import React, { useState, useRef } from 'react';
import { Button } from '../../../ui/Button';
import { Input } from '../../../ui/Input';
import { useValidateFileOnly } from '../../../../api/hooks/dataImport';
import { ImportValidationResponse } from '../../../../api/types/dataImport';
import { useCurrentTenant } from '../../../../stores/tenant.store';
import { useCreateIngredient } from '../../../../api/hooks/inventory';
import { useImportFileOnly } from '../../../../api/hooks/dataImport';
import { useClassifyProductsBatch } from '../../../../api/hooks/classification';
import { useAuth } from '../../../../contexts/AuthContext';

interface UploadSalesDataStepProps {
  onNext: () => void;
  onPrevious: () => void;
  onComplete: (data?: any) => void;
  isFirstStep: boolean;
  isLastStep: boolean;
}

interface ProgressState {
  stage: string;
  progress: number;
  message: string;
}

interface InventoryItem {
  suggestion_id: string;
  original_name: string;
  suggested_name: string;
  product_type: string;
  category: string;
  unit_of_measure: string;
  confidence_score: number;
  estimated_shelf_life_days?: number;
  requires_refrigeration: boolean;
  requires_freezing: boolean;
  is_seasonal: boolean;
  suggested_supplier?: string;
  notes?: string;
  sales_data?: {
    total_quantity: number;
    average_daily_sales: number;
    peak_day: string;
    frequency: number;
  };
  // UI-specific fields
  selected: boolean;
  stock_quantity: number;
  cost_per_unit: number;
}

export const UploadSalesDataStep: React.FC<UploadSalesDataStepProps> = ({
  onPrevious,
  onComplete,
  isFirstStep
}) => {
  const [selectedFile, setSelectedFile] = useState<File | null>(null);
  const [isValidating, setIsValidating] = useState(false);
  const [validationResult, setValidationResult] = useState<ImportValidationResponse | null>(null);
  const [inventoryItems, setInventoryItems] = useState<InventoryItem[]>([]);
  const [showInventoryStep, setShowInventoryStep] = useState(false);
  const [isCreating, setIsCreating] = useState(false);
  const [error, setError] = useState<string>('');
  const [progressState, setProgressState] = useState<ProgressState | null>(null);
  const fileInputRef = useRef<HTMLInputElement>(null);

  const currentTenant = useCurrentTenant();
  const { user } = useAuth();
  const { validateFile } = useValidateFileOnly();
  const createIngredient = useCreateIngredient();
  const { importFile } = useImportFileOnly();
  const classifyProducts = useClassifyProductsBatch();

  const handleFileSelect = async (event: React.ChangeEvent<HTMLInputElement>) => {
    const file = event.target.files?.[0];
    if (file) {
      setSelectedFile(file);
      setValidationResult(null);
      setError('');
      
      // Automatically trigger validation and classification
      await handleAutoValidateAndClassify(file);
    }
  };

  const handleDrop = async (event: React.DragEvent<HTMLDivElement>) => {
    event.preventDefault();
    const file = event.dataTransfer.files[0];
    if (file) {
      setSelectedFile(file);
      setValidationResult(null);
      setError('');
      
      // Automatically trigger validation and classification
      await handleAutoValidateAndClassify(file);
    }
  };

  const handleDragOver = (event: React.DragEvent<HTMLDivElement>) => {
    event.preventDefault();
  };

  const handleAutoValidateAndClassify = async (file: File) => {
    if (!currentTenant?.id) return;

    setIsValidating(true);
    setError('');
    setProgressState({ stage: 'preparing', progress: 0, message: 'Preparando validación automática del archivo...' });

    try {
      // Step 1: Validate the file
      const result = await validateFile(
        currentTenant.id,
        file,
        {
          onProgress: (stage: string, progress: number, message: string) => {
            // Map validation progress to 0-50%
            setProgressState({ stage, progress: Math.min(progress * 0.5, 50), message });
          }
        }
      );

      if (result.success && result.validationResult) {
        setValidationResult(result.validationResult);
        setProgressState({ stage: 'analyzing', progress: 60, message: 'Validación exitosa. Generando sugerencias automáticamente...' });
        
