Connect middleware inspired by stylus

lib/middleware.js

+var sass = require('../sass')
+  , fs = require('fs')
+  , url = require('url')
+  , basename = require('path').basename
+  , dirname = require('path').dirname
+  , mkdirp = require('mkdirp')
+  , join = require('path').join;
+
+var imports = {};
+
+/**
+ * Return Connect middleware with the given `options`.
+ *
+ * Options:
+ *
+ *    `force`     Always re-compile
+ *    `debug`     Output debugging information
+ *    `src`       Source directory used to find .styl files
+ *    `dest`      Destination directory used to output .css files
+ *                when undefined defaults to `src`.
+ *
+ * Examples:
+ * 
+ * Pass the middleware to Connect, grabbing .scss files from this directory
+ * and saving .css files to _./public_.
+ * 
+ * Following that we have a `staticProvider` layer setup to serve the .css
+ * files generated by Sass.
+ * 
+ *      var server = connect.createServer(
+ *          sass.middleware({
+ *              src: __dirname
+ *            , dest: __dirname + '/public'
+ *          })
+ *        , connect.static(__dirname + '/public')
+ *      );
+ * 
+ * @param {Object} options
+ * @return {Function}
+ * @api public
+ */
+
+module.exports = function(options){
+  options = options || {};
+
+  // Accept src/dest dir
+  if ('string' == typeof options) {
+    options = { src: options };
+  }
+
+  // Force compilation
+  var force = options.force;
+
+  // Debug option
+  var debug = options.debug;
+
+  // Source dir required
+  var src = options.src;
+  if (!src) throw new Error('sass.middleware() requires "src" directory');
+
+  // Default dest dir to source
+  var dest = options.dest
+    ? options.dest
+    : src;
+
+  // Default compile callback
+  options.compile = options.compile || function(){
+    return sass
+  };
+
+  // Middleware
+  return function sass(req, res, next){
+    if ('GET' != req.method && 'HEAD' != req.method) return next();
+    var path = url.parse(req.url).pathname;
+    if (/\.css$/.test(path)) {
+      var cssPath = join(dest, path)
+        , sassPath = join(src, path.replace('.css', '.scss'));
+
+      if (debug) {
+        log('source', sassPath);
+        log('dest', cssPath);
+      }
+
+      // Ignore ENOENT to fall through as 404
+      function error(err) {
+        next('ENOENT' == err.code
+          ? null
+          : err);
+      }
+
+      // Force
+      if (force) return compile();
+
+      // Compile to cssPath
+      function compile() {
+        if (debug) log('read', cssPath);
+        fs.readFile(sassPath, 'utf8', function(err, str){
+          if (err) return error(err);
+          var style = options.compile();
+          var paths = [];
+          delete imports[sassPath];
+          style.render(str, function(css){
+            // if (err) return next(err);
+            if (debug) log('render', sassPath);
+            imports[sassPath] = paths;
+            mkdirp(dirname(cssPath), 0700, function(err){
+              if (err) return error(err);
+              fs.writeFile(cssPath, css, 'utf8', next);
+            });
+          });
+        });
+      }
+
+      // Re-compile on server restart, disregarding
+      // mtimes since we need to map imports
+      if (!imports[sassPath]) return compile();
+
+      // Compare mtimes
+      fs.stat(sassPath, function(err, sassStats){
+        if (err) return error(err);
+        fs.stat(cssPath, function(err, cssStats){
+          // CSS has not been compiled, compile it!
+          if (err) {
+            if ('ENOENT' == err.code) {
+              if (debug) log('not found', cssPath);
+              compile();
+            } else {
+              next(err);
+            }
+          } else {
+            // Source has changed, compile it
+            if (sassStats.mtime > cssStats.mtime) {
+              if (debug) log('modified', cssPath);
+              compile();
+            // Already compiled, check imports
+            } else {
+              checkImports(sassPath, function(changed){
+                if (debug && changed && changed.length) {
+                  changed.forEach(function(path) {
+                    log('modified import %s', path);
+                  });
+                }
+                changed && changed.length ? compile() : next();
+              });
+            }
+          }
+        });
+      });
+    } else {
+      next();
+    }
+  }
+};
+
+/**
+ * Check `path`'s imports to see if they have been altered.
+ *
+ * @param {String} path
+ * @param {Function} fn
+ * @api private
+ */
+
+function checkImports(path, fn) {
+  var nodes = imports[path];
+  if (!nodes) return fn();
+  if (!nodes.length) return fn();
+
+  var pending = nodes.length
+    , changed = [];
+
+  nodes.forEach(function(imported){
+    fs.stat(imported.path, function(err, stat){
+      // error or newer mtime
+      if (err || !imported.mtime || stat.mtime > imported.mtime) {
+        changed.push(imported.path);
+      }
+      --pending || fn(changed);
+    });
+  });
+}
+
+/**
+ * Log a message.
+ *
+ * @api private
+ */
+
+function log(key, val) {
+  console.error('  \033[90m%s :\033[0m \033[36m%s\033[0m', key, val);
+}
\ No newline at end of file

package.json

@@ -8,7 +8,9 @@
     "type": "git",
     "url": "git://github.com/andrew/node-sass.git"
   },
-  "dependencies": {},
+  "dependencies": {
+    "mkdirp": "0.3.x"
+  },
   "devDependencies": {},
   "optionalDependencies": {},
   "engines": {