import { v1 } from '@standard-schema/spec';

/**
 * Configures a provider that supports username and password authentication. This is usually
 * paired with the `PasswordUI`.
 *
 * ```ts
 * import { PasswordUI } from "@nestri/auth/ui/password"
 * import { PasswordProvider } from "@nestri/auth/provider/password"
 *
 * export default issuer({
 *   providers: {
 *     password: PasswordProvider(
 *       PasswordUI({
 *         copy: {
 *           error_email_taken: "This email is already taken."
 *         },
 *         sendCode: (email, code) => console.log(email, code)
 *       })
 *     )
 *   },
 *   // ...
 * })
 * ```
 *
 * Behind the scenes, the `PasswordProvider` asks its config what to put on
 * each screen. Each callback returns a `Screen` — a description of what is
 * being asked for — and the issuer's renderer decides how it is drawn.
 *
 * ```ts
 * PasswordProvider({
 *   // ...
 *   login: (req, form, error) => Promise<Screen>
 *   register: (req, state, form, error) => Promise<Screen>
 *   change: (req, state, form, error) => Promise<Screen>
 * })
 * ```
 *
 * @packageDocumentation
 */
import { UnknownStateError } from '../error.js';
import { generateUnbiasedDigits, timingSafeCompare } from '../random.js';
import { Storage } from '../storage/storage.js';
import { MARK_PASSWORD } from '../ui/mark.js';
import type { Screen } from '../ui/screen.js';
import { Provider } from './provider.js';

/**
 * @internal
 */
export interface PasswordHasher<T> {
	hash(password: string): Promise<T>;
	verify(password: string, compare: T): Promise<boolean>;
}

export interface PasswordConfig {
	/**
	 * @internal
	 */
	length?: number;
	/**
	 * @internal
	 */
	hasher?: PasswordHasher<any>;
	/**
	 * The request handler to generate the UI for the login screen.
	 *
	 * In case of an error, this is called again with the `error`.
	 *
	 * Returns a `Screen` describing what to ask for, not a rendered page.
	 */
	login: (req: Request, form?: FormData, error?: PasswordLoginError) => Promise<Screen>;
	/**
	 * The request handler to generate the UI for the register screen.
	 *
	 * Also passes in the current `state` of the flow and any `error` that occurred.
	 *
	 * Returns a `Screen` describing what to ask for, not a rendered page.
	 */
	register: (
		req: Request,
		state: PasswordRegisterState,
		form?: FormData,
		error?: PasswordRegisterError
	) => Promise<Screen>;
	/**
	 * The request handler to generate the UI for the change password screen.
	 *
	 * Also passes in the current `state` of the flow and any `error` that occurred.
	 *
	 * Returns a `Screen` describing what to ask for, not a rendered page.
	 */
	change: (
		req: Request,
		state: PasswordChangeState,
		form?: FormData,
		error?: PasswordChangeError
	) => Promise<Screen>;
	/**
	 * Callback to send the confirmation pin code to the user.
	 *
	 * @example
	 * ```ts
	 * {
	 *   sendCode: async (email, code) => {
	 *     // Send an email with the code
	 *   }
	 * }
	 * ```
	 */
	sendCode: (email: string, code: string) => Promise<void>;
	/**
	 * Callback to validate the password on sign up and password reset.
	 *
	 * @example
	 * ```ts
	 * {
	 *   validatePassword: (password) => {
	 *      return password.length < 8 ? "Password must be at least 8 characters" : undefined
	 *   }
	 * }
	 * ```
	 */
	validatePassword?:
		| v1.StandardSchema
		| ((password: string) => Promise<string | undefined> | string | undefined);
}

/**
 * The states that can happen on the register screen.
 *
 * | State | Description |
 * | ----- | ----------- |
 * | `start` | The user is asked to enter their email address and password to start the flow. |
 * | `code` | The user needs to enter the pin code to verify their email. |
 */
export type PasswordRegisterState =
	| {
			type: 'start';
	  }
	| {
			type: 'code';
			code: string;
			email: string;
			password: string;
	  };

