import { useMemo, useState } from 'react';
import { ChevronDown, ClipboardCheck } from 'lucide-react';

import type { DirectorAcknowledgmentDocumentRow } from '@/business/director-dashboard/types';
import { cn } from '@/lib/utils';

interface DirectorAcknowledgmentTrackingPanelProps {
  readonly documents: readonly DirectorAcknowledgmentDocumentRow[];
}

export function DirectorAcknowledgmentTrackingPanel({
  documents,
}: DirectorAcknowledgmentTrackingPanelProps) {
  const [isPanelExpanded, setIsPanelExpanded] = useState(false);
  const [expandedDocumentIds, setExpandedDocumentIds] = useState<ReadonlySet<string>>(
    () => new Set(),
  );
  const groupedDocuments = useMemo(() => groupDocumentsByCategory(documents), [documents]);
  const missingAcknowledgmentCount = documents.reduce(
    (total, document) => total + document.missingCount,
    0,
  );

  function toggleDocument(documentId: string) {
    setExpandedDocumentIds((current) => {
      const next = new Set(current);
      if (next.has(documentId)) {
        next.delete(documentId);
      } else {
        next.add(documentId);
      }
      return next;
    });
  }

  return (
    <section className="rounded-2xl border border-violet-100 bg-white p-5 text-gray-900 shadow-sm">
      <button
        type="button"
        onClick={() => setIsPanelExpanded((current) => !current)}
        className="mb-4 flex w-full items-center justify-between gap-4 text-left focus-visible:outline-none focus-visible:ring-2 focus-visible:ring-violet-400 focus-visible:ring-offset-2"
        aria-expanded={isPanelExpanded}
        aria-controls="director-acknowledgment-results-panel"
      >
        <span>
          <span className="flex items-center gap-2 font-semibold text-gray-800">
            <ClipboardCheck size={18} className="text-emerald-600" />
            Document Acknowledgments
          </span>
          <span className="mt-1 block text-sm text-gray-500">
            {documents.length} documents · {missingAcknowledgmentCount} missing acknowledgments
          </span>
        </span>
        <ChevronDown
          size={20}
          className={cn('shrink-0 text-gray-400 transition-transform', isPanelExpanded && 'rotate-180')}
          aria-hidden="true"
        />
      </button>

      <div id="director-acknowledgment-results-panel">
        {isPanelExpanded && groupedDocuments.length === 0 ? (
          <p className="rounded-xl bg-gray-50 px-4 py-3 text-sm text-gray-500">
            No active documents are assigned to this scope yet.
          </p>
        ) : isPanelExpanded ? (
          <div className="space-y-5">
            {groupedDocuments.map((group) => (
              <div key={group.category} className="space-y-2">
                <p className="text-xs font-bold uppercase text-gray-500">
                  {group.label}
                </p>
                <div className="overflow-hidden rounded-xl border border-gray-100">
                  {group.documents.map((document, index) => {
                    const isExpanded = expandedDocumentIds.has(document.id);
                    return (
                      <div
                        key={document.id}
                        className={index > 0 ? 'border-t border-gray-100' : undefined}
                      >
                        <button
                          type="button"
                          onClick={() => toggleDocument(document.id)}
                          className="flex w-full items-center justify-between gap-4 bg-white px-4 py-3 text-left transition-transform hover:scale-[1.005] focus-visible:outline-none focus-visible:ring-2 focus-visible:ring-violet-400 focus-visible:ring-offset-2"
                          aria-expanded={isExpanded}
                          aria-controls={`acknowledgment-${document.id}`}
                        >
                          <span className="min-w-0">
                            <span className="block truncate text-sm font-semibold text-gray-800">
                              {document.title}
                            </span>
                            <span className="mt-1 block text-xs text-gray-500">
                              Version {document.version}
                            </span>
                          </span>
                          <span className="flex shrink-0 items-center gap-3">
                            <span className={getStatusClassName(document.missingCount)}>
                              {document.acknowledgedCount}/{document.totalStaff}
                            </span>
                            <ChevronDown
                              size={18}
                              className={cn('text-gray-400 transition-transform', isExpanded && 'rotate-180')}
                              aria-hidden="true"
                            />
                          </span>
                        </button>
                        {isExpanded && (
                          <div
                            id={`acknowledgment-${document.id}`}
                            className="bg-gray-50 px-4 py-3"
                          >
                            {document.missingStaff.length === 0 ? (
                              <p className="text-sm text-emerald-700">
                                Every staff member in scope has acknowledged this version.
                              </p>
                            ) : (
                              <div className="space-y-2">
                                <p className="text-xs font-semibold uppercase text-gray-500">
                                  Not acknowledged
                                </p>
                                {document.missingStaff.map((staff) => (
                                  <div
                                    key={`${document.id}-${staff.userId}`}
                                    className="flex flex-wrap items-center justify-between gap-2 rounded-lg bg-white px-3 py-2 text-sm"
                                  >
                                    <span className="font-medium text-gray-800">{staff.name}</span>
                                    <span className="text-xs capitalize text-gray-500">
                                      {staff.role}
                                    </span>
                                  </div>
                                ))}
                              </div>
                            )}
                          </div>
                        )}
                      </div>
                    );
                  })}
                </div>
              </div>
            ))}
          </div>
        ) : (
          <p className="rounded-xl bg-gray-50 px-4 py-3 text-sm text-gray-500">
            Expand to review document acknowledgment status by category.
          </p>
        )}
      </div>
    </section>
  );
}

function groupDocumentsByCategory(
  documents: readonly DirectorAcknowledgmentDocumentRow[],
): readonly {
  readonly category: string;
  readonly label: string;
  readonly documents: readonly DirectorAcknowledgmentDocumentRow[];
}[] {
  const groups = new Map<string, DirectorAcknowledgmentDocumentRow[]>();
  const labels = new Map<string, string>();
  for (const document of documents) {
    const rows = groups.get(document.category) ?? [];
    rows.push(document);
    groups.set(document.category, rows);
    labels.set(document.category, document.categoryLabel);
  }
  return [...groups.entries()].map(([category, rows]) => ({
    category,
    label: labels.get(category) ?? category,
    documents: rows,
  }));
}

function getStatusClassName(missingCount: number): string {
  return missingCount > 0
    ? 'rounded-lg bg-amber-100 px-2.5 py-1 text-xs font-semibold text-amber-700'
    : 'rounded-lg bg-emerald-100 px-2.5 py-1 text-xs font-semibold text-emerald-700';
}
