import React, { useState, useEffect } from 'react';
import { useLocation, useNavigate, useSearchParams } from 'react-router-dom';
import {
  Box,
  Container,
  Typography,
  Button,
  CircularProgress,
  Alert,
  Breadcrumbs,
  Link,
  Stack,
  Card,
  CardContent,
  Table,
  TableBody,
  TableCell,
  TableContainer,
  TableHead,
  TableRow,
  Paper,
  Chip,
  Grid,
  Divider,
  Tabs,
  Tab
} from '@mui/material';
import {
  ArrowBack,
  Refresh,
  History,
  Download
} from '@mui/icons-material';

import MaterialComparisonResult from '../components/MaterialComparisonResult';
import { compareMaterialRevisions, confirmMaterialPurchase, fetchMaterials, api } from '../api';
import { exportComparisonToExcel } from '../utils/excelExport';

const MaterialComparisonPage = () => {
  const navigate = useNavigate();
  const [searchParams] = useSearchParams();
  const [loading, setLoading] = useState(true);
  const [confirmLoading, setConfirmLoading] = useState(false);
  const [error, setError] = useState(null);
  const [comparisonResult, setComparisonResult] = useState(null);
  const [selectedTab, setSelectedTab] = useState(0);

  // URL 파라미터에서 정보 추출
  const jobNo = searchParams.get('job_no');
  const currentRevision = searchParams.get('revision');
  const previousRevision = searchParams.get('prev_revision');
  const filename = searchParams.get('filename');

  useEffect(() => {
    if (jobNo && currentRevision) {
      loadComparison();
    } else {
      setError('필수 파라미터가 누락되었습니다 (job_no, revision)');
      setLoading(false);
    }
  }, [jobNo, currentRevision, previousRevision]);

  const loadComparison = async () => {
    try {
      setLoading(true);
      setError(null);
      
      console.log('🔍 자재 비교 실행 - 파라미터:', { 
        jobNo, 
        currentRevision, 
        previousRevision,
        filename 
      });

      // 🚨 테스트: MaterialsPage API 직접 호출해서 길이 정보 확인
      try {
        // ✅ API 함수 사용 - 테스트용 자재 조회
        const testResult = await fetchMaterials({ 
          job_no: jobNo, 
          revision: currentRevision, 
          limit: 10 
        });
        const pipeData = testResult.data.materials?.filter(m => m.classified_category === 'PIPE');
        console.log('🧪 MaterialsPage API 테스트 (길이 있는지 확인):', pipeData);
        if (pipeData && pipeData.length > 0) {
          console.log('🧪 첫 번째 파이프 상세:', JSON.stringify(pipeData[0], null, 2));
        }
      } catch (e) {
        console.log('🧪 MaterialsPage API 테스트 실패:', e);
      }
      
      const result = await compareMaterialRevisions(
        jobNo, 
        currentRevision, 
        previousRevision, 
        true // 결과 저장
      );
      
      console.log('✅ 비교 결과 성공:', result);
      console.log('🔍 전체 데이터 구조:', JSON.stringify(result.data || result, null, 2));
      setComparisonResult(result.data || result);
      
    } catch (err) {
      console.error('❌ 자재 비교 실패:', {
        message: err.message,
        response: err.response?.data,
        status: err.response?.status,
        params: { jobNo, currentRevision, previousRevision }
      });
      setError(err.response?.data?.detail || err.message || '자재 비교 중 오류가 발생했습니다');
    } finally {
      setLoading(false);
    }
  };

  const handleConfirmPurchase = async (confirmations) => {
    try {
      setConfirmLoading(true);
      
      console.log('발주 확정 실행:', { jobNo, currentRevision, confirmations });
      
      const result = await confirmMaterialPurchase(
        jobNo,
        currentRevision,
        confirmations,
        'user'
      );
      
      console.log('발주 확정 결과:', result);
      
      // 성공 메시지 표시 후 비교 결과 새로고침
      alert(`${result.confirmed_items?.length || confirmations.length}개 항목의 발주가 확정되었습니다!`);
      
      // 비교 결과 새로고침 (재고 상태가 변경되었을 수 있음)
      await loadComparison();
      
