/*

Making Bombs with ZAS:
Make burny fire with lots of burning
Draw off 5000K gas from burny fire
Separate gas into oxygen and phoron components
Obtain phoron and oxygen tanks filled up about 50-75% with normal-temp gas
Fill rest with super hot gas from separated canisters, they should be about 125C now.
Attach to transfer valve and open. BOOM.

*/

//#define FIREDBG

/turf/var/obj/fire/fire = null

//Some legacy definitions so fires can be started.
atom/proc/temperature_expose(datum/gas_mixture/air, exposed_temperature, exposed_volume)
	return null


turf/proc/hotspot_expose(exposed_temperature, exposed_volume, soh = 0)


/turf/simulated/hotspot_expose(exposed_temperature, exposed_volume, soh)
	if(fire_protection > world.time-300)
		return 0
	if(locate(/obj/fire) in src)
		return 1
	var/datum/gas_mixture/air_contents = return_air()
	if(!air_contents || exposed_temperature < PHORON_MINIMUM_BURN_TEMPERATURE)
		return 0

	var/igniting = 0
	var/obj/effect/decal/cleanable/liquid_fuel/liquid = locate() in src

	if(air_contents.check_combustability(liquid))
		igniting = 1

		create_fire(exposed_temperature)
	return igniting

/zone/proc/process_fire()
	var/datum/gas_mixture/burn_gas = air.remove_ratio(vsc.fire_consuption_rate, fire_tiles.len)

	var/firelevel = burn_gas.zburn(src, fire_tiles, force_burn = 1, no_check = 1)

	air.merge(burn_gas)

	if(firelevel)
		for(var/turf/T in fire_tiles)
			if(T.fire)
				T.fire.firelevel = firelevel
			else
				var/obj/effect/decal/cleanable/liquid_fuel/fuel = locate() in T
				fire_tiles -= T
				fuel_objs -= fuel
	else
		for(var/turf/simulated/T in fire_tiles)
			if(istype(T.fire))
				T.fire.RemoveFire()
			T.fire = null
		fire_tiles.Cut()
		fuel_objs.Cut()

	if(!fire_tiles.len)
		air_master.active_fire_zones.Remove(src)

/zone/proc/remove_liquidfuel(var/used_liquid_fuel, var/remove_fire=0)
	if(!fuel_objs.len)
		return
	
	//As a simplification, we remove fuel equally from all fuel sources. It might be that some fuel sources have more fuel, 
	//some have less, but whatever. It will mean that sometimes we will remove a tiny bit less fuel then we intended to.
	
	var/fuel_to_remove = used_liquid_fuel/(fuel_objs.len*LIQUIDFUEL_AMOUNT_TO_MOL) //convert back to liquid volume units
	
	for(var/O in fuel_objs)
		var/obj/effect/decal/cleanable/liquid_fuel/fuel = O
		if(!istype(fuel))
			fuel_objs -= fuel
			continue

		fuel.amount -= fuel_to_remove
		if(fuel.amount <= 0)
			fuel_objs -= fuel
			if(remove_fire)
				var/turf/T = fuel.loc
				if(istype(T) && T.fire) qdel(T.fire)
			qdel(fuel)

/turf/proc/create_fire(fl)
	return 0

/turf/simulated/create_fire(fl)
	if(fire)
		fire.firelevel = max(fl, fire.firelevel)
		return 1

	if(!zone)
		return 1

	fire = new(src, fl)
	air_master.active_fire_zones |= zone

	var/obj/effect/decal/cleanable/liquid_fuel/fuel = locate() in src
	zone.fire_tiles |= src
	if(fuel) zone.fuel_objs += fuel

	return 0

/obj/fire
	//Icon for fire on turfs.

	anchored = 1
	mouse_opacity = 0

	blend_mode = BLEND_ADD

	icon = 'icons/effects/fire.dmi'
	icon_state = "1"
	light_color = "#ED9200"
	layer = TURF_LAYER

	var/firelevel = 1 //Calculated by gas_mixture.calculate_firelevel()

/obj/fire/process()
	. = 1

	var/turf/simulated/my_tile = loc
	if(!istype(my_tile) || !my_tile.zone)
		if(my_tile.fire == src)
			my_tile.fire = null
		RemoveFire()
		return 1

	var/datum/gas_mixture/air_contents = my_tile.return_air()

	if(firelevel > 6)
		icon_state = "3"
		set_light(7, 3)
	else if(firelevel > 2.5)
		icon_state = "2"
		set_light(5, 2)
	else
		icon_state = "1"
		set_light(3, 1)

	for(var/mob/living/L in loc)
		L.FireBurn(firelevel, air_contents.temperature, air_contents.return_pressure())  //Burn the mobs!

	loc.fire_act(air_contents, air_contents.temperature, air_contents.volume)
	for(var/atom/A in loc)
		A.fire_act(air_contents, air_contents.temperature, air_contents.volume)

	//spread
	for(var/direction in cardinal)
		var/turf/simulated/enemy_tile = get_step(my_tile, direction)

		if(istype(enemy_tile))
			if(my_tile.open_directions & direction) //Grab all valid bordering tiles
				if(!enemy_tile.zone || enemy_tile.fire)
					continue

				//if(!enemy_tile.zone.fire_tiles.len) TODO - optimize
				var/datum/gas_mixture/acs = enemy_tile.return_air()
				var/obj/effect/decal/cleanable/liquid_fuel/liquid = locate() in enemy_tile
				if(!acs || !acs.check_combustability(liquid))
					continue

				//If extinguisher mist passed over the turf it's trying to spread to, don't spread and
				//reduce firelevel.
				if(enemy_tile.fire_protection > world.time-30)
					firelevel -= 1.5
					continue