/**
 * The errors that can happen on the register screen.
 *
 * | Error | Description |
 * | ----- | ----------- |
 * | `email_taken` | The email is already taken. |
 * | `invalid_email` | The email is invalid. |
 * | `invalid_code` | The code is invalid. |
 * | `invalid_password` | The password is invalid. |
 * | `password_mismatch` | The passwords do not match. |
 */
export type PasswordRegisterError =
	| {
			type: 'invalid_code';
	  }
	| {
			type: 'email_taken';
	  }
	| {
			type: 'invalid_email';
	  }
	| {
			type: 'invalid_password';
	  }
	| {
			type: 'password_mismatch';
	  }
	| {
			type: 'validation_error';
			message?: string;
	  };

/**
 * The state of the password change flow.
 *
 * | State | Description |
 * | ----- | ----------- |
 * | `start` | The user is asked to enter their email address to start the flow. |
 * | `code` | The user needs to enter the pin code to verify their email. |
 * | `update` | The user is asked to enter their new password and confirm it. |
 */
export type PasswordChangeState =
	| {
			type: 'start';
			redirect: string;
	  }
	| {
			type: 'code';
			code: string;
			email: string;
			redirect: string;
	  }
	| {
			type: 'update';
			redirect: string;
			email: string;
	  };

/**
 * The errors that can happen on the change password screen.
 *
 * | Error | Description |
 * | ----- | ----------- |
 * | `invalid_email` | The email is invalid. |
 * | `invalid_code` | The code is invalid. |
 * | `invalid_password` | The password is invalid. |
 * | `password_mismatch` | The passwords do not match. |
 */
export type PasswordChangeError =
	| {
			type: 'invalid_email';
	  }
	| {
			type: 'invalid_code';
	  }
	| {
			type: 'invalid_password';
	  }
	| {
			type: 'password_mismatch';
	  }
	| {
			type: 'validation_error';
			message: string;
	  };

/**
 * The errors that can happen on the login screen.
 *
 * | Error | Description |
 * | ----- | ----------- |
 * | `invalid_email` | The email is invalid. |
 * | `invalid_password` | The password is invalid. |
 */
export type PasswordLoginError =
	| {
			type: 'invalid_password';
	  }
	| {
			type: 'invalid_email';
	  };

export function PasswordProvider(config: PasswordConfig): Provider<{ email: string }> {
	const hasher = config.hasher ?? ScryptHasher();
	function generate() {
		return generateUnbiasedDigits(6);
	}
	return {
		type: 'password',
		display: { name: 'Password', icon: MARK_PASSWORD },
		init(routes, ctx) {
			routes.get('/authorize', async (c) => ctx.screen(c, await config.login(c.req.raw)));

			routes.post('/authorize', async (c) => {
				const fd = await c.req.formData();
				async function error(err: PasswordLoginError) {
					return ctx.screen(c, await config.login(c.req.raw, fd, err));
				}
				const email = fd.get('email')?.toString()?.toLowerCase();
				if (!email) return error({ type: 'invalid_email' });
				const hash = await Storage.get<HashedPassword>(ctx.storage, ['email', email, 'password']);
				const password = fd.get('password')?.toString();
				if (!password || !hash || !(await hasher.verify(password, hash)))
					return error({ type: 'invalid_password' });
				return ctx.success(
					c,
					{
						email: email
					},
					{
						invalidate: async (subject) => {
							await Storage.set(ctx.storage, ['email', email, 'subject'], subject);
						}
					}
				);
			});

			routes.get('/register', async (c) => {
				const state: PasswordRegisterState = {
					type: 'start'
				};
				await ctx.set(c, 'provider', 60 * 60 * 24, state);
				return ctx.screen(c, await config.register(c.req.raw, state));
			});

			routes.post('/register', async (c) => {
				const fd = await c.req.formData();
				const email = fd.get('email')?.toString()?.toLowerCase();
				const action = fd.get('action')?.toString();
				const provider = await ctx.get<PasswordRegisterState>(c, 'provider');

				async function transition(next: PasswordRegisterState, err?: PasswordRegisterError) {
					await ctx.set<PasswordRegisterState>(c, 'provider', 60 * 60 * 24, next);
					return ctx.screen(c, await config.register(c.req.raw, next, fd, err));
				}