    } catch (err) {
      console.error('발주 확정 실패:', err);
      alert('발주 확정 중 오류가 발생했습니다: ' + (err.response?.data?.detail || err.message));
    } finally {
      setConfirmLoading(false);
    }
  };

  const handleRefresh = () => {
    loadComparison();
  };

  const handleGoBack = () => {
    // BOM 상태 페이지로 이동
    if (jobNo) {
      navigate(`/bom-status?job_no=${jobNo}`);
    } else {
      navigate(-1);
    }
  };

  const handleExportToExcel = () => {
    if (!comparisonResult) {
      alert('내보낼 비교 데이터가 없습니다.');
      return;
    }

    const additionalInfo = {
      jobNo: jobNo,
      currentRevision: currentRevision,
      previousRevision: previousRevision,
      filename: filename
    };

    const baseFilename = `리비전비교_${jobNo}_${currentRevision}_vs_${previousRevision}`;
    
    exportComparisonToExcel(comparisonResult, baseFilename, additionalInfo);
  };

  const renderComparisonResults = () => {
    const { summary, new_items = [], modified_items = [], removed_items = [] } = comparisonResult;
    
    return (
      <Box>
        {/* 요약 통계 카드 */}
        <Grid container spacing={3} sx={{ mb: 3 }}>
          <Grid item xs={12} md={3}>
            <Card>
              <CardContent sx={{ textAlign: 'center' }}>
                <Typography variant="h4" color="primary" gutterBottom>
                  {summary?.new_items_count || 0}
                </Typography>
                <Typography variant="h6">신규 자재</Typography>
                <Typography variant="body2" color="text.secondary">
                  새로 추가된 자재
                </Typography>
              </CardContent>
            </Card>
          </Grid>
          <Grid item xs={12} md={3}>
            <Card>
              <CardContent sx={{ textAlign: 'center' }}>
                <Typography variant="h4" color="warning.main" gutterBottom>
                  {summary?.modified_items_count || 0}
                </Typography>
                <Typography variant="h6">변경 자재</Typography>
                <Typography variant="body2" color="text.secondary">
                  수량이 변경된 자재
                </Typography>
              </CardContent>
            </Card>
          </Grid>
          <Grid item xs={12} md={3}>
            <Card>
              <CardContent sx={{ textAlign: 'center' }}>
                <Typography variant="h4" color="error.main" gutterBottom>
                  {summary?.removed_items_count || 0}
                </Typography>
                <Typography variant="h6">삭제 자재</Typography>
                <Typography variant="body2" color="text.secondary">
                  제거된 자재
                </Typography>
              </CardContent>
            </Card>
          </Grid>
          <Grid item xs={12} md={3}>
            <Card>
              <CardContent sx={{ textAlign: 'center' }}>
                <Typography variant="h4" color="success.main" gutterBottom>
                  {summary?.total_current_items || 0}
                </Typography>
                <Typography variant="h6">총 자재</Typography>
                <Typography variant="body2" color="text.secondary">
                  현재 리비전 전체
                </Typography>
              </CardContent>
            </Card>
          </Grid>
        </Grid>

        {/* 탭으로 구분된 자재 목록 */}
        <Card>
          <Tabs
            value={selectedTab}
            onChange={(e, newValue) => setSelectedTab(newValue)}
            variant="fullWidth"
          >
            <Tab label={`신규 자재 (${new_items.length})`} />
            <Tab label={`변경 자재 (${modified_items.length})`} />
            <Tab label={`삭제 자재 (${removed_items.length})`} />
          </Tabs>

