const crypto = require('crypto');
const fs = require('fs');
const gzip = require('gzip-size');
const path = require('path');

// load pure package metadata
const pureDir = path.dirname(require.resolve('purecss'));
const { version } = require(path.resolve(pureDir, 'package.json'));
const pureFiles = path.resolve(pureDir, 'build');
const pureMin = fs.readFileSync(path.resolve(pureFiles, 'pure-min.css'), 'utf8');

// use pure-min.css to determine site integrity hash
const sriHash = crypto.createHash('sha384').update(pureMin, 'utf8').digest('base64');

// copy/pastable code snippet for users
module.exports.PURE_DOWNLOAD_SNIPPET = `<link rel="stylesheet" href="https://cdn.jsdelivr.net/npm/purecss@${version}/build/pure-min.css" integrity="sha384-${sriHash}" crossorigin="anonymous">`;

// calculate each pure module size
module.exports.moduleSizes = function moduleSizes() {
    const files = fs.readdirSync(pureFiles);

    // collect all minified module files
    const modules = files.filter(file => (/-min\.css$/).test(file))
        .map(file => file.replace(/-min\.css$/, ''));

    // get sizes across all modules
    const moduleSizes = modules.map(module => {
        const filePath = path.join(pureFiles, module + '-min.css');
        const contents = fs.readFileSync(filePath, { encoding: 'utf-8' });
        return gzip.sync(contents);
    });

    // return final list of sizes
    return moduleSizes.reduce((map, size, i) => {
        map[modules[i]] = size;
        return map;
    }, {});
};