// Smart Environmental & Civil Engineering Calculators
// Comprehensive calculation library with exception handling

interface CalculationResult {
  value: number;
  unit: string;
  category: string;
  recommendation?: string;
  confidence: number;
  warnings?: string[];
}

interface WaterQualityParams {
  pH?: number;
  bod?: number;
  cod?: number;
  tds?: number;
  turbidity?: number;
  chloride?: number;
  hardness?: number;
  temperature?: number;
}

interface AirQualityParams {
  pm25?: number;
  pm10?: number;
  so2?: number;
  no2?: number;
  co?: number;
  o3?: number;
  temperature?: number;
  humidity?: number;
}

interface SoilParams {
  ph?: number;
  nitrogen?: number;
  phosphorus?: number;
  potassium?: number;
  organicCarbon?: number;
  moisture?: number;
  electricalConductivity?: number;
}

class SmartCalculators {
  
  // Water Quality Analysis
  calculateWaterQuality(params: WaterQualityParams): CalculationResult[] {
    try {
      const results: CalculationResult[] = [];
      const warnings: string[] = [];

      // Validate inputs
      this.validateNumericParams(params, 'Water Quality');

      // pH Analysis
      if (params.pH !== undefined) {
        const phResult = this.analyzePH(params.pH);
        results.push(phResult);
        if (phResult.warnings) warnings.push(...phResult.warnings);
      }

      // BOD Analysis
      if (params.bod !== undefined) {
        const bodResult = this.analyzeBOD(params.bod);
        results.push(bodResult);
        if (bodResult.warnings) warnings.push(...bodResult.warnings);
      }

      // COD Analysis
      if (params.cod !== undefined) {
        const codResult = this.analyzeCOD(params.cod);
        results.push(codResult);
        if (codResult.warnings) warnings.push(...codResult.warnings);
      }

      // TDS Analysis
      if (params.tds !== undefined) {
        const tdsResult = this.analyzeTDS(params.tds);
        results.push(tdsResult);
        if (tdsResult.warnings) warnings.push(...tdsResult.warnings);
      }

      // Overall Water Quality Index
      if (results.length > 0) {
        const wqiResult = this.calculateWQI(params);
        results.push(wqiResult);
      }

      return results;
    } catch (error) {
      throw new Error(`Water quality calculation failed: ${error instanceof Error ? error.message : 'Unknown error'}`);
    }
  }

  // Air Quality Analysis
  calculateAirQuality(params: AirQualityParams): CalculationResult[] {
    try {
      const results: CalculationResult[] = [];
      
      this.validateNumericParams(params, 'Air Quality');

      // PM2.5 Analysis
      if (params.pm25 !== undefined) {
        results.push(this.analyzePM25(params.pm25));
      }

      // PM10 Analysis
      if (params.pm10 !== undefined) {
        results.push(this.analyzePM10(params.pm10));
      }

      // Overall AQI
      if (params.pm25 !== undefined || params.pm10 !== undefined) {
        const aqiResult = this.calculateAQI(params);
        results.push(aqiResult);
      }

      return results;
    } catch (error) {
      throw new Error(`Air quality calculation failed: ${error instanceof Error ? error.message : 'Unknown error'}`);
    }
  }

  // Soil Quality Analysis
  calculateSoilQuality(params: SoilParams): CalculationResult[] {
    try {
      const results: CalculationResult[] = [];
      
      this.validateNumericParams(params, 'Soil Quality');

      // Soil pH Analysis
      if (params.ph !== undefined) {
        results.push(this.analyzeSoilPH(params.ph));
      }

      // NPK Analysis
      if (params.nitrogen !== undefined || params.phosphorus !== undefined || params.potassium !== undefined) {
        results.push(this.analyzeNPK(params));
      }

      // Soil Health Index
      const soilHealthIndex = this.calculateSoilHealthIndex(params);
      results.push(soilHealthIndex);

      return results;
    } catch (error) {
      throw new Error(`Soil quality calculation failed: ${error instanceof Error ? error.message : 'Unknown error'}`);
    }
  }

