import React, { useState, useMemo } from 'react';
import { ExcelRow, COLUMNS } from '../types';
import { Search, ChevronDown, ChevronUp, X, Edit2, Save } from 'lucide-react';
import { cn } from '../lib/utils';
import { ColumnFilterPopover } from './ColumnFilterPopover';

interface MissingDataViewProps {
  data: ExcelRow[];
  headers: string[];
  onSaveRow: (rowIndex: number, updatedRow: ExcelRow) => void;
  onCaptureState: (message: string) => void;
}

function formatDateValue(val: any): string {
  if (val === null || val === undefined || val === '') return '';
  if (typeof val === 'number') {
    if (val >= 25569 && val <= 60000) {
      const excelEpoch = new Date(1899, 11, 30);
      const date = new Date(excelEpoch.getTime() + val * 86400000);
      return date.toLocaleDateString('en-GB', { day: '2-digit', month: '2-digit', year: 'numeric' });
    }
    return '';
  }
  return String(val);
}

function isEmptyOrEpoch(val: any): boolean {
  if (val === null || val === undefined || val === '') return true;
  if (typeof val === 'number') {
    if (val === 0 || val === 1) return true;
    if (val >= 25569 && val <= 60000) return false;
    return true;
  }
  const s = String(val).trim();
  if (s === '' || s === '0' || s === '1') return true;
  if (s.endsWith('/1900')) return true;
  return false;
}

type TabType = 'missingLaunch';

interface EditingState {
  rowIndex: number;
  classification: string;
  launchDate: string;
  readyToOrder: string;
}

export function MissingDataView({ data, headers, onSaveRow, onCaptureState }: MissingDataViewProps) {
  const [activeTab, setActiveTab] = useState<TabType>('missingLaunch');
  const [search, setSearch] = useState('');
  const [sortCol, setSortCol] = useState<number | null>(null);
  const [sortDesc, setSortDesc] = useState(false);
  const [page, setPage] = useState(1);
  const [editing, setEditing] = useState<EditingState | null>(null);
  const [columnFilters, setColumnFilters] = useState<Record<number, string[]>>({});
  const [openFilter, setOpenFilter] = useState<number | null>(null);
  const pageSize = 100;

  const launchDateCol = useMemo(() =>
    headers.findIndex(h => h.toLowerCase().includes('launch')), [headers]);
  const readyToOrderCol = useMemo(() =>
    headers.findIndex(h => h.toLowerCase().includes('ready')), [headers]);

  const launchHeader = launchDateCol >= 0 ? headers[launchDateCol] : 'Launch Date';
  const readyHeader = readyToOrderCol >= 0 ? headers[readyToOrderCol] : 'Ready to Order';

  const columns = [
    { col: COLUMNS.ARTICLE_NO, label: 'SKU', width: 100 },
    { col: COLUMNS.ARTICLE_NAME, label: 'Name', width: 220 },
    { col: COLUMNS.CLASSIFICATION, label: 'Classification', width: 130 },
    ...(launchDateCol >= 0 ? [{ col: launchDateCol, label: launchHeader, width: 130 }] : []),
    ...(readyToOrderCol >= 0 ? [{ col: readyToOrderCol, label: readyHeader, width: 130 }] : []),
  ];

  const columnUniqueValues = useMemo(() => {
    const cols = columns.map(c => c.col);
    const result: Record<number, Set<string>> = {};
    cols.forEach(col => result[col] = new Set());
    
    data.forEach(row => {
      cols.forEach(col => {
        let val: any = row[col];
        if (col === launchDateCol || col === readyToOrderCol) {
          val = formatDateValue(val) || String(val ?? '');
        } else {
          val = String(val ?? '');
        }
        if (val) result[col].add(val);
      });
    });
    return result;
  }, [data, columns, launchDateCol, readyToOrderCol]);

  const getUniqueValues = (col: number): string[] => {
    const values = columnUniqueValues[col];
    if (!values) return [];
    return Array.from(values).sort() as string[];
  };

  const filteredData = useMemo(() => {
    let result = data.map((row, index) => ({ row, index }));

    if (activeTab === 'missingLaunch') {
      result = result.filter(r => {
        const val = launchDateCol >= 0 ? r.row[launchDateCol] : undefined;
        return isEmptyOrEpoch(val);
      });
    }

    if (search) {
      const s = search.toLowerCase();
      result = result.filter(r =>
        String(r.row[COLUMNS.ARTICLE_NO] || '').toLowerCase().includes(s) ||
        String(r.row[COLUMNS.ARTICLE_NAME] || '').toLowerCase().includes(s)
      );
    }