				if (action === 'register' && provider.type === 'start') {
					const password = fd.get('password')?.toString();
					const repeat = fd.get('repeat')?.toString();
					if (!email) return transition(provider, { type: 'invalid_email' });
					if (!password) return transition(provider, { type: 'invalid_password' });
					if (password !== repeat) return transition(provider, { type: 'password_mismatch' });
					if (config.validatePassword) {
						let validationError: string | undefined;
						try {
							if (typeof config.validatePassword === 'function') {
								validationError = await config.validatePassword(password);
							} else {
								const res = await config.validatePassword['~standard'].validate(password);

								if (res.issues?.length) {
									throw new Error(res.issues.map((issue) => issue.message).join(', '));
								}
							}
						} catch (error) {
							validationError = error instanceof Error ? error.message : undefined;
						}
						if (validationError)
							return transition(provider, {
								type: 'validation_error',
								message: validationError
							});
					}
					const existing = await Storage.get(ctx.storage, ['email', email, 'password']);
					if (existing) return transition(provider, { type: 'email_taken' });
					const code = generate();
					await config.sendCode(email, code);
					return transition({
						type: 'code',
						code,
						password: await hasher.hash(password),
						email
					});
				}

				if (action === 'register' && provider.type === 'code') {
					const code = generate();
					await config.sendCode(provider.email, code);
					return transition({
						type: 'code',
						code,
						password: provider.password,
						email: provider.email
					});
				}

				if (action === 'verify' && provider.type === 'code') {
					const code = fd.get('code')?.toString();
					if (!code || !timingSafeCompare(code, provider.code))
						return transition(provider, { type: 'invalid_code' });
					const existing = await Storage.get(ctx.storage, ['email', provider.email, 'password']);
					if (existing) return transition({ type: 'start' }, { type: 'email_taken' });
					await Storage.set(ctx.storage, ['email', provider.email, 'password'], provider.password);
					return ctx.success(c, {
						email: provider.email
					});
				}

				return transition({ type: 'start' });
			});

			routes.get('/change', async (c) => {
				let redirect = c.req.query('redirect_uri') || getRelativeUrl(c, './authorize');
				const state: PasswordChangeState = {
					type: 'start',
					redirect
				};
				await ctx.set(c, 'provider', 60 * 60 * 24, state);
				return ctx.screen(c, await config.change(c.req.raw, state));
			});

			routes.post('/change', async (c) => {
				const fd = await c.req.formData();
				const action = fd.get('action')?.toString();
				const provider = await ctx.get<PasswordChangeState>(c, 'provider');
				if (!provider) throw new UnknownStateError();

				async function transition(next: PasswordChangeState, err?: PasswordChangeError) {
					await ctx.set<PasswordChangeState>(c, 'provider', 60 * 60 * 24, next);
					return ctx.screen(c, await config.change(c.req.raw, next, fd, err));
				}

				if (action === 'code') {
					const email = fd.get('email')?.toString()?.toLowerCase();
					if (!email)
						return transition(
							{ type: 'start', redirect: provider.redirect },
							{ type: 'invalid_email' }
						);
					const code = generate();
					await config.sendCode(email, code);

					return transition({
						type: 'code',
						code,
						email,
						redirect: provider.redirect
					});
				}

				if (action === 'verify' && provider.type === 'code') {
					const code = fd.get('code')?.toString();
					if (!code || !timingSafeCompare(code, provider.code))
						return transition(provider, { type: 'invalid_code' });
					return transition({
						type: 'update',
						email: provider.email,
						redirect: provider.redirect
					});
				}

				if (action === 'update' && provider.type === 'update') {
					const existing = await Storage.get(ctx.storage, ['email', provider.email, 'password']);
					if (!existing) return c.redirect(provider.redirect, 302);

					const password = fd.get('password')?.toString();
					const repeat = fd.get('repeat')?.toString();
					if (!password) return transition(provider, { type: 'invalid_password' });
					if (password !== repeat) return transition(provider, { type: 'password_mismatch' });

					if (config.validatePassword) {
						let validationError: string | undefined;
						try {
							if (typeof config.validatePassword === 'function') {
								validationError = await config.validatePassword(password);
							} else {
								const res = await config.validatePassword['~standard'].validate(password);

