import { useEffect, useRef, useState } from 'react';

import { Link, useOutletContext, useParams } from 'react-router-dom';
import type { StoredMessage } from 'tinode-sdk';
import { Drafty } from 'tinode-sdk';

import { Icon } from '@/app/Icon';
import { EmojiPanel } from '@/features/messages/EmojiPanel';
import { ForwardPickerModal } from '@/features/messages/ForwardPickerModal';
import { MessageContextMenu } from '@/features/messages/MessageContextMenu';
import { MessageRow } from '@/features/messages/MessageBubble';
import { VoiceRecorder } from '@/features/messages/VoiceRecorder';
import { useBootstrap } from '@/lib/api/hooks';
import { favoriteMessages, recallMessage } from '@/lib/api/messages';
import { avatarBgClass, avatarLetter } from '@/lib/avatar';
import { FETCH_PAGE_TRIGGER, MESSAGES_PAGE } from '@/lib/config';
import { availableActions, type MessageAction } from '@/lib/messages/actions';
import { renderDrafty } from '@/lib/messages/drafty';
import { sendFile, sendImage, sendVoice } from '@/lib/tinode/attachments';
import { useChatList, useTinode, useTopicMessages } from '@/lib/tinode/hooks';
import { forwardMessage, sendReply, sendText } from '@/lib/tinode/send';
import { closeConversation, openConversation } from '@/lib/tinode/topics';
import { useSessionStore } from '@/stores/session';

interface OutletCtx {
  onToggleDetail: () => void;
  /** Whether the detail panel is CURRENTLY shown -- true always at >=1280px (docked, no close
   *  affordance), true/false at 960-1279px depending on the drawer's open state. Drives the header
   *  "i" button's highlight; previously hardcoded to the breakpoint itself (always blue at
   *  960-1279px regardless of the drawer's real state, always grey at >=1280px despite the panel
   *  being permanently open there) rather than this actual state. */
  detailVisible: boolean;
}

interface ContextMenuState {
  x: number;
  y: number;
  msg: StoredMessage;
}

export function ConversationView() {
  const { topicId } = useParams();
  const { onToggleDetail, detailVisible } = useOutletContext<OutletCtx>();
  const myUserId = useSessionStore((s) => s.myUserId);
  const tinode = useTinode();
  const contacts = useChatList();
  const contact = contacts.find((c) => c.topic === topicId);
  const messages = useTopicMessages(topicId);
  const bootstrap = useBootstrap();
  // Keyed by topicId, not a single string -- ConversationView is one long-lived instance reused
  // across every conversation (the route is `:topicId`, React Router doesn't remount on param
  // change), so a plain single draft leaks the PREVIOUS conversation's unsent text into whichever
  // one you open next.
  const [draftByTopic, setDraftByTopic] = useState<Record<string, string>>({});
  const draft = (topicId && draftByTopic[topicId]) || '';
  const setDraft = (value: string) => {
    if (topicId) setDraftByTopic((prev) => ({ ...prev, [topicId]: value }));
  };
  const [menu, setMenu] = useState<ContextMenuState | null>(null);
  const [selectMode, setSelectMode] = useState(false);
  const [selectedSeqs, setSelectedSeqs] = useState<Set<number>>(new Set());
  const [loadingOlder, setLoadingOlder] = useState(false);
  const [recording, setRecording] = useState(false);
  const [bulkForwardOpen, setBulkForwardOpen] = useState(false);
  const [replyTo, setReplyTo] = useState<StoredMessage | null>(null);
  const [forwardMsg, setForwardMsg] = useState<StoredMessage | null>(null);
  const [emojiOpen, setEmojiOpen] = useState(false);
  const streamRef = useRef<HTMLDivElement>(null);
  const autoScrollRef = useRef(true);

  useEffect(() => {
    if (!topicId) return undefined;
    openConversation(topicId).catch(() => {});
    return () => closeConversation(topicId);
  }, [topicId]);

  useEffect(() => {
    setSelectMode(false);
    setSelectedSeqs(new Set());
    setMenu(null);
    setReplyTo(null);
    setForwardMsg(null);
    setBulkForwardOpen(false);
    setEmojiOpen(false);
    // Unmounting VoiceRecorder stops its media stream via its own cleanup effect -- without this,
    // a recording started in conversation A silently keeps going after navigating to B, and its
    // onSend callback (re-created every render off the CURRENT topicId) would publish the eventual
    // recording into B instead of the conversation the user was actually recording in.
    setRecording(false);
  }, [topicId]);

  useEffect(() => {
    if (autoScrollRef.current) {
      streamRef.current?.scrollTo({ top: streamRef.current.scrollHeight });
    }
  }, [messages.length]);

  useEffect(() => {
    if (!topicId || messages.length === 0) return;
    tinode.getTopic(topicId).noteRead(0);
  }, [topicId, messages.length, tinode]);

  if (!topicId) return null;
  const topic = tinode.getTopic(topicId);
  const peerName = contact?.public?.fn || topicId;
  const isGroup = topic.isGroupType();

