/// The random offset applied to square coordinates, causes intermingling at biome borders
#define BIOME_RANDOM_SQUARE_DRIFT 2
// Categories for spawned things
#define CAVE_SPAWN_MOB "mob"
#define CAVE_SPAWN_FEATURE "feature"
#define CAVE_SPAWN_TENDRIL "tendril"
#define CAVE_SPAWN_MEGAFAUNA "megafauna"

/datum/map_generator/cave_generator
	var/name = "Cave Generator"
	///Weighted list of the types that spawns if the turf is open
	var/weighted_open_turf_types = list(/turf/open/misc/asteroid/airless = 1)
	///Expanded list of the types that spawns if the turf is open
	var/open_turf_types
	///Weighted list of the types that spawns if the turf is closed
	var/weighted_closed_turf_types = list(/turf/closed/mineral/random = 1)
	///Expanded list of the types that spawns if the turf is closed
	var/closed_turf_types


	///Weighted list of mobs that can spawn in the area.
	var/list/weighted_mob_spawn_list
	///Expanded list of mobs that can spawn in the area. Reads from the weighted list
	var/list/mob_spawn_list
	///The mob spawn list but with no megafauna markers. autogenerated
	var/list/mob_spawn_no_mega_list
	// Weighted list of Megafauna that can spawn in the area
	var/list/weighted_megafauna_spawn_list
	///Expanded list of Megafauna that can spawn in the area. Reads from the weighted list
	var/list/megafauna_spawn_list
	///Weighted list of flora that can spawn in the area.
	var/list/weighted_flora_spawn_list
	///Expanded list of flora that can spawn in the area. Reads from the weighted list
	var/list/flora_spawn_list
	///Weighted list of extra features that can spawn in the area, such as geysers.
	var/list/weighted_feature_spawn_list
	///Expanded list of extra features that can spawn in the area. Reads from the weighted list
	var/list/feature_spawn_list
	/// An associative list of biome type to the list of turfs that were
	/// generated of that biome specifically. Helps to improve the efficiency
	/// of biome-related operations. Is populated through
	/// `generate_terrain_with_biomes()`.
	var/list/generated_turfs_per_biome = list()
	/// Same as generated_turfs_per_biome, but additionally indexed by area
	var/list/generated_turfs_per_area_biome = list()
	/// 2D list of all biomes based on heat and humidity combos. Associative by
	/// `BIOME_X_HEAT` and then by `BIOME_X_HUMIDITY` (i.e.
	/// `possible_biomes[BIOME_LOW_HEAT][BIOME_LOWMEDIUM_HUMIDITY]`).
	/// Check /datum/map_generator/cave_generator/jungle for an example
	/// of how to set it up properly.
	var/list/possible_biomes = list()
	/// Used to select "zoom" level into the perlin noise, higher numbers
	/// result in slower transitions
	var/perlin_zoom = 65

	/// Should we populate turfs through biome datums if we have such
	var/biome_population = TRUE
	/// Noise threshold above which a biome is considered high heat
	var/high_heat_threshold = -0.1
	/// Noise threshold above which a biome is considered medium heat
	var/medium_heat_threshold = -0.3
	/// Noise threshold above which a biome is considered high humidity
	var/high_humidity_threshold = -0.1
	/// Noise threshold above which a biome is considered medium humidity
	var/medium_humidity_threshold = -0.3
	/// Should all generators on the same z level use the same seeds?
	var/shared_seed = TRUE
	/// Stamp size for DBP noise, aka frequency
	var/biome_stamp_size = 75
	/// Stored noise maps per z level if we use a shared seed
	var/static_biome_maps = list()

	/// Base chance of spawning a mob
	var/mob_spawn_chance = 6
	/// Base chance of spawning flora
	var/flora_spawn_chance = 2
	/// Base chance of spawning features
	var/feature_spawn_chance = 0.25
	/// Unique ID for this spawner
	var/string_gen

	/// Radius around features within which we avoid spawning other features
	var/feature_exclusion_radius = 7
	/// Radius around mobs which we avoid spawning other mobs
	var/mob_exclusion_radius = 12
	/// Radius around megafauna within which we avoid spawning tendrils
	var/megafauna_exclusion_radius = 7

	///Chance of cells starting closed
	var/initial_closed_chance = 45
	///Amount of smoothing iterations
	var/smoothing_iterations = 20
	///How much neighbours does a dead cell need to become alive
	var/birth_limit = 4
	///How little neighbours does a alive cell need to die
	var/death_limit = 3


