'use client';

import { useState, useCallback, useRef } from 'react';
import { useRouter } from 'next/navigation';
import { PageLayout } from '@/components/organisms/PageLayout';
import { PageHeader } from '@/components/organisms/PageHeader';
import { Card, CardContent, CardHeader, CardTitle } from '@/components/ui/card';
import { Button } from '@/components/ui/button';
import { Checkbox } from '@/components/ui/checkbox';
import {
  Table,
  TableBody,
  TableCell,
  TableHead,
  TableHeader,
  TableRow,
} from '@/components/ui/table';
import { Trash2, Users, Download } from 'lucide-react';
import type { Employee, CSVEmployeeRow, CSVValidationResult } from './types';

interface CSVUploadPageProps {
  onUpload: (employees: Employee[]) => void;
}

export function CSVUploadPage({ onUpload }: CSVUploadPageProps) {
  const router = useRouter();
  const [file, setFile] = useState<File | null>(null);
  const [validationResults, setValidationResults] = useState<CSVValidationResult[]>([]);
  const [isProcessing, setIsProcessing] = useState(false);
  const [selectedRows, setSelectedRows] = useState<Set<number>>(new Set());
  const fileInputRef = useRef<HTMLInputElement>(null);

  // 파일 선택
  const handleFileSelect = useCallback((e: React.ChangeEvent<HTMLInputElement>) => {
    const selectedFile = e.target.files?.[0];
    if (selectedFile) {
      setFile(selectedFile);
      setValidationResults([]);
      setSelectedRows(new Set());
    }
  }, []);

  // 파일 제거
  const handleRemoveFile = useCallback(() => {
    setFile(null);
    setValidationResults([]);
    setSelectedRows(new Set());
    if (fileInputRef.current) {
      fileInputRef.current.value = '';
    }
  }, []);

  // 파일변환 (CSV 파싱)
  const handleConvert = async () => {
    if (!file) return;

    setIsProcessing(true);
    try {
      const text = await file.text();
      const lines = text.split('\n').map(line => line.trim()).filter(line => line);

      if (lines.length < 2) {
        setValidationResults([]);
        return;
      }

      // 헤더 파싱
      const headers = lines[0].split(',').map(h => h.trim());

      // 데이터 파싱 및 유효성 검사
      const results: CSVValidationResult[] = lines.slice(1).map((line, index) => {
        const values = line.split(',').map(v => v.trim());
        const data: CSVEmployeeRow = {
          name: values[headers.indexOf('이름')] || values[headers.indexOf('name')] || '',
          phone: values[headers.indexOf('휴대폰')] || values[headers.indexOf('phone')] || undefined,
          email: values[headers.indexOf('이메일')] || values[headers.indexOf('email')] || undefined,
          departmentName: values[headers.indexOf('부서')] || values[headers.indexOf('department')] || undefined,
          positionName: values[headers.indexOf('직책')] || values[headers.indexOf('position')] || undefined,
          hireDate: values[headers.indexOf('입사일')] || values[headers.indexOf('hireDate')] || undefined,
          status: values[headers.indexOf('상태')] || values[headers.indexOf('status')] || undefined,
        };

        // 유효성 검사
        const errors: string[] = [];
        if (!data.name) {
          errors.push('이름은 필수입니다');
        }
        if (data.email && !/^[^\s@]+@[^\s@]+\.[^\s@]+$/.test(data.email)) {
          errors.push('이메일 형식이 올바르지 않습니다');
        }
        if (data.phone && !/^\d{3}-\d{4}-\d{4}$/.test(data.phone)) {
          errors.push('휴대폰 형식이 올바르지 않습니다 (000-0000-0000)');
        }

        return {
          row: index + 2,
          data,
          isValid: errors.length === 0,
          errors,
        };
      });

      setValidationResults(results);
    } catch {
      console.error('CSV 파싱 오류');
    } finally {
      setIsProcessing(false);
    }
  };

