add groups model and db code

src/groups.js

@@ -0,0 +1,91 @@
+/* jshint node:true */
+
+'use strict';
+
+exports = module.exports = {
+    GroupError: GroupError,
+
+    create: create,
+    remove: remove,
+    get: get
+};
+
+var assert = require('assert'),
+    DatabaseError = require('./databaseerror.js'),
+    uuid = require('node-uuid'),
+    _ = require('underscore');
+
+// http://dustinsenos.com/articles/customErrorsInNode
+// http://code.google.com/p/v8/wiki/JavaScriptStackTraceApi
+function GroupError(reason, errorOrMessage) {
+    assert.strictEqual(typeof reason, 'string');
+    assert(errorOrMessage instanceof Error || typeof errorOrMessage === 'string' || typeof errorOrMessage === 'undefined');
+
+    Error.call(this);
+    Error.captureStackTrace(this, this.constructor);
+
+    this.name = this.constructor.name;
+    this.reason = reason;
+    if (typeof errorOrMessage === 'undefined') {
+        this.message = reason;
+    } else if (typeof errorOrMessage === 'string') {
+        this.message = errorOrMessage;
+    } else {
+        this.message = 'Internal error';
+        this.nestedError = errorOrMessage;
+    }
+}
+util.inherits(GroupError, Error);
+GroupError.INTERNAL_ERROR = 'Internal Error';
+GroupError.ALREADY_EXISTS = 'Already Exists';
+GroupError.NOT_FOUND = 'Not Found';
+GroupError.BAD_NAME = 'Bad name';
+
+function validateGroupname(name) {
+    assert.strictEqual(typeof name, 'string');
+
+    if (name.length <= 2) return new GroupError(GroupError.BAD_NAME, 'name must be atleast 3 chars');
+    if (name.length > 256) return new GroupError(GroupError.BAD_NAME, 'name too long');
+
+    return null;
+}
+
+function create(name, callback) {
+    assert.strictEqual(typeof name, 'string');
+    assert.strictEqual(typeof callback, 'function');
+
+    var error = validateGroupname(name);
+    if (error) return callback(error);
+
+    groupdb.add(uuid.v4(), name, function (error) {
+        if (error && error.reason === DatabaseError.ALREADY_EXISTS) return callback(new GroupError(UserError.ALREADY_EXISTS));
+        if (error) return callback(new UserError(GroupError.INTERNAL_ERROR, error));
+
+        callback(null);
+    });
+}
+
+function remove(id, callback) {
+    assert.strictEqual(typeof id, 'string');
+    assert.strictEqual(typeof callback, 'function');
+
+    groupdb.del(id, function (error) {
+        if (error && error.reason === DatabaseError.NOT_FOUND) return callback(new UserError(UserError.NOT_FOUND));
+        if (error) return callback(new UserError(UserError.INTERNAL_ERROR, error));
+
+        callback(null);
+    });
+}
+
+function get(id, callback) {
+    assert.strictEqual(typeof id, 'string');
+    assert.strictEqual(typeof callback, 'function');
+
+    groupdb.get(id, function (error, result) {
+        if (error && error.reason === DatabaseError.NOT_FOUND) return callback(new UserError(UserError.NOT_FOUND));
+        if (error) return callback(new UserError(UserError.INTERNAL_ERROR, error));
+
+        return callback(null, result);
+    });
+}
+