#include <cassert>

#if 0
#include <assimp/cimport.h>
#include <assimp/scene.h>
#include <assimp/postprocess.h>
#endif

#include <glm/glm.hpp>
#include <glm/geometric.hpp>
#include <glm/gtc/matrix_transform.hpp>

#include "dumbLog.h"

#include "mesh.h"


// WIP
bool meInitAssimp() { return false; }

bool meLoadFromFile(mesh_group& mesh_group, const char* filepath)
{
	return false;
}

simple_mesh*
meInitMesh(uint num_vertices) { return nullptr; }

void
meFreeMeshGroup(mesh_group& mesh_group) {}

void
meFreeSimpleMesh(simple_mesh* mesh) {}

void
meShutdownAssimp() {}

// WIP


#if 0
// forward declarations

mesh_info* allocateMeshInfo(uint num_vertices, uint num_indices);
void assimpLogCB(const char* message, char* user);
mesh_info* copyMeshInfo(const aiScene* scene, aiMesh* mesh);
inline glm::vec3 copyVector(aiVector3D v_in, glm::vec3& v_out);
void freeMesh(mesh_info* mesh);
bool loadDiffuseTexture(const aiScene* scene, aiMesh* mesh, mesh_info* mi);
bool validateScene(const aiScene* scene, const char* filepath);

// interface

bool
meInitAssimp()
{
	LOG(Info) << "Initializing Assimp\n";
	aiLogStream ls;
	ls.callback = assimpLogCB;
	aiAttachLogStream(&ls);

	return true;
}

bool
meLoadFromFile(mesh_group& mesh_group, const char* filepath)
{
	LOG(Info) << "Loading file: " << filepath << "\n";
	const aiScene* scene = aiImportFile(filepath, aiProcessPreset_TargetRealtime_MaxQuality);

	if (!validateScene(scene, filepath))
		return false;

	mesh_group.num_meshes = scene->mNumMeshes;
	mesh_group.meshes = UTIL_ALLOC(mesh_group.num_meshes, mesh_info*);

	for (uint i = 0; i < scene->mNumMeshes; i++) {
		aiMesh* mesh = scene->mMeshes[i];
		mesh_info* mi = copyMeshInfo(scene, mesh);

		if (!mesh->HasTextureCoords(0) ||
			!loadDiffuseTexture(scene, mesh, mi))
		{
			LOG(Error) << "Error loading texture, cleaning up import\n";
			freeMesh(mi);
			aiReleaseImport(scene);
			return false;
		}

		mesh_group.meshes[i] = mi;
	}

	aiReleaseImport(scene);
	return true;
}

simple_mesh*
meInitMesh(uint num_vertices)
{
	assert(num_vertices > 0);
	simple_mesh* sm = UTIL_ALLOC(1, simple_mesh);
	sm->model_transform = glm::mat4(1.0);
	sm->num_vertices = num_vertices;
	sm->vertices = UTIL_ALLOC(num_vertices, glm::vec3);
	sm->vert_colors = UTIL_ALLOC(num_vertices, glm::vec3);
	return sm;
}

void
meFreeMeshGroup(mesh_group& mesh_group)
{
	for (uint i = 0; i < mesh_group.num_meshes; i++)
		freeMesh(mesh_group.meshes[i]);

	utilSafeFree(mesh_group.meshes);
	mesh_group.num_meshes = 0;
	mesh_group.meshes = nullptr;
}

void
meFreeSimpleMesh(simple_mesh* mesh)
{
	assert(mesh != nullptr);
	utilSafeFree(mesh->vertices);
	mesh->vertices = nullptr;
	utilSafeFree(mesh->vert_colors);
	mesh->vert_colors = nullptr;
	mesh->num_vertices = 0;
}

void
meShutdownAssimp()
{
	aiDetachAllLogStreams();
}


// internal

mesh_info*
allocateMeshInfo(uint num_vertices, uint num_indices)
{
	mesh_info* mi = UTIL_ALLOC(1, mesh_info);
	mi->model_transform = glm::mat4(1);