        // Step 2: Automatically trigger classification
        await generateInventorySuggestionsAuto(result.validationResult);
      } else {
        setError(result.error || 'Error al validar el archivo');
        setProgressState(null);
        setIsValidating(false);
      }
    } catch (error) {
      setError('Error validando archivo: ' + (error instanceof Error ? error.message : 'Error desconocido'));
      setProgressState(null);
      setIsValidating(false);
    }
  };


  const generateInventorySuggestionsAuto = async (validationData: ImportValidationResponse) => {
    if (!currentTenant?.id) {
      setError('No hay datos de validación disponibles para generar sugerencias');
      setIsValidating(false);
      setProgressState(null);
      return;
    }

    try {
      setProgressState({ stage: 'analyzing', progress: 65, message: 'Analizando productos de ventas...' });

      // Extract product data from validation result - use the exact backend structure
      const products = validationData.product_list?.map((productName: string) => ({
        product_name: productName
      })) || [];

      if (products.length === 0) {
        setError('No se encontraron productos en los datos de ventas');
        setProgressState(null);
        setIsValidating(false);
        return;
      }

      setProgressState({ stage: 'classifying', progress: 75, message: 'Clasificando productos con IA...' });

      // Call the classification API
      const suggestions = await classifyProducts.mutateAsync({
        tenantId: currentTenant.id,
        batchData: { products }
      });

      setProgressState({ stage: 'preparing', progress: 90, message: 'Preparando sugerencias de inventario...' });

      // Convert API response to InventoryItem format - use exact backend structure plus UI fields
      const items: InventoryItem[] = suggestions.map(suggestion => {
        // Calculate default stock quantity based on sales data
        const defaultStock = Math.max(
          Math.ceil((suggestion.sales_data?.average_daily_sales || 1) * 7), // 1 week supply
          1
        );
        
        // Estimate cost per unit based on category
        const estimatedCost = suggestion.category === 'Dairy' ? 5.0 : 
                             suggestion.category === 'Baking Ingredients' ? 2.0 : 
                             3.0;

        return {
          // Exact backend fields
          suggestion_id: suggestion.suggestion_id,
          original_name: suggestion.original_name,
          suggested_name: suggestion.suggested_name,
          product_type: suggestion.product_type,
          category: suggestion.category,
          unit_of_measure: suggestion.unit_of_measure,
          confidence_score: suggestion.confidence_score,
          estimated_shelf_life_days: suggestion.estimated_shelf_life_days,
          requires_refrigeration: suggestion.requires_refrigeration,
          requires_freezing: suggestion.requires_freezing,
          is_seasonal: suggestion.is_seasonal,
          suggested_supplier: suggestion.suggested_supplier,
          notes: suggestion.notes,
          sales_data: suggestion.sales_data,
          // UI-specific fields
          selected: suggestion.confidence_score > 0.7, // Auto-select high confidence items
          stock_quantity: defaultStock,
          cost_per_unit: estimatedCost
        };
      });

      setInventoryItems(items);
      setShowInventoryStep(true);
      setProgressState(null);
      setIsValidating(false);
    } catch (err) {
      console.error('Error generating inventory suggestions:', err);
      setError('Error al generar sugerencias de inventario. Por favor, inténtalo de nuevo.');
      setProgressState(null);
      setIsValidating(false);
    }
  };


  const handleToggleSelection = (id: string) => {
    setInventoryItems(items =>
      items.map(item =>
        item.suggestion_id === id ? { ...item, selected: !item.selected } : item
      )
    );
  };

  const handleUpdateItem = (id: string, field: keyof InventoryItem, value: number) => {
    setInventoryItems(items =>
      items.map(item =>
        item.suggestion_id === id ? { ...item, [field]: value } : item
      )
    );
  };

