@yuanhua/cli/lib/generate.js

@yuanhua/cli

const chalk = require('chalk');
// https://www.helplib.com/GitHub/article_108070
const Metalsmith = require('metalsmith');
const Handlebars = require('handlebars');
const async = require('async');
const render = require('consolidate').handlebars.render;
const path = require('path');
const multimatch = require('multimatch');
const getOptions = require('./options');
const ask = require('./ask');
const filter = require('./filter');
const logger = require('./logger');

// register handlebars helper
Handlebars.registerHelper('if_eq', function(a, b, opts) {
  return a === b ? opts.fn(this) : opts.inverse(this);
});

Handlebars.registerHelper('unless_eq', function(a, b, opts) {
  return a === b ? opts.inverse(this) : opts.fn(this);
});

/**
 * Generate a template given a `src` and `dest`.
 *
 * @param {String} name
 * @param {String} src
 * @param {String} dest
 * @param {Function} done
 */

module.exports = function generate(name, src, dest, done) {
  // 处理npm名和作者信息
  const opts = getOptions(name, src);

  // 1、 一个极其简单，易于使用的可以插入 static 站点发生器
  const metalsmith = Metalsmith(path.join(src, 'template'));

  const data = Object.assign(metalsmith.metadata(), {
    destDirName: name,
    inPlace: dest === process.cwd(),
    noEscape: true,
  });
  opts.helpers &&
    Object.keys(opts.helpers).map(key => {
      Handlebars.registerHelper(key, opts.helpers[key]);
    });

  const helpers = { chalk, logger };

  if (opts.metalsmith && typeof opts.metalsmith.before === 'function') {
    opts.metalsmith.before(metalsmith, opts, helpers);
  }

  // 2、use
  metalsmith
    .use(askQuestions(opts.prompts) /* 将给定的plugin 函数添加到中间件堆栈*/)
    .use(filterFiles(opts.filters)) // 将给定的plugin 函数添加到中间件堆栈
    .use(renderTemplateFiles(opts.skipInterpolation)); // 将给定的plugin 函数添加到中间件堆栈

  if (typeof opts.metalsmith === 'function') {
    opts.metalsmith(metalsmith, opts, helpers);
  } else if (opts.metalsmith && typeof opts.metalsmith.after === 'function') {
    opts.metalsmith.after(metalsmith, opts, helpers);
  }

  metalsmith
    .clean(false)
    .source('.') // 模板文件 path // start from template root instead of `./src` which is Metalsmith's default for `source`
    .destination(dest) // 最终编译好的文件存放位置
    .build((err, files) => {
      done(err);
      if (typeof opts.complete === 'function') {
        const helpers = { chalk, logger, files };
        opts.complete(data, helpers);
      } else {
        logMessage(opts.completeMessage, data);
      }
    });

  return data;
};

/**
 * Create a middleware for asking questions.
 *
 * @param {Object} prompts
 * @return {Function}
 */

function askQuestions(prompts) {
  return (files, metalsmith, done) => {
    ask(prompts, metalsmith.metadata(), done);
  };
}

/**
 * Create a middleware for filtering files.
 *
 * @param {Object} filters
 * @return {Function}
 */

function filterFiles(filters) {
  return (files, metalsmith, done) => {
    filter(files, filters, metalsmith.metadata(), done);
  };
}

/**
 * Template in place plugin.
 *
 * @param {Object} files
 * @param {Metalsmith} metalsmith
 * @param {Function} done
 */

function renderTemplateFiles(skipInterpolation) {
  skipInterpolation =
    typeof skipInterpolation === 'string' ? [skipInterpolation] : skipInterpolation;
  return (files, metalsmith, done) => {
    const keys = Object.keys(files);
    const metalsmithMetadata = metalsmith.metadata();
    async.each(
      keys,
      (file, next) => {
        // skipping files with skipInterpolation option
        if (skipInterpolation && multimatch([file], skipInterpolation, { dot: true }).length) {
          return next();
        }
        const str = files[file].contents.toString();
        // do not attempt to render files that do not have mustaches
        if (!/{{([^{}]+)}}/g.test(str)) {
          return next();
        }
        render(str, metalsmithMetadata, (err, res) => {
          if (err) {
            err.message = `[${file}] ${err.message}`;
            return next(err);
          }
          files[file].contents = new Buffer(res);
          next();
        });
      },
      done
    );
  };
}

/**
 * Display template complete message.
 *
 * @param {String} message
 * @param {Object} data
 */

function logMessage(message, data) {
  if (!message) return;
  render(message, data, (err, res) => {
    if (err) {
      console.error('\n   Error when rendering template complete message: ' + err.message.trim());
    } else {
      console.log(
        '\n' +
          res
            .split(/\r?\n/g)
            .map(line => '   ' + line)
            .join('\n')
      );
    }
  });
}