import { Buffer } from 'node:buffer';
import crypto from 'node:crypto';
import fs from 'node:fs/promises';
import util from 'node:util';
import { shapes } from '@dicebear/collection';
import { createAvatar } from '@dicebear/core';
import { faker } from '@faker-js/faker';
import config from 'config';
import { verify as verifyCaptcha } from 'hcaptcha';

import slugify from '../utils/slugify.js';
import { sendEmails } from './email.js';
import { HttpError } from './errors.js';
import { knexOwner as knex } from './knex.js';
import initLogger, { initAccessLogger } from './logger.js';
import redis from './redis.js';
import { curateUser, fetchUser } from './users.js';

const logger = initLogger();
const accessLogger = initAccessLogger();
const scrypt = util.promisify(crypto.scrypt);

async function verifyPassword(password, storedPassword) {
	const [salt, hash] = storedPassword.split('/');
	const hashedPassword = (await scrypt(password, salt, 64)).toString('hex');

	if (hashedPassword === hash) {
		return true;
	}

	throw new HttpError('Username or password incorrect', 401);
}

async function generateAvatar(user) {
	const avatar = createAvatar(shapes, {
		seed: user.username,
		backgroundColor: ['f65596', '9b004b', '006b68', '5abab6'],
		shape1Color: ['f65596', 'ff6d7e', 'ff8d69', 'ffb15b', 'ffd55c', 'f9f871'],
		shape2Color: ['c162c6', '6074dd', '007dd2', '007ba9', '007170'],
		shape3Color: ['f65596', 'ff6d7e', 'ff8d69', 'ffb15b', 'ffd55c', 'f9f871'],
	});

	await fs.mkdir('media/avatars', { recursive: true });
	await avatar.png().toFile(`media/avatars/${user.id}_${user.username}.png`);

	logger.verbose(`Generated avatar for '${user.username}' (${user.id})`);
}

async function checkLoginCooldown(identifier, attemptThreshold) {
	if (!identifier) {
		return false;
	}

	const cooldownKey = `traxxx:login_cooldown:${slugify(identifier, '_')}`;
	const attempts = JSON.parse(await redis.get(cooldownKey) || '0');

	if (attempts >= attemptThreshold) {
		throw new HttpError(`Please wait a few minutes before attempting another login`, 409);
	}
}

async function setLoginCooldown(identifier, attemptCooldown) {
	if (!identifier) {
		return false;
	}

	const cooldownKey = `traxxx:login_cooldown:${slugify(identifier, '_')}`;

	await redis.incr(cooldownKey);
	await redis.expire(cooldownKey, attemptCooldown * 60);
}

export async function login(credentials, userIp) {
	if (!config.auth.login) {
		throw new HttpError('Logins are currently disabled', 503);
	}

	if (!credentials.username) {
		throw new HttpError('Please provide a username or e-mail', 400);
	}

	if (!credentials.password) {
		throw new HttpError('Please provide a password', 400);
	}

	await Promise.all([
		checkLoginCooldown(credentials.username, config.auth.loginCredentialAttempts),
		checkLoginCooldown(userIp, config.auth.loginIpAttempts),
	]);

	const { user } = await fetchUser(credentials.username.trim(), {
		email: true,
		raw: true,
	}).catch(async () => {
		await Promise.all([
			setLoginCooldown(credentials.username, config.auth.loginCredentialCooldown),
			setLoginCooldown(userIp, config.auth.loginIpCooldown),
		]);

		throw new HttpError('Username or password incorrect', 401);
	});

	try {
		await verifyPassword(credentials.password, user.password);
	}
	catch (error) {
		await Promise.all([
			setLoginCooldown(credentials.username, config.auth.loginCredentialCooldown),
			setLoginCooldown(userIp, config.auth.loginIpCooldown),
		]);

		throw error;
	}

	await knex('users')
		.update('last_login', 'NOW()')
		.update('last_ip', userIp)
		.where('id', user.id);

	logger.verbose(`Login from '${user.username}' (${user.id}, ${userIp})`);

	try {
		await fs.access(`media/avatars/${user.id}_${user.username}.png`);
	}
	catch (error) {
		await generateAvatar(user);
	}