  /**
   * "加载更多" (README §3.2/old app's messages-view.jsx): not simple since/before paging -- computes
   * which seq ranges are actually missing from the local cache within the currently-visible window
   * (topic.msgHasMoreMessages) and fills exactly those gaps (topic.getMessagesPage), since messages
   * can have server-side deletions punching holes in an otherwise-contiguous range.
   */
  const loadOlder = async () => {
    if (loadingOlder) return;
    const el = streamRef.current;
    const min = topic.minMsgSeq();
    const max = topic.maxMsgSeq();
    const gaps = topic.msgHasMoreMessages(min, max, false);
    if (gaps.length === 0) return;
    setLoadingOlder(true);
    const prevHeight = el?.scrollHeight ?? 0;
    const prevTop = el?.scrollTop ?? 0;
    try {
      await topic.getMessagesPage(MESSAGES_PAGE, gaps, min, max);
    } finally {
      setLoadingOlder(false);
      requestAnimationFrame(() => {
        if (el) el.scrollTop = prevTop + (el.scrollHeight - prevHeight);
      });
    }
  };

  const handleScroll = () => {
    const el = streamRef.current;
    if (!el) return;
    autoScrollRef.current = el.scrollHeight - el.scrollTop - el.clientHeight < 80;
    if (el.scrollTop <= FETCH_PAGE_TRIGGER) {
      loadOlder();
    }
  };

  const submit = () => {
    const text = draft.trim();
    if (!text) return;
    setDraft('');
    if (replyTo) {
      const label = myUserId && replyTo.from === myUserId ? '我' : peerName;
      sendReply(topic, text, replyTo, label);
      setReplyTo(null);
    } else {
      sendText(topic, text);
    }
  };

  const handleKeyDown = (e: React.KeyboardEvent<HTMLTextAreaElement>) => {
    if (e.key !== 'Enter' || e.shiftKey) return;
    // Guards against CJK IME candidate-selection Enter keystrokes being mistaken for submit --
    // a real, unfixed bug class in the old app (confirmed by its own research: zero isComposing/
    // compositionstart/keyCode-229 guards anywhere in that codebase).
    if (e.nativeEvent.isComposing) return;
    e.preventDefault();
    submit();
  };

  const toggleSelect = (seq: number) => {
    setSelectedSeqs((prev) => {
      const next = new Set(prev);
      if (next.has(seq)) next.delete(seq);
      else next.add(seq);
      return next;
    });
  };

  const exitSelectMode = () => {
    setSelectMode(false);
    setSelectedSeqs(new Set());
  };

  const bulkDelete = () => {
    if (selectedSeqs.size === 0) return;
    if (!window.confirm(`删除已选择的 ${selectedSeqs.size} 条消息？`)) return;
    topic.delMessagesList([...selectedSeqs], false);
    exitSelectMode();
  };

  const bulkFavorite = () => {
    if (selectedSeqs.size === 0) return;
    favoriteMessages([...selectedSeqs].map((seq) => ({ topic: topicId, seq }))).catch(() => {});
    exitSelectMode();
  };

  const bulkForward = (targetTopic: string) => {
    const target = tinode.getTopic(targetTopic);
    for (const seq of selectedSeqs) {
      const msg = topic.findMessage(seq);
      if (msg) forwardMessage(topicId, msg, target);
    }
    setBulkForwardOpen(false);
    exitSelectMode();
  };

  const handleAction = (action: MessageAction) => {
    const msg = menu?.msg;
    setMenu(null);
    if (!msg || typeof msg.seq !== 'number') return;
    switch (action) {
      case 'copy':
        navigator.clipboard.writeText(Drafty.toPlainText(msg.content ?? '')).catch(() => {});
        break;
      case 'recall':
        recallMessage(topicId, msg.seq)
          .then(() => topic.delMessagesList([msg.seq], true))
          .catch(() => {});
        break;
      case 'delete':
        topic.delMessagesList([msg.seq], false);
        break;
      case 'select':
        setSelectMode(true);
        setSelectedSeqs(new Set([msg.seq]));
        break;
      case 'quote':
        setReplyTo(msg);
        break;
      case 'favorite':
        favoriteMessages([{ topic: topicId, seq: msg.seq }]).catch(() => {});
        break;
      case 'forward':
        setForwardMsg(msg);
        break;
    }
  };