/datum/map_generator/cave_generator/New()
	. = ..()
	if(!weighted_mob_spawn_list)
		weighted_mob_spawn_list = list(
			/mob/living/basic/mining/basilisk = 4,
			/mob/living/basic/mining/goldgrub = 1,
			/mob/living/basic/mining/goliath/ancient = 5,
			/mob/living/basic/mining/hivelord = 3,
		)
	mob_spawn_list = expand_weights(weighted_mob_spawn_list)
	mob_spawn_no_mega_list = expand_weights(weighted_mob_spawn_list - SPAWN_MEGAFAUNA)
	if(!weighted_megafauna_spawn_list)
		weighted_megafauna_spawn_list = GLOB.megafauna_spawn_list
	megafauna_spawn_list = expand_weights(weighted_megafauna_spawn_list)
	if(!weighted_flora_spawn_list)
		weighted_flora_spawn_list = list(
			/obj/structure/flora/ash/leaf_shroom = 2,
			/obj/structure/flora/ash/cap_shroom = 2,
			/obj/structure/flora/ash/stem_shroom = 2,
			/obj/structure/flora/ash/cacti = 1,
			/obj/structure/flora/ash/tall_shroom = 2,
			/obj/structure/flora/ash/seraka = 2,
		)
	flora_spawn_list = expand_weights(weighted_flora_spawn_list)
	if(!weighted_feature_spawn_list)
		weighted_feature_spawn_list = list(
			/obj/structure/geyser/random = 1,
			/obj/structure/ore_vent/random = 1,
		)
	feature_spawn_list = expand_weights(weighted_feature_spawn_list)
	open_turf_types = expand_weights(weighted_open_turf_types)
	closed_turf_types = expand_weights(weighted_closed_turf_types)

/datum/map_generator/cave_generator/generate_terrain(list/turfs, area/generate_in)
	. = ..()
	if(!(generate_in.area_flags_mapping & CAVES_ALLOWED))
		return

	if(length(possible_biomes))
		return generate_terrain_with_biomes(turfs, generate_in)

	var/start_time = REALTIMEOFDAY
	string_gen = rustg_cnoise_generate("[initial_closed_chance]", "[smoothing_iterations]", "[birth_limit]", "[death_limit]", "[world.maxx]", "[world.maxy]") //Generate the raw CA data

	for(var/turf/gen_turf as anything in turfs) //Go through all the turfs and generate them
		//SKYRAT EDIT ADDITION
		if(istype(gen_turf, /turf/open/space/mirage))
			continue
		//SKYRAT EDIT END

		var/closed = string_gen[world.maxx * (gen_turf.y - 1) + gen_turf.x] != "0"
		var/turf/new_turf = pick(closed ? closed_turf_types : open_turf_types)

		// The assumption is this will be faster then changeturf, and changeturf isn't required since by this point
		// The old tile hasn't got the chance to init yet
		new_turf = new new_turf(gen_turf)

		if(gen_turf.turf_flags & NO_RUINS)
			new_turf.turf_flags |= NO_RUINS

	var/message = "[name] terrain generation finished in [(REALTIMEOFDAY - start_time)/10]s!"
	to_chat(world, span_boldannounce("[message]"), MESSAGE_TYPE_DEBUG)
	log_world(message)


/**
 * This proc handles including biomes in the cave generation. This is slower than
 * `generate_terrain()`, so please use it only if you actually need biomes.
 *
 * This should only be called by `generate_terrain()`, if you have to call this,
 * you're probably doing something wrong.
 */
/datum/map_generator/cave_generator/proc/generate_terrain_with_biomes(list/turf/turfs, area/generate_in)
	if(!(generate_in.area_flags_mapping & CAVES_ALLOWED))
		return

	var/humidity_seed = null
	var/heat_seed = null

	// Make sure that all caves on the same z level generate smoothly regardless of the area
	if (shared_seed)
		var/static/list/static_heat = null
		var/static/list/static_humi = null
		if (!static_heat)
			static_heat = list()
			static_humi = list()

		var/z_key = "[turfs[1].z]"
		if (!static_heat[z_key])
			static_heat[z_key] = rand(0, 50000)
			static_humi[z_key] = rand(0, 50000)

		heat_seed = static_heat[z_key]
		humidity_seed = static_humi[z_key]
	else
		humidity_seed = rand(0, 50000)
		heat_seed = rand(0, 50000)

	var/start_time = REALTIMEOFDAY
	string_gen = rustg_cnoise_generate("[initial_closed_chance]", "[smoothing_iterations]", "[birth_limit]", "[death_limit]", "[world.maxx]", "[world.maxy]") //Generate the raw CA data

