using System;

using System.Collections.Generic;

using System.Text;

using Substrate.Nbt;

namespace Substrate

{

/// <summary>

/// Functions to query and manage a collection of entities.

/// </summary>

public class EntityCollection : IEnumerable<TypedEntity>

{

private TagNodeList _entities;

private bool _dirty;

/// <summary>

/// Gets or sets a value indicating whether this collection contains unsaved changes.

/// </summary>

public bool IsDirty

{

get { return _dirty; }

set { _dirty = value; }

}

/// <summary>

/// Creates a new <see cref="EntityCollection"/> around a <see cref="TagNodeList"/> containing Entity nodes.

/// </summary>

/// <param name="entities">A <see cref="TagNodeList"/> containing Entity nodes.</param>

public EntityCollection (TagNodeList entities)

{

_entities = entities;

}

/// <summary>

/// Gets a list of all entities in the collection that match a given id (type).

/// </summary>

/// <param name="id">The id (type) of entities that should be returned.</param>

/// <returns>A list of <see cref="TypedEntity"/> objects matching the given id (type).</returns>

public List<TypedEntity> FindAll (string id)

{

List<TypedEntity> set = new List<TypedEntity>();

foreach (TagNodeCompound ent in _entities) {

TagNode eid;

if (!ent.TryGetValue("id", out eid)) {

continue;

}

if (eid.ToTagString().Data != id) {

continue;

}

TypedEntity obj = EntityFactory.Create(ent);

if (obj != null) {

set.Add(obj);

}

}

return set;

}

/// <summary>

/// Gets a list of all entities in the collection that match a given condition.

/// </summary>

/// <param name="match">A <see cref="Predicate{T}"/> defining the matching condition.</param>

/// <returns>A list of <see cref="TypedEntity"/> objects matching the given condition.</returns>

public List<TypedEntity> FindAll (Predicate<TypedEntity> match)

{

List<TypedEntity> set = new List<TypedEntity>();

foreach (TagNodeCompound ent in _entities) {

TypedEntity obj = EntityFactory.Create(ent);

if (obj == null) {

continue;

}

if (match(obj)) {

set.Add(obj);

}

}

return set;

}

/// <summary>

/// Adds a <see cref="TypedEntity"/> to the collection.

/// </summary>

/// <param name="ent">The <see cref="TypedEntity"/> object to add.</param>

/// <remarks>It is up to the developer to ensure that the <see cref="TypedEntity"/> being added to the collection has a position that

/// is within acceptable range of the collection. <see cref="EntityCollection"/> transparently back other objects such as

/// <see cref="IChunk"/> objects, which have a well-defined position in global space. The <see cref="EntityCollection"/> itself has

/// no concept of position and will not enforce constraints on the positions of <see cref="TypedEntity"/> objects being added.</remarks>

public void Add (TypedEntity ent)

{

_entities.Add(ent.BuildTree());

_dirty = true;

}

/// <summary>

/// Removes all entities matching the given id (type) from the collection.

/// </summary>

/// <param name="id">The id (type) of entities that should be removed.</param>

/// <returns>A count of the number of entities that were removed.</returns>

public int RemoveAll (string id)

{

int rem = _entities.RemoveAll(val =>

{

TagNodeCompound cval = val as TagNodeCompound;

if (cval == null) {

return false;

}

TagNode sval;

if (!cval.TryGetValue("id", out sval)) {

return false;

}

return (sval.ToTagString().Data == id);

});

if (rem > 0) {

_dirty = true;

}

return rem;

}

/// <summary>

/// Removes all entities matching the given condition from the collection.

/// </summary>

/// <param name="match">A <see cref="Predicate{T}"/> defining the matching condition.</param>

/// <returns>A count of the number of entities that were removed.</returns>

public int RemoveAll (Predicate<TypedEntity> match)

{

int rem = _entities.RemoveAll(val =>

{

TagNodeCompound cval = val as TagNodeCompound;

if (cval == null) {

return false;

}

TypedEntity obj = EntityFactory.Create(cval);

if (obj == null) {

return false;

}

return match(obj);

});

if (rem > 0) {

_dirty = true;

}

return rem;

}

#region IEnumerable<Entity> Members

/// <summary>

/// Returns an enumerator that iterates through all entities.

/// </summary>

/// <returns>An <see cref="Enumerator"/> for this object.</returns>

public IEnumerator<TypedEntity> GetEnumerator ()

{

return new Enumerator(_entities);

}

#endregion

#region IEnumerable Members

/// <summary>

/// Returns an enumerator that iterates through all entities.

/// </summary>

/// <returns>An <see cref="Enumerator"/> for this object.</returns>

System.Collections.IEnumerator System.Collections.IEnumerable.GetEnumerator ()

{

return new Enumerator(_entities);

}

#endregion

/// <summary>

/// Enumerates the entities within an <see cref="EntityCollection"/>.

/// </summary>

private struct Enumerator : IEnumerator<TypedEntity>

{

private IEnumerator<TagNode> _enum;

private bool _next;

private TypedEntity _cur;

internal Enumerator (TagNodeList entities)

{

_enum = entities.GetEnumerator();

_cur = null;

_next = false;

}

#region IEnumerator<Entity> Members

/// <summary>

/// Gets the <see cref="TypedEntity"/> at the current position of the enumerator.

/// </summary>

public TypedEntity Current

{

get

{

if (_next == false) {

throw new InvalidOperationException();

}

return _cur;

}

}

#endregion

#region IDisposable Members

/// <summary>

/// Releases all resources used by the <see cref="Enumerator"/>.

/// </summary>

public void Dispose () { }

#endregion

#region IEnumerator Members

/// <summary>

/// Gets the <see cref="TypedEntity"/> at the current position of the enumerator.

/// </summary>

object System.Collections.IEnumerator.Current

{

get { return Current; }

}

/// <summary>

/// Advances the enumerator to the next <see cref="TypedEntity"/> in the <see cref="EntityCollection"/>.

/// </summary>

/// <returns>True if the enumerator was successfully advanced to the next position; false if the enumerator advanced past the end of the collection.</returns>

public bool MoveNext ()

{

if (!_enum.MoveNext()) {

_next = false;

return false;

}

_cur = EntityFactory.Create(_enum.Current.ToTagCompound());

if (_cur == null)

_cur = EntityFactory.CreateGeneric(_enum.Current.ToTagCompound());

_next = true;

return true;

}

/// <summary>

/// Sets the enumerator to its initial position, which is before the first <see cref="TypedEntity"/> in the collection.

/// </summary>

void System.Collections.IEnumerator.Reset ()

{

_cur = null;

_next = false;

_enum.Reset();

}

#endregion

}

}

}