  // 행 선택
  const handleSelectRow = useCallback((rowIndex: number, checked: boolean) => {
    setSelectedRows(prev => {
      const newSet = new Set(prev);
      if (checked) {
        newSet.add(rowIndex);
      } else {
        newSet.delete(rowIndex);
      }
      return newSet;
    });
  }, []);

  // 전체 선택
  const handleSelectAll = useCallback((checked: boolean) => {
    if (checked) {
      const validIndices = validationResults
        .filter(r => r.isValid)
        .map((_, index) => index);
      setSelectedRows(new Set(validIndices));
    } else {
      setSelectedRows(new Set());
    }
  }, [validationResults]);

  // 양식 다운로드
  const handleDownloadTemplate = () => {
    const headers = ['이름', '휴대폰', '이메일', '부서', '직책', '입사일', '상태'];
    const sampleData = ['홍길동', '010-1234-5678', 'hong@company.com', '개발팀', '팀원', '2024-01-01', '재직'];
    const csv = [headers.join(','), sampleData.join(',')].join('\n');

    const blob = new Blob(['\uFEFF' + csv], { type: 'text/csv;charset=utf-8;' });
    const link = document.createElement('a');
    link.href = URL.createObjectURL(blob);
    link.download = '사원등록_양식.csv';
    link.click();
  };

  // 업로드 실행
  const handleUpload = () => {
    const selectedResults = validationResults.filter((_, index) => selectedRows.has(index));
    const employees: Employee[] = selectedResults.map((r, index) => ({
      id: String(Date.now() + index),
      name: r.data.name,
      phone: r.data.phone,
      email: r.data.email,
      status: (r.data.status === '재직' || r.data.status === 'active') ? 'active' :
              (r.data.status === '휴직' || r.data.status === 'leave') ? 'leave' :
              (r.data.status === '퇴직' || r.data.status === 'resigned') ? 'resigned' : 'active',
      hireDate: r.data.hireDate,
      departmentPositions: r.data.departmentName ? [{
        id: String(Date.now() + index),
        departmentId: '',
        departmentName: r.data.departmentName,
        positionId: '',
        positionName: r.data.positionName || '',
      }] : [],
      createdAt: new Date().toISOString(),
      updatedAt: new Date().toISOString(),
    }));

    onUpload(employees);
    router.push('/ko/hr/employee-management');
  };

  const validCount = validationResults.filter(r => r.isValid).length;
  const isAllSelected = validCount > 0 && selectedRows.size === validCount;

  return (
    <PageLayout>
      <PageHeader
        title="CSV 일괄 등록"
        description="CSV로 정보를 일괄 등록합니다"
        icon={Users}
      />

      <div className="space-y-6">
        {/* 일괄 등록 카드 */}
        <Card>
          <CardHeader>
            <CardTitle className="text-lg">일괄 등록</CardTitle>
          </CardHeader>
          <CardContent className="space-y-4">
            {/* CSV 파일 선택 영역 */}
            <div className="flex items-center gap-4">
              <div className="flex items-center gap-2">
                <span className="text-sm font-medium">CSV 파일</span>
                <span className="text-xs text-muted-foreground">CSV 파일 50MB 이하 가능</span>
              </div>
            </div>

            <div className="flex items-center gap-4">
              {/* 찾기 버튼 */}
              <input
                ref={fileInputRef}
                type="file"
                accept=".csv"
                onChange={handleFileSelect}
                className="hidden"
                id="csv-file-input"
              />
              <Button
                variant="outline"
                onClick={() => fileInputRef.current?.click()}
                className="px-6"
              >
                찾기
              </Button>

              {/* 파일명 표시 */}
              {file && (
                <div className="flex items-center gap-2 px-3 py-1.5 border rounded">
                  <span className="text-sm">{file.name}</span>
                  <button
                    onClick={handleRemoveFile}
                    className="text-muted-foreground hover:text-foreground"
                  >
                    <Trash2 className="h-4 w-4" />
                  </button>
                </div>
              )}

