// Copyright (C) 2016-2016 ChaosForge Ltd
// http://chaosforge.org/
//
// This file is part of Nova libraries. 
// For conditions of distribution and use, see copying.txt file in root folder.

#include "nv/engine/renderer.hh"

#include "nv/core/profiler.hh"

using namespace nv;

renderer::renderer( context* ctx )
	: m_context( ctx )
{
	for ( auto& i : m_statistics ) i = 0;

	struct qvtx
	{
		nv::vec2 position;
		nv::vec2 texcoord;
	};

	qvtx quad[] = {
		qvtx{ vec2( -1.0f,-1.0f ), vec2( 0.0f, 0.0f ) },
		qvtx{ vec2( 1.0f,-1.0f ),  vec2( 1.0f, 0.0f ) },
		qvtx{ vec2( 1.0f,1.0f ),   vec2( 1.0f, 1.0f ) },
		qvtx{ vec2( 1.0f,1.0f ),   vec2( 1.0f, 1.0f ) },
		qvtx{ vec2( -1.0f,1.0f ),  vec2( 0.0f, 1.0f ) },
		qvtx{ vec2( -1.0f,-1.0f ), vec2( 0.0f, 0.0f ) },
	};
	m_quad = m_context->create_vertex_array( quad, 6, STATIC_DRAW );
}

void renderer::sort()
{
	stable_sort( m_elements.begin(), m_elements.end(), renderer_element_compare() );
}


void renderer::render( const scene_state& s, const render_pass& pass )
{
	scene_state ss( s );
	m_context->bind( pass.fbuffer, FRAMEBUFFER );
	m_context->set_draw_buffers( pass.output_count, pass.output );
	m_context->set_viewport( ss.get_viewport() );

	if ( pass.cstate.buffers != buffer_mask::NO_BUFFER )
		m_context->clear( pass.cstate );

	for ( uint32 i = 0; i < size( pass.binds ); ++i )
		if ( pass.binds[i] )
			m_context->bind( pass.binds[i], texture_slot( i ) );

	resource_id current_mat;
	mat4 model = ss.get_model();
	for ( const renderer_element& element : m_elements )
		if ( match( element.flags, pass ) )
		{
			ss.set_model( model * element.model.extract() );
			if ( auto mesh = element.mesh.lock() )
				if ( mesh->count > 0 )
					if ( auto program = pass.programs[mesh->shader].lock() )
					{
						if ( element.mat.id() != current_mat )
						{
							if ( auto mat = element.mat.lock() )
							{
								for ( uint32 i = 0; i < 8; ++i )
									if ( mat->textures[i] && !pass.binds[i] )
										m_context->bind( mat->textures[i], nv::texture_slot( i ) );
								current_mat = element.mat.id();
							}
						}

						m_context->get_device()->set_opt_uniform( *program, "nv_bone_offset", element.bone_offset );
						m_context->get_device()->set_opt_uniform( *program, "nv_flags", unsigned( *element.flags.data() ) );

						m_context->apply_engine_uniforms( *program, ss );
						m_context->draw( TRIANGLES, pass.rstate, *program, mesh->va, mesh->count );

						m_statistics[TRIANGLE_COUNT] += mesh->count / 3;
						m_statistics[DRAW_CALL]++;
					}
		}

	m_context->bind( pass.fbuffer, FRAMEBUFFER );
}

void renderer::render( const scene_state& ss, const render_pass& pass, vertex_array va, uint32 va_count, uint32 program_idx )
{
	m_context->bind( pass.fbuffer, FRAMEBUFFER );
	m_context->set_draw_buffers( pass.output_count, pass.output );
	m_context->set_viewport( ss.get_viewport() );

	if ( pass.cstate.buffers != buffer_mask::NO_BUFFER )
		m_context->clear( pass.cstate );

	for ( uint32 i = 0; i < size( pass.binds ); ++i )
		if ( pass.binds[i] )
			m_context->bind( pass.binds[i], texture_slot(i) );

	if ( auto program = pass.programs[program_idx].lock() )
	{
		m_context->apply_engine_uniforms( *program, ss );
		m_context->draw( TRIANGLES, pass.rstate, *program, va, va_count );
		m_statistics[ TRIANGLE_COUNT ] += 2;
		m_statistics[ DRAW_CALL ]++;
	}

	m_context->bind( pass.fbuffer, FRAMEBUFFER );
}

void nv::renderer::render_direct( const scene_state& s, const render_pass& pass, const nv::array_view< renderer_direct_element >& elements, uint32 program_idx )
{
	if ( m_elements.size() == 0 ) return;

	scene_state ss( s );
	render_state rs( pass.rstate );
	m_context->bind( pass.fbuffer, FRAMEBUFFER );
	m_context->set_draw_buffers( pass.output_count, pass.output );
	m_context->set_viewport( ss.get_viewport() );


	if ( pass.cstate.buffers != buffer_mask::NO_BUFFER )
		m_context->clear( pass.cstate );

	for ( uint32 i = 0; i < size( pass.binds ); ++i )
		if ( pass.binds[i] )
			m_context->bind( pass.binds[i], texture_slot( i ) );

	resource_id current_mat;
	resource_id current_prog;

	mat4 model = ss.get_model();
	for ( uint32 index = 0; index < elements.size(); ++index )
	{
		const renderer_direct_element& element = elements[index];
		if ( match( element.flags, pass ) )
		{
			ss.set_model( model * element.model.extract() );
			if ( element.count > 0 )
			{
				if ( auto program = element.programs[program_idx].lock() )
				{
					if ( element.material.id() != current_mat )
					{
						if ( auto mat = element.material.lock() )
						{
							for ( uint32 i = 0; i < 8; ++i )
								if ( mat->textures[i] && !pass.binds[i] )
									m_context->bind( mat->textures[i], nv::texture_slot( i ) );
							current_mat = element.material.id();
						}
					}

					m_context->get_device()->set_opt_uniform( *program, "nv_flags", unsigned( *element.flags.data() ) );
					m_context->get_device()->set_opt_uniform( *program, "nv_index", unsigned( index ) );
					m_context->apply_engine_uniforms( *program, ss );
					if ( rs.blending != element.blending )
						rs.blending = element.blending;

					if ( element.instances > 0 )
						m_context->draw_instanced( TRIANGLES, rs, *program, element.instances, element.va, element.count, element.first );
					else
						m_context->draw( TRIANGLES, rs, *program, element.va, element.count, element.first );

					m_statistics[TRIANGLE_COUNT] += ( element.count / 3 ) * max< uint32 >( element.instances, 1 );
					m_statistics[DRAW_CALL]++;
				}
			}
		}
	}
	m_context->bind( pass.fbuffer, FRAMEBUFFER );
}