/*
This file is part of Minitrem.

Minitrem is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation, either version 2 of the License, or
(at your option) any later version.

Minitrem is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
GNU General Public License for more details.

You should have received a copy of the GNU General Public License
along with Minitrem.  If not, see <http://www.gnu.org/licenses/>.
*/

#include <iostream>
#include <cinttypes>
#include <cmath>
#include <cassert>
#include <map>
#include <list>
#include <unordered_set>
#include <sstream>
#include <stack>
#include <SFML/Graphics.hpp>
#include <SFML/Audio.hpp>
#include "math.hpp"

#define COUNT(A) (sizeof(A) / sizeof((A)[0]))

extern bool debug_draw_cmodels;
extern bool debug_draw_paths;
extern bool debug_draw_tile_coords;
extern bool debug_AI;

// time in nanoseconds
// nclock() never returns 0, so it can be used as a null value
typedef uint64_t ntime_t;
ntime_t nclock(void);

namespace procgen {
	class prng_t {
		uint32_t state = 0;

	public:
		void seed(uint32_t seed);
		uint32_t next(void);
		float next_float(void);
		void unit_vec(float out[2]);
		v2f_t unit_vec2(void);

	};

	class perlin_noise_t {
		size_t size;
		float (*table)[2] = nullptr;

		float table_dot(size_t nx, size_t ny, float dx, float dy);

	public:
		~perlin_noise_t();

		void generate(prng_t *prng, size_t size);
		float get(v2f_t x, float scale);
	};
}

namespace render { class state_t; }

namespace world {
	#define SECTOR_SIZE 8

	typedef int64_t coord_t;
	typedef vec_t<coord_t, 2> sector_index_t;
	typedef vec_t<coord_t, 2> tile_index_t;

	static tile_index_t neighbor_offsets[8] = {
		{+1, 0}, {+1, +1}, {0, +1}, {-1, +1},
		{-1, 0}, {-1, -1}, {0, -1}, {+1, -1}
	};

	class tile_t {
	public:
		unsigned type : 8;
		unsigned neighbors : 8;
		unsigned variant : 8;
	};

	sector_index_t sector_index_at(v2f_t x);
	tile_index_t tile_index_at(v2f_t x);

	class entity_t;

	typedef enum {
		SECTOR_EMPTY,
		SECTOR_PARTIAL,
		SECTOR_FULL
	} sector_level_t;

	class sector_t {
	public:
		sector_index_t index;
		rectf_t bounds;
		std::unordered_set<entity_t*> ents;
		sector_level_t level;
		tile_t tiles[SECTOR_SIZE * SECTOR_SIZE];
	};

	typedef int cflags_t;

	typedef struct {
		cflags_t cflags;
		rectf_t bounds;
	} cmodel_t;

	typedef struct {
		bool hit;
		v2f_t end;
		float frac;
	} trace_t;

	void register_tile(uint8_t type, cflags_t cflags);

	class world_t {
		procgen::prng_t prng;

		std::map<sector_index_t, sector_t> sectors;

		void generate_tile(tile_t *tile, tile_index_t index);
		void generate(sector_t *sector, sector_index_t index, sector_level_t level);

	protected:
		friend render::state_t;

	public:
		procgen::perlin_noise_t perlin;

		void (*generator)(world_t *world, sector_index_t index, sector_t *sector,
		                  bool gen_tiles, bool gen_decos, void *data) = 0;
		void *generator_data = 0;

		world_t(void);

		sector_t *get_sector(sector_index_t index, sector_level_t level);
		tile_t *get_tile(tile_index_t index, sector_level_t level);

		bool find_path(v2f_t src, v2f_t dst, cmodel_t *cmodel, entity_t *ignore, std::list<v2f_t> *path);

