#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/log/log.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 tile;

	struct grid
	{
		util::array<tile, 2> tiles;
		util::array<bool, 2> item_target;

		util::array<util::hash_set<geom::point<int, 2>>, 2> belts;

		static grid create();

		static geom::point<int, 2> const indices[9];

		static geom::vector<int, 2> const neighbours[4];
	};

	geom::point<int, 2> const grid::indices[9] =
	{
		{0, 0},
		{1, 0},
		{2, 0},
		{0, 1},
		{1, 1},
		{2, 1},
		{0, 2},
		{1, 2},
		{2, 2},
	};

	geom::vector<int, 2> const grid::neighbours[4] =
	{
		{1, 0},
		{0, 1},
		{-1, 0},
		{0, -1},
	};

	struct empty{};

	struct source
	{
		color type;
	};

	struct factory
	{
		color input;
		color output;
	};

	struct zoomer
	{
		struct grid grid;
	};

	using tile_variant = std::variant<empty, source, factory, zoomer>;

	struct tile
		: tile_variant
	{
		using tile_variant::variant;
	};

	grid grid::create()
	{
		grid result;

		result.tiles.resize({3, 3});
		result.belts.resize({3, 3});
		result.item_target.resize({9, 9}, false);

		return result;
	}

	struct item
	{
		color type;
		geom::point<int, 2> start;
		geom::point<int, 2> target;
		float pos;
	};

	geom::point<int, 2> item_to_cell(geom::point<int, 2> const & p)
	{
		return {geom::idiv(p[0], 3), geom::idiv(p[1], 3)};
	}

	geom::point<int, 2> cell_center_to_item(geom::point<int, 2> const & p)
	{
		return {p[0] * 3 + 1, p[1] * 3 + 1};
	}

	geom::point<int, 2> task_sink_to_item(geom::point<int, 2> p)
	{
		p[0] *= 3;
		p[1] *= 3;

		if (p[0] == -3)
			p += geom::vector{2, 1};
		else if (p[1] == -3)
			p += geom::vector{1, 2};
		else if (p[0] == 9)
			p += geom::vector{0, 1};
		else if (p[1] == 9)
			p += geom::vector{1, 0};

		return p;
	}

	bool within_grid(geom::point<int, 2> const & p)
	{
		return p[0] >= 0 && p[0] < 3 && p[1] >= 0 && p[1] < 3;
	}

	bool item_within_grid(geom::point<int, 2> const & p)
	{
		return p[0] >= 0 && p[0] < 9 && p[1] >= 0 && p[1] < 9;
	}

	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
	{
		color type;

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

		static constexpr int freq = 3;
	};

	struct map
	{
		struct grid grid;

		util::hash_map<geom::point<int, 2>, task> tasks;

		std::vector<item> items;

		timestamp time = {};

		float spawn_timer = 0.f;
	};

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

		while (true)
		{
			type = random::uniform_from(rng, color_values());
			if (map.tasks.size() >= 3)
				break;

			bool good = true;
			for (auto const & t : map.tasks)
				if (t.second.type == type)
					good = false;

			if (good)
				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.tasks.contains({x, y}))
				continue;

			map.tasks[{x, y}] = {type};
			break;
		}
	}

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

		result.grid = grid::create();

		generate_next_task(rng, result);

		return result;
	}

	void draw(map const & map, gfx::painter & painter)
	{
		float const grid_width = 0.1f;
		geom::box<float, 2> source_box{{{0.2f, 0.8f}, {0.2f, 0.8f}}};

		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);
		}

		auto & grid = map.grid;

		for (auto p : grid::indices)
			for (auto q : grid.belts(p))
				painter.line(geom::cast<float>(p) + geom::vector{0.5f, 0.5f}, geom::cast<float>(q) + geom::vector{0.5f, 0.5f}, 0.3f, {191, 191, 191, 255}, true);

		for (auto p : grid::indices)
		{
			for (auto q : grid.belts(p))
			{
				for (int i = 0; i < 3; ++i)
				{
					geom::vector d = geom::cast<float>(q - p);

					auto c = geom::cast<float>(p) + geom::vector{0.5f, 0.5f} + d * (i / 3.f);

					auto n = geom::ort(d);

					c += d / 6.f;

					float s = 1.f / 24.f;

					d *= s;
					n *= s;

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

		for (auto p : grid::indices)
		{
			auto const & cell = grid.tiles(p);

			if (auto source = std::get_if<struct source>(&cell))
			{
				painter.rect(source_box + geom::vector{p[0] * 1.f, p[1] * 1.f}, to_color(source->type));
				painter.text({p[0] + 0.5f, p[1] + 0.5f}, "180/m", {.scale = {0.01f, -0.01f}, .c = {0, 0, 0, 255}});
			}
			else if (auto factory = std::get_if<struct factory>(&cell))
			{
				auto box = source_box + geom::vector{p[0] * 1.f, p[1] * 1.f};
				painter.triangle(box.corner(0, 0), box.corner(1, 1), box.corner(0, 1), to_color(factory->input));
				painter.triangle(box.corner(0, 0), box.corner(1, 0), box.corner(1, 1), to_color(factory->output));
			}
		}

		for (auto const & task : map.tasks)
		{
			painter.rect(source_box + geom::vector{task.first[0] * 1.f, task.first[1] * 1.f}, to_color(task.second.type));
			painter.text(geom::point{task.first[0] + 0.5f, task.first[1] + 0.5f}, std::format("{}/m", task.second.received.size() * task::freq), {.scale = {0.01f, -0.01f}, .c = {0, 0, 0, 255}});
		}