          <CardContent>
            {selectedTab === 0 && renderMaterialTable(new_items, 'new')}
            {selectedTab === 1 && renderMaterialTable(modified_items, 'modified')}
            {selectedTab === 2 && renderMaterialTable(removed_items, 'removed')}
          </CardContent>
        </Card>
      </Box>
    );
  };

    const renderMaterialTable = (items, type) => {
    if (items.length === 0) {
      return (
        <Alert severity="info">
          {type === 'new' && '새로 추가된 자재가 없습니다.'}
          {type === 'modified' && '수량이 변경된 자재가 없습니다.'}
          {type === 'removed' && '삭제된 자재가 없습니다.'}
        </Alert>
      );
    }

    console.log(`🔍 ${type} 테이블 렌더링:`, items); // 디버깅용

    return (
      <TableContainer component={Paper} variant="outlined">
        <Table size="small">
          <TableHead>
            <TableRow>
              <TableCell>카테고리</TableCell>
              <TableCell>자재 설명</TableCell>
              <TableCell>사이즈</TableCell>
              <TableCell>재질</TableCell>
              {type === 'modified' && (
                <>
                  <TableCell align="center">이전 수량</TableCell>
                  <TableCell align="center">현재 수량</TableCell>
                  <TableCell align="center">변경량</TableCell>
                </>
              )}
              {type !== 'modified' && <TableCell align="center">수량</TableCell>}
              <TableCell>단위</TableCell>
              <TableCell>길이(mm)</TableCell>
            </TableRow>
          </TableHead>
          <TableBody>
            {items.map((item, index) => {
              console.log(`🔍 항목 ${index}:`, item); // 각 항목 확인
              
              // 파이프인 경우 길이 정보 표시
              console.log(`🔧 길이 확인 - ${item.category}:`, item.pipe_details); // 디버깅
              console.log(`🔧 전체 아이템:`, item); // 전체 구조 확인
              
              let lengthInfo = '-';
              if (item.category === 'PIPE' && item.pipe_details?.length_mm && item.pipe_details.length_mm > 0) {
                const avgUnitLength = item.pipe_details.length_mm;
                const currentTotalLength = item.pipe_details.total_length_mm || (item.quantity || 0) * avgUnitLength;
                
                if (type === 'modified') {
                  // 변경된 파이프: 백엔드에서 계산된 실제 길이 사용
                  let prevTotalLength, lengthChange;
                  
                  if (item.previous_pipe_details && item.previous_pipe_details.total_length_mm) {
                    // 백엔드에서 실제 이전 총길이를 제공한 경우
                    prevTotalLength = item.previous_pipe_details.total_length_mm;
                    lengthChange = currentTotalLength - prevTotalLength;
                  } else {
                    // 백업: 비율 계산
                    const prevRatio = (item.previous_quantity || 0) / (item.current_quantity || item.quantity || 1);
                    prevTotalLength = currentTotalLength * prevRatio;
                    lengthChange = currentTotalLength - prevTotalLength;
                  }
                  
                  lengthInfo = (
                    <Box>
                      <Typography variant="body2">
                        이전: {Math.round(prevTotalLength).toLocaleString()}mm → 현재: {Math.round(currentTotalLength).toLocaleString()}mm
                      </Typography>
                      <Typography 
                        variant="body2" 
                        fontWeight="bold"
                        color={lengthChange > 0 ? 'success.main' : lengthChange < 0 ? 'error.main' : 'text.primary'}
                      >
                        변화: {lengthChange > 0 ? '+' : ''}{Math.round(lengthChange).toLocaleString()}mm
                      </Typography>
                    </Box>
                  );
                } else {
                  // 신규/삭제된 파이프: 실제 총길이 사용
                  lengthInfo = (
                    <Box>
                      <Typography variant="body2" fontWeight="bold">
                        총 길이: {Math.round(currentTotalLength).toLocaleString()}mm
                      </Typography>
                    </Box>
                  );
                }
              } else if (item.category === 'PIPE') {
                lengthInfo = '길이 정보 없음';
              }
              
