  const seenBefore = new Map();
  return JSON.stringify(this, function replacer(this: unknown, key: string, value: unknown) {
    if (typeof value === 'object' && value !== null) {
      if (seenBefore.has(value)) {
        return '(cycle)';
      }

      seenBefore.set(value, true);
    }

    if (value instanceof HTMLElement) {
      const idAttribute = value.id ? ` id="${value.id}"` : '';
      const classAttribute = value.classList.value ? ` class="${value.classList.value}"` : '';

      return `<${value.nodeName.toLowerCase()}${idAttribute}${classAttribute}>${value.hasChildNodes() ? '...' : ''}</${
          value.nodeName.toLowerCase()}>`;
    }

    if (this instanceof CSSStyleDeclaration) {
      // Do not add number keys to the output.
      if (!isNaN(Number(key))) {
        return undefined;
      }
    }

    return value;
  });
}

export async function sanitizeStyleChanges(selector: string,
                                           styles: Record<string, string>): Promise<Record<string, string>> {
  const cssStyleValue: string[] = [];
  const changedStyles: string[] = [];
  const kebabStyles = Platform.StringUtilities.toKebabCaseKeys(styles);
  for (const [style, value] of Object.entries(kebabStyles)) {
    // Build up the CSS style
    cssStyleValue.push(`${style}: ${value};`);
    // Keep track of what style changed to query later.
    changedStyles.push(style);
  }

  if (typeof CSSStyleSheet === 'undefined' || typeof CSSStyleRule === 'undefined') {
    return kebabStyles;
  }

  const styleSheet = new CSSStyleSheet({disabled: true});
  // Build up the CSS stylesheet value.
  await styleSheet.replace(`${selector} { ${cssStyleValue.join(' ')} }`);

  const sanitizedStyles: Record<string, string> = {};
  for (const cssRule of styleSheet.cssRules) {
    if (!(cssRule instanceof CSSStyleRule)) {
      continue;
    }
    for (const style of changedStyles) {
      const value = cssRule.style.getPropertyValue(style);
      if (value) {
        sanitizedStyles[style] = value;
      }
    }
  }

  return sanitizedStyles;
}

export function dispatchAiAssistanceDoneEvent(): void {
  if (typeof window !== 'undefined') {
    window.dispatchEvent(new CustomEvent('aiassistancedone'));
  }
}