import { useCallback, useMemo, useState } from 'react';

import { MarkdownViewer } from '@renderer/components/chat/viewers/MarkdownViewer';
import { ReplyQuoteBlock } from '@renderer/components/team/activity/ReplyQuoteBlock';
import { MentionableTextarea } from '@renderer/components/ui/MentionableTextarea';
import { Tooltip, TooltipContent, TooltipTrigger } from '@renderer/components/ui/tooltip';
import { useDraftPersistence } from '@renderer/hooks/useDraftPersistence';
import { useMarkCommentsRead } from '@renderer/hooks/useMarkCommentsRead';
import { useStore } from '@renderer/store';
import { buildReplyBlock, parseMessageReply } from '@renderer/utils/agentMessageFormatting';
import { formatAgentRole } from '@renderer/utils/formatAgentRole';
import { getModifierKeyName } from '@renderer/utils/keyboardUtils';
import { formatDistanceToNow } from 'date-fns';
import { ChevronDown, ChevronUp, MessageSquare, Reply, Send, X } from 'lucide-react';

import type { MentionSuggestion } from '@renderer/types/mention';
import type { ResolvedTeamMember, TaskComment } from '@shared/types';

const MAX_COMMENT_LENGTH = 2000;

interface TaskCommentsSectionProps {
  teamName: string;
  taskId: string;
  comments: TaskComment[];
  members: ResolvedTeamMember[];
}

export const TaskCommentsSection = ({
  teamName,
  taskId,
  comments,
  members,
}: TaskCommentsSectionProps): React.JSX.Element => {
  const addTaskComment = useStore((s) => s.addTaskComment);
  const addingComment = useStore((s) => s.addingComment);
  const commentsRef = useMarkCommentsRead(teamName, taskId, comments);

  const [replyTo, setReplyTo] = useState<{ author: string; text: string } | null>(null);
  const [expandedCommentIds, setExpandedCommentIds] = useState<Set<string>>(new Set());

  const toggleCommentExpanded = useCallback((commentId: string) => {
    setExpandedCommentIds((prev) => {
      const next = new Set(prev);
      if (next.has(commentId)) next.delete(commentId);
      else next.add(commentId);
      return next;
    });
  }, []);

  const draft = useDraftPersistence({ key: `taskComment:${teamName}:${taskId}` });

  const mentionSuggestions = useMemo<MentionSuggestion[]>(
    () =>
      members.map((m) => ({
        id: m.name,
        name: m.name,
        subtitle: formatAgentRole(m.role) ?? formatAgentRole(m.agentType) ?? undefined,
        color: m.color,
      })),
    [members]
  );

  const trimmed = draft.value.trim();
  const remaining = MAX_COMMENT_LENGTH - trimmed.length;
  const canSubmit = trimmed.length > 0 && trimmed.length <= MAX_COMMENT_LENGTH && !addingComment;

  const handleSubmit = useCallback(async () => {
    if (!canSubmit) return;
    try {
      const text = replyTo ? buildReplyBlock(replyTo.author, replyTo.text, trimmed) : trimmed;
      await addTaskComment(teamName, taskId, text);
      draft.clearDraft();
      setReplyTo(null);
    } catch {
      // Error is stored in addCommentError via store
    }
  }, [canSubmit, addTaskComment, teamName, taskId, trimmed, draft, replyTo]);

  return (
    <div ref={commentsRef}>
      <div className="mb-2 flex items-center gap-1.5 text-xs font-medium text-[var(--color-text-muted)]">
        <MessageSquare size={12} />
        Comments
        {comments.length > 0 ? (
          <span className="rounded-full bg-[var(--color-surface-raised)] px-1.5 py-0 text-[10px]">
            {comments.length}
          </span>
        ) : null}
      </div>

