import React from "react";

import { HttpTimelinePostInfo } from "@/http/timeline";

import TimelinePostListView, {
  TimelinePostListViewProps,
} from "./TimelinePostListView";

export interface TimelinePagedPostListViewProps {
  className?: string;
  style?: React.CSSProperties;
  posts: HttpTimelinePostInfo[];
  onReload: () => void;
}

const TimelinePagedPostListView: React.FC<TimelinePagedPostListViewProps> = (
  props
) => {
  const { className, style, posts, onReload } = props;

  const [lastViewCount, setLastViewCount] = React.useState<number>(10);

  const viewingPosts = React.useMemo(() => {
    const p: TimelinePostListViewProps["posts"] =
      lastViewCount >= posts.length
        ? posts.slice()
        : posts.slice(-lastViewCount);

    for (let i = 0; i < p.length; i++) {
      p[p.length - i - 1].enterDelay = (i % 10) * 0.4;
    }

    return p;
  }, [posts, lastViewCount]);

  React.useEffect(() => {
    if (lastViewCount < posts.length) {
      const listener = (): void => {
        if (window.scrollY === 0 && lastViewCount < posts.length) {
          setLastViewCount(lastViewCount + 10);
        }
      };
      window.addEventListener("scroll", listener);
      return () => window.removeEventListener("scroll", listener);
    }
  }, [lastViewCount, posts]);

  return (
    <TimelinePostListView
      className={className}
      style={style}
      posts={viewingPosts}
      onReload={onReload}
    />
  );
};

export default TimelinePagedPostListView;