maternal-app/maternal-web/lib/utils/unitConversion.ts

import { MeasurementSystem } from '@/hooks/useLocale';

export interface ConvertedValue {
  value: number;
  unit: string;
}

/**
 * Convert weight from kilograms to the preferred measurement system
 */
export function convertWeight(
  valueInKg: number,
  system: MeasurementSystem
): ConvertedValue {
  if (system === 'imperial') {
    // Convert kg to lbs (1 kg = 2.20462 lbs)
    return {
      value: valueInKg * 2.20462,
      unit: 'lb',
    };
  }
  return {
    value: valueInKg,
    unit: 'kg',
  };
}

/**
 * Convert weight to kilograms from the preferred measurement system
 */
export function convertWeightToKg(
  value: number,
  system: MeasurementSystem
): number {
  if (system === 'imperial') {
    // Convert lbs to kg
    return value / 2.20462;
  }
  return value;
}

/**
 * Convert height from centimeters to the preferred measurement system
 */
export function convertHeight(
  valueInCm: number,
  system: MeasurementSystem
): ConvertedValue {
  if (system === 'imperial') {
    // Convert cm to inches (1 cm = 0.393701 inches)
    const inches = valueInCm * 0.393701;
    return {
      value: inches,
      unit: 'in',
    };
  }
  return {
    value: valueInCm,
    unit: 'cm',
  };
}

/**
 * Convert height to centimeters from the preferred measurement system
 */
export function convertHeightToCm(
  value: number,
  system: MeasurementSystem
): number {
  if (system === 'imperial') {
    // Convert inches to cm
    return value / 0.393701;
  }
  return value;
}

/**
 * Convert temperature from Celsius to the preferred measurement system
 */
export function convertTemperature(
  valueInCelsius: number,
  system: MeasurementSystem
): ConvertedValue {
  if (system === 'imperial') {
    // Convert Celsius to Fahrenheit: F = (C × 9/5) + 32
    return {
      value: (valueInCelsius * 9) / 5 + 32,
      unit: '°F',
    };
  }
  return {
    value: valueInCelsius,
    unit: '°C',
  };
}

/**
 * Convert temperature to Celsius from the preferred measurement system
 */
export function convertTemperatureToCelsius(
  value: number,
  system: MeasurementSystem
): number {
  if (system === 'imperial') {
    // Convert Fahrenheit to Celsius: C = (F - 32) × 5/9
    return ((value - 32) * 5) / 9;
  }
  return value;
}

/**
 * Convert volume from milliliters to the preferred measurement system
 */
export function convertVolume(
  valueInMl: number,
  system: MeasurementSystem
): ConvertedValue {
  if (system === 'imperial') {
    // Convert ml to oz (1 oz = 29.5735 ml)
    return {
      value: valueInMl / 29.5735,
      unit: 'oz',
    };
  }
  return {
    value: valueInMl,
    unit: 'ml',
  };
}

/**
 * Convert volume to milliliters from the preferred measurement system
 */
export function convertVolumeToMl(
  value: number,
  system: MeasurementSystem
): number {
  if (system === 'imperial') {
    // Convert oz to ml
    return value * 29.5735;
  }
  return value;
}

/**
 * Get the unit symbol for a measurement type
 */
export function getUnitSymbol(
  type: 'weight' | 'height' | 'temperature' | 'volume',
  system: MeasurementSystem
): string {
  const units = {
    metric: {
      weight: 'kg',
      height: 'cm',
      temperature: '°C',
      volume: 'ml',
    },
    imperial: {
      weight: 'lb',
      height: 'in',
      temperature: '°F',
      volume: 'oz',
    },
  };

  return units[system][type];
}

/**
 * Get conversion factor for a measurement type
 */
export function getConversionFactor(
  type: 'weight' | 'height' | 'temperature' | 'volume'
): { toImperial: number; toMetric: number } {
  const factors = {
    weight: { toImperial: 2.20462, toMetric: 1 / 2.20462 },
    height: { toImperial: 0.393701, toMetric: 1 / 0.393701 },
    temperature: { toImperial: 1, toMetric: 1 }, // Temperature uses formula, not factor
    volume: { toImperial: 1 / 29.5735, toMetric: 29.5735 },
  };

  return factors[type];
}