  const handleSelectAll = () => {
    const allSelected = inventoryItems.every(item => item.selected);
    setInventoryItems(items =>
      items.map(item => ({ ...item, selected: !allSelected }))
    );
  };

  const handleCreateInventory = async () => {
    const selectedItems = inventoryItems.filter(item => item.selected);
    
    if (selectedItems.length === 0) {
      setError('Por favor selecciona al menos un artículo de inventario para crear');
      return;
    }

    if (!currentTenant?.id) {
      setError('No se encontró información del tenant');
      return;
    }

    setIsCreating(true);
    setError('');

    try {
      const createdIngredients = [];

      for (const item of selectedItems) {
        // Ensure reorder_point > minimum_stock_level as required by backend validation
        const minimumStock = Math.max(1, Math.ceil(item.stock_quantity * 0.2));
        const calculatedReorderPoint = Math.ceil(item.stock_quantity * 0.3);
        const reorderPoint = Math.max(minimumStock + 2, calculatedReorderPoint, minimumStock + 1);
        
        console.log(`📊 Inventory validation for "${item.suggested_name}":`, {
          stockQuantity: item.stock_quantity,
          minimumStock,
          calculatedReorderPoint,
          finalReorderPoint: reorderPoint,
          isValid: reorderPoint > minimumStock
        });
        
        const ingredientData = {
          name: item.suggested_name,
          category: item.category,
          unit_of_measure: item.unit_of_measure,
          low_stock_threshold: minimumStock,
          max_stock_level: item.stock_quantity * 2,
          reorder_point: reorderPoint,
          shelf_life_days: item.estimated_shelf_life_days || 30,
          requires_refrigeration: item.requires_refrigeration,
          requires_freezing: item.requires_freezing,
          is_seasonal: item.is_seasonal,
          average_cost: item.cost_per_unit,
          notes: item.notes || `Creado durante onboarding - Confianza: ${Math.round(item.confidence_score * 100)}%`
        };

        const created = await createIngredient.mutateAsync({
          tenantId: currentTenant.id,
          ingredientData
        });

        createdIngredients.push({
          ...created,
          initialStock: item.stock_quantity
        });
      }

      // After inventory creation, import the sales data
      console.log('Importing sales data after inventory creation...');
      let salesImportResult = null;
      try {
        if (selectedFile) {
          const result = await importFile(
            currentTenant.id,
            selectedFile,
            {
              onProgress: (stage, progress, message) => {
                console.log(`Import progress: ${stage} - ${progress}% - ${message}`);
                setProgressState({ 
                  stage: 'importing', 
                  progress, 
                  message: `Importando datos de ventas: ${message}` 
                });
              }
            }
          );
          
          salesImportResult = result;
          if (result.success) {
            console.log('Sales data imported successfully');
          } else {
            console.warn('Sales import completed with issues:', result.error);
          }
        }
      } catch (importError) {
        console.error('Error importing sales data:', importError);
        // Don't fail the entire process if import fails - the inventory has been created successfully
      }

      setProgressState(null);
      onComplete({
        createdIngredients,
        totalItems: selectedItems.length,
        validationResult,
        file: selectedFile,
        salesImportResult,
        inventoryConfigured: true, // Flag for ML training dependency
        shouldAutoCompleteSuppliers: true, // Flag to trigger suppliers auto-completion after step completion
        userId: user?.id // Pass user ID for suppliers completion
      });
    } catch (err) {
      console.error('Error creating inventory items:', err);
      setError('Error al crear artículos de inventario. Por favor, inténtalo de nuevo.');
      setIsCreating(false);
      setProgressState(null);
    }
  };

  const formatFileSize = (bytes: number) => {
    if (bytes === 0) return '0 Bytes';
    const k = 1024;
    const sizes = ['Bytes', 'KB', 'MB', 'GB'];
    const i = Math.floor(Math.log(bytes) / Math.log(k));
    return parseFloat((bytes / Math.pow(k, i)).toFixed(2)) + ' ' + sizes[i];
  };

