import { computed } from 'vue';
import type { GlobalToken } from '../theme/interface';
import { useToken } from '../theme/internal';

export type Breakpoint = 'xxxl' | 'xxl' | 'xl' | 'lg' | 'md' | 'sm' | 'xs';
export type BreakpointMap = Record<Breakpoint, string>;
export type ScreenMap = Partial<Record<Breakpoint, boolean>>;
export type ScreenSizeMap = Partial<Record<Breakpoint, number>>;

export const responsiveArray: Breakpoint[] = ['xxxl', 'xxl', 'xl', 'lg', 'md', 'sm', 'xs'];
type SubscribeFunc = (screens: ScreenMap) => void;

const getResponsiveMap = (token: GlobalToken): BreakpointMap => ({
  xs: `(max-width: ${token.screenXSMax}px)`,
  sm: `(min-width: ${token.screenSM}px)`,
  md: `(min-width: ${token.screenMD}px)`,
  lg: `(min-width: ${token.screenLG}px)`,
  xl: `(min-width: ${token.screenXL}px)`,
  xxl: `(min-width: ${token.screenXXL}px)`,
  xxxl: `{min-width: ${token.screenXXXL}px}`,
});

export default function useResponsiveObserver() {
  const [, token] = useToken();

  return computed(() => {
    const responsiveMap: BreakpointMap = getResponsiveMap(token.value);
    const subscribers = new Map<Number, SubscribeFunc>();
    let subUid = -1;
    let screens = {};

    return {
      matchHandlers: {} as {
        [prop: string]: {
          mql: MediaQueryList;
          listener: ((this: MediaQueryList, ev: MediaQueryListEvent) => any) | null;
        };
      },
      dispatch(pointMap: ScreenMap) {
        screens = pointMap;
        subscribers.forEach(func => func(screens));
        return subscribers.size >= 1;
      },
      subscribe(func: SubscribeFunc): number {
        if (!subscribers.size) this.register();
        subUid += 1;
        subscribers.set(subUid, func);
        func(screens);
        return subUid;
      },
      unsubscribe(paramToken: number) {
        subscribers.delete(paramToken);
        if (!subscribers.size) this.unregister();
      },
      unregister() {
        Object.keys(responsiveMap).forEach((screen: string) => {
          const matchMediaQuery = responsiveMap[screen];
          const handler = this.matchHandlers[matchMediaQuery];
          handler?.mql.removeListener(handler?.listener);
        });
        subscribers.clear();
      },
      register() {
        Object.keys(responsiveMap).forEach((screen: string) => {
          const matchMediaQuery = responsiveMap[screen];
          const listener = ({ matches }: { matches: boolean }) => {
            this.dispatch({
              ...screens,
              [screen]: matches,
            });
          };
          const mql = window.matchMedia(matchMediaQuery);
          mql.addListener(listener);
          this.matchHandlers[matchMediaQuery] = {
            mql,
            listener,
          };

          listener(mql);
        });
      },
      responsiveMap,
    };
  });
}