    (Object.entries(columnFilters) as [string, string[]][]).forEach(([colIdx, filterValues]) => {
      if (!filterValues || filterValues.length === 0) return;
      const colIdxNum = parseInt(colIdx);
      result = result.filter(r => {
        const val: any = r.row[colIdxNum];
        const displayVal = colIdxNum === launchDateCol || colIdxNum === readyToOrderCol
          ? formatDateValue(val) || String(val ?? '')
          : String(val ?? '');
        return filterValues.includes(displayVal);
      });
    });

    if (sortCol !== null) {
      result.sort((a, b) => {
        const valA = a.row[sortCol];
        const valB = b.row[sortCol];
        if (typeof valA === 'number' && typeof valB === 'number') {
          return sortDesc ? valB - valA : valA - valB;
        }
        const sA = String(valA || '');
        const sB = String(valB || '');
        return sortDesc ? sB.localeCompare(sA) : sA.localeCompare(sB);
      });
    }

    return result;
  }, [data, activeTab, search, sortCol, sortDesc, launchDateCol, columnFilters]);

  const paginatedData = useMemo(() => {
    const start = (page - 1) * pageSize;
    return filteredData.slice(start, start + pageSize);
  }, [filteredData, page]);

  const totalPages = Math.ceil(filteredData.length / pageSize);

  const handleSort = (col: number) => {
    if (sortCol === col) setSortDesc(d => !d);
    else { setSortCol(col); setSortDesc(false); }
  };

  const openEdit = (rowIndex: number, row: ExcelRow) => {
    setEditing({
      rowIndex,
      classification: String(row[COLUMNS.CLASSIFICATION] || ''),
      launchDate: launchDateCol >= 0 ? formatDateValue(row[launchDateCol]) || String(row[launchDateCol] ?? '') : '',
      readyToOrder: readyToOrderCol >= 0 ? formatDateValue(row[readyToOrderCol]) || String(row[readyToOrderCol] ?? '') : '',
    });
  };

  const handleSave = () => {
    if (!editing) return;
    const row = data[editing.rowIndex];
    onCaptureState(`Updated product ${row[COLUMNS.ARTICLE_NO]}`);
    const newRow = [...row];
    newRow[COLUMNS.CLASSIFICATION] = editing.classification;
    if (launchDateCol >= 0) newRow[launchDateCol] = editing.launchDate;
    if (readyToOrderCol >= 0) newRow[readyToOrderCol] = editing.readyToOrder;
    onSaveRow(editing.rowIndex, newRow);
    setEditing(null);
  };

  const tabs: { id: TabType; label: string }[] = [
    { id: 'missingLaunch', label: 'Missing Launch Date' },
  ];

  const editingRow = editing ? data[editing.rowIndex] : null;

  return (
    <div className="flex flex-col h-full">
      <div className="flex flex-wrap gap-2 mb-6">
        {tabs.map(tab => (
          <button
            key={tab.id}
            onClick={() => { setActiveTab(tab.id); setPage(1); }}
            className={cn(
              "px-4 py-2 rounded-md text-sm font-medium transition-colors",
              activeTab === tab.id
                ? "bg-indigo-600 text-white shadow-md"
                : "bg-slate-800 text-slate-400 hover:bg-slate-700 hover:text-white"
            )}
          >
            {tab.label}
          </button>
        ))}
      </div>

