#include <psemek/app/default_application_factory.hpp>
#include <psemek/gfx/gl.hpp>
#include <psemek/gfx/painter.hpp>
#include <psemek/util/array.hpp>
#include <psemek/random/generator.hpp>
#include <psemek/random/device.hpp>
#include <psemek/random/uniform.hpp>
#include <psemek/util/hash_table.hpp>
#include <psemek/util/enum.hpp>
#include <psemek/util/clock.hpp>
#include <psemek/geom/box.hpp>
#include <psemek/geom/camera.hpp>
#include <psemek/ecs/container.hpp>
#include <psemek/ecs/declare_uuid.hpp>

#include <psemek/log/log.hpp>

#include <boost/container/flat_set.hpp>

#include <variant>
#include <deque>
#include <format>

namespace gmtk
{

	using namespace psemek;

	psemek_declare_enum(color, std::uint32_t,
		(red)
		(green)
		(blue)
	)

	gfx::color_rgba to_color(color c)
	{
		switch (c)
		{
		case color::red: return {255, 127, 127, 255};
		case color::green: return {127, 255, 127, 255};
		case color::blue: return {127, 127, 255, 255};
		}
		throw util::unknown_enum_value_exception{c};
	}

	struct location
	{
		int level;
		geom::point<int, 2> coords;

		geom::point<float, 2> center() const
		{
			float s = std::pow(3.f, -level);
			return {(coords[0] + 0.5f) * s, (coords[1] + 0.5f) * s};
		}

		geom::box<float, 2> bbox() const
		{
			float s = std::pow(3.f, -level);
			return {{{(coords[0] + 0) * s, (coords[0] + 1) * s}, {(coords[1] + 0) * s, (coords[1] + 1) * s}}};
		}

		location down() const
		{
			return {level + 1, {coords[0] * 3 + 1, coords[1] * 3 + 1}};
		}

		location up() const
		{
			return {level - 1, {geom::idiv(coords[0], 3), geom::idiv(coords[1], 3)}};
		}

		friend bool operator == (location const & x, location const & y) = default;
		friend auto operator <=> (location const & x, location const & y) = default;
	};

	struct location_hash
	{
		std::size_t operator()(location const & x) const noexcept
		{
			return util::hash_all(x.level, x.coords[0], x.coords[1]);
		}
	};

	struct vertex
	{
		psemek_ecs_declare_uuid("vertex")

		struct location location;
	};

	struct source
	{
		psemek_ecs_declare_uuid("source")

		color type;
	};

	struct transformer
	{
		psemek_ecs_declare_uuid("transformer")

		color input;
		color output;
	};

	struct path_vertex
	{
		psemek_ecs_declare_uuid("path_vertex")

		struct location location;

		boost::container::flat_set<ecs::handle> belts = {};
	};

	struct occupied
	{
		psemek_ecs_declare_uuid("occupied")

		ecs::handle entity;
	};

	struct item
	{
		psemek_ecs_declare_uuid("item")

		color type;
		location start;
		ecs::handle target = ecs::handle::null();
		float state = 0.f;
	};

	bool within_grid(location const & l)
	{
		int max = std::pow(3, l.level + 1);
		return l.coords[0] >= 0 && l.coords[0] < max && l.coords[1] >= 0 && l.coords[1] < 3;
	}

	struct timestamp
	{
		int trunc = 0;
		float frac = 0.f;

		timestamp & operator += (float dt)
		{
			frac += dt;
			int t = std::floor(frac);
			trunc += t;
			frac -= t;
			return *this;
		}

		friend auto operator <=> (timestamp const & x, timestamp const & y) = default;
	};

	struct task
	{
		psemek_ecs_declare_uuid("task")

		color type;

