import { useEffect, useRef } from 'react';

import { FileIcon } from '@renderer/components/team/editor/FileIcon';
import { getTeamColorSet } from '@renderer/constants/teamColors';
import { nameColorSet } from '@renderer/utils/projectColor';
import { Loader2, UsersRound } from 'lucide-react';

import type { MentionSuggestion } from '@renderer/types/mention';

interface MentionSuggestionListProps {
  suggestions: MentionSuggestion[];
  selectedIndex: number;
  onSelect: (s: MentionSuggestion) => void;
  query: string;
  /** When true, adjusts empty state text to mention files */
  hasFileSearch?: boolean;
  /** When true, shows a loading spinner for file search */
  filesLoading?: boolean;
}

const HighlightedName = ({ name, query }: { name: string; query: string }): React.JSX.Element => {
  if (!query) return <span>{name}</span>;

  const lower = name.toLowerCase();
  const qLower = query.toLowerCase();
  const idx = lower.indexOf(qLower);

  if (idx < 0) return <span>{name}</span>;

  const before = name.slice(0, idx);
  const match = name.slice(idx, idx + query.length);
  const after = name.slice(idx + query.length);

  return (
    <span>
      {before}
      <span className="bg-[var(--color-accent)]/25 rounded text-[var(--color-text)]">{match}</span>
      {after}
    </span>
  );
};

/** Section header for grouped suggestion lists */
const SectionHeader = ({ label }: { label: string }): React.JSX.Element => (
  <li className="px-3 pb-0.5 pt-1.5 text-[10px] uppercase tracking-wider text-[var(--color-text-muted)]">
    {label}
  </li>
);

export const MentionSuggestionList = ({
  suggestions,
  selectedIndex,
  onSelect,
  query,
  hasFileSearch,
  filesLoading,
}: MentionSuggestionListProps): React.JSX.Element => {
  const listRef = useRef<HTMLUListElement>(null);

  useEffect(() => {
    const list = listRef.current;
    if (!list) return;
    // Query by role=option to skip section headers
    const options = list.querySelectorAll('[role="option"]');
    const selected = options[selectedIndex] as HTMLElement | undefined;
    selected?.scrollIntoView({ block: 'nearest' });
  }, [selectedIndex]);

  if (suggestions.length === 0) {
    return (
      <div className="rounded-md border border-[var(--color-border)] bg-[var(--color-surface-overlay)] px-3 py-2 text-xs text-[var(--color-text-muted)]">
        {hasFileSearch ? 'No matching members, teams, or files' : 'No matching members'}
      </div>
    );
  }

  // Categorize suggestions
  type Section = 'member' | 'team' | 'file';
  const getSuggestionSection = (s: MentionSuggestion): Section => {
    if (s.type === 'file') return 'file';
    if (s.type === 'team') return 'team';
    return 'member';
  };

  const sectionLabel: Record<Section, string> = {
    member: 'Members',
    team: 'Teams',
    file: 'Files',
  };

  // Determine which sections are present
  const presentSections = new Set(suggestions.map(getSuggestionSection));
  const showSections = presentSections.size > 1;

  // Build items with section headers inserted
  const items: React.JSX.Element[] = [];
  let currentSection: Section | null = null;
  let optionIndex = 0;

  for (const s of suggestions) {
    const section = getSuggestionSection(s);
    const isFile = section === 'file';
    const isTeam = section === 'team';

    // Insert section header on transition
    if (showSections && section !== currentSection) {
      items.push(<SectionHeader key={`section-${section}`} label={sectionLabel[section]} />);
      currentSection = section;
    }

    const isSelected = optionIndex === selectedIndex;
    const colorSet = isFile
      ? null
      : s.color
        ? getTeamColorSet(s.color)
        : isTeam
          ? nameColorSet(s.name)
          : null;
    const idx = optionIndex;
    optionIndex++;

    items.push(
      <li
        key={s.id}
        role="option"
        aria-selected={isSelected}
        data-index={idx}
        className={`flex cursor-pointer items-center gap-2 rounded-sm px-3 py-1.5 text-xs transition-colors ${
          isSelected
            ? 'bg-[var(--color-accent)]/15 ring-[var(--color-accent)]/30 text-[var(--color-text)] ring-1 ring-inset'
            : 'text-[var(--color-text-secondary)] hover:bg-[var(--color-surface-raised)]'
        }`}
        onMouseDown={(e) => {
          e.preventDefault();
          onSelect(s);
        }}
      >
        {isFile ? (
          <FileIcon fileName={s.name} className="size-3.5" />
        ) : isTeam ? (
          <UsersRound
            size={13}
            className="shrink-0"
            style={{ color: colorSet?.text ?? 'var(--color-text-muted)' }}
          />
        ) : (
          <span
            className="inline-block size-2.5 shrink-0 rounded-full"
            style={{ backgroundColor: colorSet?.border ?? 'var(--color-text-muted)' }}
          />
        )}
        <span
          className={isFile ? 'truncate' : 'font-medium'}
          style={colorSet ? { color: colorSet.text } : undefined}
        >
          <HighlightedName name={s.name} query={query} />
        </span>
        {isTeam && s.isOnline !== undefined ? (
          <span
            className="inline-block size-1.5 shrink-0 rounded-full"
            style={{ backgroundColor: s.isOnline ? '#22c55e' : '#71717a' }}
            title={s.isOnline ? 'Online' : 'Offline'}
          />
        ) : null}
        {s.subtitle ? (
          <span className="truncate text-[var(--color-text-muted)]">{s.subtitle}</span>
        ) : null}
      </li>
    );
  }

  return (
    <ul
      ref={listRef}
      role="listbox"
      className="max-h-48 overflow-y-auto rounded-md border border-[var(--color-border)] bg-[var(--color-surface-overlay)] py-1"
    >
      {items}
      {filesLoading ? (
        <li className="flex items-center gap-2 px-3 py-1.5 text-[10px] text-[var(--color-text-muted)]">
          <Loader2 size={10} className="shrink-0 animate-spin" />
          <span>Searching files...</span>
        </li>
      ) : null}
    </ul>
  );
};