"use client";

import type { ReactNode, Ref } from "react";
import { canDelete, type CardPost } from "@/lib/feed-model";
import type { DiscoverExpert, DiscoverMinnect } from "@/lib/discover";
import { Composer, type ComposerProps } from "./Composer";
import { GrowButton, IconButton } from "./Buttons";
import { PostCard } from "./PostCard";
import { useCompactLayout } from "./layout-context";
import { MobileFeed, type CurrentSlide } from "./MobileFeed";

export type FeedStatus = "loading" | "ready" | "error";

export interface FeedViewProps {
  posts: CardPost[];
  status: FeedStatus;
  loadingMore: boolean;
  loadMoreFailed: boolean;
  newCount: number;
  onRetry: () => void;
  onShowNew: () => void;
  /** Reloads the first page; the header shows the button when it is given. */
  onRefresh?: () => void;
  refreshing?: boolean;
  /** The last refresh failed; the posts stay and a small message shows in the header. */
  refreshFailed?: boolean;
  onToggleLike?: (post: CardPost) => void;
  likeBusy?: ReadonlySet<string>;
  likeErrors?: ReadonlySet<string>;
  onSignedOut?: () => void;
  /** The signed-in person's feed user id; delete is offered only on their own posts. */
  feedUserId?: string | null;
  onDelete?: (post: CardPost) => void;
  deleteBusy?: ReadonlySet<string>;
  deleteErrors?: ReadonlySet<string>;
  composer?: ComposerProps;
  sentinelRef?: Ref<HTMLDivElement>;
  /** The scrolling feed list; the page itself never scrolls. */
  listRef?: Ref<HTMLDivElement>;
  now?: number;
  /** Another page can load; the phone feed ends with a loading slide. */
  hasMore?: boolean;
  /** Phone layout only: experts for the featured slide after the second post. */
  featuredExperts?: DiscoverExpert[];
  /** Phone layout only: trending minnects for the Discover sheet. */
  trendingMinnects?: DiscoverMinnect[];
  /** Phone layout only: the Find experts panel shown in the Discover sheet. */
  searchPanel?: ReactNode;
  /** Phone layout only: the slide on screen changed (for the dock). */
  onCurrentChange?: (slide: CurrentSlide) => void;
  /** Phone layout only: the dock's comments button, for the post on screen. */
  onOpenComments?: (postId: string) => void;
  /** Phone layout only: the dock's new-post button. */
  onOpenComposer?: () => void;
  /** Phone layout only: the dock's More button (the Discover sheet). */
  onOpenMore?: () => void;
}

function Spinner() {
  return <span className="spinner" role="status" aria-label="Loading" />;
}

/** Shimmer placeholder card shown while the next page loads. */
function SkeletonCard() {
  return (
    <div className="feed-skel" role="status" aria-label="Loading more posts" data-testid="feed-skeleton">
      <div className="feed-skel-head">
        <span className="feed-skel-dot" />
        <span className="feed-skel-lines">
          <span className="feed-skel-line feed-skel-w40" />
          <span className="feed-skel-line feed-skel-w25" />
        </span>
      </div>
      <span className="feed-skel-line feed-skel-w100" />
      <span className="feed-skel-line feed-skel-w80" />
      <span className="feed-skel-media" />
    </div>
  );
}

function RefreshIcon({ spinning }: { spinning: boolean }) {
  return (
    <svg
      viewBox="0 0 24 24"
      fill="none"
      stroke="currentColor"
      strokeWidth="2"
      strokeLinecap="round"
      strokeLinejoin="round"
      aria-hidden="true"
      className={spinning ? "refresh-icon refresh-icon-spin" : "refresh-icon"}
    >
      <path d="M21 12a9 9 0 1 1-2.64-6.36" />
      <path d="M21 3v6h-6" />
    </svg>
  );
}

export function RefreshButton({ onRefresh, busy }: { onRefresh: () => void; busy?: boolean }) {
  return (
    <IconButton
      label="Refresh feed"
      shape="round"
      size="sm"
      icon={<RefreshIcon spinning={!!busy} />}
      disabled={busy}
      aria-busy={busy || undefined}
      onClick={onRefresh}
    />
  );
}

function FeedPanel({ children, composer, onRefresh, busy, refreshFailed }: { children: ReactNode; composer?: ReactNode; onRefresh?: () => void; busy?: boolean; refreshFailed?: boolean }) {
  return (
    <section className="tile panel feed" aria-labelledby="h-feed">
      <div className="panel-head feed-head">
        <h2 id="h-feed" className="type-title type-title-strong">Home feed</h2>
        {refreshFailed ? <span className="feed-refresh-error" role="alert">Could not refresh. Try again.</span> : null}
        {onRefresh ? <RefreshButton onRefresh={onRefresh} busy={busy} /> : null}
      </div>
      {composer}
      {children}
    </section>
  );
}

export function FeedView(p: FeedViewProps) {
  // At 760px and below the feed is the full-screen snap reel instead of the panel.
  const compact = useCompactLayout();
  if (compact) return <MobileFeed {...p} />;
  if (p.status === "loading") {
    return (
      <FeedPanel onRefresh={p.onRefresh} busy>
        <div className="feed-center">
          <Spinner />
        </div>
      </FeedPanel>
    );
  }
  if (p.status === "error") {
    return (
      <FeedPanel onRefresh={p.onRefresh}>
        <div className="feed-message" role="alert">
          <p>The feed did not load.</p>
          <button type="button" onClick={p.onRetry}>Try again</button>
        </div>
      </FeedPanel>
    );
  }
  return (
    <FeedPanel composer={p.composer ? <Composer {...p.composer} /> : null} onRefresh={p.onRefresh} busy={p.refreshing} refreshFailed={p.refreshFailed}>
      <div ref={p.listRef} className="feed-list panel-scroll fade-edges">
        {p.newCount > 0 ? (
          <div className="feed-pill">
            <GrowButton label={p.newCount === 1 ? "1 new post" : `${p.newCount} new posts`} onClick={p.onShowNew} />
          </div>
        ) : null}
        {p.posts.length === 0 ? (
          <p className="feed-message">No posts yet.</p>
        ) : (
          p.posts.map((post, i) => <PostCard
              key={post.key}
              post={post}
              index={i}
              now={p.now}
              onToggleLike={p.onToggleLike}
              likeBusy={p.likeBusy?.has(post.key)}
              likeError={p.likeErrors?.has(post.key)}
              onSignedOut={p.onSignedOut}
              canDelete={canDelete(post, p.feedUserId)}
              onDelete={p.onDelete}
              deleteBusy={p.deleteBusy?.has(post.key)}
              deleteError={p.deleteErrors?.has(post.key)}
            />)
        )}
        {p.loadMoreFailed ? (
          <div className="feed-message" role="alert">
            <p>The feed did not load.</p>
            <button type="button" onClick={p.onRetry}>Try again</button>
          </div>
        ) : null}
        {p.loadingMore ? <SkeletonCard /> : null}
        <div ref={p.sentinelRef} className="sentinel" aria-hidden="true" />
      </div>
    </FeedPanel>
  );
}