import type { Root as MdastRoot } from 'mdast';
import type { MdxJsxAttribute } from 'mdast-util-mdx-jsx';
import { join, dirname } from 'node:path';
import { CONTINUE, visit } from 'unist-util-visit';

import type { Result } from '../types/result.js';
import { downloadImage } from '../utils/images.js';
import { createFilename } from '../utils/path.js';

export async function downloadImagesFromFile(
  root: MdastRoot,
  url: string | URL
): Promise<Array<Result<[string, string]>>> {
  url = new URL(url);
  const imageUrls: Array<string> = [];

  visit(root, function (node) {
    let imageUrl: string | undefined = undefined;
    if (node.type === 'image') {
      imageUrl = node.url;
    } else if (node.type === 'mdxJsxFlowElement') {
      imageUrl = node.attributes.find(
        (attr) => attr.type === 'mdxJsxAttribute' && (attr.name === 'src' || attr.name === 'img')
      )?.value as string | undefined;
    }

    if (!imageUrl) return CONTINUE;

    if (imageUrl.startsWith('/')) {
      imageUrl = new URL(imageUrl, url.origin).toString();
    }
    imageUrls.push(imageUrl);
  });

  const rootPath = join(process.cwd(), '/images');
  const filename = createFilename(rootPath, url, '');
  const localRootPath = filename ? dirname(filename) : rootPath;

  const imageResults = await Promise.all(
    imageUrls.map(async (imageUrl) => await downloadImage(imageUrl, localRootPath))
  );

  const imagePathsMap = new Map<string, string>(
    imageResults.filter((result) => result.success).map((result) => result.data as [string, string])
  );

  visit(root, function (node, index, parent) {
    if (node.type === 'image') {
      if (node.url.startsWith('/')) {
        node.url = imagePathsMap.get(new URL(node.url, url.origin).toString()) ?? node.url;
      } else {
        node.url = imagePathsMap.get(node.url) ?? node.url;
      }
      if (parent && typeof index === 'number') parent.children[index] = node;
    } else if (node.type === 'mdxJsxFlowElement') {
      const urlAttr = (node.attributes as Array<MdxJsxAttribute>).find(
        // eslint-disable-next-line @typescript-eslint/no-unnecessary-condition
        (attr) => attr.type === 'mdxJsxAttribute' && (attr.name === 'src' || attr.name === 'img')
      );
      if (!urlAttr) return CONTINUE;

      urlAttr.value = imagePathsMap.get(urlAttr.value as string) ?? urlAttr.value;
      if (parent && typeof index === 'number') parent.children[index] = node;
    }
  });

  return imageResults;
}