  const handlePickImage = (e: React.ChangeEvent<HTMLInputElement>) => {
    const file = e.target.files?.[0];
    e.target.value = '';
    if (file) sendImage(topic, file).catch(() => {});
  };

  const handlePickFile = (e: React.ChangeEvent<HTMLInputElement>) => {
    const file = e.target.files?.[0];
    e.target.value = '';
    if (file) sendFile(topic, file).catch(() => {});
  };

  return (
    <div className="flex h-full w-full flex-col bg-surface-chat">
      <header className="flex h-15 flex-none items-center justify-between border-b border-border-panel bg-white px-5">
        {selectMode ? (
          <>
            <span className="text-[15px] font-medium text-text-heading">已选择 {selectedSeqs.size} 条消息</span>
            <button type="button" onClick={exitSelectMode} className="text-sm text-accent">
              取消
            </button>
          </>
        ) : (
          <>
            <div className="flex items-center gap-2.5">
              <Link to="/messages" className="grid h-9.5 w-9.5 flex-none place-items-center text-text-heading md:hidden">
                <Icon name="arrow_back_ios_new" />
              </Link>
              <span
                className={`grid h-9.5 w-9.5 flex-none place-items-center rounded-lg text-sm font-medium text-white ${avatarBgClass(topicId)}`}
              >
                {avatarLetter(peerName)}
              </span>
              <div className="flex flex-col">
                <strong className="text-base font-semibold text-text-heading">{peerName}</strong>
                <span className={`text-xs ${contact?.online ? 'text-online' : 'text-text-tertiary-2'}`}>
                  {contact?.online ? '在线' : '离线'}
                </span>
              </div>
            </div>
            <div className="flex items-center gap-1">
              <button type="button" className="grid h-9.5 w-9.5 place-items-center rounded-lg text-text-tertiary-1">
                <Icon name="call" />
              </button>
              <button type="button" className="grid h-9.5 w-9.5 place-items-center rounded-lg text-text-tertiary-1">
                <Icon name="videocam" />
              </button>
              <button type="button" className="grid h-9.5 w-9.5 place-items-center rounded-lg text-text-tertiary-1">
                <Icon name="search" />
              </button>
              <button
                type="button"
                onClick={onToggleDetail}
                className={`grid h-9.5 w-9.5 place-items-center rounded-lg ${detailVisible ? 'bg-accent-soft-bg text-accent' : 'text-text-tertiary-1'}`}
              >
                <Icon name="info" />
              </button>
            </div>
          </>
        )}
      </header>

      <div ref={streamRef} onScroll={handleScroll} className="flex flex-1 flex-col gap-4 overflow-y-auto px-7 py-5">
        {loadingOlder ? <div className="py-2 text-center text-xs text-text-tertiary-4">加载中…</div> : null}
        {messages.map((msg) => (
          <MessageRow
            key={msg.seq}
            topic={topic}
            msg={msg}
            mine={!!myUserId && msg.from === myUserId}
            isGroup={isGroup}
            peerName={peerName}
            myUserId={myUserId}
            selectMode={selectMode}
            selected={typeof msg.seq === 'number' && selectedSeqs.has(msg.seq)}
            menuActive={typeof msg.seq === 'number' && menu?.msg.seq === msg.seq}
            onToggleSelect={toggleSelect}
            onContextMenu={(e, m) => setMenu({ x: e.clientX, y: e.clientY, msg: m })}
          />
        ))}
      </div>