  const selectedCount = inventoryItems.filter(item => item.selected).length;
  const allSelected = inventoryItems.length > 0 && inventoryItems.every(item => item.selected);

  if (showInventoryStep) {
    return (
      <div className="space-y-6">
        <div className="text-center">
          <p className="text-[var(--text-secondary)] mb-6">
            ¡Perfecto! Hemos analizado automáticamente tus datos de ventas y generado estas sugerencias de inventario inteligentes. 
            Revisa y selecciona los artículos que te gustaría agregar a tu inventario.
          </p>
        </div>

        {/* Summary */}
        <div className="bg-[var(--bg-secondary)] rounded-lg p-4">
          <div className="flex flex-col sm:flex-row sm:justify-between sm:items-center space-y-3 sm:space-y-0">
            <div className="text-center sm:text-left">
              <p className="font-medium text-sm sm:text-base">
                {selectedCount} de {inventoryItems.length} artículos seleccionados
              </p>
              <p className="text-xs sm:text-sm text-[var(--text-secondary)]">
                Los artículos con alta confianza están preseleccionados
              </p>
            </div>
            <Button
              variant="outline"
              size="sm"
              onClick={handleSelectAll}
              className="w-full sm:w-auto"
            >
              {allSelected ? 'Deseleccionar Todos' : 'Seleccionar Todos'}
            </Button>
          </div>
        </div>

        {/* Inventory Items */}
        <div className="space-y-4 max-h-96 overflow-y-auto">
          {inventoryItems.map((item) => (
            <div
              key={item.suggestion_id}
              className={`border rounded-lg p-4 transition-colors ${
                item.selected
                  ? 'border-[var(--color-primary)] bg-[var(--color-primary)]/5'
                  : 'border-[var(--border-secondary)]'
              }`}
            >
              <div className="flex items-start gap-4">
                <div className="flex-shrink-0 pt-1">
                  <input
                    type="checkbox"
                    checked={item.selected}
                    onChange={() => handleToggleSelection(item.suggestion_id)}
                    className="w-4 h-4 text-[var(--color-primary)] border-[var(--border-secondary)] rounded focus:ring-[var(--color-primary)]"
                  />
                </div>

                <div className="flex-1 space-y-3">
                  <div>
                    <h3 className="font-medium text-[var(--text-primary)]">
                      {item.suggested_name}
                    </h3>
                    <p className="text-sm text-[var(--text-secondary)]">
                      {item.category} • Unidad: {item.unit_of_measure}
                    </p>
                    <div className="flex items-center gap-2 mt-1">
                      <span className="text-xs bg-[var(--bg-tertiary)] px-2 py-1 rounded">
                        Confianza: {Math.round(item.confidence_score * 100)}%
                      </span>
                      {item.requires_refrigeration && (
                        <span className="text-xs bg-blue-100 text-blue-800 px-2 py-1 rounded">
                          Requiere refrigeración
                        </span>
                      )}
                      {item.requires_freezing && (
                        <span className="text-xs bg-cyan-100 text-cyan-800 px-2 py-1 rounded">
                          Requiere congelación
                        </span>
                      )}
                      {item.is_seasonal && (
                        <span className="text-xs bg-green-100 text-green-800 px-2 py-1 rounded">
                          Producto estacional
                        </span>
                      )}
                    </div>
                  </div>

