1 files changed, 61 insertions, 1 deletions
diff --git a/lib/plugins/plugin.js b/lib/plugins/plugin.js
index 8397205..e9af9d4 100644
--- a/lib/plugins/plugin.js
+++ b/lib/plugins/plugin.js
@@ -1,8 +1,68 @@
+var path = require('path');
+var resolve = require('resolve');
 
-function BookPlugin() {
+var Promise = require('../utils/promise');
 
+var PLUGIN_PREFIX = 'gitbook-plugin-';
 
+// Return an absolute name for the plugin (the one on NPM)
+function npmId(name) {
+    if (name.indexOf(PLUGIN_PREFIX) === 0) return name;
+    return [PLUGIN_PREFIX, name].join('');
 }
 
 
+function BookPlugin(book, pluginId) {
+    this.book = book;
+    this.id = pluginId;
+    this.npmId = npmId(pluginId);
+
+    this.packageInfos = undefined;
+    this.content = undefined;
+
+}
+
+// Return true if plugin has been loaded correctly
+BookPlugin.prototype.isLoaded = function() {
+    return Boolean(this.packageInfos && this.content);
+};
+
+// Load this plugin
+BookPlugin.prototype.load = function() {
+    var that = this;
+
+    if (this.isLoaded()) {
+        return Promise.reject(new Error('Plugin "' + this.id + '" is already loaded'));
+    }
+
+    // Try loading plugins from different location
+    return Promise.some([
+        this.book.resolve('node_modules'),
+        __dirname
+    ], function(baseDir) {
+        try {
+            var res = resolve.sync(name+'/package.json', { basedir: baseDir });
+
+            that.baseDir = path.dirname(res);
+            that.packageInfos = require(res);
+            that.content = require(resolve.sync(name, { basedir: baseDir }));
+
+            return true;
+        } catch (err) {
+            if (err.code != 'MODULE_NOT_FOUND') throw(err);
+
+            that.packageInfos = undefined;
+            that.content = undefined;
+
+            return false;
+        }
+    })
+
+    .then(function() {
+        if (!that.isLoaded()) {
+            throw new Error('Couldn\'t locate plugin "' + that.id + '", Run \'gitbook install\' to install plugins from registry.');
+        }
+    });
+};
+
 module.exports = BookPlugin;