wallet-core/packages/taler-util/src/helpers.ts

124 lines
3.2 KiB
TypeScript

/*
This file is part of TALER
(C) 2016 GNUnet e.V.
TALER is free software; you can redistribute it and/or modify it under the
terms of the GNU General Public License as published by the Free Software
Foundation; either version 3, or (at your option) any later version.
TALER is distributed in the hope that it will be useful, but WITHOUT ANY
WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR
A PARTICULAR PURPOSE. See the GNU General Public License for more details.
You should have received a copy of the GNU General Public License along with
TALER; see the file COPYING. If not, see <http://www.gnu.org/licenses/>
*/
/**
* Small helper functions that don't fit anywhere else.
*/
/**
* Imports.
*/
import { AmountJson } from "./amounts.js";
import * as Amounts from "./amounts.js";
import { URL } from "./url.js";
/**
* Show an amount in a form suitable for the user.
* FIXME: In the future, this should consider currency-specific
* settings such as significant digits or currency symbols.
*/
export function amountToPretty(amount: AmountJson): string {
const x = amount.value + amount.fraction / Amounts.amountFractionalBase;
return `${x} ${amount.currency}`;
}
/**
* Canonicalize a base url, typically for the exchange.
*
* See http://api.taler.net/wallet.html#general
*/
export function canonicalizeBaseUrl(url: string): string {
if (!url.startsWith("http") && !url.startsWith("https")) {
url = "https://" + url;
}
const x = new URL(url);
if (!x.pathname.endsWith("/")) {
x.pathname = x.pathname + "/";
}
x.search = "";
x.hash = "";
return x.href;
}
/**
* Convert object to JSON with canonical ordering of keys
* and whitespace omitted.
*
* See RFC 4885 (https://tools.ietf.org/html/rfc8785).
*/
export function canonicalJson(obj: any): string {
// Check for cycles, etc.
obj = JSON.parse(JSON.stringify(obj));
if (typeof obj === "string") {
return JSON.stringify(obj);
}
if (typeof obj === "number" || typeof obj === "boolean" || obj === null) {
return JSON.stringify(obj);
}
if (Array.isArray(obj)) {
const objs: string[] = obj.map((e) => canonicalJson(e));
return `[${objs.join(",")}]`;
}
const keys: string[] = [];
for (const key in obj) {
keys.push(key);
}
keys.sort();
let s = "{";
for (let i = 0; i < keys.length; i++) {
const key = keys[i];
s += JSON.stringify(key) + ":" + canonicalJson(obj[key]);
if (i !== keys.length - 1) {
s += ",";
}
}
return s + "}";
}
/**
* Lexically compare two strings.
*/
export function strcmp(s1: string, s2: string): -1 | 0 | 1 {
if (s1 < s2) {
return -1;
}
if (s1 > s2) {
return 1;
}
return 0;
}
/**
* Shorthand function for formatted JSON stringification.
*/
export function j2s(x: any): string {
return JSON.stringify(x, undefined, 2);
}
/**
* Use this to filter null or undefined from an array in a type-safe fashion
*
* example:
* const array: Array<T | undefined> = [undefined, null]
* const filtered: Array<T> = array.filter(notEmpty)
*
* @param value
* @returns
*/
export function notEmpty<T>(value: T | null | undefined): value is T {
return value !== null && value !== undefined;
}