	// fetched the raw user for password verification, don't return directly to user
	return curateUser(user, user);
}

async function hashPassword(password) {
	const salt = crypto.randomBytes(16).toString('hex');
	const hashedPassword = (await scrypt(password, salt, 64)).toString('hex');
	const storedPassword = `${salt}/${hashedPassword}`;

	return {
		storedPassword,
		hashedPassword,
		salt,
	};
}

async function tokenCooldown(identifier) {
	const cooldownKey = `traxxx:token_cooldown:${slugify(identifier, '_')}`;

	if (await redis.exists(cooldownKey)) {
		throw new HttpError(`Please wait a few minutes before requesting another token`, 409);
	}

	await redis.set(cooldownKey, JSON.stringify(true));
	await redis.expire(cooldownKey, config.auth.tokenCooldown * 60);
}

export async function sendEmailVerification(user, customEmail, trigger) {
	if (!config.email.enabled) {
		throw new HttpError('E-mail verification is disabled', 503);
	}

	if (!user) {
		throw new HttpError('No user provided', 401);
	}

	const email = customEmail || user.email;

	if (!email) {
		throw new HttpError('No e-mail address provided', 400);
	}

	await tokenCooldown(email);

	const tokenKey = `traxxx:token_email:${user.id}`;
	const token = crypto.randomBytes(32).toString('hex');

	const tokenData = {
		email,
		token,
	};

	await redis.set(tokenKey, JSON.stringify(tokenData));
	await redis.expire(tokenKey, config.auth.emailTokenExpiry * 60);

	const verifyUrl = `${config.web.address}/verify/email?${new URLSearchParams({
		userId: user.id,
		token,
	}).toString()}`;

	logger.info(`E-mail verification sent to ${user.username} (${user.id}): ${verifyUrl}`);

	await sendEmails([{
		template: 'verify',
		to: email,
		subject: 'Please verify your traxxx e-mail address',
		props: {
			user,
			verifyUrl,
			trigger,
		},
	}]);
}

export async function verifyEmail(userId, emailToken) {
	if (!userId) {
		throw new HttpError('User ID not provided', 400);
	}

	if (!emailToken) {
		throw new HttpError('Token not provided', 400);
	}

	const tokenKey = `traxxx:token_email:${userId}`;
	const tokenEntry = await redis.getDel(tokenKey);

	if (!tokenEntry) {
		throw new HttpError('Invalid verification link', 401);
	}

	const { token, email } = JSON.parse(tokenEntry);

	if (!token
		|| !email
		|| emailToken.length !== token.length
		|| !crypto.timingSafeEqual(Buffer.from(emailToken, 'hex'), Buffer.from(token, 'hex'))) {
		throw new HttpError('Invalid verification link', 401);
	}

	const updated = await knex('users')
		.where('id', userId)
		.update({
			email,
			email_verified: true,
		});

	if (updated === 0) {
		throw new HttpError('E-mail verification failed because the user could not be found', 404);
	}
}

export async function sendPasswordReset(credential) {
	if (!config.email.enabled) {
		throw new HttpError('Password reset is disabled', 503);
	}

	if (!credential) {
		throw new HttpError('No credential provided', 400);
	}

	await tokenCooldown(credential);

	const user = await fetchUser(credential, {
		email: true,
		includePrivate: true,
		throwError: false,
	});

