var Promise = require('../utils/promise');

var listForBook = require('./listForBook');
var listInstalledForBook = require('./listInstalledForBook');
var loadPlugin = require('./loadPlugin');


/**
    Load a list of plugins in a book

    @param {Book}
    @return {Promise<Map<String:Plugin>}
*/
function loadForBook(book) {
    var logger = book.getLogger();
    var requirements = listForBook(book);
    var requirementsKeys = requirements.keys().toList();

    return listInstalledForBook(book)
    .then(function(installed) {
        // Filter out plugins not listed of first level
        // (aka pre-installed plugins)
        installed = installed.filter(function(plugin) {
            return (
                plugin.getDepth() > 1 ||
                requirements.has(plugin.getName())
            );
        });

        // Sort plugins to match list in book.json
        installed = installed.sort(function(a, b){
            return requirementsKeys.indexOf(a.getName()) < requirementsKeys.indexOf(b.getName()) ? -1 : 1;
        });

        // Log state
        logger.info.ln(installed.size + ' are installed');
        if (requirements.size != installed.size) {
            logger.info.ln(requirements.size + ' explicitly listed');
        }

        // Verify that all plugins are present
        var notInstalled = requirementsKeys.filter(function(name) {
            return !installed.has(name);
        });

        if (notInstalled.size > 0) {
            throw new Error('Couldn\'t locate plugins "' + notInstalled.join(', ') + '", Run \'gitbook install\' to install plugins from registry.');
        }

        return Promise.map(installed, function(plugin) {
            return loadPlugin(plugin);
        });
    });
}


module.exports = loadForBook;