using GLTF.Utilities;
using Newtonsoft.Json;

namespace GLTF.Schema
{
	public enum BufferViewTarget
	{
		/// <summary>
		/// For animation or
		/// </summary>
		None = 0,
		/// <summary>
		/// For vertex data
		/// </summary>
		ArrayBuffer = 34962,
		/// <summary>
		/// For index data
		/// </summary>
		ElementArrayBuffer = 34963,
	}

	/// <summary>
	/// A view into a buffer generally representing a subset of the buffer.
	/// </summary>
	public class BufferView : GLTFChildOfRootProperty
	{
		/// <summary>
		/// The index of the buffer.
		/// </summary>
		public BufferId Buffer;

		/// <summary>
		/// The offset into the buffer in bytes.
		/// <minimum>0</minimum>
		/// </summary>
		public uint ByteOffset;

		/// <summary>
		/// The length of the bufferView in bytes.
		/// <minimum>0</minimum>
		/// </summary>
		public uint ByteLength;

		/// <summary>
		/// The stride, in bytes, between vertex attributes or other interleavable data.
		/// When this is zero, data is tightly packed.
		/// <minimum>0</minimum>
		/// <maximum>255</maximum>
		/// </summary>
		public uint ByteStride;

		/// <summary>
		/// The target that the WebGL buffer should be bound to.
		/// All valid values correspond to WebGL enums.
		/// When this is not provided, the bufferView contains animation or skin data.
		/// </summary>
		public BufferViewTarget Target = BufferViewTarget.None;

		public BufferView()
		{
		}

		public BufferView(BufferView bufferView, GLTFRoot gltfRoot) : base(bufferView, gltfRoot)
		{
			Buffer = new BufferId(bufferView.Buffer, gltfRoot);
			ByteOffset = bufferView.ByteOffset;
			ByteLength = bufferView.ByteLength;
			ByteStride = bufferView.ByteStride;
			Target = bufferView.Target;
		}

		public static BufferView Deserialize(GLTFRoot root, JsonReader reader)
		{
			var bufferView = new BufferView();

			while (reader.Read() && reader.TokenType == JsonToken.PropertyName)
			{
				var curProp = reader.Value.ToString();

				switch (curProp)
				{
					case "buffer":
						bufferView.Buffer = BufferId.Deserialize(root, reader);
						break;
					case "byteOffset":
						bufferView.ByteOffset = reader.ReadDoubleAsUInt32();
						break;
					case "byteLength":
						bufferView.ByteLength = reader.ReadDoubleAsUInt32();
						break;
					case "byteStride":
						bufferView.ByteStride = reader.ReadDoubleAsUInt32();
						break;
					case "target":
						bufferView.Target = (BufferViewTarget)reader.ReadAsInt32().Value;
						break;
					default:
						bufferView.DefaultPropertyDeserializer(root, reader);
						break;
				}
			}

			return bufferView;
		}

		public override void Serialize(JsonWriter writer)
		{
			writer.WriteStartObject();

			writer.WritePropertyName("buffer");
			writer.WriteValue(Buffer.Id);

			if (ByteOffset != 0)
			{
				writer.WritePropertyName("byteOffset");
				writer.WriteValue(ByteOffset);
			}

			writer.WritePropertyName("byteLength");
			writer.WriteValue(ByteLength);

			if (ByteStride != 0)
			{
				writer.WritePropertyName("byteStride");
				writer.WriteValue(ByteStride);
			}

			if (Target != BufferViewTarget.None)
			{
				writer.WritePropertyName("target");
				writer.WriteValue((int)Target);
			}

			base.Serialize(writer);

			writer.WriteEndObject();
		}
	}
}