package material

import (
	"errors"
	"os"

	"git.tek.govt.hu/dowerx/opengl-deferred/types/asset"
	"git.tek.govt.hu/dowerx/opengl-deferred/types/shader"
	"git.tek.govt.hu/dowerx/opengl-deferred/types/texture"
	"github.com/go-gl/gl/v4.6-core/gl"
	"gopkg.in/yaml.v3"
)

type MaterialDefiniton struct {
	Shader   string `yaml:"shader"`
	Textures []struct {
		Slot    uint32 `yaml:"slot"`
		Texture string `yaml:"texture"`
	} `yaml:"textures"`
	Values []struct {
		Type  string      `yaml:"type"`
		Name  string      `yaml:"name"`
		Value interface{} `yaml:"value"`
	} `yaml:"values"`
}

type Material struct {
	Shader     *shader.Shader
	ShaderName string
	Textures   []struct {
		Slot        uint32
		Texture     *texture.Texture
		TextureName string
	}
	Values []Value
}

func (m Material) Delete() {}

func (m *Material) Apply() {
	m.Shader.Use()

	for _, t := range m.Textures {
		t.Texture.Bind(gl.TEXTURE0 + t.Slot)
	}

	for _, v := range m.Values {
		v.Apply(m.Shader)
	}
}

func Load(path string, assets map[string]asset.Asset) (Material, error) {
	var definition MaterialDefiniton
	var material Material

	data, err := os.ReadFile(path)
	if err != nil {
		return material, err
	}

	if err = yaml.Unmarshal(data, &definition); err != nil {
		return material, err
	}

	material.ShaderName = definition.Shader
	for _, t := range definition.Textures {
		material.Textures = append(material.Textures, struct {
			Slot        uint32
			Texture     *texture.Texture
			TextureName string
		}{Slot: t.Slot, TextureName: t.Texture})
	}

	for _, vdef := range definition.Values {
		var value Value

		switch vdef.Type {
		case "int":
			intval, ok := vdef.Value.(int32)
			if !ok {
				return material, err
			}
			value = IntValue{Name: vdef.Name, Value: intval}
		default:
			return material, errors.New("Unknown value: " + vdef.Type)
		}

		material.Values = append(material.Values, value)
	}

	return material, err
}

func (m *Material) AttachAssets(assets map[string]asset.Asset) error {
	tmpShader, ok := assets[m.ShaderName].(shader.Shader)
	if !ok {
		return errors.New("Failed to attach shader to material: " + m.ShaderName)
	}
	m.Shader = &tmpShader

	for i, t := range m.Textures {
		tmpTexture, ok := assets[t.TextureName].(texture.Texture)
		if !ok {
			return errors.New("Failed to attach texture to material: " + t.TextureName)
		}
		m.Textures[i].Texture = &tmpTexture
	}

	return nil
}