#version 330 core
layout (location = 0) in vec3 aPos;
layout (location = 1) in vec3 aNormal;
layout (location = 2) in vec2 aTexCoords;
layout (location = 3) in vec3 aTangent;
layout (location = 4) in vec3 aBitangent;
layout (location = 5) in ivec4 boneIds;
layout (location = 6) in vec4 weights;

out vec3 FragPos;
out vec3 Normal;
out vec2 TexCoords;
out vec4 FragPosLightSpace;
out mat3 TBN;

uniform mat4 projection;
uniform mat4 view;
uniform mat4 model;
uniform mat4 lightSpaceMatrix;
uniform bool hasBones;

const int MAX_BONES = 100;
const int MAX_BONE_INFLUENCE = 4;
uniform mat4 finalBonesMatrices[MAX_BONES];

vec4 AnimateBones() {
  vec4 totalPosition = vec4(0.0f);
  for(int i = 0; i < MAX_BONE_INFLUENCE; i++) {
    if(boneIds[i] == -1) continue;

    if(boneIds[i] >= MAX_BONES) {
      totalPosition = vec4(aPos, 1.0f);
      break;
    }

    int bone_id = boneIds[i];
    vec4 localPosition = finalBonesMatrices[bone_id] * vec4(aPos, 1.0f);
    totalPosition += localPosition * weights[i];
    vec3 localNormal = mat3(finalBonesMatrices[boneIds[i]]) * aNormal;
  }

  return totalPosition;
}

void main()
{
  vec4 totalPosition = hasBones ? AnimateBones() : vec4(aPos, 1.0);

  FragPos = vec3(model * vec4(aPos, 1.0));
  Normal = transpose(inverse(mat3(model))) * aNormal;
  TexCoords = aTexCoords;
  FragPosLightSpace = lightSpaceMatrix * vec4(FragPos, 1.0);
  gl_Position = projection * view * model * totalPosition;

  vec3 T = normalize(vec3(model * vec4(aTangent, 0.0)));
  vec3 B = normalize(vec3(model * vec4(aBitangent, 0.0)));
  vec3 N = normalize(vec3(model * vec4(aNormal, 0.0)));
  TBN = mat3(T, B, N);
}