import { useCallback, useEffect, useMemo, useState } from "react";
import type {
  ColumnSnapshot,
  ColumnState,
  ColumnView,
  DeckAccount,
  DeckColumn,
  FullscreenState,
  TimelineState,
} from "../types/app";
import type { Tweet } from "../lib/fetching/types";
import { twitterClient } from "../lib/client/twitterClient";
import { TweetCard } from "./TweetCard";

export type TimelineConfig = DeckColumn & {
  kind: Exclude<DeckColumn["kind"], "chat">;
};

type TimelineView = Extract<ColumnView, { type: "timeline" }>;

interface TimelineColumnProps {
  column: TimelineConfig;
  account: DeckAccount;
  onRemove: () => void;
  onStateChange: (columnId: string, state: ColumnState) => void;
  onSnapshot: (columnId: string, snapshot: ColumnSnapshot) => void;
  onEnterFullscreen: (payload: FullscreenState) => void;
  columnIndex: number;
}

export function TimelineColumn({
  column,
  account,
  onRemove,
  onStateChange,
  onSnapshot,
  onEnterFullscreen,
  columnIndex,
}: TimelineColumnProps) {
  const [state, setState] = useState<TimelineState>({
    tweets: [],
    cursorTop: "",
    cursorBottom: "",
    isLoading: false,
    isAppending: false,
  });
  const [error, setError] = useState<string | undefined>();
  const [transitionDirection, setTransitionDirection] = useState<
    "forward" | "backward" | null
  >(null);

  const baseView = useMemo(
    () => createBaseView(column),
    [column.kind, column.title, column.listId, column.listName],
  );
  const initialStack = useMemo<ColumnView[]>(() => {
    return column.state?.stack?.length ? column.state.stack : [baseView];
  }, [column.state, baseView]);

  const [viewStack, setViewStack] = useState<ColumnView[]>(initialStack);

  useEffect(() => {
    setViewStack(initialStack);
  }, [initialStack]);

  const activeView = viewStack[viewStack.length - 1] ?? baseView;
  const canGoBack = viewStack.length > 1;

  const descriptor = useMemo(
    () => describeView(column, activeView),
    [column, activeView],
  );

  const handleMaximize = useCallback(() => {
    onEnterFullscreen({
      column: column,
      columnLabel: descriptor.label,
      accent: account.accent,
      tweets: state.tweets,
      index: 0,
      columnIndex,
    });
  }, [
    state.tweets,
    onEnterFullscreen,
    column.id,
    descriptor.label,
    account.accent,
    columnIndex,
  ]);

  const handleAnimationEnd = useCallback(() => {
    setTransitionDirection(null);
  }, []);

  const pushView = useCallback((view: ColumnView) => {
    setTransitionDirection("forward");
    setViewStack((prev) => [...prev, view]);
  }, []);

  const popView = useCallback(() => {
    setViewStack((prev) => {
      if (prev.length <= 1) return prev;
      setTransitionDirection("backward");
      return prev.slice(0, -1);
    });
  }, []);

  useEffect(() => {
    onStateChange(column.id, { stack: viewStack });
  }, [column.id, onStateChange, viewStack]);

  useEffect(() => {
    onSnapshot(column.id, { tweets: state.tweets, label: descriptor.label });
  }, [column.id, state.tweets, descriptor.label, onSnapshot]);

  const fetchPage = useCallback(
    async (cursor?: string) => {
      const payload: Record<string, unknown> = { cookie: account.cookie };
      //
      let mode: string;

      if (activeView.type === "thread") {
        mode = "thread";
        payload.tweetId = activeView.tweetId;
      } else if (activeView.type === "user") {
        mode = "user";
        payload.userId = activeView.userId;
      } else {
        mode = activeView.mode;
        if (activeView.mode === "list" && activeView.listId) {
          payload.listId = activeView.listId;
        }
      }

      if (cursor) payload.cursor = cursor;
      return twitterClient.timeline(mode, payload);
    },
    [account.cookie, activeView],
  );

  const refresh = useCallback(async () => {
    if (
      activeView.type === "timeline" &&
      activeView.mode === "list" &&
      !activeView.listId
    ) {
      setError("Select a list for this column");
      return;
    }
    setState((prev) => ({ ...prev, isLoading: true }));
    setError(undefined);
    try {
      const data = await fetchPage(state.cursorTop);
      setState({
        tweets: data.tweets,
        cursorTop: data.cursorTop,
        cursorBottom: data.cursorBottom,
        isLoading: false,
        isAppending: false,
      });
    } catch (err) {
      console.error(err);
      setError(err instanceof Error ? err.message : "Failed to load timeline");
      setState((prev) => ({ ...prev, isLoading: false, isAppending: false }));
    }
  }, [activeView, fetchPage]);