		// In last 15 seconds
		std::deque<timestamp> received = {};

		static constexpr int freq = 3;
	};

	struct map
	{
		ecs::container world;

		int current_level = 0;
		geom::point<int, 2> current_origin = {0, 0};

		timestamp time = {};

		float spawn_timer = 0.f;
	};

	template <typename Component, util::uuid UUID>
	struct index_base
	{
		static constexpr util::uuid uuid()
		{
			return UUID;
		}

		index_base(ecs::container & world)
			: world_(world)
		{
			world.apply<Component>([this](ecs::handle entity, Component const & v){
				index_[v.location] = entity;
			});

			world.constructor<Component>([this](ecs::handle entity, Component const & v){
				index_[v.location] = entity;
			});

			world.destructor<Component>([this](Component const & v){
				index_.erase(v.location);
			});
		}

		std::optional<ecs::handle> find(location const & l) const
		{
			if (auto it = index_.find(l); it != index_.end())
				return it->second;
			return std::nullopt;
		}

		ecs::handle get(location const & l) const
		{
			if (auto entity = find(l))
				return *entity;

			return world_.create(Component{l});
		}

	private:
		ecs::container & world_;
		util::hash_map<location, ecs::handle, location_hash> index_;
	};

	using index = index_base<vertex, util::make_uuid("vertex_index")>;
	using path_index = index_base<path_vertex, util::make_uuid("path_vertex_index")>;

	void generate_next_task(random::generator & rng, map & map)
	{
		color type;

		util::hash_set<color> existing_tasks;
		int task_count = 0;
		map.world.apply<task const>([&](task const & task)
		{
			existing_tasks.insert(task.type);
			task_count += 1;
		});

		while (true)
		{
			type = random::uniform_from(rng, color_values());
			if (task_count >= 3)
				break;

			if (!existing_tasks.contains(type))
				break;
		}

		while (true)
		{
			int x = random::uniform(rng, 0, 2);
			int y = random::uniform<bool>(rng) ? -1 : 3;
			if (random::uniform<bool>(rng))
				std::swap(x, y);

			if (map.world.index<index>().find({0, {x, y}}))
				continue;

			map.world.create(
				vertex{{0, {x, y}}},
				task{type}
			);

			break;
		}
	}

	map starting_map(random::generator & rng)
	{
		map result;

		result.world.index<index>();
		result.world.index<path_index>();

		generate_next_task(rng, result);

		return result;
	}

	void draw(map & map, gfx::painter & painter)
	{
		float const grid_width = 0.1f;

		for (int x = 0; x <= 3; ++x)
		{
			painter.line({x, 0.f}, {x, 3.f}, grid_width, gfx::black, true);
			painter.line({0.f, x}, {3.f, x}, grid_width, gfx::black, true);
		}

		map.world.apply<path_vertex const>([&](path_vertex const & vertex)
		{
			for (auto b : vertex.belts)
			{
				auto q = map.world.get(b).get<path_vertex const>().location;
				painter.line(vertex.location.center(), q.center(), 0.3f, {191, 191, 191, 255}, true);
			}
		});

		map.world.apply<path_vertex const>([&](path_vertex const & vertex)
		{
			for (auto b : vertex.belts)
			{
				auto q = map.world.get(b).get<path_vertex const>().location;

				geom::vector d = q.center() - vertex.location.center();

				auto c = vertex.location.center() + d / 2.f;

				auto n = geom::ort(d);

				float s = 1.f / 6.f;

				d *= s * 0.5f;
				n *= s;

				painter.triangle(c - d + n, c - d - n, c + d, {255, 127, 0, 255});
			}
		});

		map.world.apply<vertex const, source const>([&](vertex const & v, source const & s)
		{
			painter.rect(geom::shrink(v.location.bbox(), 0.2f), to_color(s.type));
			painter.text(v.location.center(), "180/m", {.scale = {0.01f, -0.01f}, .c = {0, 0, 0, 255}});
		});

		map.world.apply<vertex const, transformer const>([&](vertex const & v, transformer const & t)
		{
			auto box = geom::shrink(v.location.bbox(), 0.2f);
			painter.triangle(box.corner(0, 0), box.corner(1, 1), box.corner(0, 1), to_color(t.input));
			painter.triangle(box.corner(0, 0), box.corner(1, 0), box.corner(1, 1), to_color(t.output));
		});

		map.world.apply<vertex const, task const>([&](vertex const & v, task const & t)
		{
			painter.rect(geom::shrink(v.location.bbox(), 0.2f), to_color(t.type));
			painter.text(v.location.center(), std::format("{}/m", t.received.size() * task::freq), {.scale = {0.01f, -0.01f}, .c = {0, 0, 0, 255}});
		});

