#include "HydraShadowPipeline.h"

#include "HydraRenderStage.h"
#include "../engine/HydraEngine.h"
#include "../buffer/HydraBufferManager.h"
#include "../buffer/HydraTextureBufferManager.h"
#include "../buffer/HydraLightBufferManager.h"
#include "PerFrameUBO.hpp"

#include "../camera/HydraCamera.h"
#include "../renderer/HydraRenderer.h"
#include "../ecs/HydraECS.h"
#include "../ecs/systems/HydraRenderSystem.h"
#include "../ecs/systems/HydraShadowSourceSystem.h"
#include "../mesh/StandardVertex.h"
#include "../actor/HydraActorManager.h"
#include "../actor/HydraOutputActor.h"



void HydraShadowPipeline::Initialise()
{
    _CreateUBOs();
    _CreateFrameBuffer();
    _CreateRenderStage();
}

void HydraShadowPipeline::Shutdown()
{
}

void HydraShadowPipeline::Render()
{
    HydraECS* ecs = GetEngine()->ECS();
    std::shared_ptr<HydraRenderSystem> render_system = ecs->GetSystem<HydraRenderSystem>();
    std::shared_ptr<HydraShadowSourceSystem> shadow_system = ecs->GetSystem<HydraShadowSourceSystem>();
    uint32_t shadow_idx =0;
    for(HydraID entity_id:shadow_system->Entities)
    {
        _UpdateUBO(shadow_idx);
        _BindFrameBufferAttachments(entity_id);
        GetEngine()->Renderer()->BeginFrame();   
        for(uint32_t rs_idx = 0; rs_idx <m_render_stages.size(); rs_idx++)
        {
            m_render_stages[rs_idx]->Render(render_system->Entities);
        }
        GetEngine()->Renderer()->EndFrame();   
       glBindFramebuffer(GL_FRAMEBUFFER, 0);
        shadow_idx++;
    }
  
}

void HydraShadowPipeline::_CreateRenderStage()
{
    HydraRenderStage* render_stage = new HydraRenderStage();
    std::string shader_path = std::string(shader_base);
    HydraBufferManager* buffer_manager = GetEngine()->BufferManager();

    HydraID pos_buffer_id = buffer_manager->FindBuffer("PositionsBuffer");    
    HydraID shadow_buffer_id = buffer_manager->FindBuffer("ShadowBuffer");    
    HydraID per_frame_buffer_id = buffer_manager->FindBuffer("ShadowPerFrameUBO");

    HydraShaderBinding shader_binding = {};
    
    shader_binding.block_name.push_back("PositionsBuffer");
    shader_binding.binding_point.push_back(1);
    shader_binding.buffer_id.push_back(pos_buffer_id);
    shader_binding.buffer_type.push_back(HYDRA_BUFFER_TYPE::HYDRA_SSBO_BUFFER);
    
    shader_binding.block_name.push_back("ShadowMapSets");
    shader_binding.binding_point.push_back(0);
    shader_binding.buffer_id.push_back(shadow_buffer_id);
    shader_binding.buffer_type.push_back(HYDRA_BUFFER_TYPE::HYDRA_SSBO_BUFFER);

    shader_binding.block_name.push_back("shadow_per_frame");
    shader_binding.binding_point.push_back(0);
    shader_binding.buffer_id.push_back(per_frame_buffer_id);
    shader_binding.buffer_type.push_back(HYDRA_BUFFER_TYPE::HYDRA_UBO_BUFFER);

    std::vector<uint32_t> textures;

    render_stage->Initialise(shader_path + "shadow_shader.vert", 
        shader_path + "shadow_shader.frag", 
        shader_path + "shadow_shader.geom",
        shader_binding, 
        m_frame_buffer_id,
        textures,
        true,
        HYDRA_RENDERABLE_TYPE::HYDRA_COLOUR);
    m_render_stages.push_back(render_stage);
}

void HydraShadowPipeline::_UpdateUBO(uint32_t shadow_idx)
{
     HydraBufferManager* buffer_manager = GetEngine()->BufferManager();
    buffer_manager->UpdatePartialBuffer(m_per_frame_ubo,3*sizeof(float), sizeof(uint32_t), &shadow_idx);
    glBindBuffer(GL_UNIFORM_BUFFER, m_per_frame_ubo);
}

void HydraShadowPipeline::_BindFrameBufferAttachments(HydraID entity_id)
{
    HydraShadowSourceComponent shad_comp = GetEngine()->ECS()->GetComponent<HydraShadowSourceComponent>(entity_id);
    HydraTextureBuffer texture = GetEngine()->TextureBufferManager()->GetTexture(shad_comp.shadow_texture_id);
    glBindFramebuffer(GL_FRAMEBUFFER, m_frame_buffer_id);

    glBindTexture(GL_TEXTURE_2D, texture.gl_tex_id);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR); 
    glFramebufferTexture2D(GL_FRAMEBUFFER, GL_DEPTH_ATTACHMENT, GL_TEXTURE_2D, texture.gl_tex_id, 0);

    GLenum draw_buffers[4] = {GL_COLOR_ATTACHMENT0, GL_COLOR_ATTACHMENT1, GL_COLOR_ATTACHMENT2, GL_COLOR_ATTACHMENT3};

    glDrawBuffer(GL_NONE);
    glReadBuffer(GL_NONE);
    glBindTexture(GL_TEXTURE_2D, 0);


    glClearColor(0.0f, 0.0f, 0.0f, 0.0f);

    glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT); // we're not using the stencil buffer now
    glEnable(GL_DEPTH_TEST);
    glBindFramebuffer(GL_FRAMEBUFFER, 0);
    
}

void HydraShadowPipeline::_CreateFrameBuffer()
{
    HydraEngine* engine = GetEngine();
    HydraTextureBufferManager* tex_buffer_manager = engine->TextureBufferManager();
    HydraRenderSettings render_settings = engine->RenderSettings();
    glGenFramebuffers(1, &m_frame_buffer_id);
    glBindFramebuffer(GL_FRAMEBUFFER, m_frame_buffer_id);  
}
void HydraShadowPipeline::_CreateUBOs()
{
    HydraBufferManager* buffer_manager = GetEngine()->BufferManager();

    m_per_frame_ubo = buffer_manager->CreateGPUBuffer("ShadowPerFrameUBO", 
    sizeof(float)*4, 0, HYDRA_BUFFER_TYPE::HYDRA_UBO_BUFFER);
}