query.ts

import {
  decode,
  decodeQueryValue,
  encodeQueryKey,
  encodeQueryValue,
} from "./encoding";

export type QueryValue =
  | string
  | number
  | undefined
  | null
  | Record<string, any>;
export type QueryObject = Record<string, QueryValue | QueryValue[]>;

export function parseQuery(parametersString = ""): QueryObject {
  const object: QueryObject = {};
  if (parametersString[0] === "?") {
    parametersString = parametersString.slice(1);
  }
  for (const parameter of parametersString.split("&")) {
    const s = parameter.match(/([^=]+)=?(.*)/) || [];
    if (s.length < 2) {
      continue;
    }
    const key = decode(s[1]);
    if (key === "__proto__" || key === "constructor") {
      continue;
    }
    const value = decodeQueryValue(s[2] || "");
    if (typeof object[key] !== "undefined") {
      if (Array.isArray(object[key])) {
        (object[key] as string[]).push(value);
      } else {
        object[key] = [object[key] as string, value];
      }
    } else {
      object[key] = value;
    }
  }
  return object;
}

export function encodeQueryItem(
  key: string,
  value: QueryValue | QueryValue[]
): string {
  if (typeof value === "number" || typeof value === "boolean") {
    value = String(value);
  }
  if (!value) {
    return encodeQueryKey(key);
  }

  if (Array.isArray(value)) {
    return value
      .map((_value) => `${encodeQueryKey(key)}=${encodeQueryValue(_value)}`)
      .join("&");
  }

  return `${encodeQueryKey(key)}=${encodeQueryValue(value)}`;
}

export function stringifyQuery(query: QueryObject) {
  return Object.keys(query)
    .filter((k) => query[k] !== undefined)
    .map((k) => encodeQueryItem(k, query[k]))
    .join("&");
}