      {comments.length > 0 ? (
        <div className="mb-3 space-y-2">
          {comments.map((comment) => (
            <div
              key={comment.id}
              className="group rounded-md border border-[var(--color-border)] bg-[var(--color-surface)] p-2.5"
            >
              <div className="mb-1 flex items-center gap-2 text-[10px] text-[var(--color-text-muted)]">
                <span
                  className="font-medium"
                  style={{
                    color:
                      comment.author === 'user'
                        ? 'var(--color-text-secondary)'
                        : (members.find((m) => m.name === comment.author)?.color ??
                          'var(--color-text-secondary)'),
                  }}
                >
                  {comment.author}
                </span>
                <span>
                  {(() => {
                    const date = new Date(comment.createdAt);
                    return isNaN(date.getTime())
                      ? 'unknown time'
                      : formatDistanceToNow(date, { addSuffix: true });
                  })()}
                </span>
                <button
                  type="button"
                  className="flex items-center gap-0.5 text-[var(--color-text-muted)] opacity-0 transition-opacity hover:text-[var(--color-text-secondary)] group-hover:opacity-100"
                  onClick={() => toggleCommentExpanded(comment.id)}
                  title={expandedCommentIds.has(comment.id) ? 'Свернуть' : 'Развернуть'}
                >
                  {expandedCommentIds.has(comment.id) ? (
                    <ChevronUp size={12} />
                  ) : (
                    <ChevronDown size={12} />
                  )}
                </button>
                <button
                  type="button"
                  className="ml-auto flex items-center gap-0.5 text-[var(--color-text-muted)] opacity-0 transition-opacity hover:text-[var(--color-text-secondary)] group-hover:opacity-100"
                  onClick={() =>
                    setReplyTo({
                      author: comment.author,
                      text: parseMessageReply(comment.text)?.replyText ?? comment.text,
                    })
                  }
                >
                  <Reply size={11} />
                  Reply
                </button>
              </div>
              <div className="text-xs">
                {(() => {
                  const reply = parseMessageReply(comment.text);
                  const expanded = expandedCommentIds.has(comment.id);
                  return reply ? (
                    <ReplyQuoteBlock
                      reply={reply}
                      bodyMaxHeight={expanded ? undefined : 'max-h-56'}
                    />
                  ) : (
                    <MarkdownViewer
                      content={comment.text}
                      maxHeight={expanded ? undefined : 'max-h-[120px]'}
                    />
                  );
                })()}
              </div>
            </div>
          ))}
        </div>
      ) : null}

      {replyTo ? (
        <div className="mb-2 flex items-start gap-2 rounded-md border border-[var(--color-border)] bg-[var(--color-surface-raised)] p-2">
          <div className="min-w-0 flex-1">
            <div className="mb-0.5 text-[10px] font-medium text-[var(--color-text-muted)]">
              Replying to{' '}
              <span
                className="font-semibold"
                style={{
                  color:
                    replyTo.author === 'user'
                      ? 'var(--color-text-secondary)'
                      : (members.find((m) => m.name === replyTo.author)?.color ??
                        'var(--color-text-secondary)'),
                }}
              >
                @{replyTo.author}
              </span>
            </div>
            <div className="line-clamp-3 text-[11px] text-[var(--color-text-muted)]">
              {replyTo.text}
            </div>
          </div>
          <Tooltip>
            <TooltipTrigger asChild>
              <button
                type="button"
                className="shrink-0 rounded p-0.5 text-[var(--color-text-muted)] transition-colors hover:bg-[var(--color-surface)] hover:text-[var(--color-text-secondary)]"
                onClick={() => setReplyTo(null)}
              >
                <X size={12} />
              </button>
            </TooltipTrigger>
            <TooltipContent side="left">Cancel reply</TooltipContent>
          </Tooltip>
        </div>
      ) : null}

      <div className="relative">
        <MentionableTextarea
          id={`task-comment-${taskId}`}
          placeholder={`Add a comment... (${getModifierKeyName()}+Enter to send)`}
          value={draft.value}
          onValueChange={draft.setValue}
          suggestions={mentionSuggestions}
          minRows={2}
          maxRows={8}
          maxLength={MAX_COMMENT_LENGTH}
          disabled={addingComment}
          cornerAction={
            <button
              type="button"
              className="inline-flex shrink-0 items-center gap-1 rounded-full bg-blue-600 px-3 py-1.5 text-[11px] font-medium text-white shadow-sm transition-colors hover:bg-blue-500 disabled:cursor-not-allowed disabled:opacity-50"
              disabled={!canSubmit}
              onClick={() => void handleSubmit()}
            >
              <Send size={12} />
              Comment
            </button>
          }
          footerRight={
            <div className="flex items-center gap-2">
              {remaining < 200 ? (
                <span
                  className={`text-[10px] ${remaining < 100 ? 'text-yellow-400' : 'text-[var(--color-text-muted)]'}`}
                >
                  {remaining} chars left
                </span>
              ) : null}
              {draft.isSaved ? (
                <span className="text-[10px] text-[var(--color-text-muted)]">Draft saved</span>
              ) : null}
            </div>
          }
        />
      </div>
    </div>
  );
};