	var/humidity_gen = list()
	humidity_gen[BIOME_HIGH_HUMIDITY] = rustg_dbp_generate("[humidity_seed]", "60", "[biome_stamp_size]", "[world.maxx]", "[high_heat_threshold]", "1.1")
	humidity_gen[BIOME_MEDIUM_HUMIDITY] = rustg_dbp_generate("[humidity_seed]", "60", "[biome_stamp_size]", "[world.maxx]", "[medium_heat_threshold]", "[high_heat_threshold]")

	var/heat_gen = list()
	heat_gen[BIOME_HIGH_HEAT] = rustg_dbp_generate("[heat_seed]", "60", "[biome_stamp_size]", "[world.maxx]", "[high_heat_threshold]", "1.1")
	heat_gen[BIOME_MEDIUM_HEAT] = rustg_dbp_generate("[heat_seed]", "60", "[biome_stamp_size]", "[world.maxx]", "[medium_heat_threshold]", "[high_heat_threshold]")

	if (shared_seed)
		static_biome_maps["[turfs[1].z]"] = list(
			BIOME_HIGH_HUMIDITY = humidity_gen[BIOME_HIGH_HUMIDITY],
			BIOME_MEDIUM_HUMIDITY = humidity_gen[BIOME_MEDIUM_HUMIDITY],
			BIOME_HIGH_HEAT = heat_gen[BIOME_HIGH_HEAT],
			BIOME_MEDIUM_HEAT = heat_gen[BIOME_MEDIUM_HEAT],
		)

	var/list/to_generate = list()
	for(var/turf/gen_turf as anything in turfs) //Go through all the turfs and generate them
		var/closed = string_gen[world.maxx * (gen_turf.y - 1) + gen_turf.x] != "0"
		var/datum/biome/selected_biome

		// Here comes the meat of the biome code.
		var/drift_x = clamp((gen_turf.x + rand(-BIOME_RANDOM_SQUARE_DRIFT, BIOME_RANDOM_SQUARE_DRIFT)), 1, world.maxx) // / perlin_zoom
		var/drift_y = clamp((gen_turf.y + rand(-BIOME_RANDOM_SQUARE_DRIFT, BIOME_RANDOM_SQUARE_DRIFT)), 2, world.maxy) // / perlin_zoom

		// Where we go in the generated string (generated outside of the loop for s p e e d)
		var/coordinate = world.maxx * (drift_y - 1) + drift_x

		// Type of humidity zone we're in (LOW-MEDIUM-HIGH)
		var/humidity_level = text2num(humidity_gen[BIOME_HIGH_HUMIDITY][coordinate]) ? \
			BIOME_HIGH_HUMIDITY : text2num(humidity_gen[BIOME_MEDIUM_HUMIDITY][coordinate]) ? BIOME_MEDIUM_HUMIDITY : BIOME_LOW_HUMIDITY
		// Type of heat zone we're in (LOW-MEDIUM-HIGH)
		var/heat_level = text2num(heat_gen[BIOME_HIGH_HEAT][coordinate]) ? \
			BIOME_HIGH_HEAT : text2num(heat_gen[BIOME_MEDIUM_HEAT][coordinate]) ? BIOME_MEDIUM_HEAT : BIOME_LOW_HEAT

		selected_biome = possible_biomes[heat_level][humidity_level]
		LAZYSET(to_generate[selected_biome], gen_turf, closed)
		CHECK_TICK

	for(var/biome in to_generate)
		var/datum/biome/generating_biome = SSmapping.biomes[biome]
		var/list/turf/generated_turfs = generating_biome.generate_turfs_for_terrain(to_generate[biome])
		generated_turfs_per_biome[biome] = (generated_turfs_per_biome[biome] || list()) + generated_turfs
		var/list/area_list = generated_turfs_per_area_biome[biome]
		if (!area_list)
			area_list = list()
			generated_turfs_per_area_biome[biome] = area_list
		area_list[generate_in] = generated_turfs

	var/message = "[name] terrain generation finished in [(REALTIMEOFDAY - start_time)/10]s!"
	to_chat(world, span_boldannounce("[message]"), MESSAGE_TYPE_DEBUG)
	log_world(message)

