#include <psemek/gfx/painter.hpp>
#include <psemek/gfx/program.hpp>
#include <psemek/gfx/mesh.hpp>
#include <psemek/geom/constants.hpp>

static const char vertex_source[] =
R"(#version 330

uniform mat4 u_transform;

layout (location = 0) in vec4 in_position;
layout (location = 1) in vec4 in_color;

out vec4 color;

void main()
{
	gl_Position = u_transform * in_position;
	color = in_color;
}
)";

static const char fragment_source[] =
R"(#version 330

in vec4 color;

out vec4 out_color;

void main()
{
	out_color = color;
}
)";

namespace psemek::gfx
{

	struct painter::impl
	{
		struct vertex
		{
			geom::point<float, 3> position;
			color_rgba color;
		};

		gfx::program program{vertex_source, fragment_source};
		gfx::indexed_mesh mesh;

		std::vector<vertex> vertices;
		std::vector<std::uint32_t> indices;

		impl()
		{
			mesh.setup<geom::vector<float, 3>, gfx::normalized<color_rgba>>();
		}
	};

	painter::painter()
		: pimpl_{std::make_unique<struct impl>()}
	{}

	painter::~painter() = default;

	void painter::quad(geom::point<float, 2> const & p, float width, color const & c)
	{
		std::uint32_t const base = impl().vertices.size();
		float const r = width / 2.f;

		impl().vertices.push_back({{p[0] - r, p[1] - r, 0.f}, c});
		impl().vertices.push_back({{p[0] + r, p[1] - r, 0.f}, c});
		impl().vertices.push_back({{p[0] - r, p[1] + r, 0.f}, c});
		impl().vertices.push_back({{p[0] + r, p[1] + r, 0.f}, c});

		impl().indices.push_back(base + 0);
		impl().indices.push_back(base + 1);
		impl().indices.push_back(base + 3);
		impl().indices.push_back(base + 0);
		impl().indices.push_back(base + 3);
		impl().indices.push_back(base + 2);
	}

	void painter::circle(geom::point<float, 2> const & p, float r, color const & c)
	{
		std::uint32_t const base = impl().vertices.size();

		int const quality = 24;

		impl().vertices.push_back({{p[0], p[1], 0.f}, c});
		for (int i = 0; i < quality; ++i)
		{
			float const a = (geom::pi * 2.f * i) / quality;
			impl().vertices.push_back({{p[0] + r * std::cos(a), p[1] + r * std::sin(a), 0.f}, c});
		}

		for (int i = 0; i < quality; ++i)
		{
			impl().indices.push_back(base);
			impl().indices.push_back(base + 1 + i);
			impl().indices.push_back(base + 1 + ((i + 1) % quality));
		}
	}

	void painter::line(geom::point<float, 2> const & p0, geom::point<float, 2> const & p1, float width, color const & c, bool smooth)
	{
		std::uint32_t const base = impl().vertices.size();
		float const r = width / 2.f;

		auto const d = geom::normalized(p1 - p0);
		geom::vector<float, 2> const o { -d[1], d[0] };

		impl().vertices.push_back({{p0[0] + r * o[0], p0[1] + r * o[1], 0.f}, c});
		impl().vertices.push_back({{p0[0] - r * o[0], p0[1] - r * o[1], 0.f}, c});
		impl().vertices.push_back({{p1[0] + r * o[0], p1[1] + r * o[1], 0.f}, c});
		impl().vertices.push_back({{p1[0] - r * o[0], p1[1] - r * o[1], 0.f}, c});

		impl().indices.push_back(base + 0);
		impl().indices.push_back(base + 1);
		impl().indices.push_back(base + 3);
		impl().indices.push_back(base + 0);
		impl().indices.push_back(base + 3);
		impl().indices.push_back(base + 2);

		if (smooth)
		{
			circle(p0, r, c);
			circle(p1, r, c);
		}
	}

	void painter::render(geom::matrix<float, 4, 4> const & transform)
	{
		impl().mesh.load(impl().vertices, impl().indices, gl::STREAM_DRAW);
		impl().vertices.clear();
		impl().indices.clear();

		impl().program.bind();
		impl().program["u_transform"] = transform;
		impl().mesh.draw(gl::TRIANGLES);
	}

}