Adding source map support (#102)

* Adding source map support

Resolves #101

* Remove unused fs

1 files changed, 68 insertions, 0 deletions

diff --git a/src/source-maps.js b/src/source-maps.js
new file mode 100644
index 0000000..9e65867
--- /dev/null
+++ b/src/source-maps.js
@@ -0,0 +1,68 @@
+'use strict';
+
+const Promise = require('bluebird');
+
+const fs = require('fs');
+
+const path = require('path');
+
+const debug_ = require('debug');
+
+const debugVerbose = debug_('purs-loader:verbose');
+
+module.exports = function sourceMap(psModule, js) {
+  const options = psModule.options;
+
+  const jsPath = psModule.jsPath;
+
+  const srcPath = psModule.srcPath;
+
+  const source = psModule.source;
+
+  const remainingRequest = psModule.remainingRequest;
+
+  const sourceMapPath = path.join(path.dirname(jsPath), 'index.js.map');
+
+  const isSourceMapsEnabled = options.pscArgs && options.pscArgs.sourceMaps;
+
+  return new Promise((resolve, reject) => {
+    if (!isSourceMapsEnabled) {
+      resolve({
+        js: js,
+        map: undefined
+      });
+    }
+    else {
+      debugVerbose('loading source map %s', sourceMapPath);
+
+      fs.readFile(sourceMapPath, 'utf-8', (error, result) => {
+        if (error) {
+          reject(error);
+        }
+        else {
+          try {
+            const map = Object.assign(JSON.parse(result), {
+              sources: [
+                remainingRequest
+              ],
+              file: path.normalize(srcPath),
+              sourcesContent: [
+                source
+              ]
+            });
+
+            const jsRemovedMapUrl = js.replace(/^\/\/# sourceMappingURL=[^\r\n]*/gm, '')
+
+            resolve({
+              js: jsRemovedMapUrl,
+              map: map
+            });
+          }
+          catch (error) {
+            reject(error);
+          }
+        }
+      })
+    }
+  });
+};