import { isPiWebPluginId } from "./pluginIds.js";

const MACHINE_PLUGIN_ID_PREFIX = "machine.";

export interface MachineScopedPluginIdParts {
  machineId: string;
  pluginId: string;
}

export function machineScopedPluginId(machineId: string, pluginId: string): string {
  if (machineId === "") throw new Error("Machine id is required");
  if (!isPiWebPluginId(pluginId)) throw new Error(`Invalid PI WEB plugin id: ${pluginId}`);
  return `${MACHINE_PLUGIN_ID_PREFIX}${stringToHex(machineId)}.${pluginId}`;
}

export function parseMachineScopedPluginId(pluginId: string): MachineScopedPluginIdParts | undefined {
  if (!pluginId.startsWith(MACHINE_PLUGIN_ID_PREFIX)) return undefined;
  const rest = pluginId.slice(MACHINE_PLUGIN_ID_PREFIX.length);
  const separator = rest.indexOf(".");
  if (separator < 1) return undefined;

  const encodedMachineId = rest.slice(0, separator);
  const sourcePluginId = rest.slice(separator + 1);
  if (!isHexString(encodedMachineId) || !isPiWebPluginId(sourcePluginId)) return undefined;

  const machineId = hexToString(encodedMachineId);
  if (machineId === "") return undefined;
  return { machineId, pluginId: sourcePluginId };
}

function stringToHex(value: string): string {
  return [...new TextEncoder().encode(value)]
    .map((byte) => byte.toString(16).padStart(2, "0"))
    .join("");
}

function hexToString(value: string): string {
  const bytes = new Uint8Array(value.length / 2);
  for (let index = 0; index < value.length; index += 2) {
    bytes[index / 2] = Number.parseInt(value.slice(index, index + 2), 16);
  }
  return new TextDecoder().decode(bytes);
}

function isHexString(value: string): boolean {
  return value.length > 0 && value.length % 2 === 0 && /^[0-9a-f]+$/u.test(value);
}