import { readFile } from 'fs/promises';
import { join } from 'path';

import { chapterBasedSuperBlocks } from '../../../../packages/shared/src/config/curriculum';
import {
  SUPERBLOCK_META_DIR,
  BLOCK_META_DIR,
  ENGLISH_LANG_DIR
} from '../configs/paths';

import { SuperBlockMeta } from '../interfaces/superblock-meta';
import { PartialMeta } from '../interfaces/partial-meta';

import { Intro } from '../interfaces/intro';

type Block = {
  name: string;
  path: string;
};

type BlockLocation = {
  blocks: Block[];
  currentSuperBlock: string;
};

export const getBlocks = async (sup: string): Promise<BlockLocation> => {
  const superBlockDataPath = join(SUPERBLOCK_META_DIR, sup + '.json');
  const superBlockMetaFile = await readFile(superBlockDataPath, {
    encoding: 'utf8'
  });
  const superBlockMeta = JSON.parse(superBlockMetaFile) as SuperBlockMeta;

  const introDataPath = join(ENGLISH_LANG_DIR, 'intro.json');
  const introFile = await readFile(introDataPath, {
    encoding: 'utf8'
  });
  const introData = JSON.parse(introFile) as Intro;

  let blocks: { name: string; path: string }[] = [];

  if (chapterBasedSuperBlocks.includes(sup)) {
    blocks = superBlockMeta.chapters!.map(chapter => {
      const chapters = Object.entries(introData[sup]['chapters']!);
      const chapterTrueName = chapters.filter(
        x => x[0] === chapter.dashedName
      )[0][1];
      return {
        name: chapterTrueName,
        path: 'chapters/' + chapter.dashedName
      };
    });
  } else {
    blocks = await Promise.all(
      superBlockMeta.blocks!.map(async block => {
        const blockStructurePath = join(BLOCK_META_DIR, block + '.json');
        const blockMetaFile = await readFile(blockStructurePath, {
          encoding: 'utf8'
        });
        const blockMeta = JSON.parse(blockMetaFile) as PartialMeta;
        return {
          name: blockMeta.name,
          path: block
        };
      })
    );
  }

  return { blocks: blocks, currentSuperBlock: introData[sup]?.title };
};