              return (
                <TableRow key={index}>
                  <TableCell>
                    <Chip 
                      label={item.category} 
                      size="small" 
                      color={type === 'new' ? 'primary' : type === 'modified' ? 'warning' : 'error'}
                    />
                  </TableCell>
                  <TableCell>{item.description}</TableCell>
                  <TableCell>{item.size_spec || '-'}</TableCell>
                  <TableCell>{item.material_grade || '-'}</TableCell>
                  {type === 'modified' && (
                    <>
                      <TableCell align="center">{item.previous_quantity}</TableCell>
                      <TableCell align="center">{item.current_quantity}</TableCell>
                      <TableCell align="center">
                        <Typography 
                          variant="body2" 
                          fontWeight="bold" 
                          color={item.quantity_change > 0 ? 'success.main' : 'error.main'}
                        >
                          {item.quantity_change > 0 ? '+' : ''}{item.quantity_change}
                        </Typography>
                      </TableCell>
                    </>
                  )}
                  {type !== 'modified' && (
                    <TableCell align="center">
                      <Typography variant="body2" fontWeight="bold">
                        {item.quantity}
                      </Typography>
                    </TableCell>
                  )}
                  <TableCell>{item.unit || 'EA'}</TableCell>
                  <TableCell align="center">
                    <Typography variant="body2" color={lengthInfo !== '-' ? 'primary.main' : 'text.secondary'}>
                      {lengthInfo}
                    </Typography>
                  </TableCell>
                </TableRow>
              );
            })}
          </TableBody>
        </Table>
      </TableContainer>
    );
  };

  const renderHeader = () => (
    <Box sx={{ mb: 3 }}>
      <Breadcrumbs sx={{ mb: 2 }}>
        <Link 
          component="button" 
          variant="body2" 
          onClick={() => navigate('/jobs')}
          sx={{ textDecoration: 'none' }}
        >
          프로젝트 목록
        </Link>
        <Link 
          component="button" 
          variant="body2" 
          onClick={() => navigate(`/materials?job_no=${jobNo}`)}
          sx={{ textDecoration: 'none' }}
        >
          {jobNo}
        </Link>
        <Typography variant="body2" color="textPrimary">
          자재 비교
        </Typography>
      </Breadcrumbs>

      <Stack direction="row" justifyContent="space-between" alignItems="center">
        <Box>
          <Typography variant="h4" gutterBottom>
            자재 리비전 비교
          </Typography>
          <Typography variant="body1" color="textSecondary">
            {filename && `파일: ${filename}`}
            <br />
            {previousRevision ? 
              `${previousRevision} → ${currentRevision} 비교` : 
              `${currentRevision} (이전 리비전 없음)`
            }
          </Typography>
        </Box>
        
        <Stack direction="row" spacing={2}>
          <Button
            variant="outlined"
            startIcon={<Refresh />}
            onClick={handleRefresh}
            disabled={loading}
          >
            새로고침
          </Button>
          <Button
            variant="outlined"
            color="primary"
            startIcon={<Download />}
            onClick={handleExportToExcel}
            disabled={!comparisonResult}
          >
            엑셀 내보내기
          </Button>
          <Button
            variant="outlined"
            startIcon={<ArrowBack />}
            onClick={handleGoBack}
          >
            BOM 목록으로
          </Button>
        </Stack>
      </Stack>
    </Box>
  );

  if (loading) {
    return (
      <Container maxWidth="xl" sx={{ py: 4 }}>
        {renderHeader()}
        <Box display="flex" justifyContent="center" alignItems="center" minHeight="400px">
          <Stack alignItems="center" spacing={2}>
            <CircularProgress size={60} />
            <Typography variant="h6" color="textSecondary">
              자재 비교 중...
            </Typography>
            <Typography variant="body2" color="textSecondary">
              리비전간 차이점을 분석하고 있습니다
            </Typography>
          </Stack>
        </Box>
      </Container>
    );
  }

  if (error) {
    return (
      <Container maxWidth="xl" sx={{ py: 4 }}>
        {renderHeader()}
        <Alert severity="error" sx={{ mb: 3 }}>
          <Typography variant="h6" gutterBottom>
            자재 비교 실패
          </Typography>
          <Typography variant="body2">
            {error}
          </Typography>
        </Alert>
        <Button
          variant="contained"
          startIcon={<Refresh />}
          onClick={handleRefresh}
        >
          다시 시도
        </Button>
      </Container>
    );
  }

  return (
    <Container maxWidth="xl" sx={{ py: 4 }}>
      {renderHeader()}
      
      {comparisonResult && renderComparisonResults()}
    </Container>
  );
};

export default MaterialComparisonPage;