using NModbus;
using System.Xml.Linq;

namespace ModbusSimulationProtocol.Data;

public class PointSource<TPoint> : IPointSource<TPoint>
{
    private readonly string _name;
    private readonly int _capacity;
    private readonly TPoint[] _points;
    private readonly object _lock = new();
    
    /// <summary>
    /// The implementation to the <typeparamref name="TPoint"/> register.
    /// </summary>
    /// <param name="name">The name of this register.</param>
    /// <param name="capacity">A number between 1 and 65536 inclusive.</param>
    public PointSource(string name, int capacity = 65536)
    {
        ArgumentOutOfRangeException.ThrowIfLessThanOrEqual(capacity, ushort.MinValue, nameof(capacity));
        ArgumentOutOfRangeException.ThrowIfGreaterThan(capacity, ushort.MaxValue + 1, nameof(capacity));

        _name = name;
        _capacity = capacity;
        _points = new TPoint[_capacity];
    }

    public TPoint[] ReadPoints(ushort startAddress, ushort numberOfPoints)
    {
        if (numberOfPoints == 0) return [];

        int start = startAddress;
        int count = numberOfPoints;

        ArgumentOutOfRangeException.ThrowIfGreaterThanOrEqual(start, _capacity, nameof(start));
        ArgumentOutOfRangeException.ThrowIfGreaterThan(start + count, _capacity, $"{start}+{count}");

        lock (_lock)
        {
            TPoint[] snapshot = new TPoint[count];
            Array.Copy(_points, start, snapshot, 0, count);
            return snapshot;
        }
    }

    public void WritePoints(ushort startAddress, TPoint[] points)
    {
        if (points.Length == 0) return;

        int start = startAddress;
        int count = points.Length;

        ArgumentOutOfRangeException.ThrowIfGreaterThanOrEqual(start, _capacity, nameof(start));
        ArgumentOutOfRangeException.ThrowIfGreaterThan(start + count, _capacity, $"{start}+{count}");

        lock (_lock)
        {
            Array.Copy(points, 0, _points, start, count);
        }
    }
}