// Constants for carbon calculations
const EMISSION_FACTOR = 3.206; // tons of CO₂ per ton of fuel
const FUEL_DENSITY = 0.85; // tons per m³ (or metric tons per kiloliter)
const GALLONS_TO_LITERS = 3.78541; // 1 US gallon = 3.78541 liters
const LITERS_TO_CUBIC_METERS = 0.001; // 1 liter = 0.001 m³

// Available currencies
const currencies = {
  USD: { code: 'USD', symbol: '$', rate: 1 },
  EUR: { code: 'EUR', symbol: '€', rate: 0.92 },
  GBP: { code: 'GBP', symbol: '£', rate: 0.79 },
  CHF: { code: 'CHF', symbol: 'CHF', rate: 0.88 },
};

// Format currency
function formatCurrency(amountUSD, currency) {
  if (!currency) {
    currency = currencies.USD;
  }
  
  // Convert USD amount to target currency
  const convertedAmount = amountUSD * currency.rate;
  
  return `${currency.symbol}${convertedAmount.toLocaleString(undefined, {
    minimumFractionDigits: 0,
    maximumFractionDigits: 0,
  })}`;
}

// Get currency by code
function getCurrencyByCode(code) {
  return currencies[code] || currencies.USD;
}

// Calculate trip carbon
function calculateTripCarbon(vesselData, distance, speed, fuelRateLitersPerHour) {
  const tripHours = distance / speed;
  
  // Calculate total fuel consumption in liters
  const fuelConsumptionLiters = fuelRateLitersPerHour * tripHours;
  
  // Convert liters to tons for CO₂ calculation
  const fuelConsumptionTons = (fuelConsumptionLiters * LITERS_TO_CUBIC_METERS) * FUEL_DENSITY;
  
  // Calculate CO₂ emissions
  const fuelRateTonsPerHour = (fuelRateLitersPerHour * LITERS_TO_CUBIC_METERS) * FUEL_DENSITY;
  const emissionsPerNM = (fuelRateTonsPerHour * EMISSION_FACTOR) / speed;
  const totalEmissions = emissionsPerNM * distance;

  return {
    distance,
    duration: tripHours,
    fuelConsumption: Math.round(fuelConsumptionLiters),
    co2Emissions: Number(totalEmissions.toFixed(2))
  };
}

// Calculate carbon from fuel
function calculateCarbonFromFuel(fuelAmount, isGallons = false) {
  // Convert to liters if input is in gallons
  const liters = isGallons ? fuelAmount * GALLONS_TO_LITERS : fuelAmount;
  
  // Convert liters to cubic meters (m³)
  const cubicMeters = liters * LITERS_TO_CUBIC_METERS;
  
  // Convert volume to mass (tons)
  const fuelTons = cubicMeters * FUEL_DENSITY;
  
  // Calculate CO₂ emissions
  const co2Emissions = fuelTons * EMISSION_FACTOR;
  
  return Number(co2Emissions.toFixed(2));
}

// Sample vessel data
const sampleVessel = {
  imo: '1234567',
  vesselName: 'Sample Yacht',
  type: 'Yacht',
  length: 50,
  width: 9,
  estimatedEnginePower: 2250
};

// Default portfolio for fallback
const DEFAULT_PORTFOLIO = {
  id: 1,
  name: "Puffin Maritime Portfolio",
  description: "A curated selection of high-impact carbon removal projects focused on maritime sustainability.",
  projects: [
    {
      id: "dac-1",
      name: "Direct Air Capture",
      description: "Permanent carbon removal through direct air capture technology",
      shortDescription: "Direct air capture in Iceland",
      imageUrl: "https://images.unsplash.com/photo-1553547274-0df401ae03c9",
      pricePerTon: 200,
      location: "Iceland",
      type: "Direct Air Capture",
      verificationStandard: "Verified Carbon Standard",
      impactMetrics: {
        co2Reduced: 1000
      }
    },
    {
      id: "ocean-1",
      name: "Ocean Carbon Removal",
      description: "Enhanced ocean carbon capture through marine permaculture",
      shortDescription: "Marine carbon capture",
      imageUrl: "https://images.unsplash.com/photo-1498623116890-37e912163d5d",
      pricePerTon: 200,
      location: "Global Oceans",
      type: "Ocean-Based",
      verificationStandard: "Gold Standard",
      impactMetrics: {
        co2Reduced: 5000
      }
    }
  ],
  pricePerTon: 200,
  currency: 'USD'
};

// Simplified analytics
const analytics = {
  pageView: function(path) {
    console.log(`Analytics pageView: ${path}`);
  },
  event: function(category, action, label) {
    console.log(`Analytics event: ${category} - ${action} - ${label}`);
  },
  error: function(error, message) {
    console.error(`Analytics error: ${message}`, error);
  }
};

// Create portfolio API call (with fallback to default)
async function getPortfolios() {
  try {
    // In a real implementation, this would be an API call
    // For demo purposes, we'll just return the default portfolio after a small delay
    return new Promise((resolve) => {
      setTimeout(() => resolve([DEFAULT_PORTFOLIO]), 1000);
    });
  } catch (error) {
    console.warn('Failed to fetch portfolios from API, using fallback');
    return [DEFAULT_PORTFOLIO];
  }
}

// Create offset order API call (simulated)
async function createOffsetOrder(portfolioId, tons, dryRun = false) {
  try {
    // Simulate API call
    return new Promise((resolve) => {
      setTimeout(() => {
        resolve({
          id: `order-${Math.floor(Math.random() * 1000000)}`,
          amountCharged: tons * 200 * 100, // in cents
          currency: 'USD',
          tons: tons,
          portfolio: DEFAULT_PORTFOLIO,
          status: 'completed',
          createdAt: new Date().toISOString(),
          dryRun: dryRun
        });
      }, 1500);
    });
  } catch (error) {
    console.error('Failed to create offset order', error);
    throw new Error('Failed to create offset order. Please try again.');
  }
}

// Email validation
function validateEmail(email) {
  const emailRegex = /^[^\s@]+@[^\s@]+\.[^\s@]+$/;
  return emailRegex.test(email);
}

// Send form submission (simulated)
async function sendFormSubmission(data) {
  return new Promise((resolve) => {
    setTimeout(() => resolve({ success: true }), 1000);
  });
}