using System;
using GLTF.Extensions;
using GLTF.Math;
using Newtonsoft.Json;

namespace GLTF.Schema
{
	/// <summary>
	/// A set of parameter values that are used to define the metallic-roughness
	/// material model from Physically-Based Rendering (PBR) methodology.
	/// </summary>
	public class PbrMetallicRoughness : GLTFProperty
	{
		/// <summary>
		/// The RGBA components of the base color of the material.
		/// The fourth component (A) is the opacity of the material.
		/// These values are linear.
		/// </summary>
		public Color BaseColorFactor = Color.White;

		/// <summary>
		/// The base color texture.
		/// This texture contains RGB(A) components in sRGB color space.
		/// The first three components (RGB) specify the base color of the material.
		/// If the fourth component (A) is present, it represents the opacity of the
		/// material. Otherwise, an opacity of 1.0 is assumed.
		/// </summary>
		public TextureInfo BaseColorTexture;

		/// <summary>
		/// The metalness of the material.
		/// A value of 1.0 means the material is a metal.
		/// A value of 0.0 means the material is a dielectric.
		/// Values in between are for blending between metals and dielectrics such as
		/// dirty metallic surfaces.
		/// This value is linear.
		/// </summary>
		public double MetallicFactor = 1;

		/// <summary>
		/// The roughness of the material.
		/// A value of 1.0 means the material is completely rough.
		/// A value of 0.0 means the material is completely smooth.
		/// This value is linear.
		/// </summary>
		public double RoughnessFactor = 1;

		/// <summary>
		/// The metallic-roughness texture has two components.
		/// The first component (R) contains the metallic-ness of the material.
		/// The second component (G) contains the roughness of the material.
		/// These values are linear.
		/// If the third component (B) and/or the fourth component (A) are present,
		/// they are ignored.
		/// </summary>
		public TextureInfo MetallicRoughnessTexture;

		public PbrMetallicRoughness()
		{
		}

		public PbrMetallicRoughness(PbrMetallicRoughness pbrMetallicRoughness, GLTFRoot gltfRoot) : base(pbrMetallicRoughness)
		{
			if(pbrMetallicRoughness == null) 
			{
				return;
			}

			BaseColorFactor = pbrMetallicRoughness.BaseColorFactor;

			if (pbrMetallicRoughness.BaseColorTexture != null)
			{
				BaseColorTexture = new TextureInfo(pbrMetallicRoughness.BaseColorTexture, gltfRoot);
			}

			MetallicFactor = pbrMetallicRoughness.MetallicFactor;
			RoughnessFactor = pbrMetallicRoughness.RoughnessFactor;

			if (pbrMetallicRoughness.MetallicRoughnessTexture != null)
			{
				MetallicRoughnessTexture = new TextureInfo(pbrMetallicRoughness.MetallicRoughnessTexture, gltfRoot);
			}
		}

		public static PbrMetallicRoughness Deserialize(GLTFRoot root, JsonReader reader)
		{
			var metallicRoughness = new PbrMetallicRoughness();

			if (reader.Read() && reader.TokenType != JsonToken.StartObject)
			{
				throw new Exception("Asset must be an object.");
			}

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

				switch (curProp)
				{
					case "baseColorFactor":
						metallicRoughness.BaseColorFactor = reader.ReadAsRGBAColor();
						break;
					case "baseColorTexture":
						metallicRoughness.BaseColorTexture = TextureInfo.Deserialize(root, reader);
						break;
					case "metallicFactor":
						metallicRoughness.MetallicFactor = reader.ReadAsDouble().Value;
						break;
					case "roughnessFactor":
						metallicRoughness.RoughnessFactor = reader.ReadAsDouble().Value;
						break;
					case "metallicRoughnessTexture":
						metallicRoughness.MetallicRoughnessTexture = TextureInfo.Deserialize(root, reader);
						break;
					default:
						metallicRoughness.DefaultPropertyDeserializer(root, reader);
						break;
				}
			}

			return metallicRoughness;
		}

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

			if (BaseColorFactor != Color.White)
			{
				writer.WritePropertyName("baseColorFactor");
				writer.WriteStartArray();
				writer.WriteValue(BaseColorFactor.R);
				writer.WriteValue(BaseColorFactor.G);
				writer.WriteValue(BaseColorFactor.B);
				writer.WriteValue(BaseColorFactor.A);
				writer.WriteEndArray();
			}

			if (BaseColorTexture != null)
			{
				writer.WritePropertyName("baseColorTexture");
				BaseColorTexture.Serialize(writer);
			}

			if (MetallicFactor != 1.0f)
			{
				writer.WritePropertyName("metallicFactor");
				writer.WriteValue(MetallicFactor);
			}

			if (RoughnessFactor != 1.0f)
			{
				writer.WritePropertyName("roughnessFactor");
				writer.WriteValue(RoughnessFactor);
			}

			if (MetallicRoughnessTexture != null)
			{
				writer.WritePropertyName("metallicRoughnessTexture");
				MetallicRoughnessTexture.Serialize(writer);
			}

			base.Serialize(writer);

			writer.WriteEndObject();
		}
	}
}