import { createContext, useContext, useEffect, useState } from "react";
import { browser, isExt, isGm, isWeb } from "../libs/browser";
import {
  STOKEY_SETTING,
  STOKEY_RULES,
  STOKEY_SYNC,
  DEFAULT_SETTING,
  DEFAULT_RULES,
  DEFAULT_SYNC,
} from "../config";
import storage from "../libs/storage";

/**
 * 默认配置
 */
export const defaultStorage = {
  [STOKEY_SETTING]: DEFAULT_SETTING,
  [STOKEY_RULES]: DEFAULT_RULES,
  [STOKEY_SYNC]: DEFAULT_SYNC,
};

const activeKeys = Object.keys(defaultStorage);

const StoragesContext = createContext(null);

export function StoragesProvider({ children }) {
  const [storages, setStorages] = useState(null);

  const handleChanged = (changes) => {
    if (isWeb || isGm) {
      const { key, oldValue, newValue } = changes;
      changes = {
        [key]: {
          oldValue,
          newValue,
        },
      };
    }
    const newStorages = {};
    Object.entries(changes)
      .filter(
        ([key, { oldValue, newValue }]) =>
          activeKeys.includes(key) && oldValue !== newValue
      )
      .forEach(([key, { newValue }]) => {
        newStorages[key] = JSON.parse(newValue);
      });
    if (Object.keys(newStorages).length !== 0) {
      setStorages((pre) => ({ ...pre, ...newStorages }));
    }
  };

  useEffect(() => {
    // 首次从storage同步配置到内存
    (async () => {
      const curStorages = {};
      for (const key of activeKeys) {
        const val = await storage.get(key);
        if (val) {
          curStorages[key] = JSON.parse(val);
        } else {
          await storage.setObj(key, defaultStorage[key]);
          curStorages[key] = defaultStorage[key];
        }
      }
      setStorages(curStorages);
    })();

    // 监听storage，并同步到内存中
    storage.onChanged(handleChanged);

    // 解除监听
    return () => {
      if (isExt) {
        browser.storage.onChanged.removeListener(handleChanged);
      } else {
        window.removeEventListener("storage", handleChanged);
      }
    };
  }, []);

  return (
    <StoragesContext.Provider value={storages}>
      {children}
    </StoragesContext.Provider>
  );
}

export function useStorages() {
  return useContext(StoragesContext);
}