                  {item.selected && (
                    <div className="grid grid-cols-1 sm:grid-cols-2 lg:grid-cols-3 gap-3 sm:gap-4 pt-3 border-t border-[var(--border-secondary)]">
                      <Input
                        label="Stock Inicial"
                        type="number"
                        min="0"
                        value={item.stock_quantity.toString()}
                        onChange={(e) => handleUpdateItem(
                          item.suggestion_id,
                          'stock_quantity',
                          Number(e.target.value)
                        )}
                        size="sm"
                      />
                      <Input
                        label="Costo por Unidad (€)"
                        type="number"
                        min="0"
                        step="0.01"
                        value={item.cost_per_unit.toString()}
                        onChange={(e) => handleUpdateItem(
                          item.suggestion_id,
                          'cost_per_unit',
                          Number(e.target.value)
                        )}
                        size="sm"
                      />
                      <Input
                        label="Días de Caducidad"
                        type="number"
                        min="1"
                        value={(item.estimated_shelf_life_days || 30).toString()}
                        onChange={(e) => handleUpdateItem(
                          item.suggestion_id,
                          'estimated_shelf_life_days',
                          Number(e.target.value)
                        )}
                        size="sm"
                        className="sm:col-span-2 lg:col-span-1"
                      />
                    </div>
                  )}
                </div>
              </div>
            </div>
          ))}
        </div>

        {error && (
          <div className="bg-[var(--color-error)]/10 border border-[var(--color-error)]/20 rounded-lg p-4">
            <p className="text-[var(--color-error)]">{error}</p>
          </div>
        )}

        {/* Actions */}
        <div className="flex flex-col sm:flex-row justify-end gap-3 sm:gap-0">{/* Removed back button */}

          <Button
            onClick={handleCreateInventory}
            isLoading={isCreating}
            loadingText="Creando Inventario..."
            size="lg"
            disabled={selectedCount === 0}
            className="w-full sm:w-auto"
          >
            <span className="hidden sm:inline">
              Crear {selectedCount} Artículo{selectedCount !== 1 ? 's' : ''} de Inventario
            </span>
            <span className="sm:hidden">
              Crear {selectedCount} Artículo{selectedCount !== 1 ? 's' : ''}
            </span>
          </Button>
        </div>
      </div>
    );
  }

  return (
    <div className="space-y-6">
      <div className="text-center">
        <p className="text-[var(--text-secondary)] mb-6">
          Sube tus datos de ventas (formato CSV o JSON) y automáticamente validaremos y generaremos sugerencias de inventario inteligentes.
        </p>
      </div>

      {/* File Upload Area */}
      <div
        className={`border-2 border-dashed rounded-lg p-8 text-center transition-colors ${
          selectedFile
            ? 'border-[var(--color-success)] bg-[var(--color-success)]/5'
            : 'border-[var(--border-secondary)] hover:border-[var(--color-primary)] hover:bg-[var(--color-primary)]/5'
        }`}
        onDrop={handleDrop}
        onDragOver={handleDragOver}
      >
        <input
          ref={fileInputRef}
          type="file"
          accept=".csv,.json"
          onChange={handleFileSelect}
          className="hidden"
        />

        {selectedFile ? (
          <div className="space-y-4">
            <div className="text-[var(--color-success)]">
              <svg className="mx-auto h-12 w-12 mb-4" fill="none" stroke="currentColor" viewBox="0 0 24 24">
                <path strokeLinecap="round" strokeLinejoin="round" strokeWidth={2} d="M9 12l2 2 4-4m6 2a9 9 0 11-18 0 9 9 0 0118 0z" />
              </svg>
              <p className="text-lg font-medium">Archivo Seleccionado</p>
              <p className="text-[var(--text-secondary)]">{selectedFile.name}</p>
              <p className="text-sm text-[var(--text-tertiary)]">
                {formatFileSize(selectedFile.size)}
              </p>
            </div>
            <Button
              variant="outline"
              onClick={() => fileInputRef.current?.click()}
            >
              Choose Different File
            </Button>
          </div>
        ) : (
          <div className="space-y-4">
            <svg className="mx-auto h-12 w-12 text-[var(--text-tertiary)]" stroke="currentColor" fill="none" viewBox="0 0 48 48">
              <path d="M28 8H12a4 4 0 00-4 4v20m32-12v8m0 0v8a4 4 0 01-4 4H12a4 4 0 01-4-4v-4m32-4l-3.172-3.172a4 4 0 00-5.656 0L28 28M8 32l9.172-9.172a4 4 0 015.656 0L28 28m0 0l4 4m4-24h8m-4-4v8m-12 4h.02" strokeWidth={2} strokeLinecap="round" strokeLinejoin="round" />
            </svg>
            <div>
              <p className="text-lg font-medium">Drop your sales data here</p>
              <p className="text-[var(--text-secondary)]">or click to browse files</p>
              <p className="text-sm text-[var(--text-tertiary)] mt-2">
                Supported formats: CSV, JSON (max 100MB)<br/>
                <span className="text-[var(--color-primary)]">Auto-validates and generates suggestions</span>
              </p>
            </div>
            <Button
              variant="outline"
              onClick={() => fileInputRef.current?.click()}
            >
              Choose File
            </Button>
          </div>
        )}
      </div>

