import { TranslatedString } from "@gnu-taler/taler-util";
import { useEffect, useState } from "preact/hooks";
import { memoryMap } from "../index.browser.js";

export type NotificationMessage = ErrorNotification | InfoNotification;

export interface ErrorNotification {
  type: "error";
  title: TranslatedString;
  description?: TranslatedString;
  debug?: string;
}
export interface InfoNotification {
  type: "info";
  title: TranslatedString;
}

const storage = memoryMap<Map<string, NotificationMessage>>();
const NOTIFICATION_KEY = "notification";

export function notify(notif: NotificationMessage): void {
  const currentState: Map<string, NotificationMessage> =
    storage.get(NOTIFICATION_KEY) ?? new Map();
  const newState = currentState.set(hash(notif), notif);
  storage.set(NOTIFICATION_KEY, newState);
}
export function notifyError(
  title: TranslatedString,
  description: TranslatedString | undefined,
  debug?: any,
) {
  notify({
    type: "error" as const,
    title,
    description,
    debug,
  });
}
export function notifyInfo(title: TranslatedString) {
  notify({
    type: "info" as const,
    title,
  });
}

type Notification = {
  message: NotificationMessage;
  remove: () => void;
};

export function useNotifications(): Notification[] {
  const [value, setter] = useState<Map<string, NotificationMessage>>(new Map());
  useEffect(() => {
    return storage.onUpdate(NOTIFICATION_KEY, () => {
      const mem = storage.get(NOTIFICATION_KEY) ?? new Map();
      setter(mem);
    });
  });

  return Array.from(value.values()).map((message, idx) => {
    return {
      message,
      remove: () => {
        const mem = storage.get(NOTIFICATION_KEY) ?? new Map();
        const newState = new Map(mem);
        newState.delete(hash(message));
        storage.set(NOTIFICATION_KEY, newState);
      },
    };
  });
}

function hashCode(str: string): string {
  if (str.length === 0) return "0";
  let hash = 0;
  let chr;
  for (let i = 0; i < str.length; i++) {
    chr = str.charCodeAt(i);
    hash = (hash << 5) - hash + chr;
    hash |= 0; // Convert to 32bit integer
  }
  return hash.toString(16);
}

function hash(msg: NotificationMessage): string {
  let str = (msg.type + ":" + msg.title) as string;
  if (msg.type === "error") {
    if (msg.description) {
      str += ":" + msg.description;
    }
    if (msg.debug) {
      str += ":" + msg.debug;
    }
  }
  return hashCode(str);
}