Fix deasync production build failure (#777)

* it works

* fixes

* fixes

* more fixes

* rm copy-webpack-plugin

* fixes

* fix

server/build/node-loader.js

@@ -10,4 +10,4 @@ module.exports = function nodeLoader(m, q) {
       throw new Error('dlopen: Cannot open ' + modulePath + ': ' + e);
     }
   `);
-}
+}

server/build/webpack.614.prod.conf.js

@@ -18,6 +18,10 @@ module.exports = {
         test: /\.js$/,
         use: [
           { loader: 'babel-loader' }
+        ],
+        test: /\.node$/,
+        use: [
+          { loader: './build/node-loader' }
         ]
       }
     ]

server/build/webpack.prod.conf.js

@@ -1,15 +1,61 @@
+const webpack = require('webpack');
+const path = require('path');
+const fs = require('fs');
+
 var base = require('./webpack.base.conf');
 
+const nodeVersion = 'node-' + /[0-9]+/.exec(process.versions.node)[0];
+const PLATFORM = `${process.platform}-${process.arch}-${nodeVersion}`;
+
+const DEASYNC_NODE_MODULES_PATH = path.resolve(
+  'node_modules',
+  'deasync',
+  'bin',
+  PLATFORM
+);
+
+const DEASYNC_DIST_PATH = path.resolve('dist', 'bin', PLATFORM);
+
+if(!fs.existsSync(DEASYNC_NODE_MODULES_PATH)) {
+  throw new Error(`deasync doesn't support this platform: ${PLATFORM}`);
+}
 
 base.mode = 'production';
 
-base.module.rules.push({
-  test: /\.node$/,
-  use: [
-    { loader: './build/node-loader' },
-    { loader: 'file-loader', options: { name: '[name].[ext]' } },
-  ]
-});
+base.externals = base.externals ? base.externals : [];
+base.externals.push(
+  function (context, request, callback) {
+    if(request.indexOf('bindings') === 0) {
+      callback(null, `() => require('./deasync.node')`)
+    } else {
+      callback();
+    }
+  }
+);
+
+const prodRules = [
+  {
+    test: /\.node$/,
+    use: [
+      { loader: './build/node-loader' },
+      { loader: 'file-loader', options: { name: '[name].[ext]' } }
+    ]
+  }
+];
+
+let contextPathMapping = {};
+contextPathMapping[path.resolve(DEASYNC_DIST_PATH, 'deasync')] = './deasync.node';
+
+const prodPlugins = [
+  new webpack.ContextReplacementPlugin(
+    /deasync/,
+    DEASYNC_NODE_MODULES_PATH,
+    contextPathMapping
+  )
+];
+
+base.module.rules = [...base.module.rules, ...prodRules];
+base.plugins = [...base.plugins, ...prodPlugins];
 
 module.exports = base;