#include "HydraShadowSourceSystem.h"
#include "../../engine/HydraEngine.h"
#include "../../camera/HydraCamera.h"
#include "../HydraECS.h"
#include "../components/HydraShadowSourceComponent.h"
#include "../components/HydraPositionComponent.h"
#include "../components/HydraLightComponent.h"

#include "../../buffer/HydraShadowBuffer.h"
#include "../../buffer/HydraTextureBufferManager.h"

#include "../../scheduler/HydraTaskScheduler.h"
#include "../../task/buffer/HydraCreateGPUBufferTask.hpp"
#include "../../task/buffer/HydraUpdateWholeGPUBufferTask.hpp"
#include "../../task/buffer/HydraUpdatePartialGPUBufferTask.hpp"
#include "../../task/buffer/HydraCreateUnBoundTextureTask.hpp"

#include "../../actor/HydraActorManager.h"


void HydraShadowSourceSystem::Initialise()
{
    HydraTaskScheduler *task_scheduler = GetEngine()->TaskScheduler();

    HydraID create_gpu_buffer_task_id = task_scheduler->CreateTask<HydraCreateGPUBufferTask>(HydraThreadAffinity::Render);
    HydraCreateGPUBufferTask *task = static_cast<HydraCreateGPUBufferTask *>(task_scheduler->GetTask(create_gpu_buffer_task_id));
    task->Intialise("ShadowBuffer", 1, MAX_SHADOWS * sizeof(HydraShadowBuffer), &m_shadow_buffer_id, HYDRA_BUFFER_TYPE::HYDRA_SSBO_BUFFER);
    task_scheduler->WaitForTask(create_gpu_buffer_task_id);
}

void HydraShadowSourceSystem::InitialiseComponent(HydraID entity_id)
{    
    HydraEngine* engine = GetEngine();
    HydraECS* ecs = engine->ECS();
    HydraLightComponent& light_comp = ecs->GetComponent<HydraLightComponent>(entity_id);
    switch(light_comp.light_type)
    {
        case (int)HYDRA_LIGHT_TYPE::HYDRA_LIGHT_DIRECTIONAL:
            _InitialiseDirectionalLight(entity_id);
            break;
    }

}

void HydraShadowSourceSystem::UpdateSystem(float delta_t_seconds)
{
    HydraEngine* engine = GetEngine();
    HydraECS* ecs = engine->ECS();
    std::vector<HydraShadowSourceComponent> shadows;
    for(HydraID entity_id:Entities)
    {

        HydraLightComponent& light_comp = ecs->GetComponent<HydraLightComponent>(entity_id);
        switch(light_comp.light_type)
        {
            case (int)HYDRA_LIGHT_TYPE::HYDRA_LIGHT_DIRECTIONAL:
                _UpdateDirectionalLight(entity_id);                
                break;
        }

        HydraShadowSourceComponent shad_comp = ecs->GetComponent<HydraShadowSourceComponent>(entity_id);
        shadows.push_back(shad_comp);
    }
    _WriteToGPU(shadows);
}

void HydraShadowSourceSystem::_UpdateDirectionalLight(HydraID entity_id)
{
    HydraEngine* engine = GetEngine();
    HydraECS* ecs = engine->ECS();
    HydraPositionComponent pos_comp = ecs->GetComponent<HydraPositionComponent>(entity_id);
    HydraShadowSourceComponent& shad_comp = ecs->GetComponent<HydraShadowSourceComponent>(entity_id);


     float view_size = 5.0f;
        float view_near = -5.0f;
        float view_far = 5.0f;

        float PI = 3.1415927;
        float TWO_PI = 6.2831854;

        glm::vec3 light_dir = glm::vec3(0, 0, -1);
        glm::mat3 light_rot = glm::mat3(1);
        glm::vec3 light_euler = pos_comp.orientation;
        light_rot = glm::eulerAngleXYZ(light_euler.x, light_euler.y, light_euler.z);

        light_dir = light_rot * light_dir;
        light_dir = glm::normalize(light_dir);
        glm::vec3 camera_pos = GetEngine()->Camera()->GetPosition();
        for (uint32_t i = 0; i < 6; i++)
        {
            glm::vec3 light_pos = camera_pos; // - (light_dir * light_distance);

            glm::mat4 light_trans = glm::translate(light_pos * glm::vec3(-1, -1, -1));
            glm::mat4 light_orient = glm::eulerAngleXYZ(light_euler.x, light_euler.y, light_euler.z);
            glm::mat4 view = light_orient * light_trans;
            glm::mat4 proj = glm::orthoRH<float>(view_size, -view_size, -view_size, view_size, -15000, 15000);
            // glm::mat4 proj =  glm::orthoRH<float>(view_size, -view_size, -view_size, view_size, view_near, view_far);

            shad_comp.far_plane[i] = view_far;
            shad_comp.near_plane[i] = view_near;
            shad_comp.light_space_proj[i] = proj;
            shad_comp.light_space_view[i] = view;

            view_far *= 3.0f;
            view_near = -view_far;
            view_size *= 3.0f;
        }
}

void HydraShadowSourceSystem::_InitialiseDirectionalLight(HydraID entity_id)
{
    HydraEngine* engine = GetEngine();
    HydraECS* ecs = engine->ECS();
    HydraTextureBufferManager* tex_man = engine->TextureBufferManager();
    HydraShadowSourceComponent& shad_comp = ecs->GetComponent<HydraShadowSourceComponent>(entity_id);
    shad_comp.entity_id = entity_id;
    shad_comp.cascade_count = 6;

    HydraTaskScheduler *task_scheduler = GetEngine()->TaskScheduler();

    HydraID create_texture_task_id = task_scheduler->CreateTask<HydraCreateUnBoundTextureTask>(HydraThreadAffinity::Render);
    HydraCreateUnBoundTextureTask *task = static_cast<HydraCreateUnBoundTextureTask *>(task_scheduler->GetTask(create_texture_task_id));
    task->Initialise("shadow", SHADOW_MAP_SIZE, SHADOW_MAP_SIZE, GL_R32F, GL_R32F, GL_LINEAR, GL_LINEAR, 6, GL_BYTE, 0, nullptr, &shad_comp.shadow_texture_id);
    task_scheduler->WaitForTask(create_texture_task_id);
}

void HydraShadowSourceSystem::_WriteToGPU(std::vector<HydraShadowSourceComponent> shadows)
{
    HydraEngine* engine = GetEngine();
    HydraECS* ecs = engine->ECS();
    
    void *buffer = static_cast<void *>(shadows.data());
    HydraTaskScheduler *task_scheduler = GetEngine()->TaskScheduler();

    HydraID update_buffer_task_id = task_scheduler->CreateTask<HydraUpdatePartialGPUBufferTask>(HydraThreadAffinity::Render);
    HydraUpdatePartialGPUBufferTask *task = static_cast<HydraUpdatePartialGPUBufferTask *>(task_scheduler->GetTask(update_buffer_task_id));
    task->Intialise(m_shadow_buffer_id, 0, sizeof(HydraLightComponent) * shadows.size(), buffer);
    task_scheduler->WaitForTask(update_buffer_task_id);
}