      <div className="flex flex-wrap gap-4 mb-6 bg-slate-800/50 p-4 rounded-xl border border-slate-700/50">
        <div className="flex-1 min-w-[200px] relative">
          <Search className="absolute left-3 top-1/2 -translate-y-1/2 w-4 h-4 text-slate-500" />
          <input
            type="text"
            placeholder="Search SKU or Name..."
            value={search}
            onChange={e => { setSearch(e.target.value); setPage(1); }}
            className="w-full pl-9 pr-10 py-2 bg-slate-900/50 border border-slate-700 rounded-md text-sm text-white focus:outline-none focus:border-indigo-500 focus:ring-1 focus:ring-indigo-500"
          />
          {search && (
            <button
              onClick={() => { setSearch(''); setPage(1); }}
              className="absolute right-3 top-1/2 -translate-y-1/2 text-slate-400 hover:text-white"
            >
              <X className="w-4 h-4" />
            </button>
          )}
        </div>
        <div className="flex items-center text-xs text-slate-500">
          {filteredData.length} items
        </div>
      </div>

      <div className="flex-1 bg-slate-800 rounded-xl border border-slate-700 shadow-xl overflow-hidden flex flex-col">
        <div className="overflow-x-auto flex-1">
          <table className="w-full text-left text-xs">
            <thead className="bg-slate-900/80 text-slate-400 sticky top-0 z-10">
              <tr>
                {columns.map(({ col, label, width }) => {
                  const selectedFilters = columnFilters[col] || [];
                  const allValues = getUniqueValues(col);
                  const filterCount = selectedFilters.length;
                  return (
                  <th
                    key={col}
                    style={{ width, minWidth: width }}
                    className="px-2 py-2 font-medium border-r border-slate-700/30 relative"
                  >
                    <div
                      className="flex items-center gap-1 cursor-pointer select-none hover:text-white"
                      onClick={() => handleSort(col)}
                    >
                      {label}
                      {sortCol === col && (
                        sortDesc ? <ChevronDown className="w-3 h-3" /> : <ChevronUp className="w-3 h-3" />
                      )}
                    </div>
                    <div className="mt-1 relative">
                      <button
                        onClick={(e) => { e.stopPropagation(); setOpenFilter(openFilter === col ? null : col); }}
                        className={cn(
                          "w-full flex items-center justify-between px-1.5 py-0.5 bg-slate-800 border rounded text-[10px] transition-colors",
                          filterCount > 0 ? "border-indigo-500 text-white" : "border-slate-600 text-slate-400 hover:border-slate-500"
                        )}
                      >
                        <span className="truncate">{filterCount > 0 ? `${filterCount} selected` : 'Filter...'}</span>
                        <ChevronDown className={cn("w-3 h-3 transition-transform", openFilter === col && "rotate-180")} />
                      </button>
                      {openFilter === col && (
                        <ColumnFilterPopover
                          uniqueValues={allValues}
                          selectedValues={selectedFilters}
                          onToggle={(val) => setColumnFilters(prev => {
                            const current = prev[col] || [];
                            if (current.includes(val)) {
                              return { ...prev, [col]: current.filter(v => v !== val) };
                            }
                            return { ...prev, [col]: [...current, val] };
                          })}
                          onSelectAll={(vals) => setColumnFilters(prev => ({ ...prev, [col]: vals }))}
                          onClear={() => { setColumnFilters(prev => { const n = { ...prev }; delete n[col]; return n; }); }}
                          onClose={() => setOpenFilter(null)}
                        />
                      )}
                    </div>
                  </th>
                );})}
                <th className="px-2 py-2 font-medium text-right" style={{ width: 60 }}></th>
              </tr>
            </thead>
            <tbody className="divide-y divide-slate-700/30">
              {paginatedData.map(({ row, index }) => (
                <tr key={index} className="hover:bg-slate-700/20 transition-colors">
                  <td className="px-3 py-2 font-mono text-indigo-400 truncate" style={{ width: 100 }}>
                    {row[COLUMNS.ARTICLE_NO]}
                  </td>
                  <td className="px-3 py-2 font-medium text-slate-200 truncate" style={{ width: 220 }} title={row[COLUMNS.ARTICLE_NAME]}>
                    {row[COLUMNS.ARTICLE_NAME]}
                  </td>
                  <td className="px-3 py-2 truncate" style={{ width: 130 }}>
                    {row[COLUMNS.CLASSIFICATION] && String(row[COLUMNS.CLASSIFICATION]).trim() !== '' ? (
                      <span className={cn(
                        "px-1.5 py-0.5 rounded-[4px] text-[10px] font-bold border",
                        String(row[COLUMNS.CLASSIFICATION]).includes('OOC')
                          ? "bg-amber-500/10 text-amber-500 border-amber-500/20"
                          : "bg-slate-700/50 text-slate-400 border-slate-600/50"
                      )}>
                        {row[COLUMNS.CLASSIFICATION]}
                      </span>
                    ) : (
                      <span className="inline-flex items-center px-1.5 py-0.5 rounded text-[10px] font-medium bg-red-500/10 text-red-400 border border-red-500/20">Empty</span>
                    )}
                  </td>
                  {launchDateCol >= 0 && (
                    <td className="px-3 py-2 truncate font-mono text-slate-300" style={{ width: 130 }}>
                      {isEmptyOrEpoch(row[launchDateCol]) ? (
                        <span className="inline-flex items-center px-1.5 py-0.5 rounded text-[10px] font-medium bg-red-500/10 text-red-400 border border-red-500/20">Empty</span>
                      ) : (
                        formatDateValue(row[launchDateCol]) || String(row[launchDateCol])
                      )}
                    </td>
                  )}
                  {readyToOrderCol >= 0 && (
                    <td className="px-3 py-2 truncate font-mono text-slate-300" style={{ width: 130 }}>
                      {row[readyToOrderCol] !== null && row[readyToOrderCol] !== undefined && row[readyToOrderCol] !== '' ? (
                        formatDateValue(row[readyToOrderCol]) || String(row[readyToOrderCol])
                      ) : (
                        <span className="inline-flex items-center px-1.5 py-0.5 rounded text-[10px] font-medium bg-slate-700/50 text-slate-500 border border-slate-600/50">—</span>
                      )}
                    </td>
                  )}
                  <td className="px-3 py-2 text-right" style={{ width: 60 }}>
                    <button
                      onClick={() => openEdit(index, row)}
                      className="p-1.5 text-slate-500 hover:text-indigo-400 hover:bg-indigo-400/10 rounded transition-colors"
                    >
                      <Edit2 className="w-4 h-4" />
                    </button>
                  </td>
                </tr>
              ))}
              {paginatedData.length === 0 && (
                <tr>
                  <td colSpan={columns.length + 1} className="px-4 py-8 text-center text-slate-500">
                    No items found.
                  </td>
                </tr>
              )}
            </tbody>
          </table>
        </div>