  // NDVI Calculation
  calculateNDVI(redBand: number, nirBand: number): CalculationResult {
    try {
      if (redBand === undefined || nirBand === undefined) {
        throw new Error('Red and NIR band values are required for NDVI calculation');
      }

      if (redBand < 0 || nirBand < 0) {
        throw new Error('Band values cannot be negative');
      }

      if (redBand + nirBand === 0) {
        throw new Error('Cannot calculate NDVI: sum of bands is zero');
      }

      const ndvi = (nirBand - redBand) / (nirBand + redBand);
      
      let category = 'Unknown';
      let recommendation = '';
      let confidence = 85;

      if (ndvi < 0) {
        category = 'Water/Snow';
        recommendation = 'Indicates water bodies or snow-covered areas';
      } else if (ndvi < 0.2) {
        category = 'Bare Soil/Rock';
        recommendation = 'Low vegetation coverage, consider soil conservation measures';
      } else if (ndvi < 0.5) {
        category = 'Sparse Vegetation';
        recommendation = 'Moderate vegetation, suitable for grassland or agricultural areas';
      } else if (ndvi < 0.8) {
        category = 'Dense Vegetation';
        recommendation = 'Healthy vegetation coverage, good for forest or agricultural productivity';
      } else {
        category = 'Very Dense Vegetation';
        recommendation = 'Excellent vegetation health, optimal growing conditions';
      }

      return {
        value: parseFloat(ndvi.toFixed(4)),
        unit: 'index',
        category,
        recommendation,
        confidence,
        warnings: ndvi < 0.1 ? ['Very low vegetation coverage detected'] : undefined
      };
    } catch (error) {
      throw new Error(`NDVI calculation failed: ${error instanceof Error ? error.message : 'Unknown error'}`);
    }
  }

  // Load Estimation for Structures
  calculateLoadEstimation(params: {
    deadLoad?: number;
    liveLoad?: number;
    windLoad?: number;
    seismicLoad?: number;
    structureType?: string;
  }): CalculationResult {
    try {
      this.validateNumericParams(params, 'Load Estimation');

      const { deadLoad = 0, liveLoad = 0, windLoad = 0, seismicLoad = 0, structureType = 'general' } = params;

      // Load combinations as per IS 875
      const combinations = [
        1.5 * (deadLoad + liveLoad), // Basic combination
        1.2 * (deadLoad + liveLoad + windLoad), // Wind combination
        1.2 * (deadLoad + liveLoad + seismicLoad), // Seismic combination
        0.9 * deadLoad + 1.5 * windLoad, // Wind uplift
      ];

      const designLoad = Math.max(...combinations);
      
      let recommendation = '';
      const safetyFactor = designLoad / (deadLoad + liveLoad || 1);
      
      if (safetyFactor > 2.5) {
        recommendation = 'Over-designed structure, consider optimization';
      } else if (safetyFactor > 1.5) {
        recommendation = 'Safe design with adequate safety margin';
      } else {
        recommendation = 'Consider increasing safety factors or reviewing design';
      }

      return {
        value: parseFloat(designLoad.toFixed(2)),
        unit: 'kN',
        category: 'Structural Load',
        recommendation,
        confidence: 90,
        warnings: safetyFactor < 1.5 ? ['Low safety factor detected'] : undefined
      };
    } catch (error) {
      throw new Error(`Load estimation failed: ${error instanceof Error ? error.message : 'Unknown error'}`);
    }
  }

  // Stormwater Management
  calculateStormwaterRunoff(params: {
    area?: number;
    rainfallIntensity?: number;
    runoffCoefficient?: number;
    timeOfConcentration?: number;
  }): CalculationResult {
    try {
      this.validateNumericParams(params, 'Stormwater');

      const { area, rainfallIntensity, runoffCoefficient = 0.5, timeOfConcentration } = params;

      if (!area || !rainfallIntensity) {
        throw new Error('Area and rainfall intensity are required for stormwater calculation');
      }

      if (area <= 0 || rainfallIntensity <= 0) {
        throw new Error('Area and rainfall intensity must be positive values');
      }

      if (runoffCoefficient < 0 || runoffCoefficient > 1) {
        throw new Error('Runoff coefficient must be between 0 and 1');
      }

