import { defaultSchema } from 'hast-util-sanitize';
import deepmerge from 'ts-deepmerge';

type Attributes = typeof defaultSchema.attributes;

type ExtractPropertyDefinition<T> =
  T extends Record<string, (infer U)[]> ? U : never;

type PropertyDefinition = ExtractPropertyDefinition<NonNullable<Attributes>>;

const excludeRestrictedClassAttributes = (
  propertyDefinitions: PropertyDefinition[],
): PropertyDefinition[] => {
  if (propertyDefinitions == null) {
    return propertyDefinitions;
  }

  return propertyDefinitions.filter((propertyDefinition) => {
    if (!Array.isArray(propertyDefinition)) {
      return true;
    }
    return (
      propertyDefinition[0] !== 'class' && propertyDefinition[0] !== 'className'
    );
  });
};

// generate relaxed schema
const relaxedSchemaAttributes: Record<string, PropertyDefinition[]> =
  structuredClone(defaultSchema.attributes) ?? {};
relaxedSchemaAttributes.a = excludeRestrictedClassAttributes(
  relaxedSchemaAttributes.a,
);
relaxedSchemaAttributes.ul = excludeRestrictedClassAttributes(
  relaxedSchemaAttributes.ul,
);
relaxedSchemaAttributes.li = excludeRestrictedClassAttributes(
  relaxedSchemaAttributes.li,
);

/**
 * reference: https://meta.stackexchange.com/questions/1777/what-html-tags-are-allowed-on-stack-exchange-sites,
 *            https://github.com/jch/html-pipeline/blob/70b6903b025c668ff3c02a6fa382031661182147/lib/html/pipeline/sanitization_filter.rb#L41
 */

export const tagNames: Array<string> = [
  ...(defaultSchema.tagNames ?? []),
  '-',
  'abbr',
  'bdo',
  'bdi',
  'button',
  'caption',
  'cite',
  'col',
  'colgroup',
  'data',
  'dfn',
  'figure',
  'figcaption',
  'iframe',
  'mark',
  'rb',
  'small',
  'time',
  'u',
  'video',
  'wbr',
];

export const attributes: Attributes = deepmerge(relaxedSchemaAttributes, {
  a: ['target'],
  abbr: ['title'],
  bdo: ['dir'],
  caption: [],
  cite: [],
  dfn: ['title'],
  figure: [],
  figcaption: [],
  iframe: ['allow', 'referrerpolicy', 'sandbox', 'src'],
  mark: [],
  small: [],
  time: ['datetime'],
  video: ['controls', 'src', 'muted', 'preload', 'width', 'height', 'autoplay'],
  wbr: [],
  // The special value 'data*' as a property name can be used to allow all data properties.
  // see: https://github.com/syntax-tree/hast-util-sanitize/
  '*': ['key', 'class', 'className', 'style', 'role', 'data*'],
});