        <div className="bg-slate-900 border-t border-slate-700 p-4 flex items-center justify-between text-xs text-slate-500">
          <div>Showing {paginatedData.length} of {filteredData.length} items</div>
          <div className="flex items-center gap-2">
            <button
              disabled={page === 1}
              onClick={() => setPage(p => p - 1)}
              className="px-2 py-1 rounded bg-slate-800 hover:bg-slate-700 disabled:opacity-50 transition-colors"
            >
              Previous
            </button>
            <span className="text-slate-300">Page {page} of {totalPages || 1}</span>
            <button
              disabled={page === totalPages || totalPages === 0}
              onClick={() => setPage(p => p + 1)}
              className="px-2 py-1 rounded bg-slate-800 hover:bg-slate-700 disabled:opacity-50 transition-colors"
            >
              Next
            </button>
          </div>
        </div>
      </div>

      {/* Focused edit panel */}
      {editing && editingRow && (
        <>
          <div className="fixed inset-0 bg-slate-950/50 backdrop-blur-sm z-40" onClick={() => setEditing(null)} />
          <div className="fixed right-0 top-0 bottom-0 w-[400px] bg-slate-800 border-l border-slate-700 shadow-2xl z-50 flex flex-col animate-in slide-in-from-right duration-200">
            <div className="flex items-center justify-between p-6 border-b border-slate-700 bg-slate-800/50">
              <div>
                <h2 className="text-lg font-bold text-white">Edit Fields</h2>
                <p className="text-xs text-slate-400 mt-0.5">
                  {editingRow[COLUMNS.ARTICLE_NO]} — {editingRow[COLUMNS.ARTICLE_NAME]}
                </p>
              </div>
              <button
                onClick={() => setEditing(null)}
                className="p-2 text-slate-400 hover:text-white hover:bg-slate-700 rounded-full transition-colors"
              >
                <X className="w-5 h-5" />
              </button>
            </div>