      // Rational method: Q = CiA
      const runoff = runoffCoefficient * rainfallIntensity * area;

      let recommendation = '';
      if (runoffCoefficient > 0.8) {
        recommendation = 'High runoff coefficient - consider implementing green infrastructure';
      } else if (runoffCoefficient > 0.5) {
        recommendation = 'Moderate runoff - adequate drainage system required';
      } else {
        recommendation = 'Low runoff coefficient - natural infiltration is significant';
      }

      return {
        value: parseFloat(runoff.toFixed(2)),
        unit: 'm³/hr',
        category: 'Stormwater Runoff',
        recommendation,
        confidence: 85,
        warnings: runoff > 1000 ? ['High runoff volume - flood risk assessment recommended'] : undefined
      };
    } catch (error) {
      throw new Error(`Stormwater calculation failed: ${error instanceof Error ? error.message : 'Unknown error'}`);
    }
  }

  // Noise Level Analysis
  calculateNoiseLevel(params: {
    soundLevels?: number[];
    timeWeighted?: boolean;
    zoneType?: 'residential' | 'commercial' | 'industrial' | 'silent';
  }): CalculationResult {
    try {
      const { soundLevels, timeWeighted = false, zoneType = 'residential' } = params;

      if (!soundLevels || soundLevels.length === 0) {
        throw new Error('Sound level measurements are required');
      }

      soundLevels.forEach((level, index) => {
        if (typeof level !== 'number' || level < 0 || level > 150) {
          throw new Error(`Invalid sound level at position ${index + 1}: must be between 0-150 dB`);
        }
      });

      // Calculate equivalent noise level
      let leq: number;
      if (timeWeighted) {
        // Time-weighted average
        const sum = soundLevels.reduce((acc, level) => acc + Math.pow(10, level / 10), 0);
        leq = 10 * Math.log10(sum / soundLevels.length);
      } else {
        // Simple average
        leq = soundLevels.reduce((acc, level) => acc + level, 0) / soundLevels.length;
      }

      // Noise limits as per CPCB norms
      const limits = {
        residential: { day: 55, night: 45 },
        commercial: { day: 65, night: 55 },
        industrial: { day: 75, night: 70 },
        silent: { day: 50, night: 40 }
      };

      const limit = limits[zoneType];
      let recommendation = '';
      let warnings: string[] = [];

      if (leq > limit.day) {
        warnings.push(`Exceeds daytime noise limit for ${zoneType} zone (${limit.day} dB)`);
        recommendation = 'Noise control measures required - consider sound barriers or source control';
      } else if (leq > limit.night) {
        warnings.push(`Exceeds nighttime noise limit for ${zoneType} zone (${limit.night} dB)`);
        recommendation = 'Moderate noise levels - monitor during night hours';
      } else {
        recommendation = 'Noise levels within acceptable limits';
      }

      return {
        value: parseFloat(leq.toFixed(1)),
        unit: 'dB(A)',
        category: 'Noise Level',
        recommendation,
        confidence: 88,
        warnings: warnings.length > 0 ? warnings : undefined
      };
    } catch (error) {
      throw new Error(`Noise level calculation failed: ${error instanceof Error ? error.message : 'Unknown error'}`);
    }
  }

  // Private helper methods
  private validateNumericParams(params: any, calculationType: string): void {
    for (const [key, value] of Object.entries(params)) {
      if (value !== undefined && typeof value !== 'number') {
        throw new Error(`${calculationType}: Parameter '${key}' must be a number`);
      }
      if (value !== undefined && (isNaN(value) || !isFinite(value))) {
        throw new Error(`${calculationType}: Parameter '${key}' must be a valid finite number`);
      }
    }
  }

  private analyzePH(ph: number): CalculationResult {
    let category = '';
    let recommendation = '';
    const warnings: string[] = [];

    if (ph < 0 || ph > 14) {
      throw new Error('pH must be between 0 and 14');
    }

