'use strict';

// we cannot use semver here, because dependencies are not installed yet
// so the version checks get a bit messy

const fs = require('fs');
const path = require('path');
const child_process = require('child_process');
const os = require('os');

// where yunkong2 is installed
const rootDir = __dirname.substr(0, __dirname.lastIndexOf('node_modules'));


function checkNpmVersion() {
	// Get npm version
	try {
		// remove local node_modules\.bin dir from path
		// or we potentially get a wrong npm version
		let newEnv = Object.assign({}, process.env);
		newEnv.PATH = (newEnv.PATH || newEnv.Path || newEnv.path)
			.split(path.delimiter)
			.filter(dir => {
				dir = dir.toLowerCase();
				return !(dir.indexOf('yunkong2') > -1 && dir.indexOf(path.join('node_modules', '.bin')) > -1);

			})
			.join(path.delimiter);

		let npmVersion = child_process.execSync('npm -v', {encoding: 'utf8', env: newEnv});
		npmVersion = npmVersion.trim();
		console.log('NPM version: ' + npmVersion);

		if (gte(npmVersion, '5.0.0') && lt(npmVersion, '5.7.1')) {
			console.warn('!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!');
			console.warn('WARNING:');
			console.warn('You are using an unsupported npm version!');
			console.warn('This can lead to problems when installing further packages');
			console.warn();
			console.warn('Please use "npm install -g npm@4" to downgrade npm to 4.x or ');
			console.warn('use "npm install -g npm@latest" to install a supported version of npm 5!');
			console.warn('You need to make sure to repeat this step after installing an update to NodeJS and/or npm.');
			console.warn('!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!');
		}
		return npmVersion;
	} catch (e) {
		console.error('Could not check npm version: ' + e);
		console.error('Assuming that correct version is installed.');
		process.exit(0);
	}
}

if (gte(checkNpmVersion(), '5.0.0')) {
	// disables NPM's package-lock.json on NPM >= 5 because that creates heaps of problems
	console.log('npm version >= 5: disabling package-lock');
	fs.writeFileSync(path.join(rootDir, '.npmrc'), 'package-lock=false' + os.EOL, 'utf8');
}

process.exit(0);

// ======================================
// all the functions to replace `semver`:

/**
 * @typedef {{major: number, minor: number, build: number}} Version
 */
/**
 * Parses a version string
 * @param {string} version The version string to parse
 * @returns {Version | null} The parsed version
 */
function parseVersion(version) {
	const versionRegExp = /^v?(\d+)\.(\d+)\.(\d+).*?/;
	const parsed = versionRegExp.exec(version);
	if (!parsed) return null;

	return {
		major: +parsed[1],
		minor: +parsed[2],
		build: +parsed[3]
	};
}

/**
 * Checks if v1 > v2
 * @param {Version | string} v1 
 * @param {Version | string} v2 
 */
function gt(v1, v2) {
	if (typeof v1 === "string") v1 = parseVersion(v1);
	if (typeof v2 === "string") v2 = parseVersion(v2);

	if (v1.major > v2.major) return true;
	else if (v1.major < v2.major) return false;

	if (v1.minor > v2.minor) return true;
	else if (v1.minor < v2.minor) return false;

	return (v1.build > v2.build);
}

/**
 * Checks if v1 < v2
 * @param {Version | string} v1 
 * @param {Version | string} v2 
 */
function lt(v1, v2) {
	if (typeof v1 === "string") v1 = parseVersion(v1);
	if (typeof v2 === "string") v2 = parseVersion(v2);

	if (v1.major < v2.major) return true;
	else if (v1.major > v2.major) return false;

	if (v1.minor < v2.minor) return true;
	else if (v1.minor > v2.minor) return false;

	return (v1.build < v2.build);
}

/**
 * Checks if v1 == v2
 * @param {Version | string} v1 
 * @param {Version | string} v2 
 */
function eq(v1, v2) {
	if (typeof v1 === "string") v1 = parseVersion(v1);
	if (typeof v2 === "string") v2 = parseVersion(v2);

	if (v1.major !== v2.major) return false;
	if (v1.minor !== v2.minor) return false;
	return v1.build === v2.build;
}

/**
 * Checks if v1 != v2
 * @param {Version | string} v1 
 * @param {Version | string} v2 
 */
function ne(v1, v2) {
	return !eq(v1, v2);
}

/**
 * Checks if v1 >= v2
 * @param {Version | string} v1 
 * @param {Version | string} v2 
 */
function gte(v1, v2) {
	return gt(v1, v2) || eq(v1, v2);
}

/**
 * Checks if v1 <= v2
 * @param {Version | string} v1 
 * @param {Version | string} v2 
 */
function lte(v1, v2) {
	return lt(v1, v2) || eq(v1, v2);
}