using System;
using UnityEngine; // Used for Tooltip attributes, can be removed if not needed for standalone math.

// OceanCalculations.cs
// This static class centralizes empirical data and mathematical calculations
// specifically for the Earth's oceans (hydrosphere).
// All values are based on empirical data from WGS 84 and geological models.

public static class OceanCalculations
{
    // --- Fundamental Earth Constants (from WGS 84, needed for context) ---
    [Tooltip("WGS 84 Total Earth Mass (kg).")]
    public const double WGS84_TOTAL_EARTH_MASS_KG = 5.9722e24; // From WGS 84 reference

    [Tooltip("WGS 84 Equatorial Radius (a) in meters, used as Earth's overall outer boundary.")]
    public const double WGS84_EQUATORIAL_RADIUS_M = 6378137.0; // From WGS 84 reference

    // --- Ocean (Hydrosphere) Empirical Data ---
    [Tooltip("Total mass of the Earth's hydrosphere (oceans and all liquid surface water) in kg.")]
    public const double HYDROSPHERE_TOTAL_MASS_KG = 1.4e21; // From WGS 84 data

    [Tooltip("Average depth of the Earth's oceans in meters.")]
    public const double OCEANS_AVERAGE_DEPTH_M = 3800.0; // 3.8 km

    [Tooltip("Average density of ocean water (kg/m^3).")]
    public const double OCEAN_AVERAGE_DENSITY_KG_M3 = 1027.0; // Typical seawater density

    /// <summary>
    /// Gets the inner radius of the ocean layer from Earth's center (meters).
    /// This assumes the ocean sits on the Earth's surface (WGS84_EQUATORIAL_RADIUS_M).
    /// </summary>
    /// <returns>Inner radius of ocean layer in meters.</returns>
    public static double GetOceanInnerRadius_m()
    {
        return WGS84_EQUATORIAL_RADIUS_M;
    }

    /// <summary>
    /// Gets the outer radius of the ocean layer from Earth's center (meters).
    /// This assumes the ocean sits on the Earth's surface (WGS84_EQUATORIAL_RADIUS_M).
    /// </summary>
    /// <returns>Outer radius of ocean layer in meters.</returns>
    public static double GetOceanOuterRadius_m()
    {
        return WGS84_EQUATORIAL_RADIUS_M + OCEANS_AVERAGE_DEPTH_M;
    }

    /// <summary>
    /// Calculates the volume of the ocean layer (spherical shell).
    /// Assumes oceans are a uniform layer on the Earth's surface.
    /// </summary>
    /// <returns>Volume in cubic meters.</returns>
    public static double CalculateOceanVolume_m3()
    {
        double innerRadius = WGS84_EQUATORIAL_RADIUS_M;
        double outerRadius = GetOceanOuterRadius_m();
        return (4.0 / 3.0) * Math.PI * (Math.Pow(outerRadius, 3) - Math.Pow(innerRadius, 3));
    }

    /// <summary>
    /// Calculates the moment of inertia for the ocean layer (spherical shell).
    /// I = (2/5) * M * (R_outer^2 + R_inner * R_outer + R_inner^2)
    /// This is a simplified formula for a thin shell. For a more accurate one, refer to
    /// EarthConstantsAndCalculations.CalculateSphericalShellMomentOfInertia which uses
    /// I = (2/5) * M * (R_outer^5 - R_inner^5) / (R_outer^3 - R_inner^3)
    /// </summary>
    /// <returns>Moment of inertia in kg·m^2.</returns>
    public static double CalculateOceanMomentOfInertia()
    {
        double innerRadius = WGS84_EQUATORIAL_RADIUS_M;
        double outerRadius = GetOceanOuterRadius_m();
        // Use the more accurate formula from EarthConstantsAndCalculations
        return EarthConstantsAndCalculations.CalculateSphericalShellMomentOfInertia(HYDROSPHERE_TOTAL_MASS_KG, innerRadius, outerRadius);
    }
}


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