		map.world.apply<item const>([&](item const & i)
		{
			geom::point<float, 2> pos;
			if (i.target)
				pos = geom::lerp(i.start.center(), map.world.get(i.target).get<path_vertex const>().location.center(), i.state);
			else
				pos = i.start.center();
			painter.circle(pos, 0.075f, {0, 0, 0, 255});
			painter.circle(pos, 0.05f, to_color(i.type));
		});
	}

	void draw_selection(location const & l, gfx::painter & painter)
	{
		auto p = l.coords;
		painter.line({p[0], p[1]}, {p[0] + 1.f, p[1]}, 0.1f, {255, 0, 255, 255}, true);
		painter.line({p[0] + 1.f, p[1]}, {p[0] + 1.f, p[1] + 1.f}, 0.1f, {255, 0, 255, 255}, true);
		painter.line({p[0] + 1.f, p[1] + 1.f}, {p[0], p[1] + 1.f}, 0.1f, {255, 0, 255, 255}, true);
		painter.line({p[0], p[1] + 1.f}, {p[0], p[1]}, 0.1f, {255, 0, 255, 255}, true);
	}

	struct application
		: app::application
	{
		application(options const &, context const &)
			: rng_{random::device{}}
			, map_(starting_map(rng_))
		{}

		void on_event(app::resize_event const & event) override
		{
			screen_size_ = event.size;
		}

		void on_event(app::mouse_move_event const & event) override
		{
			mouse_ = event.position;
		}

		void on_event(app::key_event const & event) override
		{
			if (event.down && event.key == app::keycode::S)
			{
				if (selected_ && !map_.world.index<index>().find(*selected_))
				{
					util::hash_set<color> types;
					int task_count = 0;

					map_.world.apply<task const>([&](task const & t)
					{
						types.insert(t.type);
						task_count += 1;
					});

					if (task_count > 1)
						for (auto t : color_values())
							types.insert(t);

					map_.world.create(
						vertex{*selected_},
						source{random::uniform_from(rng_, types)}
					);
				}
			}

			if (event.down && event.key == app::keycode::B)
			{
				if (selected_)
				{
					if (belt_start_)
					{
						auto d = selected_->coords - belt_start_->coords;
						if (std::abs(d[0]) + std::abs(d[1]) == 1)
						{
							auto & index = map_.world.index<path_index>();
							for (int i = 0; i < 3; ++i)
							{
								auto p = belt_start_->down();
								p.coords += d * i;
								auto q = p;
								q.coords += d;

								auto s = index.get(p);
								auto t = index.get(q);

								auto & sv = map_.world.get(s).get<path_vertex>();
								auto & tv = map_.world.get(t).get<path_vertex>();

								if (sv.belts.contains(t))
									sv.belts.erase(t);
								else
								{
									if (tv.belts.contains(s))
										tv.belts.erase(s);
									sv.belts.insert(t);
								}
							}
						}
						belt_start_ = std::nullopt;
					}
					else if (within_grid(*selected_))
						belt_start_ = *selected_;
				}
			}

			if (event.down && event.key == app::keycode::F)
			{
				if (selected_ && !map_.world.index<index>().find(*selected_))
				{
					util::hash_set<color> types;
					int task_count = 0;

					map_.world.apply<task const>([&](task const & t)
					{
						types.insert(t.type);
						task_count += 1;
					});

					if (task_count == 1)
					{
						for (auto c : color_values())
							types.insert(c);
					}

					color input = random::uniform_from(rng_, types);
					types.erase(input);
					color output = random::uniform_from(rng_, types);

					map_.world.create(
						vertex{*selected_},
						transformer{input, output}
					);
				}
			}

			if (event.down && event.key == app::keycode::X)
			{
				if (selected_)
				{
					if (auto entity = map_.world.index<index>().find(*selected_))
						if (!map_.world.get(*entity).contains<task>())
							map_.world.destroy(*entity);
				}
			}

			if (event.down && event.key == app::keycode::SPACE)
			{
				generate_next_task(rng_, map_);
			}
		}

		bool running() const override
		{
			return running_;
		}

		void stop() override
		{
			running_ = false;
		}

		void update() override
		{
			float const dt = clock_.restart().count();

