const fs = require('fs')
const crypto = require('crypto')

/**
 *  Manifest
 *
 *  creates manifest-file 
 *
 *  @author Björn Hase <me@herr-hase.wtf>
 *  @license http://opensource.org/licenses/MIT The MIT License
 *  @link https://git.node001.net/tiny-components/webpack.git
 *
 */

class Manifest {

    /**
     *
     *
     *  @param {string} filename
     *  @param {string} context
     *
     */
    constructor(filename, context) {

        // filename for manifest-file
        this._filename = filename

        // context
        this._context = context

        // results for write to file
        this._results = {

        }

    }

    /**
     *  run through all assets from assetsByChunkName
     *  for each file create a hash 
     *
     *  @param {object} stats
     *
     */
    run(stats) {

        let files = Object.assign({}, stats.assetsByChunkName)

        Object.keys(files).forEach((key) => {
            files[key].forEach((file) => {
                this._results[stats.publicPath + file] = stats.publicPath + file + '?version=' + this._hash(file, stats.outputPath)
            })
        })

        fs.writeFileSync(this._context + '/' + this._filename, JSON.stringify(this._results, null, 4))
    }

    /**
     *  hash content of file 
     *
     *  @param {string} file
     *  @param {sring} stats
     *  @return {string}
     *
     */
    _hash(file, outputPath) {
        
        const data = fs.readFileSync(outputPath + '/' + file, 'utf8')
        const hash = crypto
            .createHash('md5')
            .update(data)
            .digest('hex')

        return hash
    }
}

module.exports = Manifest