  useEffect(() => {
    setState({
      tweets: [],
      cursorTop: "",
      cursorBottom: "",
      isLoading: true,
      isAppending: false,
    });
  }, [activeView]);

  useEffect(() => {
    refresh();
  }, [refresh]);

  const loadMore = useCallback(async () => {
    if (!state.cursorBottom) return;
    setState((prev) => ({ ...prev, isAppending: true }));
    try {
      const data = await fetchPage(state.cursorBottom);
      setState((prev) => ({
        tweets: [...prev.tweets, ...data.tweets],
        cursorTop: prev.cursorTop || data.cursorTop,
        cursorBottom: data.cursorBottom,
        isLoading: false,
        isAppending: false,
      }));
    } catch (err) {
      console.error(err);
      setError(err instanceof Error ? err.message : "Failed to load more");
      setState((prev) => ({ ...prev, isAppending: false }));
    }
  }, [fetchPage, state.cursorBottom, state.cursorTop]);

  const updateTweetById = useCallback(
    (tweetId: string, updater: (tweet: Tweet) => Tweet) => {
      setState((prev) => ({
        ...prev,
        tweets: prev.tweets.map((tweet) =>
          tweet.id === tweetId ? updater(tweet) : tweet,
        ),
      }));
    },
    [],
  );

  const handleRemoveBookmark = useCallback(
    async (tweetId: string) => {
      try {
        await twitterClient.removeBookmark({ cookie: account.cookie, tweetId });
        setState((prev) => ({
          ...prev,
          tweets: prev.tweets.filter((tweet) => tweet.id !== tweetId),
        }));
      } catch (err) {
        setError(
          err instanceof Error
            ? err.message
            : "Unable to remove bookmark right now",
        );
      }
    },
    [account.cookie],
  );

  const likeTweet = useCallback(
    async (tweetId: string, nextState: boolean) => {
      try {
        await twitterClient.like(tweetId, {
          cookie: account.cookie,
          undo: !nextState,
        });
        updateTweetById(tweetId, (tweet) => ({ ...tweet, liked: nextState }));
      } catch (err) {
        setError(err instanceof Error ? err.message : "Unable to update like");
      }
    },
    [account.cookie, updateTweetById],
  );

  const retweet = useCallback(
    async (tweetId: string, nextState: boolean) => {
      try {
        await twitterClient.retweet(tweetId, {
          cookie: account.cookie,
          undo: !nextState,
        });
        updateTweetById(tweetId, (tweet) => ({ ...tweet, rted: nextState }));
      } catch (err) {
        setError(
          err instanceof Error ? err.message : "Unable to update retweet",
        );
      }
    },
    [account.cookie, updateTweetById],
  );

  const bookmarkTweet = useCallback(
    async (tweetId: string, nextState: boolean) => {
      try {
        await twitterClient.bookmark(tweetId, {
          cookie: account.cookie,
          undo: !nextState,
        });
        if (column.kind === "bookmarks" && !nextState) {
          setState((prev) => ({
            ...prev,
            tweets: prev.tweets.filter((tweet) => tweet.id !== tweetId),
          }));
        } else {
          updateTweetById(tweetId, (tweet) => ({
            ...tweet,
            bookmarked: nextState,
          }));
        }
      } catch (err) {
        setError(
          err instanceof Error ? err.message : "Unable to update bookmark",
        );
      }
    },
    [account.cookie, column.kind, updateTweetById],
  );

  const replyToTweet = useCallback(
    (tweetId: string, text: string) =>
      twitterClient.reply(tweetId, {
        cookie: account.cookie,
        text,
      }),
    [account.cookie],
  );

  const handleOpenAuthor = useCallback(
    (author: Tweet["author"]) => {
      if (!author?.id) return;
      pushView({
        type: "user",
        userId: author.id,
        username: author.username,
        title: author.name || `@${author.username}`,
      });
    },
    [pushView],
  );

  const handleOpenThread = useCallback(
    (tweet: Tweet) => {
      pushView({
        type: "thread",
        tweetId: tweet.id,
        title: `Thread · ${tweet.author.name}`,
      });
    },
    [pushView],
  );

