/*
 This file is part of GNU Anastasis
 (C) 2021-2022 Anastasis SARL

 GNU Anastasis is free software; you can redistribute it and/or modify it under the
 terms of the GNU Affero General Public License as published by the Free Software
 Foundation; either version 3, or (at your option) any later version.

 GNU Anastasis 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 Affero General Public License for more details.

 You should have received a copy of the GNU Affero General Public License along with
 GNU Anastasis; see the file COPYING.  If not, see <http://www.gnu.org/licenses/>
 */

/**
 *
 * @author Sebastian Javier Marchano (sebasjm)
 */

import { Codec, codecForString } from "@gnu-taler/taler-util";
import { useEffect, useState } from "preact/hooks";
import {
  ObservableMap,
  browserStorageMap,
  localStorageMap,
  memoryMap,
} from "../utils/observable.js";

declare const opaque_StorageKey: unique symbol;

export type StorageKey<Key> = {
  id: string;
  [opaque_StorageKey]: true;
  codec: Codec<Key>;
};

export function buildStorageKey<Key>(
  name: string,
  codec: Codec<Key>,
): StorageKey<Key>;
export function buildStorageKey(name: string): StorageKey<string>;
export function buildStorageKey<Key = string>(
  name: string,
  codec?: Codec<Key>,
): StorageKey<Key> {
  return {
    id: name,
    codec: codec ?? (codecForString() as Codec<Key>),
  } as StorageKey<Key>;
}

export interface StorageState<Type = string> {
  value?: Type;
  update: (s: Type) => void;
  reset: () => void;
}

const supportLocalStorage = typeof window !== "undefined";
const supportBrowserStorage =
  typeof chrome !== "undefined" && typeof chrome.storage !== "undefined";

const storage: ObservableMap<string, string> = (function buildStorage() {
  if (supportBrowserStorage) {
    return browserStorageMap(memoryMap<string>());
  } else if (supportLocalStorage) {
    return localStorageMap();
  } else {
    return memoryMap<string>();
  }
})();

//with initial value
export function useLocalStorage<Type = string>(
  key: StorageKey<Type>,
  defaultValue: Type,
): Required<StorageState<Type>>;
//without initial value
export function useLocalStorage<Type = string>(
  key: StorageKey<Type>,
): StorageState<Type>;
// impl
export function useLocalStorage<Type = string>(
  key: StorageKey<Type>,
  defaultValue?: Type,
): StorageState<Type> {
  function convert(updated: string | undefined): Type | undefined {
    if (updated === undefined) return defaultValue; //optional
    try {
      return key.codec.decode(JSON.parse(updated));
    } catch (e) {
      //decode error
      return defaultValue;
    }
  }
  const [storedValue, setStoredValue] = useState<Type | undefined>(
    (): Type | undefined => {
      const prev = storage.get(key.id);
      return convert(prev);
    },
  );

  useEffect(() => {
    return storage.onUpdate(key.id, () => {
      const newValue = storage.get(key.id);
      setStoredValue(convert(newValue));
    });
  }, [key.id]);

  const setValue = (value?: Type): void => {
    if (value === undefined) {
      storage.delete(key.id);
    } else {
      storage.set(
        key.id,
        key.codec ? JSON.stringify(value) : (value as string),
      );
    }
  };

  return {
    value: storedValue,
    update: setValue,
    reset: () => {
      setValue(defaultValue);
    },
  };
}