const fs = require('fs');
const fetch = require('isomorphic-fetch');
const sortby = require('lodash.sortby');
const request = require('sync-request');
const ora = require('ora');
const chalk = require('chalk');

const endpoint = 'https://www.cryptocompare.com/api/data/coinlist/';

const spinner = ora('Building currencies').start();
spinner.color = 'magenta';

fetch(endpoint)
.then(response => response.json())
.then(json => {
	const sorted = sortby(json.Data, o => o.CoinName);

	const symbols = {};
	let imagesSaved = 0;

	/**
	 * Build the JSON file based on the cryptocompare coinlist.
	 */
	sorted.forEach((currency, index) => {
		const {Name, CoinName, ImageUrl} = currency;
		symbols[Name] = CoinName;

		// download the image for future use
		if (ImageUrl) {
			spinner.text = `${chalk.gray(index)} ${Name}`;
			spinner.render();
			const res = request('get', `https://www.cryptocompare.com${ImageUrl}`);
			fs.writeFileSync(`images/${Name.replace(/[:*?\\/<>|]/g, '_')}.${ImageUrl.split('.').pop()}`, res.getBody());
			imagesSaved += 1;
		}
	});

	spinner.succeed([`${imagesSaved} images saved to /images`]);

	spinner.color = 'yellow';
	spinner.start(`Saving cryptocurrencies.json file`);

	fs.writeFileSync('cryptocurrencies.json', JSON.stringify(symbols, null, 2));
	spinner.succeed(`${sorted.length} currencies saved to cryptocurrencies.json`);

	spinner.start('Saving Readme');

	/**
	 * Build the Markdown Table of currencies in the Readme.
	 */
	const template = fs.readFileSync('readme.md').toString();
	const data = JSON.parse(fs.readFileSync('cryptocurrencies.json').toString());

	const newSymbols = Object.keys(data);

	let table = `There are currently **${newSymbols.length} cryptocurrencies** represented*:\n`;
	table += '\n\n';
	table += '| Symbol | Name |\n';
	table += '| :------ | :------ |\n';

	newSymbols.forEach(symbol => {
		table += `| \`${symbol}\` | ${data[symbol]} |\n`;
	});

	table += `\n<small><em>* Last updated: ${new Date().toUTCString()}</em></small>`;

	// Look for the HTML comments in the README as a target
	const targetRegex = /<!-- BEGIN TABLE INJECT -->(\w|\W)*<!-- END TABLE INJECT -->/gim;
	const updated = template.replace(targetRegex, `<!-- BEGIN TABLE INJECT -->\n${table}\n<!-- END TABLE INJECT -->`);
	fs.writeFileSync('readme.md', updated);
	spinner.succeed(['Readme Markdown Table updated']);

	console.log('\n', 'Remember to', chalk.yellow('git commit'), 'and', chalk.yellow('npm publish'));
})
.catch(err => console.error(err));