								if (res.issues?.length) {
									throw new Error(res.issues.map((issue) => issue.message).join(', '));
								}
							}
						} catch (error) {
							validationError = error instanceof Error ? error.message : undefined;
						}
						if (validationError)
							return transition(provider, {
								type: 'validation_error',
								message: validationError
							});
					}

					await Storage.set(
						ctx.storage,
						['email', provider.email, 'password'],
						await hasher.hash(password)
					);
					const subject = await Storage.get<string>(ctx.storage, [
						'email',
						provider.email,
						'subject'
					]);
					if (subject) await ctx.invalidate(subject);

					return c.redirect(provider.redirect, 302);
				}

				return transition({ type: 'start', redirect: provider.redirect });
			});
		}
	};
}

import { TextEncoder } from 'node:util';

import * as jose from 'jose';

interface HashedPassword {}

/**
 * @internal
 */
export function PBKDF2Hasher(opts?: { iterations?: number }): PasswordHasher<{
	hash: string;
	salt: string;
	iterations: number;
}> {
	const iterations = opts?.iterations ?? 600000;
	return {
		async hash(password) {
			const encoder = new TextEncoder();
			const bytes = encoder.encode(password);
			const salt = crypto.getRandomValues(new Uint8Array(16));
			const keyMaterial = await crypto.subtle.importKey('raw', bytes, 'PBKDF2', false, [
				'deriveBits'
			]);
			const hash = await crypto.subtle.deriveBits(
				{
					name: 'PBKDF2',
					hash: 'SHA-256',
					salt: salt,
					iterations
				},
				keyMaterial,
				256
			);
			const hashBase64 = jose.base64url.encode(new Uint8Array(hash));
			const saltBase64 = jose.base64url.encode(salt);
			return {
				hash: hashBase64,
				salt: saltBase64,
				iterations
			};
		},
		async verify(password, compare) {
			const encoder = new TextEncoder();
			const passwordBytes = encoder.encode(password);
			const salt = jose.base64url.decode(compare.salt);
			const params = {
				name: 'PBKDF2',
				hash: 'SHA-256',
				salt,
				iterations: compare.iterations
			};
			const keyMaterial = await crypto.subtle.importKey('raw', passwordBytes, 'PBKDF2', false, [
				'deriveBits'
			]);
			const hash = await crypto.subtle.deriveBits(params, keyMaterial, 256);
			const hashBase64 = jose.base64url.encode(new Uint8Array(hash));
			return hashBase64 === compare.hash;
		}
	};
}
import { timingSafeEqual, randomBytes, scrypt } from 'node:crypto';

import { getRelativeUrl } from '../util.js';

/**
 * @internal
 */
export function ScryptHasher(opts?: { N?: number; r?: number; p?: number }): PasswordHasher<{
	hash: string;
	salt: string;
	N: number;
	r: number;
	p: number;
}> {
	const N = opts?.N ?? 16384;
	const r = opts?.r ?? 8;
	const p = opts?.p ?? 1;

	return {
		async hash(password) {
			const salt = randomBytes(16);
			const keyLength = 32; // 256 bits

			const derivedKey = await new Promise<Buffer>((resolve, reject) => {
				scrypt(password, salt, keyLength, { N, r, p }, (err, derivedKey) => {
					if (err) reject(err);
					else resolve(derivedKey);
				});
			});

			const hashBase64 = derivedKey.toString('base64');
			const saltBase64 = salt.toString('base64');

			return {
				hash: hashBase64,
				salt: saltBase64,
				N,
				r,
				p
			};
		},

		async verify(password, compare) {
			const salt = Buffer.from(compare.salt, 'base64');
			const keyLength = 32; // 256 bits

			const derivedKey = await new Promise<Buffer>((resolve, reject) => {
				scrypt(
					password,
					salt,
					keyLength,
					{ N: compare.N, r: compare.r, p: compare.p },
					(err, derivedKey) => {
						if (err) reject(err);
						else resolve(derivedKey);
					}
				);
			});

			return timingSafeEqual(derivedKey, Buffer.from(compare.hash, 'base64'));
		}
	};
}