import React, { useState, useRef, useEffect } from 'react';
import { Upload, Brain, CheckCircle, AlertCircle, Download, FileText, Activity, TrendingUp } from 'lucide-react';
import { Button, Card, Badge } from '../../../ui';
import { OnboardingStepProps } from '../OnboardingWizard';

type ProcessingStage = 'upload' | 'validating' | 'analyzing' | 'completed' | 'error';

interface ProcessingResult {
  // Validation data
  is_valid: boolean;
  total_records: number;
  unique_products: number;
  product_list: string[];
  validation_errors: string[];
  validation_warnings: string[];
  summary: {
    date_range: string;
    total_sales: number;
    average_daily_sales: number;
  };
  // Analysis data
  productsIdentified: number;
  categoriesDetected: number;
  businessModel: string;
  confidenceScore: number;
  recommendations: string[];
}

// Unified mock service that handles both validation and analysis
const mockDataProcessingService = {
  processFile: async (file: File, onProgress: (progress: number, stage: string, message: string) => void) => {
    return new Promise<ProcessingResult>((resolve, reject) => {
      let progress = 0;
      
      const stages = [
        { threshold: 20, stage: 'validating', message: 'Validando estructura del archivo...' },
        { threshold: 40, stage: 'validating', message: 'Verificando integridad de datos...' },
        { threshold: 60, stage: 'analyzing', message: 'Identificando productos únicos...' },
        { threshold: 80, stage: 'analyzing', message: 'Analizando patrones de venta...' },
        { threshold: 90, stage: 'analyzing', message: 'Generando recomendaciones con IA...' },
        { threshold: 100, stage: 'completed', message: 'Procesamiento completado' }
      ];

      const interval = setInterval(() => {
        if (progress < 100) {
          progress += 10;
          const currentStage = stages.find(s => progress <= s.threshold);
          if (currentStage) {
            onProgress(progress, currentStage.stage, currentStage.message);
          }
        }
        
        if (progress >= 100) {
          clearInterval(interval);
          // Return combined validation + analysis results
          resolve({
            // Validation results
            is_valid: true,
            total_records: Math.floor(Math.random() * 1000) + 100,
            unique_products: Math.floor(Math.random() * 50) + 10,
            product_list: ['Pan Integral', 'Croissant', 'Baguette', 'Empanadas', 'Pan de Centeno', 'Medialunas'],
            validation_errors: [],
            validation_warnings: [
              'Algunas fechas podrían tener formato inconsistente',
              '3 productos sin categoría definida'
            ],
            summary: {
              date_range: '2024-01-01 to 2024-12-31',
              total_sales: 15420.50,
              average_daily_sales: 42.25
            },
            // Analysis results
            productsIdentified: 15,
            categoriesDetected: 4,
            businessModel: 'artisan',
            confidenceScore: 94,
            recommendations: [
              'Se detectó un modelo de panadería artesanal con producción propia',
              'Los productos más vendidos son panes tradicionales y bollería',
              'Recomendamos categorizar el inventario por tipo de producto',
              'Considera ampliar la línea de productos de repostería'
            ]
          });
        }
      }, 400);
    });
  }
};

export const DataProcessingStep: React.FC<OnboardingStepProps> = ({
  data,
  onDataChange,
  onNext,
  onPrevious,
  isFirstStep,
  isLastStep
}) => {
  const [stage, setStage] = useState<ProcessingStage>(data.processingStage || 'upload');
  const [uploadedFile, setUploadedFile] = useState<File | null>(data.files?.salesData || null);
  const [progress, setProgress] = useState(data.processingProgress || 0);
  const [currentMessage, setCurrentMessage] = useState(data.currentMessage || '');
  const [results, setResults] = useState<ProcessingResult | null>(data.processingResults || null);
  const [dragActive, setDragActive] = useState(false);
  
  const fileInputRef = useRef<HTMLInputElement>(null);

  useEffect(() => {
    // Update parent data when state changes
    onDataChange({
      ...data,
      processingStage: stage,
      processingProgress: progress,
      currentMessage: currentMessage,
      processingResults: results,
      files: {
        ...data.files,
        salesData: uploadedFile
      }
    });
  }, [stage, progress, currentMessage, results, uploadedFile]);

  const handleDragOver = (e: React.DragEvent) => {
    e.preventDefault();
    setDragActive(true);
  };

  const handleDragLeave = (e: React.DragEvent) => {
    e.preventDefault();
    setDragActive(false);
  };

  const handleDrop = (e: React.DragEvent) => {
    e.preventDefault();
    setDragActive(false);
    