            <div className="flex-1 overflow-auto p-6 space-y-5">
              <div className="flex flex-col gap-1.5">
                <label className="text-xs font-medium text-slate-400 uppercase tracking-wider">Classification</label>
                <select
                  value={editing.classification}
                  onChange={e => setEditing(prev => prev ? { ...prev, classification: e.target.value } : prev)}
                  className={cn(
                    "w-full bg-slate-900 border rounded-md px-3 py-2.5 text-sm text-white focus:outline-none focus:ring-1 transition-colors",
                    editing.classification !== String(editingRow[COLUMNS.CLASSIFICATION] || '')
                      ? "border-blue-500 focus:ring-blue-500"
                      : "border-slate-700 focus:border-slate-500 focus:ring-slate-500"
                  )}
                >
                  <option value="">Select classification...</option>
                  {getUniqueValues(COLUMNS.CLASSIFICATION).map(val => (
                    <option key={val} value={val}>{val}</option>
                  ))}
                </select>
              </div>

              {launchDateCol >= 0 && (
                <div className="flex flex-col gap-1.5">
                  <label className="text-xs font-medium text-slate-400 uppercase tracking-wider">{launchHeader}</label>
                  <input
                    type="text"
                    value={editing.launchDate}
                    onChange={e => setEditing(prev => prev ? { ...prev, launchDate: e.target.value } : prev)}
                    placeholder="DD/MM/YYYY"
                    className={cn(
                      "w-full bg-slate-900 border rounded-md px-3 py-2.5 text-sm text-white font-mono focus:outline-none focus:ring-1 transition-colors",
                      editing.launchDate !== (formatDateValue(editingRow[launchDateCol]) || String(editingRow[launchDateCol] ?? ''))
                        ? "border-blue-500 focus:ring-blue-500"
                        : "border-slate-700 focus:border-slate-500 focus:ring-slate-500"
                    )}
                  />
                </div>
              )}

              {readyToOrderCol >= 0 && (
                <div className="flex flex-col gap-1.5">
                  <label className="text-xs font-medium text-slate-400 uppercase tracking-wider">{readyHeader}</label>
                  <input
                    type="text"
                    value={editing.readyToOrder}
                    onChange={e => setEditing(prev => prev ? { ...prev, readyToOrder: e.target.value } : prev)}
                    placeholder="DD/MM/YYYY"
                    className={cn(
                      "w-full bg-slate-900 border rounded-md px-3 py-2.5 text-sm text-white font-mono focus:outline-none focus:ring-1 transition-colors",
                      editing.readyToOrder !== (formatDateValue(editingRow[readyToOrderCol]) || String(editingRow[readyToOrderCol] ?? ''))
                        ? "border-blue-500 focus:ring-blue-500"
                        : "border-slate-700 focus:border-slate-500 focus:ring-slate-500"
                    )}
                  />
                </div>
              )}
            </div>

            <div className="p-6 border-t border-slate-700 bg-slate-800/50 flex justify-end gap-3">
              <button
                onClick={() => setEditing(null)}
                className="px-4 py-2 text-sm font-medium text-slate-300 hover:text-white hover:bg-slate-700 rounded-md transition-colors"
              >
                Cancel
              </button>
              <button
                onClick={handleSave}
                className="flex items-center gap-2 px-4 py-2 bg-blue-600 hover:bg-blue-700 text-white text-sm font-medium rounded-md shadow-lg shadow-blue-900/20 transition-colors"
              >
                <Save className="w-4 h-4" />
                Queue Changes
              </button>
            </div>
          </div>
        </>
      )}
    </div>
  );
}