	// we don't throw errors because the requesting user shouldn't know whether the account exists or not
	if (!user) {
		logger.info(`Password reset requested for unknown user '${credential}'`);
		return;
	}

	if (!user.email) {
		logger.info(`Password reset requested for '${credential}', but user '${user.username}' (${user.id}) has no e-mail address known`);
		return;
	}

	const tokenKey = `traxxx:token_password:${user.id}`;
	const token = crypto.randomBytes(32).toString('hex');

	const tokenData = {
		token,
	};

	await redis.set(tokenKey, JSON.stringify(tokenData));
	await redis.expire(tokenKey, config.auth.passwordTokenExpiry * 60);

	const verifyUrl = `${config.web.address}/recovery?${new URLSearchParams({
		userId: user.id,
		token,
	}).toString()}`;

	logger.info(`Password reset sent to ${user.username} (${user.id}): ${verifyUrl}`);

	await sendEmails([{
		template: 'recovery',
		to: user.email,
		subject: 'Reset your traxxx password',
		props: {
			user,
			verifyUrl,
		},
	}]);
}

export async function resetPassword(userId, emailToken, newPassword) {
	if (!userId) {
		throw new HttpError('User ID not provided', 400);
	}

	if (!emailToken) {
		throw new HttpError('Token not provided', 400);
	}

	if (!newPassword) {
		throw new HttpError('New password not provided', 400);
	}

	const tokenKey = `traxxx:token_password:${userId}`;
	const tokenEntry = await redis.getDel(tokenKey);

	if (!tokenEntry) {
		throw new HttpError('Invalid recovery link', 401);
	}

	const { token } = JSON.parse(tokenEntry);

	if (!token
		|| emailToken.length !== token.length
		|| !crypto.timingSafeEqual(Buffer.from(emailToken, 'hex'), Buffer.from(token, 'hex'))) {
		throw new HttpError('Invalid recovery link', 401);
	}

	const { storedPassword } = await hashPassword(newPassword);

	const updated = await knex('users')
		.where('id', userId)
		.update('password', storedPassword);

	if (updated === 0) {
		throw new HttpError('Password reset failed because the user could not be found', 404);
	}
}

export async function sendSignup(email) {
	if (!config.auth.signup || !config.email.enabled) {
		throw new HttpError('Sign-ups are disabled', 503);
	}

	if (!email) {
		throw new HttpError('No e-mail address provided', 400);
	}

	await tokenCooldown(email);

	const user = await fetchUser(email, {
		email: true,
		includePrivate: true,
		throwError: false,
	});

	if (user) {
		await sendEmails([{
			template: 'unavailable',
			to: email,
			subject: 'Someone tried to use your e-mail address for traxxx',
			props: {
				user,
			},
		}]);

		logger.info(`Duplicate signup with '${email}' attempted, user e-mailed`);

		// we don't throw an error because the requesting user shouldn't know whether the account exists or not
		return;
	}

	const token = crypto.randomBytes(32).toString('hex');
	const tokenKey = `traxxx:token_signup:${token}`;

	const tokenData = {
		email,
	};

	await redis.set(tokenKey, JSON.stringify(tokenData));
	await redis.expire(tokenKey, config.auth.signupTokenExpiry * 60);

	const verifyUrl = `${config.web.address}/signup?${new URLSearchParams({
		token,
	}).toString()}`;

	logger.info(`Signup e-mail sent to ${email}: ${verifyUrl}`);

	await sendEmails([{
		template: 'signup',
		to: email,
		subject: 'Sign up for traxxx',
		props: {
			verifyUrl,
		},
	}]);
}

export async function signup(credentials, userIp) {
	if (!config.auth.signup) {
		throw new HttpError('Sign-ups are currently disabled', 503);
	}

	if (!credentials.token) {
		throw new HttpError('Token required', 400);
	}

	if (credentials.password?.length < 3) {
		throw new HttpError('Password must be 3 characters or longer', 400);
	}

	const curatedUsername = credentials.username.trim();

	if (!curatedUsername) {
		throw new HttpError('Username required', 400);
	}

	if (curatedUsername.length < config.auth.usernameLength[0]) {
		throw new HttpError('Username is too short', 400);
	}

	if (curatedUsername.length > config.auth.usernameLength[1]) {
		throw new HttpError('Username is too long', 400);
	}

