import path, { dirname } from 'path';
import { fileURLToPath } from 'url';

/**
 * Main backend application
 */
class App{
    constructor(){
        this.root = path.resolve(dirname(fileURLToPath(import.meta.url)) + '/../../');
    }

    /**
     * The plugins used by the application
     * @type {AppPlugin[]}
     */
    plugins = [];

    /**
     * Declaration of plugin usage
     * @param {AppPlugin} plugin The plugin to be used
     */
    async use(plugin){
        this[plugin.name] = plugin;
        plugin.app = this;
        this.plugins.push(plugin);
    }

    /**
     * Initializes the application. All plugins are initialized at this stage
     */
    async init(){
        for (let p of this.plugins){
            console.debug('Initializing', p.name)
            if(p.init) await p.init(this);
        }
    }

    /**
     * Imports modules as plugins in the app by a given list
     * @param {Array} modules Modules to be imported
     */
    async importModules(modules){
        const mods = {};
        for (let m of modules){
            mods[m.name] = (await import(`../${m.path}`))[m.name];
        }
        
        for (let m of modules){
            this.use(new mods[m.name]())
        }
    }

    /**
     * Replaces a plugin
     * @param {AppPlugin} p Plugin to be replaced
     */
    async replace(p){
        let old = this[p.name];
        this.plugins[this.plugins.indexOf(old)] = p;
        this[p.name] = p;
        p.app = this;
        if(p.init) await p.init(this);
    }

    /**
     * Starts the application. All Plugins are started at this point
     */
    async start(){
        for (let p of this.plugins){
            console.debug('Starting', p.name)
            if(p.start) await p.start(this);
        }
    }
}

export default App;