    if (ph < 6.5) {
      category = 'Acidic';
      recommendation = 'Consider pH adjustment with lime or alkaline treatment';
      if (ph < 4) warnings.push('Highly acidic - may be corrosive');
    } else if (ph > 8.5) {
      category = 'Alkaline';
      recommendation = 'Consider pH adjustment with acid treatment';
      if (ph > 11) warnings.push('Highly alkaline - may be harmful');
    } else {
      category = 'Neutral';
      recommendation = 'pH within acceptable range for most applications';
    }

    return {
      value: ph,
      unit: 'pH units',
      category,
      recommendation,
      confidence: 95,
      warnings: warnings.length > 0 ? warnings : undefined
    };
  }

  private analyzeBOD(bod: number): CalculationResult {
    if (bod < 0) throw new Error('BOD cannot be negative');

    let category = '';
    let recommendation = '';
    const warnings: string[] = [];

    if (bod < 3) {
      category = 'Clean Water';
      recommendation = 'Excellent water quality';
    } else if (bod < 6) {
      category = 'Slightly Polluted';
      recommendation = 'Good water quality with minor treatment needed';
    } else if (bod < 30) {
      category = 'Moderately Polluted';
      recommendation = 'Secondary treatment required';
      warnings.push('Moderate pollution detected');
    } else {
      category = 'Heavily Polluted';
      recommendation = 'Advanced treatment required before discharge';
      warnings.push('High pollution levels - immediate action needed');
    }

    return {
      value: bod,
      unit: 'mg/L',
      category,
      recommendation,
      confidence: 90,
      warnings: warnings.length > 0 ? warnings : undefined
    };
  }

  private analyzeCOD(cod: number): CalculationResult {
    if (cod < 0) throw new Error('COD cannot be negative');

    let category = '';
    let recommendation = '';

    if (cod < 10) {
      category = 'Clean Water';
      recommendation = 'Excellent water quality';
    } else if (cod < 50) {
      category = 'Lightly Polluted';
      recommendation = 'Minor treatment may be required';
    } else if (cod < 150) {
      category = 'Moderately Polluted';
      recommendation = 'Treatment required before discharge';
    } else {
      category = 'Heavily Polluted';
      recommendation = 'Advanced treatment necessary';
    }

    return {
      value: cod,
      unit: 'mg/L',
      category,
      recommendation,
      confidence: 90
    };
  }

  private analyzeTDS(tds: number): CalculationResult {
    if (tds < 0) throw new Error('TDS cannot be negative');

    let category = '';
    let recommendation = '';

    if (tds < 500) {
      category = 'Excellent';
      recommendation = 'Suitable for drinking and most applications';
    } else if (tds < 1000) {
      category = 'Good';
      recommendation = 'Generally acceptable for most uses';
    } else if (tds < 2000) {
      category = 'Fair';
      recommendation = 'May require treatment for drinking water';
    } else {
      category = 'Poor';
      recommendation = 'Treatment required before use';
    }

    return {
      value: tds,
      unit: 'mg/L',
      category,
      recommendation,
      confidence: 88
    };
  }

  private calculateWQI(params: WaterQualityParams): CalculationResult {
    let wqi = 100;
    let factors = 0;

    // Simplified WQI calculation
    if (params.pH !== undefined) {
      const phScore = params.pH >= 6.5 && params.pH <= 8.5 ? 100 : Math.max(0, 100 - Math.abs(7 - params.pH) * 20);
      wqi = (wqi * factors + phScore) / (factors + 1);
      factors++;
    }

    if (params.bod !== undefined) {
      const bodScore = Math.max(0, 100 - params.bod * 3);
      wqi = (wqi * factors + bodScore) / (factors + 1);
      factors++;
    }

    let category = '';
    if (wqi > 80) category = 'Excellent';
    else if (wqi > 60) category = 'Good';
    else if (wqi > 40) category = 'Fair';
    else category = 'Poor';