              {/* 양식 다운로드 버튼 */}
              <Button
                variant="outline"
                onClick={handleDownloadTemplate}
                className="ml-auto gap-2"
              >
                <Download className="h-4 w-4" />
                양식 다운로드
              </Button>
            </div>

            {/* 파일변환 버튼 */}
            <Button
              onClick={handleConvert}
              disabled={!file || isProcessing}
              className="w-full bg-black hover:bg-black/90 text-white"
            >
              파일변환
            </Button>
          </CardContent>
        </Card>

        {/* 테이블 상단 정보 */}
        {validationResults.length > 0 && (
          <div className="flex items-center gap-4">
            <span className="text-sm">
              총 <strong>{validationResults.length}</strong>건
            </span>
            {selectedRows.size > 0 && (
              <span className="text-sm">
                {selectedRows.size}건 선택
              </span>
            )}
          </div>
        )}

        {/* 데이터 테이블 */}
        <Card>
          <CardContent className="pt-6">
            <div className="rounded-md border overflow-x-auto">
              <Table>
                <TableHeader>
                  <TableRow>
                    <TableHead className="w-[50px] text-center">
                      <Checkbox
                        checked={isAllSelected}
                        onCheckedChange={handleSelectAll}
                        disabled={validationResults.length === 0}
                      />
                    </TableHead>
                    <TableHead className="w-[60px] text-center">번호</TableHead>
                    <TableHead className="min-w-[80px]">이름</TableHead>
                    <TableHead className="min-w-[120px]">휴대폰</TableHead>
                    <TableHead className="min-w-[150px]">이메일</TableHead>
                    <TableHead className="min-w-[100px]">부서</TableHead>
                    <TableHead className="min-w-[100px]">직책</TableHead>
                    <TableHead className="min-w-[100px]">입사일</TableHead>
                    <TableHead className="min-w-[80px]">상태</TableHead>
                    <TableHead className="min-w-[150px]">오류</TableHead>
                  </TableRow>
                </TableHeader>
                <TableBody>
                  {validationResults.length === 0 ? (
                    <TableRow>
                      <TableCell colSpan={10} className="h-24 text-center text-muted-foreground">
                        파일 선택 및 파일 변환이 필요합니다.
                      </TableCell>
                    </TableRow>
                  ) : (
                    validationResults.map((result, index) => (
                      <TableRow
                        key={result.row}
                        className={!result.isValid ? 'bg-red-50 hover:bg-red-100' : 'hover:bg-muted/50'}
                      >
                        <TableCell className="text-center">
                          <Checkbox
                            checked={selectedRows.has(index)}
                            onCheckedChange={(checked) => handleSelectRow(index, !!checked)}
                            disabled={!result.isValid}
                          />
                        </TableCell>
                        <TableCell className="text-center text-muted-foreground">
                          {validationResults.length - index}
                        </TableCell>
                        <TableCell>{result.data.name || '-'}</TableCell>
                        <TableCell>{result.data.phone || '-'}</TableCell>
                        <TableCell>{result.data.email || '-'}</TableCell>
                        <TableCell>{result.data.departmentName || '-'}</TableCell>
                        <TableCell>{result.data.positionName || '-'}</TableCell>
                        <TableCell>{result.data.hireDate || '-'}</TableCell>
                        <TableCell>{result.data.status || '-'}</TableCell>
                        <TableCell>
                          {result.errors.length > 0 ? (
                            <span className="text-sm text-red-600">
                              {result.errors.join(', ')}
                            </span>
                          ) : (
                            <span className="text-sm text-green-600">유효</span>
                          )}
                        </TableCell>
                      </TableRow>
                    ))
                  )}
                </TableBody>
              </Table>
            </div>
          </CardContent>
        </Card>

        {/* 등록 버튼 */}
        <Button
          onClick={handleUpload}
          disabled={selectedRows.size === 0 || isProcessing}
          className="w-full"
          size="lg"
        >
          {selectedRows.size > 0 ? `${selectedRows.size}건 등록` : '등록'}
        </Button>
      </div>
    </PageLayout>
  );
}