/// Returns a biome datum that the turf was initialized with, or would be if it is present on our Z level and we use a consistent shared seed
/// Not consistent between calls by itself due to using RNG in perlin zoom, needs a static coordinate-based formula
/datum/map_generator/cave_generator/proc/get_biome_for_turf(turf/target)
	for (var/biome in generated_turfs_per_biome)
		var/list/generated_turfs = generated_turfs_per_biome[biome]
		if (generated_turfs[target])
			return biome

	var/list/biome_map = static_biome_maps["[target.z]"]
	if (!shared_seed || !biome_map)
		return null

	var/drift_x = clamp((target.x + rand(-BIOME_RANDOM_SQUARE_DRIFT, BIOME_RANDOM_SQUARE_DRIFT)), 1, world.maxx)
	var/drift_y = clamp((target.y + rand(-BIOME_RANDOM_SQUARE_DRIFT, BIOME_RANDOM_SQUARE_DRIFT)), 2, world.maxy)
	var/coordinate = world.maxx * (drift_y - 1) + drift_x

	var/humidity_level = text2num(biome_map[BIOME_HIGH_HUMIDITY][coordinate]) ? \
		BIOME_HIGH_HUMIDITY : text2num(biome_map[BIOME_MEDIUM_HUMIDITY][coordinate]) ? BIOME_MEDIUM_HUMIDITY : BIOME_LOW_HUMIDITY
	var/heat_level = text2num(biome_map[BIOME_HIGH_HEAT][coordinate]) ? \
		BIOME_HIGH_HEAT : text2num(biome_map[BIOME_MEDIUM_HEAT][coordinate]) ? BIOME_MEDIUM_HEAT : BIOME_LOW_HEAT

	return possible_biomes[heat_level][humidity_level]

/datum/map_generator/cave_generator/populate_terrain(list/turfs, area/generate_in)
	if (biome_population && length(possible_biomes))
		return populate_terrain_with_biomes(turfs, generate_in)

	// Area var pullouts to make accessing in the loop faster
	var/flora_allowed = (generate_in.area_flags_mapping & FLORA_ALLOWED) && length(flora_spawn_list)
	var/feature_allowed = (generate_in.area_flags_mapping & FLORA_ALLOWED) && length(feature_spawn_list)
	var/mobs_allowed = (generate_in.area_flags_mapping & MOB_SPAWN_ALLOWED) && length(mob_spawn_list)
	var/megas_allowed = (generate_in.area_flags_mapping & MEGAFAUNA_SPAWN_ALLOWED) && length(megafauna_spawn_list)

	var/start_time = REALTIMEOFDAY

	// Assoc list of spawned categories to
	var/list/spawn_data = list(
		CAVE_SPAWN_FEATURE = list(),
		CAVE_SPAWN_TENDRIL = list(),
		CAVE_SPAWN_MOB = list(),
		CAVE_SPAWN_MEGAFAUNA = list(),
	)

	var/list/open_turf_cache = typecacheof(open_turf_types)
	for (var/turf/target_turf as anything in turfs)
		// Only put stuff on open turfs we generated, so closed walls and rivers and stuff are skipped
		if (!is_type_in_typecache(target_turf, open_turf_cache))
			continue

		CHECK_TICK

		if (!(target_turf.turf_flags & TURF_BLOCKS_POPULATE_TERRAIN_FLORAFEATURES))
			if (flora_allowed && prob(flora_spawn_chance))
				var/flora_type = pick(flora_spawn_list)
				new flora_type(target_turf)
				continue

			if (feature_allowed && prob(feature_spawn_chance))
				var/can_spawn = TRUE
				for(var/turf/spawn_turf as anything in spawn_data[CAVE_SPAWN_FEATURE])
					if (get_dist(spawn_turf, target_turf) <= feature_exclusion_radius)
						can_spawn = FALSE
						break

				if (can_spawn)
					var/picked_feature = pick(feature_spawn_list)
					new picked_feature(target_turf)
					spawn_data[CAVE_SPAWN_FEATURE] += target_turf
					continue

		if (!mobs_allowed || !prob(mob_spawn_chance))
			continue

		var/picked_mob = pick(megas_allowed ? mob_spawn_list : mob_spawn_no_mega_list)
		var/is_megafauna = FALSE
		if (picked_mob == SPAWN_MEGAFAUNA)
			picked_mob = pick(megafauna_spawn_list)
			is_megafauna = TRUE

		var/can_spawn = TRUE
		if(ispath(picked_mob, /mob/living/basic/mining/tendril))
			// Prevents tendrils spawning in each other's collapse range
			for(var/turf/spawn_turf as anything in spawn_data[CAVE_SPAWN_TENDRIL])
				if (get_dist(spawn_turf, target_turf) <= 2)
					can_spawn = FALSE
					break