	// allocate buffers for vertex and index data from mesh
	mi->num_vertices = num_vertices;
	mi->vertices = UTIL_ALLOC(mi->num_vertices, glm::vec3);
	mi->num_indices = num_indices;
	mi->indices = UTIL_ALLOC(num_indices, uint);
	mi->normals = UTIL_ALLOC(mi->num_vertices, glm::vec3);
	mi->texture_coords = UTIL_ALLOC(mi->num_vertices, glm::vec3);

	return mi;
}

void
assimpLogCB(const char* message, char* user)
{
	// NOTE: filter 'info' messages from assimp
	if (!utilMatchPrefix(message, "Info,", 5))
		LOG(Info) << message << "\n";
}

mesh_info*
copyMeshInfo(const aiScene* scene, aiMesh* mesh)
{
	mesh_info* mi = allocateMeshInfo(mesh->mNumVertices, mesh->mNumFaces * 3);

	// copy vertices, normals, and texture coords
	for (uint i = 0; i < mi->num_vertices; i++) {
		copyVector(mesh->mVertices[i], mi->vertices[i]);
		copyVector(mesh->mNormals[i], mi->normals[i]);
		mi->texture_coords[i].x = mesh->mTextureCoords[0][i].x;
		mi->texture_coords[i].y = mesh->mTextureCoords[0][i].y;
		mi->texture_coords[i].z = 0;
	}

	// copy indices
	for (uint i = 0; i < mesh->mNumFaces; i++)
		for (uint j = 0; j < 3; j++)
			mi->indices[i * 3 + j] = mesh->mFaces[i].mIndices[j];

	return mi;
}

inline glm::vec3
copyVector(aiVector3D v_in, glm::vec3& v_out)
{
	v_out.x = v_in.x;
	v_out.y = v_in.y;
	v_out.z = v_in.z;
	return v_out;
}

void
freeMesh(mesh_info* mesh)
{
	utilFreeImage(mesh->diffuse_texture);
	utilSafeFree(mesh->vertices);
	utilSafeFree(mesh->normals);
	utilSafeFree(mesh->texture_coords);
	utilSafeFree(mesh->indices);
	utilSafeFree(mesh);
}

bool
loadDiffuseTexture(const aiScene* scene, aiMesh* mesh, mesh_info* mi)
{
	aiMaterial* mat = scene->mMaterials[mesh->mMaterialIndex];
	aiString file_name;

	if (mat->GetTextureCount(aiTextureType_DIFFUSE) < 1)
		return false;

	if (AI_SUCCESS != mat->GetTexture(
			aiTextureType_DIFFUSE, 0, &file_name, NULL, NULL, NULL, NULL, NULL))
	{
		LOG(Error) << "No diffuse texture from assimp\n";
		return false;
	} else {
		const aiTexture* tex = scene->GetEmbeddedTexture(file_name.C_Str());

		if (tex != nullptr) {
			LOG(Info) << "has embedded texture\n";
			mi->diffuse_texture = utilLoadImageBytes((const uint8*) tex->pcData, tex->mWidth);
		} else {
			LOG(Info) << "Loading texture file: " << file_name.C_Str() << "\n";
			mi->diffuse_texture = utilLoadImagePath(file_name.C_Str());
		}

		if (mi->diffuse_texture.pixels == nullptr) {
			LOG(Error) << "Error loading texture\n";
			return false;
		}
	}

	return true;
}

bool
validateScene(const aiScene* scene, const char* filepath)
{
	if (!scene) {
		LOG(Error) << "Error loading file: " << filepath << "\n";
		return false;
	}

	if (scene->mNumMeshes < 1) {
		LOG(Error) << "Scene contains no meshes\n";
		return false;
	}

	if (!scene->mMeshes[0]->HasNormals()) {
		LOG(Error) << "Mesh doesn't have normals\n";
		return false;
	}

	return true;
}
#endif