		for (auto const & item : map.items)
		{
			auto pos = geom::lerp(geom::cast<float>(item.start), geom::cast<float>(item.target), item.pos) + geom::vector{0.5f, 0.5f};
			pos[0] /= 3.f;
			pos[1] /= 3.f;
			painter.circle(pos, 0.075f, {0, 0, 0, 255});
			painter.circle(pos, 0.05f, to_color(item.type));
		}
	}

	void draw_selection(geom::point<int, 2> const & p, gfx::painter & painter)
	{
		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_ && std::holds_alternative<empty>(map_.grid.tiles(*selected_)))
				{
					util::hash_set<color> types;
					if (map_.tasks.size() == 1)
						types.insert(map_.tasks.begin()->second.type);
					else
						for (auto t : color_values())
							types.insert(t);
					map_.grid.tiles(*selected_) = source{random::uniform_from(rng_, types)};
				}
			}

			if (event.down && event.key == app::keycode::B)
			{
				if (selected_)
				{
					if (belt_start_)
					{
						auto d = *selected_ - *belt_start_;
						if (std::abs(d[0]) + std::abs(d[1]) == 1)
						{
							if (within_grid(*selected_))
								map_.grid.belts(*selected_).erase(*belt_start_);

							if (map_.grid.belts(*belt_start_).contains(*selected_))
								map_.grid.belts(*belt_start_).erase(*selected_);
							else
								map_.grid.belts(*belt_start_).insert(*selected_);
						}
						belt_start_ = std::nullopt;
					}
					else if (within_grid(*selected_))
						belt_start_ = *selected_;
				}
			}

			if (event.down && event.key == app::keycode::F)
			{
				if (selected_ && std::holds_alternative<empty>(map_.grid.tiles(*selected_)))
				{
					util::hash_set<color> types;
					for (auto const & task : map_.tasks)
						types.insert(task.second.type);

					if (types.size() == 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_.grid.tiles(*selected_) = gmtk::factory{input, output};
				}
			}

			if (event.down && event.key == app::keycode::X)
			{
				if (selected_)
				{
					map_.grid.tiles(*selected_) = empty{};
				}
			}

			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;

				for (auto p : grid::indices)
				{
					if (auto source = std::get_if<struct source>(&map_.grid.tiles(p)))
					{
						auto pos = cell_center_to_item(p);

						if (!map_.grid.item_target(pos))
						{
							auto & item = map_.items.emplace_back();
							item.type = source->type;
							item.start = pos;
							item.target = pos;
							map_.grid.item_target(pos) = true;
						}
					}
				}
			}

			for (auto & task : map_.tasks)
			{
				auto & received = task.second.received;
				auto threshold = map_.time;
				threshold.trunc -= 60 / task::freq;
				while (!received.empty() && received.front() < threshold)
					received.pop_front();
			}

			std::vector<item> alive_items;
			for (auto item : map_.items)
			{
				if (item.start != item.target)
				{
					item.pos += 3.f * dt;

					if (item.pos < 1.f)
					{
						alive_items.push_back(item);
						continue;
					}

					item.pos -= 1.f;
				}

				if (item_within_grid(item.target))
					map_.grid.item_target(item.target) = false;

				auto cell = item_to_cell(item.target);

				if (map_.tasks.contains(cell))
				{
					if (map_.tasks.at(cell).type == item.type)
						map_.tasks.at(cell).received.push_back(map_.time);
					continue;
				}

				if (item_within_grid(item.target) && item.target == cell_center_to_item(cell))
				{
					if (auto factory = std::get_if<gmtk::factory>(&map_.grid.tiles(cell)))
					{
						if (factory->input == item.type)
							item.type = factory->output;
					}
				}

				std::vector<geom::point<int, 2>> targets;

				if (geom::imod(item.target[0], 3) == 1 && geom::imod(item.target[1], 3) == 1)
				{
					for (auto q : map_.grid.belts(cell))
					{
						auto t = item.target + (q - cell);
						if (!item_within_grid(t) || !map_.grid.item_target(t))
							targets.push_back(t);
					}
				}
				else
				{
					auto s = item.target;
					if (geom::imod(s[0], 3) == 0)
						s[0] -= 1;
					else if (geom::imod(s[0], 3) == 2)
						s[0] += 1;
					else if (geom::imod(s[1], 3) == 0)
						s[1] -= 1;
					else if (geom::imod(s[1], 3) == 2)
						s[1] += 1;

					if (!item_within_grid(s) || !map_.grid.item_target(s))
						if (within_grid(item_to_cell(item.target)) && map_.grid.belts(item_to_cell(item.target)).contains(item_to_cell(s)))
							targets.push_back(s);

					auto t = item.target - (s - item.target);

					if (!item_within_grid(t) || !map_.grid.item_target(t))
						if (within_grid(item_to_cell(s)) && map_.grid.belts(item_to_cell(s)).contains(item_to_cell(item.target)))
							targets.push_back(t);
				}

				item.start = item.target;

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

				if (item_within_grid(item.target))
					map_.grid.item_target(item.target) = true;
				alive_items.push_back(item);
			}
			map_.items = std::move(alive_items);

			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_ = geom::point{x, y};
				else if (map_.tasks.contains({x, y}))
					selected_ = 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<geom::point<int, 2>> selected_;
		std::optional<geom::point<int, 2>> 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);
	}

}