			// Also avoid spawning them next to megafauna
			for(var/turf/spawn_turf as anything in spawn_data[CAVE_SPAWN_MEGAFAUNA])
				if (get_dist(spawn_turf, target_turf) <= megafauna_exclusion_radius)
					can_spawn = FALSE
					break
		else if (is_megafauna)
			// Megafauna can spawn wherever it wants as long as its not next to another mega
			for(var/turf/spawn_turf as anything in spawn_data[CAVE_SPAWN_MEGAFAUNA])
				if (get_dist(spawn_turf, target_turf) <= megafauna_exclusion_radius)
					can_spawn = FALSE
					break
		else
			for(var/turf/spawn_turf as anything in spawn_data[CAVE_SPAWN_MOB])
				if (get_dist(spawn_turf, target_turf) <= mob_exclusion_radius)
					can_spawn = FALSE
					break

		if (!can_spawn)
			continue

		if (ispath(picked_mob, /mob/living/basic/mining/tendril))
			spawn_data[CAVE_SPAWN_TENDRIL] += target_turf
		else
			if (is_megafauna)
				spawn_data[CAVE_SPAWN_MEGAFAUNA] += target_turf
			spawn_data[CAVE_SPAWN_MOB] += target_turf

		new picked_mob(target_turf)

		// There can be only one Bubblegum, so don't waste spawns on it
		if(ispath(picked_mob, /mob/living/simple_animal/hostile/megafauna/bubblegum))
			weighted_megafauna_spawn_list.Remove(picked_mob)
			megafauna_spawn_list = expand_weights(weighted_megafauna_spawn_list)
			megas_allowed = megas_allowed && length(megafauna_spawn_list)

	var/message = "[name] terrain population finished in [(REALTIMEOFDAY - start_time)/10]s!"
	add_startup_message(message) //SKYRAT EDIT CHANGE
	//to_chat(world, span_boldannounce("[message]"), MESSAGE_TYPE_DEBUG) //SKYRAT EDIT ORIGINAL
	log_world(message)

/**
 * This handles the population of terrain with biomes. Should only be called by
 * `populate_terrain()`, if you find yourself calling this, you're probably not
 * doing it right.
 *
 * This proc won't do anything if the area we're trying to generate in does not
 * have `FLORA_ALLOWED` or `MOB_SPAWN_ALLOWED` in its `area_flags`.
 */
/datum/map_generator/cave_generator/proc/populate_terrain_with_biomes(list/turfs, area/generate_in)
	// Area var pullouts to make accessing in the loop faster
	var/flora_allowed = (generate_in.area_flags_mapping & FLORA_ALLOWED)
	var/features_allowed = (generate_in.area_flags_mapping & FLORA_ALLOWED)
	var/fauna_allowed = (generate_in.area_flags_mapping & MOB_SPAWN_ALLOWED)

	var/start_time = REALTIMEOFDAY

	// No sense in doing anything here if nothing is allowed anyway.
	if(!flora_allowed && !features_allowed && !fauna_allowed)
		var/message = "[name] terrain population finished in [(REALTIMEOFDAY - start_time)/10]s!"
		to_chat(world, span_boldannounce("[message]"), MESSAGE_TYPE_DEBUG)
		log_world(message)
		return

	for(var/biome in generated_turfs_per_area_biome)
		var/datum/biome/generating_biome = SSmapping.biomes[biome]
		var/list/areas_list = generated_turfs_per_area_biome[biome]
		generating_biome.populate_turfs(areas_list[generate_in], flora_allowed, features_allowed, fauna_allowed)

		CHECK_TICK

	var/message = "[name] terrain population finished in [(REALTIMEOFDAY - start_time)/10]s!"
	to_chat(world, span_boldannounce("[message]"), MESSAGE_TYPE_DEBUG)
	log_world(message)

/datum/map_generator/cave_generator/jungle
	possible_biomes = list(
		BIOME_LOW_HEAT = list(
			BIOME_LOW_HUMIDITY = /datum/biome/plains,
			BIOME_MEDIUM_HUMIDITY = /datum/biome/mudlands,
			BIOME_HIGH_HUMIDITY = /datum/biome/water
		),
		BIOME_MEDIUM_HEAT = list(
			BIOME_LOW_HUMIDITY = /datum/biome/plains,
			BIOME_MEDIUM_HUMIDITY = /datum/biome/jungle/deep,
			BIOME_HIGH_HUMIDITY = /datum/biome/jungle
		),
		BIOME_HIGH_HEAT = list(
			BIOME_LOW_HUMIDITY = /datum/biome/wasteland,
			BIOME_MEDIUM_HUMIDITY = /datum/biome/plains,
			BIOME_HIGH_HUMIDITY = /datum/biome/jungle/deep
		)
	)


#undef BIOME_RANDOM_SQUARE_DRIFT
#undef CAVE_SPAWN_MOB
#undef CAVE_SPAWN_FEATURE
#undef CAVE_SPAWN_TENDRIL
#undef CAVE_SPAWN_MEGAFAUNA