	if (!config.auth.usernamePattern.test(curatedUsername)) {
		throw new HttpError('Username contains invalid characters', 400);
	}

	const existingUser = await knex('users')
		.where(knex.raw('lower(username)'), curatedUsername.toLowerCase())
		.first();

	if (existingUser) {
		throw new HttpError('Username already in use', 409);
	}

	if (config.auth.captcha.enabled) {
		const captchaVerification = await verifyCaptcha(config.auth.captcha.secretKey, credentials.captcha);

		if (!captchaVerification.success) {
			logger.warn(`Invalid sign-up CAPTCHA from '${curatedUsername}' (${userIp})`);
			throw new HttpError('Invalid CAPTCHA', 400);
		}
	}

	const tokenKey = `traxxx:token_signup:${credentials.token}`;
	const tokenEntry = await redis.getDel(tokenKey);

	if (!tokenEntry) {
		throw new HttpError('Invalid sign-up link', 401);
	}

	const { email } = JSON.parse(tokenEntry);

	if (!email) {
		throw new HttpError('Invalid sign-up link', 401);
	}

	const { storedPassword } = await hashPassword(credentials.password);

	const [{ id: userId }] = await knex('users')
		.insert({
			username: curatedUsername,
			email,
			password: storedPassword,
			email_verified: true,
		})
		.returning('id');

	await knex('stashes').insert({
		user_id: userId,
		name: 'Favorites',
		slug: 'favorites',
		public: false,
		primary: true,
	});

	logger.info(`Signup from '${curatedUsername}' (${userId}, ${email}, ${userIp})`);

	await generateAvatar({
		id: userId,
		username: curatedUsername,
	});

	const user = await fetchUser(userId, {
		includePrivate: true,
	});

	// no longer needed with token-first signup flow
	// await sendEmailVerification(user, null, 'signup');

	return user;
}

async function updatePassword(password, reqUser, reqSession) {
	const now = new Date();
	const { storedPassword } = await hashPassword(password);

	await knex('users')
		.where('id', reqUser.id)
		.update('password', storedPassword);

	const country = reqSession.geo?.country && await knex('countries').where('alpha2', reqSession.geo.country).first();

	await sendEmails([{
		template: 'password',
		to: reqUser.email,
		subject: 'Your traxxx password has been changed',
		props: {
			user: reqUser,
			ip: reqUser.ip,
			country: country?.name,
			timestamp: now,
		},
	}]);

	logger.info(`Password changed by ${reqUser.username} (${reqUser.id}, ${reqUser.ip})`);
}

async function updateEmail(email, reqUser) {
	const user = await fetchUser(email, {
		email: true,
		throwError: false,
	});

	if (user) {
		await sendEmails([{
			template: 'unavailable',
			to: email,
			subject: 'Someone tried to use your e-mail address for traxxx',
			props: {
				user, // not reqUser, we don't want to leak details about the requester
			},
		}]);

		return;
	}

	await sendEmailVerification(reqUser, email, 'change');
}

export async function updateUser({ credentials, password }, reqUser, reqSession) {
	if (!reqUser) {
		throw new HttpError('You are not logged in', 401);
	}

	if (!credentials?.email && !credentials.password) {
		throw new HttpError('No changeable credentials provided', 400);
	}

	if (credentials.email && !config.email.enabled) {
		throw new HttpError('E-mail is currently disabled', 503);
	}

	if (credentials.password && credentials.password?.length < 3) {
		throw new HttpError('Password must be 3 characters or longer', 400);
	}

	if (!password) {
		throw new HttpError('No current password provided', 401);
	}

	const { user } = await fetchUser(reqUser.id, {
		email: true,
		raw: true,
	}).catch(() => {
		throw new HttpError('Username or password incorrect', 401);
	});

	await verifyPassword(password, user.password);

	if (credentials.password) {
		await updatePassword(credentials.password, reqUser, reqSession);
	}

