#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();
    _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;

    glViewport(0, 0, SHADOW_MAP_SIZE, SHADOW_MAP_SIZE);

    
    glEnable(GL_DEPTH_TEST); // Depth testing must be active
    glDepthMask(GL_TRUE);    // Depth buffer must be writable
    glDepthFunc(GL_LESS);
     
    //glEnable(GL_POLYGON_OFFSET_FILL);
    //glPolygonOffset(2.5f, 1.0f);

    for (HydraID entity_id : shadow_system->Entities)
    {
        _UpdateUBO(shadow_idx);
        // _BindFrameBufferAttachments(entity_id);
        HydraShadowSourceComponent shad_comp = GetEngine()->ECS()->GetComponent<HydraShadowSourceComponent>(entity_id);
        glBindFramebuffer(GL_FRAMEBUFFER, shad_comp.frame_buffer_id);
        // HydraTextureBuffer tex_buffer = GetEngine()->TextureBufferManager()->GetTexture(shad_comp.shadow_texture_id);
        // glBindTextureUnit(tex_buffer.gl_tex_id, 0);

        float depth_value = 1.0f;
        float clear_colour[] = {0,0,0};
        glClearNamedFramebufferfv(shad_comp.frame_buffer_id, GL_DEPTH, 0, &depth_value);
        glClearNamedFramebufferfv(shad_comp.frame_buffer_id, GL_COLOR, 0, clear_colour);
     
        for (uint32_t rs_idx = 0; rs_idx < m_render_stages.size(); rs_idx++)
        {
            m_render_stages[rs_idx]->Render(render_system->Entities, INVALID_HYDRA_ID);
        }
        
        glBindFramebuffer(GL_FRAMEBUFFER, 0);
        shadow_idx++;
    }
    
    
   // glDisable(GL_POLYGON_OFFSET_FILL);
}

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 mat_buffer_id = buffer_manager->FindBuffer("MaterialBuffer");
    HydraID tex_buffer_id = buffer_manager->FindBuffer("TextureBuffer");
    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("positions_buffer");
    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("material_buffer");
    shader_binding.binding_point.push_back(2);
    shader_binding.buffer_id.push_back(mat_buffer_id);
    shader_binding.buffer_type.push_back(HYDRA_BUFFER_TYPE::HYDRA_SSBO_BUFFER);

    shader_binding.block_name.push_back("texture_buffer");
    shader_binding.binding_point.push_back(3);
    shader_binding.buffer_id.push_back(tex_buffer_id);
    shader_binding.buffer_type.push_back(HYDRA_BUFFER_TYPE::HYDRA_SSBO_BUFFER);

    shader_binding.block_name.push_back("shadow_map_sets");
    shader_binding.binding_point.push_back(5);
    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(1);
    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,
                             0,
                             textures,
                             true,
                             GL_FRONT,
                             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);
    glBindFramebuffer(GL_FRAMEBUFFER, shad_comp.frame_buffer_id);
    glBindTextureUnit(0, 0);
}


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);
}