		// FIXME: iterators instead of returning std::lists
		std::list<sector_t*> get_sectors(rectf_t rect, sector_level_t level);
		std::list<entity_t*> get_entities(rectf_t rect, cflags_t cflags);
		std::list<entity_t*> get_render_entities(rectf_t rect);

		bool test_rect(const cmodel_t *cmodel, const entity_t *ignore);
		trace_t trace(v2f_t start, v2f_t end, cflags_t cflags);

		struct {
			size_t sectors = 0, tiles = 0;
			size_t entities = 0;
		} stats;
	};

	class entity_t {
		std::vector<sector_t*> parents;

		void link_to_sector(sector_t *sector);

	protected:
		friend world_t;
		size_t cookie = 0;

	public:
		world_t *world = 0;
		int type;
		cmodel_t cmodel;
		rectf_t render_bounds;
		int render_layer = 0;

		entity_t(int type_);
		virtual ~entity_t(void) = 0;

		void link(world_t *world);
		void unlink();

		virtual void render_to(render::state_t *render) = 0;
		virtual void render_late_to(render::state_t *render) = 0;
	};

	typedef struct {
		bool accessible;
		float dist;
	} path_node_t;

	class path_finder_t {
		path_node_t *node_at(tile_index_t index);
		bool is_accessible(tile_index_t index);
		bool diagonal_test(tile_index_t index, size_t i);

	public:
		v2f_t src, dst, tile_center;
		rectf_t bounds;
		cflags_t cflags;
		path_node_t *nodes;
		size_t width, height;
		tile_index_t base;

		float shortest_dist;
		std::deque<tile_index_t> path, shortest_path;

		~path_finder_t();
		void setup_nodes(v2f_t src_, v2f_t dst_, cflags_t cflags_);
		void eliminate_nodes(rectf_t rect);
		void find_r(tile_index_t index, float dist, float limit);
		bool find(void);
		void export_path(std::list<v2f_t> *list);
	};
}

namespace interface {
	class state_t;
}

namespace game {
	bool load_assets(void);

	class entity_t;
	class unit_t;
	class effect_t;

	class die_t {
	public:
		size_t count = 1, sides = 20, bonus = 0;

		die_t(void) = default;
		die_t(size_t sides_);
		die_t(size_t count_, size_t sides_);
		die_t(size_t count_, size_t sides_, size_t bonus_);
	};

	class state_t {
		void group_say(std::string text);

	public:
		world::world_t world;
		interface::state_t *interface;
		procgen::prng_t dice_prng;
		std::unordered_set<entity_t*> awake_entities;
		std::unordered_set<unit_t*> selected_units;

		ntime_t time; // game time
		double now, dt; // FIXME: refactor the code, use ntime_t everywhere

		// frame timing data (game runs at a different frequency than the renderer)
		bool paused;
		ntime_t t0;
		size_t frames = 0, frames_since_t0, frames_behind = 0;
		ntime_t pathfinder_time = 0;

		void start(void);
		void stop(void);
		void tick(ntime_t time);
		void compute_ambience(render::state_t *render);
		void pause(void);
		void resume(void);

		// These are called by the interface.
		void select(rectf_t rect);
		void command(v2f_t x);
		void spawn_soldier(v2f_t x);

		size_t roll(die_t die);
	};
}

namespace interface {
	class state_t {
		sf::RenderWindow *window;
		game::state_t *game;

		float em;

		struct {
			v2f_t zero_point_s = v2f_t(0, 0);
			v2f_t center = v2f_t(0, 0);

			int zoom = 3;
			float zoom_s = 3.0f;

			bool panning = false;
			sf::Vector2f pan_ref;

			bool following = true;
		} camera;

		struct {
			bool selecting = false;
			rectf_t rect;
		} select;

		typedef struct {
			double time;
			std::string text;
		} log_entry_t;

		std::list<log_entry_t> log;

		double perf_hist[10] = {0};
		size_t perf_hist_index = 0;

		void start_following(void);
		void stop_following(void);
	public:
		state_t(sf::RenderWindow *window_, game::state_t *game);
		void tick(double dt);
		void render_to(render::state_t *render);

