#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/HydraDirectionalShadowSourceSystem.h"
#include "../ecs/systems/HydraSpotShadowSourceSystem.h"
#include "../ecs/components/HydraLightComponent.h"
#include "../mesh/StandardVertex.h"
#include "../actor/HydraActorManager.h"
#include "../actor/HydraOutputActor.h"

void HydraShadowPipeline::Initialise()
{
    m_render_stages.resize(2);
    _CreateUBOs();
    _CreateDirectionalRenderStage();
    _CreateSpotRenderStage();
}

void HydraShadowPipeline::Shutdown()
{
}

void HydraShadowPipeline::Render()
{
    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);
     
    _RenderDirectionalShadowMaps();
    _RenderSpotShadowMaps();

}

void HydraShadowPipeline::_RenderDirectionalShadowMaps()
{
     HydraECS *ecs = GetEngine()->ECS();
    std::shared_ptr<HydraRenderSystem> render_system = ecs->GetSystem<HydraRenderSystem>();
    std::shared_ptr<HydraDirectionalShadowSourceSystem> shadow_system = ecs->GetSystem<HydraDirectionalShadowSourceSystem>();

    for (HydraID entity_id : shadow_system->Entities)
    {
        HydraDirectionalShadowSourceComponent shad_comp = GetEngine()->ECS()->GetComponent<HydraDirectionalShadowSourceComponent>(entity_id);
        HydraLightComponent light_comp = GetEngine()->ECS()->GetComponent<HydraLightComponent>(entity_id);
        _UpdateUBO(light_comp.shadow_map_id);
        
        glBindFramebuffer(GL_FRAMEBUFFER, shad_comp.frame_buffer_id);

        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);
        m_render_stages[DIRECTIONAL_RENDER_STAGE]->Render(render_system->Entities, INVALID_HYDRA_ID);
        glBindFramebuffer(GL_FRAMEBUFFER, 0);        
    }
}

void HydraShadowPipeline::_RenderSpotShadowMaps()
{
     HydraECS *ecs = GetEngine()->ECS();
    std::shared_ptr<HydraRenderSystem> render_system = ecs->GetSystem<HydraRenderSystem>();
    std::shared_ptr<HydraSpotShadowSourceSystem> shadow_system = ecs->GetSystem<HydraSpotShadowSourceSystem>();

    for (HydraID entity_id : shadow_system->Entities)
    {
        HydraSpotShadowSourceComponent shad_comp = GetEngine()->ECS()->GetComponent<HydraSpotShadowSourceComponent>(entity_id);
        HydraLightComponent light_comp = GetEngine()->ECS()->GetComponent<HydraLightComponent>(entity_id);
        _UpdateUBO(light_comp.shadow_map_id);
        
        glBindFramebuffer(GL_FRAMEBUFFER, shad_comp.frame_buffer_id);

        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);
        m_render_stages[SPOT_RENDER_STAGE]->Render(render_system->Entities, INVALID_HYDRA_ID);
        glBindFramebuffer(GL_FRAMEBUFFER, 0);
    }
}

void HydraShadowPipeline::_CreateDirectionalRenderStage()
{
    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("DirectionalShadowBuffer");
    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("directional_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_cascade_shader.vert",
                             shader_path + "shadow_cascade_shader.frag",
                             shader_path + "shadow_cascade_shader.geom",
                             shader_binding,
                             0,
                             textures,
                             true,
                             GL_FRONT,
                             true,
                             HYDRA_RENDERABLE_TYPE::HYDRA_COLOUR);
    m_render_stages[DIRECTIONAL_RENDER_STAGE] = render_stage;
}

void HydraShadowPipeline::_CreateSpotRenderStage()
{
    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("SpotShadowBuffer");
    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("spot_shadow_map_sets");
    shader_binding.binding_point.push_back(6);
    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_spot_shader.vert",
                             shader_path + "shadow_spot_shader.frag",
                             "",
                             shader_binding,
                             0,
                             textures,
                             true,
                             GL_FRONT,
                             true,
                             HYDRA_RENDERABLE_TYPE::HYDRA_COLOUR);
    m_render_stages[SPOT_RENDER_STAGE] = 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)
{
    HydraDirectionalShadowSourceComponent shad_comp = GetEngine()->ECS()->GetComponent<HydraDirectionalShadowSourceComponent>(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);
}