fd-gulp-jsconcat/index.js

concat js files according to those rules listed on this page(http://wd.alibaba-inc.com/doc/page/work/cbu-regulations/merge)

'use strict';

var through = require('through2');
var fs = require('fs');
var path = require('path');
var gutil = require('gulp-util');
var PluginError = gutil.PluginError;
var async = require('async');
var request = require('request');
var iconv = require('iconv-lite');
var constants = require('./assets/constants');
var helper = require('./assets/helper');

module.exports = function(srcDir, opt) {
  if (!opt) opt = {};

  if (!srcDir) throw new PluginError(constants.PLUGIN_NAME, 'STYLE_BUILD_ERR: Missing srcDir option for ' + constants.PLUGIN_NAME);

  var domain = helper.getDomain(opt), localCommonDir = opt.localCommonDir;

  function transformFunc(file, encoding, transCallback) {
    var that = this;
    if (file.isNull()) return; // ignore
    if (file.isStream()) return this.emit('error', new PluginError(constants.PLUGIN_NAME,  'STYLE_BUILD_ERR: Streaming not supported'));
    parseCSSFile(file, function(fileContent) {
      file.contents = iconv.encode(fileContent, 'GBK');
      that.push(file);
      transCallback();
    });
  }

  function parseCSSFile(file, parseJSCallback) {

    var decodedContent = iconv.decode(file.contents, 'GBK'), 
      originalContent = decodedContent, lines, singleLine, 
      importMatches, importFile, fileName,
      fileMap = {}, FCTasks = [], fileContent = '';

    // 如没有匹配到@import语句，可直接返回文件内容
    // 如没有匹配到merge start/end语句，可直接返回文件内容
    if (!constants.JS_MERGE_COMMENT_RE.test(originalContent)) {
      parseJSCallback(originalContent);
      return;
    }

    if (constants.COMPRESS_FLAG_RE.test(originalContent)) {
      fileContent += '/*cmd:compress=true*/\n';
    }

    if (constants.COMPRESS_OPT.test(originalContent)) {
      fileContent += '/*cmd:jsCompressOpt=[' + constants.COMPRESS_OPT.exec(originalContent)[1] + ']*/\n';
    }

    if (constants.CONV_TO_UNICODE_RE.test(originalContent)) {
      fileContent += '/*cmd:conv2unicode=true*/\n';
    }

    lines = originalContent.split(constants.NEWLINE_RE);

    for (var i=0,leni=lines.length; i<leni; i++) {
      singleLine = lines[i];

      importMatches = constants.JS_IMPORT_RE.exec(singleLine);
      if (importMatches === null) {
        // 匹配到compress=true标识，去掉感叹号，
        // 以便之后的css minify过程能将这个注释去除
        if (constants.COMPRESS_FLAG_RE.test(singleLine)) {
          fileContent += '/*cmd:compress=true*/\n';
        } else {
          fileContent += singleLine + '\n';
        }
      } else if(singleLine.trim() !== '') {
        fileName = helper.getFileName(srcDir, importMatches[2], file, domain, localCommonDir);
        // 如果在fileMap中已有当前处理文件名的key值，
        // 则说明当前文件在之前已有引入过。
        if (fileMap[fileName]) {
          continue;
        }
        fileMap[fileName] = {
          localName: fileName,
          url: importMatches[2]
        }

        FCTasks.push(async.apply(createGetFCFunc, fileMap[fileName]));
      }
    }

    async.series(FCTasks, function(err, results) {
      if (err) {
        throw err;
      }
      fileContent += results.join('\n');
      parseJSCallback(fileContent);
    });
  }

  // 创建获取文件内容的异步task函数（async风格）
  function createGetFCFunc(fileObj, callback) {
    var content = '';
    var localName = fileObj.localName;

    if (fs.existsSync(localName)) {
      
      var buffer = fs.readFileSync(localName);

      content = iconv.decode(buffer, 'GBK');
      callback(null, content);
    } else {
      getFileContentFromUrl(fileObj , function(err, results){
        if(err) {
          callback(err, 'failed');
        }
        content = results;
        callback(null, content);
      });
    }

  }

  function getFileContentFromUrl( fileObj, cb ) {

    var localName = fileObj.localName, url = fileObj.url;

    if (url.indexOf(domain) !== -1) {
      request({
        url: url,
        encoding: null
      }, function(err, response, body) {
        if (!err && response.statusCode == 200) {
          cb(null, iconv.decode(body, 'GBK'));
        } else {
          cb(new PluginError(constants.PLUGIN_NAME, 'STYLE_BUILD_ERR: Failed to get ' + localName + '.\n'));
        }
      });
    } else {
      cb(new PluginError(constants.PLUGIN_NAME, 'STYLE_BUILD_ERR: Failed to get ' + localName + '.\n'));
    }
  }

  return through.obj(transformFunc);
};