/**
 * Copyright JS Foundation and other contributors, http://js.foundation
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 **/

var path = require("path");
var fs = require("fs-extra");
var os = require("os");
var util = require("@node-red/registry/lib/util");

var api;

var runtime;
var settings;
var exec;
var log;

var npmCommand = (process.platform === "win32") ? "npm.cmd" : "npm";

var moduleProp = {};
var moduleBase = null;

var allowInstall = true;
var allowList = ["*"];
var denyList = [];

/**
 * Initialise npm install module.
 * @param {Object} _runtime - runtime object
 */
function init(_runtime) {
    runtime = _runtime;
    settings = _runtime.settings;
    exec = _runtime.exec;
    log = _runtime.log;

    moduleProp = {};
    moduleBase = settings.userDir || process.env.NODE_RED_HOME || ".";

    if (settings.hasOwnProperty("externalModules")) {
        var em = settings.externalModules;
        if (em && em.hasOwnProperty("modules")) {
            var mod = em.modules;
            if (mod.hasOwnProperty("allowInstall")) {
                allowInstall = mod.allowInstall;
            }
            if (mod.hasOwnProperty("allowList")) {
                var alist = mod.allowList;
                if (Array.isArray(alist)) {
                    allowList = alist;
                }
                else {
                    log.warn("unexpected value of externalModule.allowList in settings.js");
                }
            }
            if (mod.hasOwnProperty("denyList")) {
                var dlist = mod.denyList;
                if (Array.isArray(dlist)) {
                    denyList = dlist;
                }
                else {
                    log.warn("unexpected value of externalModule.denyList in settings.js");
                }
            }
        }
    }
}

/**
 * Register dynamic module installation property.
 * @param {string} type - node type
 * @param {string} prop - property name
 */
function register(type, prop) {
    if (prop) {
        moduleProp[type] = prop;
    }
    else {
        delete moduleProp[prop]
    }
}

/**
 * Get path to install modules
 */
function modulePath() { // takes variable length arguments in `arguments`
    var result = moduleBase;
    result = path.join(result, "lib", "node_modules");
    for(var i = 0; i < arguments.length; i++) {
        result = path.join(result, arguments[i]);
    }
    return result;
}

/**
 * Decompose NPM module specification string
 * @param {string} module - module specification
 */
function moduleName(module) {
    var match = /^([^@]+@.+)/.exec(module);
    if (match) {
        return [match[1], match[2]];
    }
    return [module, undefined];
}

/**
 * Get NPM module package info
 * @param {string} name - module name
 * @param {string} name - module version
 */
function infoNPM(name, ver) {
    var path = modulePath(name, "package.json");
    try {
        var pkg = require(path);
        return pkg;
    }
    catch (e) {
    }
    return null;
}

/**
 * Ensure existance of module installation directory
 */
function ensureLibDirectory() {
    var path = modulePath();
    if (!fs.existsSync(path)) {
        fs.mkdirSync(path, {
            recursive: true
        });
        return fs.existsSync(path);
    }
    return true;
}

/**
 * Install NPM module 
 * @param {string} module - module specification
 */
function installNPM(module) {
    var [name, ver] = moduleName(module);
    if (!ensureLibDirectory()) {
        log.warn("failed to install: "+name);
        return;
    }
    var pkg = infoNPM(name, ver);
    if (!pkg) {
        var args = ["install", module];
        var dir = modulePath();
        return exec.run(npmCommand, args, {
            cwd: dir
        }, true).then(result => {
            if (result && (result.code === 0)) {
                log.info("successfully installed: "+name);
            }
            else {
                log.warn("failed to install: "+name);
            }
        }).catch(e => {
            var msg = e.hasOwnProperty("stderr") ? e.stderr : e;
            log.warn("failed to install: "+name);
        });
    }
    else {
        log.info("already installed: "+name);
    }
    return Promise.resolve();
}

/**
 * Check allowance of NPM module installation
 * @param {string} name - module specification
 */
function isAllowed(name) {
    if (!allowInstall) {
        return false;
    }
    var [module, ver] = moduleName(name);
    var aList = util.parseModuleList(allowList);
    var dList = util.parseModuleList(denyList);
    return util.checkModuleAllowed(module, ver, aList, dList);
}

/**
 * Check and install NPM module according to dynamic module specification
 * @param {Object} node - node object
 */
function checkInstall(node) {
    var name = null;
    if(moduleProp.hasOwnProperty(node.type)) {
        name = moduleProp[node.type];
    }
    var promises = [];
    if (name && node.hasOwnProperty(name)) {
        var modules = node[name];
        modules.forEach(module => {
            var name = module;
            if ((typeof module === "object") &&
                module &&
                module.hasOwnProperty("name")) {
                name = module.name;
            }
            if (isAllowed(name)) {
                promises.push(installNPM(name));
            }
            else {
                log.info("installation not allowed: "+name);
            }
        });
    }
    return Promise.all(promises);
}

/**
 * Load NPM module
 * @param {string} module - module to load
 */
function load(module) {
    try {
        var [name, ver] = moduleName(module);
        var path = modulePath(name);
        var npm = require(path);
        return npm;
    }
    catch (e) {
        return null;
    }
}

/**
 * Get list of installed modules
 */
function listModules() {
    var modPath = modulePath();
    if (!fs.existsSync(modPath)) {
        return [];
    }
    var dir = fs.opendirSync(modPath);
    var modules = [];
    if (dir) {
        var ent = null;
        while (ent = dir.readSync()) {
            var name = ent.name;
            if (ent.isDirectory() &&
                (name[0] !== ".")) {
                var pkgPath = path.join(modPath, name, "package.json");
                if (fs.existsSync(pkgPath)) {
                    var pkg = fs.readJSONSync(pkgPath);
                    var info = {
                        name: pkg.name,
                        version: pkg.version
                    };
                    modules.push(info);
                }
            }
        }
        dir.closeSync();
    }
    return modules;
}

api = {
    init: init,
    register: register,
    checkInstall: checkInstall,
    load: load,
    list: listModules
};
module.exports = api;