const fs = require('fs');
const yaml = require('yaml');
const path = require('path');
const async = require('async');
const dedent = require('dedent');

const blogAuthorsFile = fs.readFileSync(
 path.join(__dirname, '../src/data/blog/authors.yaml'),
 { encoding: 'utf-8' }
);

const blogAuthors = yaml.parse(blogAuthorsFile);

const applyBlogAuthors = metadataAuthors =>
 metadataAuthors
 .split(' and ')
 .map(authorName => {
 const foundAuthor = blogAuthors.find(
 author => author.name === authorName
 );

 return foundAuthor ? `'${foundAuthor.id}'` : authorName;
 })
 .join(', ');

// eslint-disable-next-line import/no-extraneous-dependencies
const metadataParser = require('markdown-yaml-metadata-parser');

const commandLineArgs = process.argv.slice(2);

const getMarkdownFilesPath = args => (args.length ? args[0] : '.');

const markdownPath = path.join(getMarkdownFilesPath(commandLineArgs));

const processMarkdownFile = (originalSlug, source) => {
 const { content, metadata } = metadataParser(source);

 const dateFromMetadata = new Date(metadata.date);

 const dateString = dateFromMetadata.toISOString().split('T')[0];

 const newFileName = `${dateString}-${originalSlug}.md`;

 const metadataAuthors = metadata.author
 ? `[${applyBlogAuthors(metadata.author)}]`
 : `['node-js-website']`;

 const newContent = dedent`
 ---
 title: ${metadata.title}
 blogAuthors: ${metadataAuthors}
 category: '${metadata.category.toLowerCase()}'
 ---
 `;

 return { content: `${newContent}\n${content}`, filename: newFileName };
};

if (fs.existsSync(markdownPath)) {
 const filenames = fs.readdirSync(path.join(markdownPath));

 const markdownFilesFromDirectory = filenames.filter(
 filename =>
 filename.toLowerCase().includes('.md') &&
 !filename.toLowerCase().includes('index.md')
 );

 const blogQueue = async.queue((filename, callback) => {
 const markdownFile = path.join(markdownPath, filename);

 fs.readFile(markdownFile, { encoding: 'utf-8' }, (_, data) => {
 const originalSlug = filename.toLowerCase().replace('.md', '');

 const { content, filename: newFileName } = processMarkdownFile(
 originalSlug,
 data
 );

 const newMarkdownFile = path.join(markdownPath, newFileName);

 fs.unlink(markdownFile, () => {});
 fs.writeFile(newMarkdownFile, content, () => callback());
 });
 });

 blogQueue.push([...markdownFilesFromDirectory]);

 // eslint-disable-next-line no-console
 blogQueue.drain(() => console.log('Finished Processing'));
}