#include "HydraDirectionalShadowSourceSystem.h"
#include "../../engine/HydraEngine.h"
#include "../../camera/HydraCamera.h"
#include "../HydraECS.h"
#include "../components/HydraDirectionalShadowSourceComponent.h"
#include "../components/HydraPositionComponent.h"
#include "../components/HydraLightComponent.h"

#include "../../buffer/HydraShadowBuffer.h"
#include "../../buffer/HydraTextureBufferManager.h"
#include "../../buffer/HydraShadowBufferManager.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 "../../task/renderer/HydraCreateCascadeShadowFrameBuffer.hpp"
#include "../../task/renderer/HydraCreateShadowFrameBuffer.hpp"
#include "../../actor/HydraActorManager.h"
#include "../../actor/HydraTestCubeActor.h"


void HydraDirectionalShadowSourceSystem::Initialise()
{

}

void HydraDirectionalShadowSourceSystem::InitialiseComponent(HydraID entity_id)
{
    HydraEngine *engine = GetEngine();
    HydraECS *ecs = engine->ECS();
    HydraLightComponent &light_comp = ecs->GetComponent<HydraLightComponent>(entity_id);

    
    HydraDirectionalShadowSourceComponent& shadow_comp = ecs->GetComponent<HydraDirectionalShadowSourceComponent>(entity_id);

    HydraID shadow_id = GetEngine()->ShadowBufferManager()->AddDirectionalShadow(shadow_comp);
    assert(shadow_id != INVALID_HYDRA_ID && "Add directional Shadow - out of shadows!");

    light_comp.shadow_map_id = shadow_id;
    light_comp.shadow_caster = 1;
    shadow_comp.shadow_id = shadow_id;
    _InitialiseShadowMap(entity_id);

    // m_shadow_actor_id = GetEngine()->ActorManager()->CreateActor<HydraTestCubeActor>();
    // GetEngine()->ActorManager()->InitialiseActor(m_shadow_actor_id);
    // GetEngine()->ActorManager()->SetPosition(m_shadow_actor_id, glm::dvec3(0, 0, 0));
}

void HydraDirectionalShadowSourceSystem::UpdateSystem(float delta_t_seconds)
{
    for (HydraID entity_id : Entities)
    {
        _UpdateShadowMap(entity_id);
    }
}

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

    float view_size = 4.0f;    
    float shadow_distance = 4.0f;
    float max_shadow_range = 100000.0f;
    
    glm::mat4 light_rot = glm::eulerAngleXYZ(pos_comp.orientation.x, pos_comp.orientation.y, pos_comp.orientation.z);
    glm::vec3 light_dir = glm::normalize(glm::vec3(light_rot * glm::vec4(0.0f, 0.0f, -1.0f, 0.0f)));

    glm::vec3 camera_pos = GetEngine()->Camera()->GetPosition();
    
    glm::vec3 light_pos = (camera_pos - (light_dir * 1000.0f));
    glm::vec3 target_pos = light_pos + light_dir;
    glm::vec3 up_vector = glm::vec3(0.0f, 1.0f, 0.0f);
    
     if (glm::abs(glm::dot(light_dir, up_vector)) > 0.99f) 
    {
        up_vector = glm::vec3(1.0f, 0.0f, 0.0f); // Prevent gimbal lock
    }
    glm::mat4 view = glm::lookAt(light_pos, target_pos, up_vector);   
    
    for (uint32_t i = 0; i < 6; i++)
    {
        float view_near = 0.1f;//max_shadow_range - shadow_distance;
        float view_far = 2000.0f;// max_shadow_range + shadow_distance;

        glm::mat4 proj = glm::ortho(-view_size, view_size, -view_size, view_size, view_near, view_far);          
        // Save data to component
        shad_comp.far_plane[i] = shadow_distance;         
        shad_comp.near_plane[i] = 0;         
        shad_comp.light_space_proj[i] = proj;         
        shad_comp.light_space_view[i] = view;          

        // Scale bounds exponentially for the next cascade tier
        view_size *= 3.0f;     
        shadow_distance  *= 3.0f;        
    }
    // GetEngine()->ActorManager()->SetPosition(m_shadow_actor_id, light_pos);
    // GetEngine()->ActorManager()->SetOrientation(m_shadow_actor_id, pos_comp.orientation.x, pos_comp.orientation.y, pos_comp.orientation.z);
    GetEngine()->ShadowBufferManager()->UpdateDirectionalShadow(shad_comp.shadow_id, shad_comp);
}


void HydraDirectionalShadowSourceSystem::_InitialiseShadowMap(HydraID entity_id)
{
    HydraEngine *engine = GetEngine();
    HydraECS *ecs = engine->ECS();
    HydraTextureBufferManager *tex_man = engine->TextureBufferManager();
    HydraDirectionalShadowSourceComponent &shad_comp = ecs->GetComponent<HydraDirectionalShadowSourceComponent>(entity_id);
    HydraLightComponent &light_comp = ecs->GetComponent<HydraLightComponent>(entity_id);

    shad_comp.entity_id = entity_id;   
    
    HydraTaskScheduler *task_scheduler = GetEngine()->TaskScheduler();

    uint32_t depth_texture_id = 0;
    HydraID create_framebuffer_task_id = task_scheduler->CreateTask<HydraCreateCascadeShadowFrameBuffer>(HydraThreadAffinity::Render);
    HydraCreateCascadeShadowFrameBuffer *fb_task = static_cast<HydraCreateCascadeShadowFrameBuffer *>(task_scheduler->GetTask(create_framebuffer_task_id));
    fb_task->Initialise(&shad_comp.shadow_texture_id, &depth_texture_id, &shad_comp.frame_buffer_id);
    
    task_scheduler->WaitForTask(create_framebuffer_task_id);
    shad_comp.shadow_texture_id = depth_texture_id;
}