      {selectMode ? (
        <div className="flex h-18 flex-none items-center justify-around border-t border-border-panel bg-white">
          <button
            type="button"
            onClick={() => setBulkForwardOpen(true)}
            disabled={selectedSeqs.size === 0}
            className="flex flex-col items-center gap-1 text-text-secondary disabled:opacity-40"
          >
            <Icon name="reply" className="text-[22px]" />
            <span className="text-xs">转发</span>
          </button>
          <button
            type="button"
            onClick={bulkFavorite}
            disabled={selectedSeqs.size === 0}
            className="flex flex-col items-center gap-1 text-text-secondary disabled:opacity-40"
          >
            <Icon name="inventory_2" className="text-[22px]" />
            <span className="text-xs">收藏</span>
          </button>
          <button type="button" onClick={bulkDelete} className="flex flex-col items-center gap-1 text-danger-text">
            <Icon name="delete_outline" className="text-[22px]" />
            <span className="text-xs">删除</span>
          </button>
        </div>
      ) : (
        <div className="flex-none border-t border-border-panel bg-white px-4 pb-3 pt-2">
          {replyTo ? (
            <div className="mb-2 flex items-center justify-between rounded-lg bg-surface-input px-3 py-1.5 text-xs text-text-tertiary-1">
              <span className="truncate">
                回复 {myUserId && replyTo.from === myUserId ? '我' : peerName}：{renderDrafty(replyTo.content)}
              </span>
              <button type="button" onClick={() => setReplyTo(null)} className="flex-none text-text-tertiary-3">
                <Icon name="close" className="text-[16px]" />
              </button>
            </div>
          ) : null}
          <div className="relative flex items-center gap-1 px-1 pb-1">
            <button
              type="button"
              onClick={() => setEmojiOpen((v) => !v)}
              className={`grid h-8.5 w-8.5 place-items-center rounded text-[22px] ${emojiOpen ? 'bg-accent-soft-bg text-accent' : 'text-icon-default'}`}
            >
              <Icon name="sentiment_satisfied_alt" />
            </button>
            {emojiOpen ? (
              <div className="absolute bottom-full left-0 z-20 mb-2">
                <EmojiPanel
                  onPick={(emoji) => {
                    setDraft(draft + emoji);
                    setEmojiOpen(false);
                  }}
                />
              </div>
            ) : null}
            <label className="grid h-8.5 w-8.5 cursor-pointer place-items-center rounded text-[22px] text-icon-default">
              <Icon name="image" />
              <input type="file" accept="image/*" onChange={handlePickImage} className="hidden" />
            </label>
            <label className="grid h-8.5 w-8.5 cursor-pointer place-items-center rounded text-[22px] text-icon-default">
              <Icon name="attach_file" />
              <input type="file" onChange={handlePickFile} className="hidden" />
            </label>
            <Icon name="contact_page" className="grid h-8.5 w-8.5 place-items-center rounded text-[22px] text-icon-default" />
            <button
              type="button"
              onClick={() => setRecording(true)}
              className="grid h-8.5 w-8.5 place-items-center rounded text-[22px] text-icon-default"
            >
              <Icon name="mic_none" />
            </button>
            <Icon name="history" className="grid h-8.5 w-8.5 place-items-center rounded text-[22px] text-icon-default" />
          </div>
          {recording ? (
            <VoiceRecorder
              onCancel={() => setRecording(false)}
              onSend={(blob, durationMs) => {
                setRecording(false);
                sendVoice(topic, blob, durationMs).catch(() => {});
              }}
            />
          ) : (
            <>
              <textarea
                value={draft}
                onChange={(e) => setDraft(e.target.value)}
                onKeyDown={handleKeyDown}
                placeholder="输入消息，Enter 发送，Shift+Enter 换行"
                className="min-h-[72px] w-full resize-none bg-transparent text-[15px] leading-normal outline-none placeholder:text-text-placeholder-1"
              />
              <div className="flex justify-end">
                <button
                  type="button"
                  onClick={submit}
                  disabled={!draft.trim()}
                  className="h-9 rounded-lg bg-btn px-5.5 text-sm font-medium text-white shadow-btn disabled:bg-btn-disabled disabled:shadow-none"
                >
                  发送
                </button>
              </div>
            </>
          )}
        </div>
      )}

      {menu ? (
        <MessageContextMenu
          x={menu.x}
          y={menu.y}
          actions={availableActions(menu.msg, myUserId, bootstrap.data?.message_policy)}
          onAction={handleAction}
          onClose={() => setMenu(null)}
        />
      ) : null}

      {forwardMsg ? (
        <ForwardPickerModal
          onClose={() => setForwardMsg(null)}
          onPick={(targetTopic) => {
            forwardMessage(topicId, forwardMsg, tinode.getTopic(targetTopic));
            setForwardMsg(null);
          }}
        />
      ) : null}

      {bulkForwardOpen ? <ForwardPickerModal onClose={() => setBulkForwardOpen(false)} onPick={bulkForward} /> : null}
    </div>
  );
}