    const files = Array.from(e.dataTransfer.files);
    if (files.length > 0) {
      handleFileUpload(files[0]);
    }
  };

  const handleFileSelect = (e: React.ChangeEvent<HTMLInputElement>) => {
    if (e.target.files && e.target.files.length > 0) {
      handleFileUpload(e.target.files[0]);
    }
  };

  const handleFileUpload = async (file: File) => {
    // Validate file type
    const validExtensions = ['.csv', '.xlsx', '.xls'];
    const fileExtension = file.name.toLowerCase().substring(file.name.lastIndexOf('.'));
    
    if (!validExtensions.includes(fileExtension)) {
      alert('Formato de archivo no válido. Usa CSV o Excel (.xlsx, .xls)');
      return;
    }

    // Check file size (max 10MB)
    if (file.size > 10 * 1024 * 1024) {
      alert('El archivo es demasiado grande. Máximo 10MB permitido.');
      return;
    }

    setUploadedFile(file);
    setStage('validating');
    setProgress(0);

    try {
      const result = await mockDataProcessingService.processFile(
        file,
        (newProgress, newStage, message) => {
          setProgress(newProgress);
          setStage(newStage as ProcessingStage);
          setCurrentMessage(message);
        }
      );
      
      setResults(result);
      setStage('completed');
    } catch (error) {
      console.error('Processing error:', error);
      setStage('error');
      setCurrentMessage('Error en el procesamiento de datos');
    }
  };

  const downloadTemplate = () => {
    const csvContent = `fecha,producto,cantidad,precio_unitario,precio_total,cliente,canal_venta
2024-01-15,Pan Integral,5,2.50,12.50,Cliente A,Tienda
2024-01-15,Croissant,3,1.80,5.40,Cliente B,Online
2024-01-15,Baguette,2,3.00,6.00,Cliente C,Tienda
2024-01-16,Pan de Centeno,4,2.80,11.20,Cliente A,Tienda
2024-01-16,Empanadas,6,4.50,27.00,Cliente D,Delivery`;

    const blob = new Blob([csvContent], { type: 'text/csv;charset=utf-8;' });
    const link = document.createElement('a');
    const url = URL.createObjectURL(blob);
    
    link.setAttribute('href', url);
    link.setAttribute('download', 'plantilla_ventas.csv');
    link.style.visibility = 'hidden';
    
    document.body.appendChild(link);
    link.click();
    document.body.removeChild(link);
  };

  const resetProcess = () => {
    setStage('upload');
    setUploadedFile(null);
    setProgress(0);
    setCurrentMessage('');
    setResults(null);
    if (fileInputRef.current) {
      fileInputRef.current.value = '';
    }
  };

  return (
    <div className="space-y-8">
      {/* Improved Upload Stage */}
      {stage === 'upload' && (
        <>
          <div
            className={`
              border-2 border-dashed rounded-2xl p-16 text-center transition-all duration-300 cursor-pointer group
              ${
                dragActive
                  ? 'border-[var(--color-primary)] bg-[var(--color-primary)]/10 scale-[1.02] shadow-lg'
                  : uploadedFile
                    ? 'border-[var(--color-success)] bg-[var(--color-success)]/10 shadow-md'
                    : 'border-[var(--border-secondary)] hover:border-[var(--color-primary)] hover:bg-[var(--bg-secondary)]/30 hover:shadow-lg'
              }
            `}
            onDragOver={handleDragOver}
            onDragLeave={handleDragLeave}
            onDrop={handleDrop}
            onClick={() => fileInputRef.current?.click()}
          >
            <input
              ref={fileInputRef}
              type="file"
              accept=".csv,.xlsx,.xls"
              onChange={handleFileSelect}
              className="hidden"
            />
            