		void print(std::string str);
	};
}

namespace render {
	class animated_texture_t {
		friend state_t;
	protected:
		sf::Texture *frames = NULL;
		size_t frame_count;

	public:
		~animated_texture_t(void);
		bool load(std::string prefix, size_t frame_count_);
	};

	class oriented_sprite_t {
	protected:
		friend state_t;
		animated_texture_t *textures;
		virtual size_t select_index(float angle, bool *mirror) = 0;

	public:
		~oriented_sprite_t(void);
	};

	class oriented_sprite_4M_t : public oriented_sprite_t {
		size_t select_index(float angle, bool *mirror);

	public:
		void load(std::string prefix, size_t xc, size_t yc, size_t nyc);
	};

	class oriented_sprite_4M2_t : public oriented_sprite_t {
		size_t select_index(float angle, bool *mirror);

	public:
		void load(std::string prefix, size_t xc, size_t yc);
	};

	typedef enum {
		ALIGN_LEFT_TOP,
		ALIGN_CENTER_BOTTOM
	} text_align_t;

	void register_tile(uint8_t type, const char *top, const char *side, float height);

	class state_t {
		sf::RenderWindow *window;

		void render_tile(world::world_t *world, v2f_t tx, world::tile_t *tile);
		void drender_text(rectf_t rect, std::string str);
		void drender_entity(world::entity_t *ent);
	public:
		ntime_t time;
		double dt;

		struct {
			size_t sectors, tiles, entities;
		} stats;

		state_t(sf::RenderWindow *window_);
		void begin_frame(ntime_t time_, double dt);
		void end_frame(void);

		void render(game::state_t *game);
		void render(double phase, animated_texture_t *anim, rectf_t bounds, sf::Color color = sf::Color::White, bool mirror = false);
		void render(double phase, oriented_sprite_t *sprite, rectf_t bounds, float angle);

		void render_text(v2f_t x, float height, std::string str, text_align_t align, sf::Color color);
		void render_rect(rectf_t rect, sf::Color color);
		void render_hlrect(rectf_t rect, sf::Color color);
		void render_line(v2f_t x0, v2f_t x1, sf::Color color);

		void debug_path(v2f_t x, std::list<v2f_t> *path);

		rectf_t window_in_world_space(void);
	};
}

namespace audio {
	void clean_sounds(void);
	void update_ambience(bool playing);

	class sound_t {
		sf::SoundBuffer buffer;

	public:
		void load(const char *path);
		void play(void);
	};

	class ambient_t {
	public:
		sf::Music sound;
		bool playing = false;
		float weight = 0.0f;

		void load(const char *path);
	};
}

extern render::state_t *debug_render;

// Divide and round to minus infinity.
template <typename T>
T divide_rmi(T x, T y, T *rem)
{
	T rv;

	if (x >= 0) {
		*rem = x % y;
		return x / y;
	}

	rv = (x + 1) / y - 1;
	*rem = x - rv * y;
	return rv;
}

// Linear interpolation.
template <typename T>
T lerp(T a, T b, T x)
{
	return a * (1 - x) + b * x;
}

// Linear map between intervals.
template <typename T>
T remap(T am, T ap, T bm, T bp, T x)
{
	return (x - am) * (bp - bm) / (ap - am) + bm;
}

template <typename T>
T clamp(T x, T m, T p)
{
	if (x < m)
		return m;
	if (x > p)
		return p;
	return x;
}

// Bilinear interpolation.
template <typename T>
T bilerp(T a, T b, T c, T d, T x, T y)
{
	T ab, cd;

	ab = lerp(a, b, x);
	cd = lerp(c, d, x);
	return lerp(ab, cd, y);
}

template <typename T>
static inline void expfade(T *a, T b, T l, T dt)
{
	*a = b + (*a - b) * exp(-l * dt);
}

template <typename T, size_t N>
static inline void expfade(vec_t<T, N> *a, vec_t<T, N>  b, float l, float dt)
{
	*a = b + (*a - b) * exp(-l * dt);
}