using System.Collections;
using System.Collections.Generic;
using System.Diagnostics;

namespace SemiColinGames {
  // An IList<T>, backed by a List<T>, that prints out a debug message any time that the Capacity
  // of the underlying List changes.
  public class ProfilingList<T> : IList<T> {
    private readonly List<T> items;
    private readonly string name;
    private int previousCapacity;

    public ProfilingList(int capacity, string name) {
      items = new List<T>(capacity);
      previousCapacity = capacity;
      this.name = name;
    }

    public bool IsReadOnly {
      get { return false; }
    }

    public void Add(T item) {
      items.Add(item);
      CheckCapacity();
    }

    public void Insert(int index, T item) {
      items.Insert(index, item);
      CheckCapacity();
    }

    [Conditional("DEBUG")]
    private void CheckCapacity() {
      if (items.Capacity != previousCapacity) {
        Debug.WriteLine($"ProfilingList {name} capacity: {previousCapacity} -> {items.Capacity}");
        previousCapacity = items.Capacity;
      }
    }

    // Everything below this point is boilerplate delegation to the underlying list.

    public void Clear() {
      items.Clear();
    }

    public bool Contains(T item) {
      return items.Contains(item);
    }

    public int Count {
      get => items.Count;
    }

    public int IndexOf(T item) {
      return items.IndexOf(item);
    }

    public bool Remove(T item) {
      return items.Remove(item);
    }

    public void CopyTo(T[] array, int arrayIndex) {
      items.CopyTo(array, arrayIndex);
    }

    public void RemoveAt(int index) {
      items.RemoveAt(index);
    }

    public T this[int index] {
      get { return items[index]; }
      set { items[index] = value; }
    }

    public IEnumerator<T> GetEnumerator() {
      return items.GetEnumerator();
    }

    IEnumerator IEnumerable.GetEnumerator() {
      return items.GetEnumerator();
    }
  }
}