            <div className="space-y-8">
              {uploadedFile ? (
                <>
                  <div className="w-20 h-20 bg-[var(--color-success)]/10 rounded-full flex items-center justify-center mx-auto">
                    <CheckCircle className="w-10 h-10 text-[var(--color-success)]" />
                  </div>
                  <div>
                    <h3 className="text-3xl font-bold text-[var(--color-success)] mb-3">
                      ¡Perfecto! Archivo listo
                    </h3>
                    <div className="bg-[var(--bg-secondary)] rounded-lg p-4 inline-block">
                      <p className="text-[var(--text-primary)] font-medium text-lg">
                        📄 {uploadedFile.name}
                      </p>
                      <p className="text-[var(--text-secondary)] text-sm mt-1">
                        {(uploadedFile.size / 1024 / 1024).toFixed(2)} MB • Listo para procesar
                      </p>
                    </div>
                  </div>
                </>
              ) : (
                <>
                  <div className="w-20 h-20 bg-[var(--color-primary)]/10 rounded-full flex items-center justify-center mx-auto group-hover:scale-110 transition-transform duration-300">
                    <Upload className="w-10 h-10 text-[var(--color-primary)]" />
                  </div>
                  <div>
                    <h3 className="text-3xl font-bold text-[var(--text-primary)] mb-4">
                      Sube tu historial de ventas
                    </h3>
                    <p className="text-[var(--text-secondary)] text-xl leading-relaxed max-w-md mx-auto">
                      Arrastra y suelta tu archivo aquí, o <span className="text-[var(--color-primary)] font-semibold">haz clic para seleccionar</span>
                    </p>
                  </div>
                  
                  {/* Visual indicators */}
                  <div className="flex justify-center space-x-8 mt-8">
                    <div className="text-center">
                      <div className="w-12 h-12 bg-green-100 rounded-lg flex items-center justify-center mx-auto mb-2">
                        <span className="text-2xl">📊</span>
                      </div>
                      <span className="text-sm text-[var(--text-secondary)]">CSV</span>
                    </div>
                    <div className="text-center">
                      <div className="w-12 h-12 bg-green-100 rounded-lg flex items-center justify-center mx-auto mb-2">
                        <span className="text-2xl">📈</span>
                      </div>
                      <span className="text-sm text-[var(--text-secondary)]">Excel</span>
                    </div>
                    <div className="text-center">
                      <div className="w-12 h-12 bg-blue-100 rounded-lg flex items-center justify-center mx-auto mb-2">
                        <span className="text-2xl">⚡</span>
                      </div>
                      <span className="text-sm text-[var(--text-secondary)]">Hasta 10MB</span>
                    </div>
                  </div>
                </>
              )}
            </div>

            <div className="mt-10 px-4 py-2 bg-[var(--bg-secondary)]/50 rounded-lg text-sm text-[var(--text-tertiary)] inline-block">
              💡 Formatos aceptados: CSV, Excel (XLSX, XLS) • Tamaño máximo: 10MB
            </div>
          </div>

          {/* Improved Template Download Section */}
          <div className="bg-gradient-to-r from-[var(--color-info)]/5 to-[var(--color-primary)]/5 rounded-xl p-6 border border-[var(--color-info)]/20">
            <div className="flex flex-col md:flex-row items-center space-y-4 md:space-y-0 md:space-x-6">
              <div className="w-16 h-16 rounded-full bg-[var(--color-info)]/10 flex items-center justify-center flex-shrink-0">
                <Download className="w-8 h-8 text-[var(--color-info)]" />
              </div>
              <div className="flex-1 text-center md:text-left">
                <h4 className="text-lg font-semibold text-[var(--text-primary)] mb-2">
                  ¿Necesitas ayuda con el formato?
                </h4>
                <p className="text-[var(--text-secondary)] mb-4">
                  Descarga nuestra plantilla Excel con ejemplos y formato correcto para tus datos de ventas
                </p>
                <Button
                  onClick={downloadTemplate}
                  className="bg-[var(--color-info)] hover:bg-[var(--color-info)]/90 text-white shadow-lg"
                >
                  <Download className="w-4 h-4 mr-2" />
                  Descargar Plantilla Gratuita
                </Button>
              </div>
            </div>
          </div>
        </>
      )}

      {/* Processing Stages */}
      {(stage === 'validating' || stage === 'analyzing') && (
        <Card className="p-8">
          <div className="text-center">
            <div className="relative mb-8">
              <div className={`w-20 h-20 rounded-full flex items-center justify-center mx-auto mb-6 ${
                stage === 'validating' 
                  ? 'bg-[var(--color-info)]/10 animate-pulse' 
                  : 'bg-[var(--color-primary)]/10 animate-pulse'
              }`}>
                {stage === 'validating' ? (
                  <FileText className={`w-8 h-8 ${stage === 'validating' ? 'text-[var(--color-info)]' : 'text-[var(--color-primary)]'}`} />
                ) : (
                  <Brain className="w-8 h-8 text-[var(--color-primary)]" />
                )}
              </div>
              
              <h3 className="text-2xl font-semibold text-[var(--text-primary)] mb-2">
                {stage === 'validating' ? 'Validando datos...' : 'Analizando con IA...'}
              </h3>
              <p className="text-[var(--text-secondary)] mb-8">
                {currentMessage}
              </p>
            </div>