			map_.time += dt;

			map_.spawn_timer += 3.f * dt;
			if (map_.spawn_timer >= 1.f)
			{
				map_.spawn_timer -= 1.f;

				map_.world.apply<vertex const, source const>(
					[&](vertex const & v, source const & s)
					{
						auto p = v.location.down();

						auto t = map_.world.index<path_index>().get(p);

						if (!map_.world.get(t).contains<occupied>())
						{
							auto i = map_.world.create(
								item{s.type, p}
							);

							map_.world.attach(t, occupied{i});
						}
					}
				);
			}


			map_.world.apply<task>([&](task & t)
			{
				auto threshold = map_.time;
				threshold.trunc -= 60 / task::freq;
				while (!t.received.empty() && t.received.front() < threshold)
					t.received.pop_front();
			});

			map_.world.apply<item>([&](ecs::handle entity, item & i)
			{
				if (i.target)
				{
					i.state += 3.f * dt;
					if (i.state < 1.f)
						return;

					i.state -= 1.f;

					i.start = map_.world.get(i.target).get<path_vertex const>().location;
					map_.world.detach<occupied>(i.target);
					i.target = ecs::handle::null();
				}
				else
				{
					map_.world.detach<occupied>(map_.world.index<path_index>().get(i.start));
				}

				if (auto cell = map_.world.index<index>().find(i.start.up()))
				{
					if (auto t = map_.world.get(*cell).get_if<task>())
					{
						if (t->type == i.type)
							t->received.push_back(map_.time);
						map_.world.destroy(entity);
						return;
					}

					if (auto t = map_.world.get(*cell).get_if<transformer>())
					{
						if (t->input == i.type)
							i.type = t->output;
					}
				}

				std::vector<ecs::handle> targets;

				for (auto b : map_.world.get(map_.world.index<path_index>().get(i.start)).get<path_vertex>().belts)
					if (!map_.world.get(b).contains<occupied>())
						targets.push_back(b);

				if (!targets.empty())
					i.target = random::uniform_from(rng_, targets);

				if (i.target)
					map_.world.attach(i.target, occupied{entity});
				else
					map_.world.attach(map_.world.index<path_index>().get(i.start), occupied{entity});
			});

			float aspect_ratio = (screen_size_[0] * 1.f) / screen_size_[1];

			view_box_[1] = {-1.f, 4.f};
			view_box_[0] = view_box_[1];
			view_box_[0] = geom::expand(view_box_[0], (view_box_[1].length() * aspect_ratio - view_box_[0].length()) / 2.f);

			selected_ = std::nullopt;

			{
				auto m = screen_to_grid(geom::cast<float>(mouse_));

				int x = std::floor(m[0]);
				int y = std::floor(m[1]);

				if (x >= 0 && x < 3 && y >= 0 && y < 3)
					selected_ = {0, geom::point{x, y}};
				else if (map_.world.index<index>().find({0, {x, y}}))
					selected_ = {0, geom::point{x, y}};
			}
		}

		void present() override
		{
			gl::ClearColor(1.f, 1.f, 1.f, 1.f);
			gl::Clear(gl::COLOR_BUFFER_BIT);

			draw(map_, painter_);

			if (selected_)
				draw_selection(*selected_, painter_);

			painter_.render(geom::orthographic_camera{view_box_}.transform());
		}

	private:
		bool running_ = true;

		random::generator rng_;
		map map_;

		util::clock<> clock_;

		geom::vector<int, 2> screen_size_{1, 1};
		geom::point<int, 2> mouse_{0, 0};

		gfx::painter painter_;

		geom::box<float, 2> view_box_;

		std::optional<location> selected_;
		std::optional<location> belt_start_;

		geom::point<float, 2> screen_to_grid(geom::point<float, 2> const & p)
		{
			return view_box_.corner(
				p[0] / screen_size_[0],
				1.f - p[1] / screen_size_[1]
			);
		}
	};

}

namespace psemek::app
{

	std::unique_ptr<application::factory> make_application_factory()
	{
		application::options options
		{
			.name = "GMTK 2024",
		};

		return default_application_factory<gmtk::application>(options);
	}

}