  const breadcrumbs = useMemo(
    () => viewStack.map((view) => labelForView(view)).join(" / "),
    [viewStack],
  );

  return (
    <article className="column">
      <header>
        <div>
          <p className="eyebrow">{descriptor.badge}</p>
          <h3>{descriptor.label}</h3>
          <p className="muted tiny">
            {descriptor.description} · {account.label}
          </p>
          {viewStack.length > 1 && <p className="muted tiny">{breadcrumbs}</p>}
        </div>
        <div className="column-actions">
          <button
            className="ghost"
            onClick={handleMaximize}
            aria-label="Maximize column"
          >
            ⤢
          </button>
          {canGoBack && (
            <button className="ghost" onClick={popView} aria-label="Go back">
              ←
            </button>
          )}
          <button
            className="ghost"
            onClick={refresh}
            aria-label="Refresh column"
          >
            ↻
          </button>
          <button
            className="ghost"
            onClick={onRemove}
            aria-label="Remove column"
          >
            ×
          </button>
        </div>
      </header>
      <div
        className={`column-content ${transitionDirection ? `slide-${transitionDirection}` : ""}`}
        onAnimationEnd={handleAnimationEnd}
      >
        {error && <p className="error">{error}</p>}
        {state.isLoading && !state.tweets.length ? (
          <div className="column-loading">Loading…</div>
        ) : (
          <div className="tweet-stack">
            {state.tweets
              .filter((t) => t.language === "th")
              .slice(0, 10)
              .map((tweet) => (
                <TweetCard
                  key={tweet.id}
                  tweet={tweet}
                  accent={account.accent}
                  allowBookmarkRemoval={column.kind === "bookmarks"}
                  onRemoveBookmark={handleRemoveBookmark}
                  onToggleLike={likeTweet}
                  onToggleRetweet={retweet}
                  onToggleBookmark={bookmarkTweet}
                  onReply={replyToTweet}
                  onOpenAuthor={handleOpenAuthor}
                  onOpenThread={handleOpenThread}
                />
              ))}
            {!state.tweets.length && !state.isLoading && (
              <p className="muted">No tweets yet. Try refreshing.</p>
            )}
            {state.cursorBottom ? (
              <div className="load-more-row">
                <button
                  className="ghost"
                  disabled={state.isAppending}
                  onClick={loadMore}
                >
                  {state.isAppending ? "Loading…" : "Load more"}
                </button>
              </div>
            ) : (
              state.tweets.length > 0 && (
                <div className="load-more-row">
                  <p className="muted">End of feed</p>
                </div>
              )
            )}
          </div>
        )}
      </div>
    </article>
  );
}

function createBaseView(column: TimelineConfig): TimelineView {
  return {
    type: "timeline",
    mode: column.kind,
    title: column.title || describeTimeline(column.kind).label,
    listId: column.listId,
    listName: column.listName,
  };
}

function labelForView(view: ColumnView): string {
  if (view.type === "timeline") {
    return view.title || describeTimeline(view.mode).label;
  }
  if (view.type === "user") {
    return view.title || `@${view.username}`;
  }
  return view.title || "Thread";
}

function describeView(column: TimelineConfig, view: ColumnView) {
  if (view.type === "timeline") {
    const base = describeTimeline(view.mode);
    if (view.mode === "list" && view.listName) {
      return {
        ...base,
        label: view.title || view.listName,
        description: `Tweets from ${view.listName}`,
      };
    }
    return {
      ...base,
      label: view.title || base.label,
    };
  }
  if (view.type === "user") {
    return {
      label: view.title || `@${view.username}`,
      badge: "Profile",
      description: `Posts from @${view.username}`,
    };
  }
  return {
    label: view.title || "Thread",
    badge: "Thread",
    description: "Deep dive into the conversation",
  };
}

function describeTimeline(kind: TimelineConfig["kind"]) {
  switch (kind) {
    case "following":
      return {
        label: "Following",
        badge: "Chrono",
        description: "Latest posts from people you follow",
      };
    case "bookmarks":
      return {
        label: "Bookmarks",
        badge: "Library",
        description: "Saved gems queued for later",
      };
    case "list":
      return {
        label: "List",
        badge: "Curated",
        description: "Tweets from a Twitter List",
      };
    default:
      return {
        label: "For You",
        badge: "Ranked",
        description: "AI-ranked home timeline",
      };
  }
}