            {/* Progress Bar */}
            <div className="mb-8">
              <div className="flex justify-between items-center mb-3">
                <span className="text-sm font-medium text-[var(--text-primary)]">
                  Progreso
                </span>
                <span className="text-sm text-[var(--text-secondary)]">{progress}%</span>
              </div>
              <div className="w-full bg-[var(--bg-secondary)] rounded-full h-3">
                <div
                  className="bg-gradient-to-r from-[var(--color-info)] to-[var(--color-primary)] h-3 rounded-full transition-all duration-500 ease-out"
                  style={{ width: `${progress}%` }}
                />
              </div>
            </div>

            {/* Processing Steps */}
            <div className="grid grid-cols-3 gap-4">
              <div className={`p-4 rounded-lg text-center ${
                progress >= 40 ? 'bg-[var(--color-success)]/10 text-[var(--color-success)]' : 'bg-[var(--bg-secondary)]'
              }`}>
                <FileText className="w-6 h-6 mx-auto mb-2" />
                <span className="text-sm font-medium">Validación</span>
              </div>
              <div className={`p-4 rounded-lg text-center ${
                progress >= 70 ? 'bg-[var(--color-success)]/10 text-[var(--color-success)]' : 'bg-[var(--bg-secondary)]'
              }`}>
                <Brain className="w-6 h-6 mx-auto mb-2" />
                <span className="text-sm font-medium">Análisis IA</span>
              </div>
              <div className={`p-4 rounded-lg text-center ${
                progress >= 100 ? 'bg-[var(--color-success)]/10 text-[var(--color-success)]' : 'bg-[var(--bg-secondary)]'
              }`}>
                <CheckCircle className="w-6 h-6 mx-auto mb-2" />
                <span className="text-sm font-medium">Completo</span>
              </div>
            </div>
          </div>
        </Card>
      )}

      {/* Simplified Results Stage */}
      {stage === 'completed' && results && (
        <div className="space-y-8">
          {/* Success Header */}
          <div className="text-center">
            <div className="w-16 h-16 bg-[var(--color-success)] rounded-full flex items-center justify-center mx-auto mb-6">
              <CheckCircle className="w-8 h-8 text-white" />
            </div>
            <h3 className="text-2xl font-semibold text-[var(--color-success)] mb-3">
              ¡Procesamiento Completado!
            </h3>
            <p className="text-[var(--text-secondary)] max-w-2xl mx-auto">
              Tus datos han sido procesados exitosamente
            </p>
          </div>

          {/* Simple Stats Cards */}
          <div className="grid grid-cols-2 md:grid-cols-4 gap-4">
            <div className="text-center p-4 bg-[var(--color-info)]/10 rounded-lg">
              <p className="text-2xl font-bold text-[var(--color-info)]">{results.total_records}</p>
              <p className="text-sm text-[var(--text-secondary)]">Registros</p>
            </div>
            
            <div className="text-center p-4 bg-[var(--color-primary)]/10 rounded-lg">
              <p className="text-2xl font-bold text-[var(--color-primary)]">{results.productsIdentified}</p>
              <p className="text-sm text-[var(--text-secondary)]">Productos</p>
            </div>
            
            <div className="text-center p-4 bg-[var(--color-success)]/10 rounded-lg">
              <p className="text-2xl font-bold text-[var(--color-success)]">{results.confidenceScore}%</p>
              <p className="text-sm text-[var(--text-secondary)]">Confianza</p>
            </div>
            
            <div className="text-center p-4 bg-[var(--bg-secondary)] rounded-lg">
              <p className="text-lg font-bold text-[var(--text-primary)]">
                {results.businessModel === 'artisan' ? 'Artesanal' : 
                 results.businessModel === 'retail' ? 'Retail' : 'Híbrido'}
              </p>
              <p className="text-sm text-[var(--text-secondary)]">Modelo</p>
            </div>
          </div>
        </div>
      )}

      {/* Error State */}
      {stage === 'error' && (
        <Card className="p-8 text-center">
          <div className="w-16 h-16 bg-[var(--color-error)] rounded-full flex items-center justify-center mx-auto mb-6">
            <AlertCircle className="w-8 h-8 text-white" />
          </div>
          <h3 className="text-xl font-semibold text-[var(--color-error)] mb-3">
            Error en el procesamiento
          </h3>
          <p className="text-[var(--text-secondary)] mb-6">
            {currentMessage}
          </p>
          <Button onClick={resetProcess} variant="outline">
            Intentar nuevamente
          </Button>
        </Card>
      )}
    </div>
  );
};