Add base for loading plugins

2 files changed, 112 insertions, 1 deletions

diff --git a/lib/plugins/manager.js b/lib/plugins/manager.js
index 8617044..b6549d6 100644
--- a/lib/plugins/manager.js
+++ b/lib/plugins/manager.js
@@ -1,10 +1,61 @@
+var _ = require('lodash');
 
+var Promise = require('../utils/promise');
 var BookPlugin = require('./plugin');
 
+
+/*
+PluginsManager is an interface to work with multiple plugins at once:
+- Extract assets from plugins
+- Call hooks for all plugins, etc
+*/
+
 function PluginsManager(book) {
     this.book = book;
     this.plugins = [];
 }
 
+// Returns a plugin by its name
+PluginsManager.prototype.get = function(name) {
+    return _.find(this.plugins, {
+        id: name
+    });
+};
+
+// Load a plugin, or a list of plugins
+PluginsManager.prototype.load = function(name) {
+    var that = this;
+
+    if (!_.isArray(name)) {
+        return Promise.serie(name, function(_name) {
+            return that.load(_name);
+        });
+    }
+
+    return Promise()
+
+    // Initiate and load the plugin
+    .then(function() {
+        var plugin;
+
+        if (!_.isString(name)) plugin = name;
+        else plugin = new BookPlugin(that.book, name);
+
+        if (that.get(plugin.id)) {
+            throw new Error('Plugin "'+plugin.id+'" is already loaded');
+        }
+
+
+        if (plugin.isLoaded()) return plugin;
+        else return plugin.load()
+            .thenResolve(plugin);
+    })
+
+    .then(function(plugin) {
+        that.plugins.push(plugin);
+    });
+};
+
+
 
 module.exports = PluginsManager;
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;