    return {
      value: parseFloat(wqi.toFixed(1)),
      unit: 'WQI',
      category: `Water Quality: ${category}`,
      recommendation: wqi > 60 ? 'Water quality is acceptable' : 'Water treatment recommended',
      confidence: 85
    };
  }

  private analyzePM25(pm25: number): CalculationResult {
    if (pm25 < 0) throw new Error('PM2.5 cannot be negative');

    let category = '';
    let recommendation = '';
    const warnings: string[] = [];

    if (pm25 <= 12) {
      category = 'Good';
      recommendation = 'Air quality is satisfactory';
    } else if (pm25 <= 35.4) {
      category = 'Moderate';
      recommendation = 'Acceptable for most people';
    } else if (pm25 <= 55.4) {
      category = 'Unhealthy for Sensitive Groups';
      recommendation = 'Sensitive individuals should limit outdoor exposure';
      warnings.push('Sensitive groups should take precautions');
    } else {
      category = 'Unhealthy';
      recommendation = 'Everyone should limit outdoor activities';
      warnings.push('Poor air quality - health advisory in effect');
    }

    return {
      value: pm25,
      unit: 'μg/m³',
      category,
      recommendation,
      confidence: 92,
      warnings: warnings.length > 0 ? warnings : undefined
    };
  }

  private analyzePM10(pm10: number): CalculationResult {
    if (pm10 < 0) throw new Error('PM10 cannot be negative');

    let category = '';
    let recommendation = '';

    if (pm10 <= 54) {
      category = 'Good';
      recommendation = 'Air quality is satisfactory';
    } else if (pm10 <= 154) {
      category = 'Moderate';
      recommendation = 'Acceptable for most people';
    } else if (pm10 <= 254) {
      category = 'Unhealthy for Sensitive Groups';
      recommendation = 'Sensitive individuals should limit outdoor exposure';
    } else {
      category = 'Unhealthy';
      recommendation = 'Everyone should limit outdoor activities';
    }

    return {
      value: pm10,
      unit: 'μg/m³',
      category,
      recommendation,
      confidence: 90
    };
  }

  private calculateAQI(params: AirQualityParams): CalculationResult {
    let maxAqi = 0;
    let dominantPollutant = '';

    if (params.pm25 !== undefined) {
      const pm25Aqi = this.convertToAQI(params.pm25, 'PM2.5');
      if (pm25Aqi > maxAqi) {
        maxAqi = pm25Aqi;
        dominantPollutant = 'PM2.5';
      }
    }

    if (params.pm10 !== undefined) {
      const pm10Aqi = this.convertToAQI(params.pm10, 'PM10');
      if (pm10Aqi > maxAqi) {
        maxAqi = pm10Aqi;
        dominantPollutant = 'PM10';
      }
    }

    let category = '';
    if (maxAqi <= 50) category = 'Good';
    else if (maxAqi <= 100) category = 'Moderate';
    else if (maxAqi <= 150) category = 'Unhealthy for Sensitive Groups';
    else if (maxAqi <= 200) category = 'Unhealthy';
    else category = 'Very Unhealthy';

    return {
      value: Math.round(maxAqi),
      unit: 'AQI',
      category: `Air Quality: ${category}`,
      recommendation: `Dominant pollutant: ${dominantPollutant}. ${category === 'Good' ? 'Air quality is acceptable' : 'Consider limiting outdoor activities'}`,
      confidence: 88
    };
  }

  private convertToAQI(concentration: number, pollutant: string): number {
    // Simplified AQI calculation based on EPA standards
    const breakpoints = {
      'PM2.5': [
        [0, 12, 0, 50],
        [12.1, 35.4, 51, 100],
        [35.5, 55.4, 101, 150],
        [55.5, 150.4, 151, 200]
      ],
      'PM10': [
        [0, 54, 0, 50],
        [55, 154, 51, 100],
        [155, 254, 101, 150],
        [255, 354, 151, 200]
      ]
    };

    const points = breakpoints[pollutant as keyof typeof breakpoints];
    if (!points) return 0;