	if (credentials.email) {
		await updateEmail(credentials.email, reqUser);
	}

	return curateUser(user, reqUser);
}

const validSettingKeys = [
	'alertNotificationsEnabled',
	'alertEmailsEnabled',
	'alertEmailsFrequency',
];

export async function updateSettings(settings, reqUser) {
	if (!reqUser) {
		throw new HttpError('You need to be authenticated to change your settings', 401);
	}

	const invalidKeys = Object.keys(settings).filter((key) => !validSettingKeys.includes(key));

	if (invalidKeys.length > 0) {
		throw new HttpError(`Invalid settings: ${invalidKeys.join()}`, 400);
	}

	if (settings.alertEmailsFrequency && !['instant', 'daily', 'weekly', 'monthly'].includes(settings.alertEmailsFrequency)) {
		throw new HttpError('Invalid email frequency setting', 400);
	}

	const [{ settings: updatedSettings }] = await knex('users')
		.where('id', reqUser.id)
		.update('settings', knex.raw('coalesce(settings, \'{}\'::jsonb) || ?::jsonb', [JSON.stringify(settings)]))
		.returning('settings');

	return updatedSettings;
}

function curateKey(key) {
	return {
		id: key.id,
		identifier: key.identifier,
		lastUsedAt: key.last_used_at,
		lastUsedIp: key.last_used_ip,
		createdAt: key.created_at,
	};
}

export async function fetchUserKeys(reqUser) {
	const keys = await knex('users_keys')
		.where('user_id', reqUser.id)
		.orderBy('created_at', 'asc');

	return keys.map((key) => curateKey(key));
}

export async function verifyKey(userId, key, req) {
	if (!key || !userId) {
		throw new HttpError('The API credentials are not provided.', 401);
	}

	const hashedKey = (await scrypt(key, '', 64)).toString('hex'); // salt redundant for randomly generated key

	const storedKey = await knex('users_keys')
		.where('user_id', userId)
		.where('key', hashedKey)
		.first();

	if (!storedKey) {
		throw new HttpError('The API credentials are invalid.', 401);
	}

	accessLogger.access({
		userId,
		identifier: storedKey.identifier,
		ip: req.userIp,
		path: req.path,
		userAgent: req.headers['user-agent'],
	});

	knex('users_keys')
		.where('id', storedKey.id)
		.update('last_used_at', knex.raw('now()'))
		.update('last_used_ip', req.userIp)
		.then(() => {
			// no need to wait for this
		});

	return fetchUser(storedKey.user_id);
}

export async function createKey(reqUser) {
	const cooldownKey = `traxxx:key_create_cooldown:${reqUser.id}`;

	if (reqUser.role !== 'admin' && await redis.exists(cooldownKey)) {
		throw new HttpError(`You can only create a new API key once every ${config.apiAccess.keyCooldown} minutes.`, 429);
	}

	const keys = await fetchUserKeys(reqUser);

	if (keys.length >= config.apiAccess.keyLimit) {
		throw new HttpError(`You can only hold ${config.apiAccess.keyLimit} API keys at one time. Please remove a key.`, 400);
	}

	const key = crypto.randomBytes(config.apiAccess.keySize).toString('base64url');
	const hashedKey = (await scrypt(key, '', 64)).toString('hex'); // salt redundant for randomly generated key

	const identifier = slugify([faker.word.adjective(), faker.animal[faker.animal.type()]()]);

	const [newKey] = await knex('users_keys')
		.insert({
			user_id: reqUser.id,
			key: hashedKey,
			identifier,
		})
		.returning('*');

	await redis.set(cooldownKey, identifier);
	await redis.expire(cooldownKey, config.apiAccess.keyCooldown * 60);

	return {
		...curateKey(newKey),
		key,
	};
}

export async function removeUserKey(reqUser, identifier) {
	await knex('users_keys')
		.where('user_id', reqUser.id)
		.where('identifier', identifier)
		.delete();
}

export async function flushUserKeys(reqUser) {
	await knex('users_keys')
		.where('user_id', reqUser.id)
		.delete();
}