      {/* Progress */}
      {progressState && (
        <div className="bg-[var(--bg-secondary)] rounded-lg p-4">
          <div className="flex justify-between text-sm mb-2">
            <span className="font-medium">{progressState.message}</span>
            <span>{progressState.progress}%</span>
          </div>
          <div className="w-full bg-[var(--bg-tertiary)] rounded-full h-2">
            <div
              className="bg-[var(--color-primary)] h-2 rounded-full transition-all duration-300"
              style={{ width: `${progressState.progress}%` }}
            />
          </div>
        </div>
      )}

      {/* Validation Results */}
      {validationResult && (
        <div className="bg-[var(--color-success)]/10 border border-[var(--color-success)]/20 rounded-lg p-4">
          <h3 className="font-semibold text-[var(--color-success)] mb-2">Validation Successful!</h3>
          <div className="space-y-2 text-sm">
            <p>Total records: {validationResult.total_records}</p>
            <p>Valid records: {validationResult.valid_records}</p>
            {validationResult.invalid_records > 0 && (
              <p className="text-[var(--color-warning)]">
                Invalid records: {validationResult.invalid_records}
              </p>
            )}
            {validationResult.warnings && validationResult.warnings.length > 0 && (
              <div className="mt-2">
                <p className="font-medium text-[var(--color-warning)]">Warnings:</p>
                <ul className="list-disc list-inside">
                  {validationResult.warnings.map((warning, index) => (
                    <li key={index} className="text-[var(--color-warning)]">
                      {typeof warning === 'string' ? warning : JSON.stringify(warning)}
                    </li>
                  ))}
                </ul>
              </div>
            )}
          </div>
        </div>
      )}

      {/* Error */}
      {error && (
        <div className="bg-[var(--color-error)]/10 border border-[var(--color-error)]/20 rounded-lg p-4">
          <p className="text-[var(--color-error)]">{error}</p>
        </div>
      )}

      {/* Actions */}
      <div className="flex flex-col sm:flex-row justify-end gap-3 sm:gap-0">{/* Removed back button */}

        {selectedFile && !showInventoryStep && (
          <div className="flex items-center justify-center px-4 py-2 bg-[var(--bg-secondary)] rounded-lg">
            {isValidating ? (
              <>
                <div className="animate-spin rounded-full h-4 w-4 border-b-2 border-[var(--color-primary)] mr-2"></div>
                <span className="text-sm text-[var(--text-secondary)]">Procesando automáticamente...</span>
              </>
            ) : validationResult ? (
              <>
                <svg className="w-4 h-4 text-[var(--color-success)] mr-2" fill="none" stroke="currentColor" viewBox="0 0 24 24">
                  <path strokeLinecap="round" strokeLinejoin="round" strokeWidth={2} d="M5 13l4 4L19 7" />
                </svg>
                <span className="text-sm text-[var(--color-success)]">Archivo procesado exitosamente</span>
              </>
            ) : null}
          </div>
        )}
      </div>
    </div>
  );
};