    for (const [cLow, cHigh, aqiLow, aqiHigh] of points) {
      if (concentration >= cLow && concentration <= cHigh) {
        return ((aqiHigh - aqiLow) / (cHigh - cLow)) * (concentration - cLow) + aqiLow;
      }
    }

    return points[points.length - 1][3]; // Return max AQI if above all ranges
  }

  private analyzeSoilPH(ph: number): CalculationResult {
    if (ph < 0 || ph > 14) throw new Error('Soil pH must be between 0 and 14');

    let category = '';
    let recommendation = '';

    if (ph < 5.5) {
      category = 'Highly Acidic';
      recommendation = 'Lime application recommended to raise pH';
    } else if (ph < 6.5) {
      category = 'Moderately Acidic';
      recommendation = 'Consider lime application for most crops';
    } else if (ph < 7.5) {
      category = 'Neutral';
      recommendation = 'Optimal pH range for most crops';
    } else if (ph < 8.5) {
      category = 'Slightly Alkaline';
      recommendation = 'Generally acceptable, monitor nutrient availability';
    } else {
      category = 'Highly Alkaline';
      recommendation = 'Consider sulfur application to lower pH';
    }

    return {
      value: ph,
      unit: 'pH units',
      category,
      recommendation,
      confidence: 94
    };
  }

  private analyzeNPK(params: SoilParams): CalculationResult {
    const { nitrogen = 0, phosphorus = 0, potassium = 0 } = params;

    if (nitrogen < 0 || phosphorus < 0 || potassium < 0) {
      throw new Error('NPK values cannot be negative');
    }

    // NPK rating based on typical soil test values
    const nRating = nitrogen > 40 ? 'High' : nitrogen > 20 ? 'Medium' : 'Low';
    const pRating = phosphorus > 25 ? 'High' : phosphorus > 15 ? 'Medium' : 'Low';
    const kRating = potassium > 150 ? 'High' : potassium > 100 ? 'Medium' : 'Low';

    const totalNPK = nitrogen + phosphorus + potassium;
    
    let recommendation = `N: ${nRating}, P: ${pRating}, K: ${kRating}. `;
    
    if (nRating === 'Low') recommendation += 'Nitrogen fertilization recommended. ';
    if (pRating === 'Low') recommendation += 'Phosphorus supplementation needed. ';
    if (kRating === 'Low') recommendation += 'Potassium application suggested.';

    return {
      value: parseFloat(totalNPK.toFixed(1)),
      unit: 'kg/ha',
      category: 'NPK Analysis',
      recommendation: recommendation.trim(),
      confidence: 87
    };
  }

  private calculateSoilHealthIndex(params: SoilParams): CalculationResult {
    let score = 0;
    let factors = 0;

    // pH contribution
    if (params.ph !== undefined) {
      const phScore = params.ph >= 6.0 && params.ph <= 7.5 ? 100 : Math.max(0, 100 - Math.abs(6.75 - params.ph) * 20);
      score += phScore;
      factors++;
    }

    // Organic carbon contribution
    if (params.organicCarbon !== undefined) {
      const ocScore = Math.min(100, params.organicCarbon * 20);
      score += ocScore;
      factors++;
    }

    // Moisture contribution
    if (params.moisture !== undefined) {
      const moistureScore = params.moisture >= 15 && params.moisture <= 25 ? 100 : Math.max(0, 100 - Math.abs(20 - params.moisture) * 5);
      score += moistureScore;
      factors++;
    }

    const healthIndex = factors > 0 ? score / factors : 50;

    let category = '';
    if (healthIndex > 80) category = 'Excellent';
    else if (healthIndex > 60) category = 'Good';
    else if (healthIndex > 40) category = 'Fair';
    else category = 'Poor';

    return {
      value: parseFloat(healthIndex.toFixed(1)),
      unit: 'index',
      category: `Soil Health: ${category}`,
      recommendation: healthIndex > 60 ? 'Soil health is adequate' : 'Soil improvement measures recommended',
      confidence: 83
    };
  }
}

export const smartCalculators = new SmartCalculators();
export { CalculationResult, WaterQualityParams, AirQualityParams, SoilParams };