// No @wordpress/* type packages are installed (this plugin talks to the WP
// globals directly, same convention as widget/ and frontend-overlay.ts), so
// blocks and the wp global are read as loosely-typed data here.
// eslint-disable-next-line @typescript-eslint/no-explicit-any
type WpBlock = any;

export type ContentIssueType = 'alt_text' | 'heading' | 'link_text' | 'video_caption';

export interface ContentIssue {
  id: string;
  type: ContentIssueType;
  message: string;
  fixable: boolean;
  clientId?: string;
  current?: string;
  context?: string;
  url?: string;
  /** core/image's attachment ID, when the image was picked from the media library (not an external URL). */
  attachmentId?: number;
}

// Generic link text that doesn't tell a screen-reader user (or anyone
// scanning link text out of context) where the link actually goes.
const GENERIC_LINK_PHRASES = [
  'click here', 'here', 'read more', 'learn more', 'this link', 'more', 'this page', 'link',
];

function flattenBlocks(blocks: WpBlock[]): WpBlock[] {
  return blocks.flatMap((block) => [block, ...flattenBlocks(block.innerBlocks ?? [])]);
}

function checkAltText(blocks: WpBlock[]): ContentIssue[] {
  return blocks
    .filter((b) => b.name === 'core/image' && !(b.attributes?.alt ?? '').trim())
    .map((b) => ({
      id: `alt-${b.clientId}`,
      type: 'alt_text' as const,
      message: 'Image is missing alt text.',
      fixable: true,
      clientId: b.clientId,
      context: b.attributes?.caption || b.attributes?.url || '',
      attachmentId: typeof b.attributes?.id === 'number' ? b.attributes.id : undefined,
    }));
}

function checkHeadingHierarchy(blocks: WpBlock[]): ContentIssue[] {
  const issues: ContentIssue[] = [];
  let prevLevel = 0;
  blocks
    .filter((b) => b.name === 'core/heading')
    .forEach((b) => {
      const level: number = b.attributes?.level ?? 2;
      if (prevLevel > 0 && level > prevLevel + 1) {
        issues.push({
          id: `heading-${b.clientId}`,
          type: 'heading',
          message: `Heading level jumps from H${prevLevel} to H${level} — screen reader users lose the outline structure.`,
          fixable: false,
        });
      }
      prevLevel = level;
    });
  return issues;
}

// core/paragraph and core/heading store their text as an HTML string in
// attributes.content — that's the same string WordPress saves to the post,
// so parsing it here (rather than requiring the separate wp-blocks package
// just to re-derive rendered HTML) is both simpler and exact.
function checkLinkText(blocks: WpBlock[]): ContentIssue[] {
  const issues: ContentIssue[] = [];
  blocks
    .filter((b) => ['core/paragraph', 'core/heading'].includes(b.name) && typeof b.attributes?.content === 'string')
    .forEach((b) => {
      const doc = new DOMParser().parseFromString(b.attributes.content, 'text/html');
      const context = (doc.body.textContent ?? '').slice(0, 200);
      doc.querySelectorAll('a').forEach((a, i) => {
        const text = (a.textContent ?? '').trim();
        if (GENERIC_LINK_PHRASES.includes(text.toLowerCase())) {
          issues.push({
            id: `link-${b.clientId}-${i}`,
            type: 'link_text',
            message: `Generic link text "${text}" doesn't describe where it goes.`,
            fixable: true,
            clientId: b.clientId,
            current: text,
            context,
            url: a.getAttribute('href') ?? '',
          });
        }
      });
    });
  return issues;
}

// Best-effort: WordPress core doesn't expose a reliable "has captions" flag
// on the video block's own attributes in every version, so this can miss
// captions added via a different route — flagged as manual-review, not
// AI-fixable, same as the heading check.
function checkVideoCaptions(blocks: WpBlock[]): ContentIssue[] {
  return blocks
    .filter((b) => b.name === 'core/video' && b.attributes?.src && !(b.attributes?.tracks?.length))
    .map((b) => ({
      id: `video-${b.clientId}`,
      type: 'video_caption' as const,
      message: 'Video has no caption/subtitle track — verify manually.',
      fixable: false,
    }));
}

export function runChecks(): ContentIssue[] {
  // eslint-disable-next-line @typescript-eslint/no-explicit-any
  const wp = (window as any).wp;
  const blocks: WpBlock[] = wp?.data?.select?.('core/block-editor')?.getBlocks?.() ?? [];
  const flat = flattenBlocks(blocks);

  return [
    ...checkAltText(flat),
    ...checkHeadingHierarchy(flat),
    ...checkLinkText(flat),
    ...checkVideoCaptions(flat),
  ];
}