				//Spread the fire.
				if(prob( 50 + 50 * (firelevel/vsc.fire_firelevel_multiplier) ) && my_tile.CanPass(null, enemy_tile, 0,0) && enemy_tile.CanPass(null, my_tile, 0,0))
					enemy_tile.create_fire(firelevel)

			else
				enemy_tile.adjacent_fire_act(loc, air_contents, air_contents.temperature, air_contents.volume)

	animate(src, color = fire_color(air_contents.temperature), 5)
	set_light(l_color = color)

/obj/fire/New(newLoc,fl)
	..()

	if(!istype(loc, /turf))
		qdel(src)
		return

	set_dir(pick(cardinal))
	
	var/datum/gas_mixture/air_contents = loc.return_air()
	color = fire_color(air_contents.temperature)
	set_light(3, 1, color)

	firelevel = fl
	air_master.active_hotspots.Add(src)

/obj/fire/proc/fire_color(var/env_temperature)
	var/temperature = max(4000*sqrt(firelevel/vsc.fire_firelevel_multiplier), env_temperature)
	return heat2color(temperature)

/obj/fire/Destroy()
	RemoveFire()

	..()

/obj/fire/proc/RemoveFire()
	var/turf/T = loc
	if (istype(T))
		set_light(0)
		
		T.fire = null
		loc = null
	air_master.active_hotspots.Remove(src)


/turf/simulated/var/fire_protection = 0 //Protects newly extinguished tiles from being overrun again.
/turf/proc/apply_fire_protection()
/turf/simulated/apply_fire_protection()
	fire_protection = world.time

//Returns the firelevel
/datum/gas_mixture/proc/zburn(zone/zone, force_burn, no_check = 0)
	. = 0
	if((temperature > PHORON_MINIMUM_BURN_TEMPERATURE || force_burn) && (no_check ||check_recombustability(zone? zone.fuel_objs : null)))
	
		#ifdef FIREDBG
		log_debug("***************** FIREDBG *****************")
		log_debug("Burning [zone? zone.name : "zoneless gas_mixture"]!")
		#endif
	
		var/gas_fuel = 0
		var/liquid_fuel = 0
		var/total_fuel = 0
		var/total_oxidizers = 0

		//*** Get the fuel and oxidizer amounts
		for(var/g in gas)
			if(gas_data.flags[g] & XGM_GAS_FUEL)
				gas_fuel += gas[g]
			if(gas_data.flags[g] & XGM_GAS_OXIDIZER)
				total_oxidizers += gas[g]
		gas_fuel *= group_multiplier
		total_oxidizers *= group_multiplier

		//Liquid Fuel
		var/fuel_area = 0
		if(zone)
			for(var/obj/effect/decal/cleanable/liquid_fuel/fuel in zone.fuel_objs)
				liquid_fuel += fuel.amount*LIQUIDFUEL_AMOUNT_TO_MOL
				fuel_area++

		total_fuel = gas_fuel + liquid_fuel
		if(total_fuel <= 0.005)
			return 0

		//*** Determine how fast the fire burns

		//get the current thermal energy of the gas mix
		//this must be taken here to prevent the addition or deletion of energy by a changing heat capacity
		var/starting_energy = temperature * heat_capacity()

		//determine how far the reaction can progress
		var/reaction_limit = min(total_oxidizers*(FIRE_REACTION_FUEL_AMOUNT/FIRE_REACTION_OXIDIZER_AMOUNT), total_fuel) //stoichiometric limit

		//calculate the firelevel.
		var/firelevel = calculate_firelevel(total_fuel, total_oxidizers, reaction_limit)
		var/firelevel_ratio = firelevel / vsc.fire_firelevel_multiplier
		
		//vapour fuels are extremely volatile! The reaction progress is a percentage of the total fuel (similar to old zburn).)
		var/min_burn = 0.30*volume*group_multiplier/CELL_VOLUME //in moles - so that fires with very small gas concentrations burn out fast
		var/gas_reaction_progress = max(min_burn, firelevel_ratio*gas_fuel)*FIRE_GAS_BURNRATE_MULT

		//liquid fuels are not as volatile, and the reaction progress depends on the size of the area that is burning. Limit the burn rate to a certain amount per area.
		var/liquid_reaction_progress = (firelevel_ratio*0.2 + 0.05)*fuel_area*FIRE_LIQUID_BURNRATE_MULT

		var/total_reaction_progress = gas_reaction_progress + liquid_reaction_progress
		var/used_fuel = min(total_reaction_progress, reaction_limit)
		var/used_oxidizers = used_fuel*(FIRE_REACTION_OXIDIZER_AMOUNT/FIRE_REACTION_FUEL_AMOUNT)
		
		#ifdef FIREDBG
		log_debug("gas_fuel = [gas_fuel], liquid_fuel = [liquid_fuel], total_oxidizers = [total_oxidizers]")
		log_debug("fuel_area = [fuel_area], total_fuel = [total_fuel], reaction_limit = [reaction_limit]")
		log_debug("firelevel -> [firelevel] / [vsc.fire_firelevel_multiplier]")
		log_debug("liquid_reaction_progress = [liquid_reaction_progress]")
		log_debug("gas_reaction_progress = [gas_reaction_progress]")
		log_debug("total_reaction_progress = [total_reaction_progress]")
		log_debug("used_fuel = [used_fuel], used_oxidizers = [used_oxidizers]; ")
		#endif

		//if the reaction is progressing too slow then it isn't self-sustaining anymore and burns out
		if(zone) //be less restrictive with canister and tank reactions
			if((!liquid_fuel || used_fuel <= FIRE_LIQUD_MIN_BURNRATE) && (!gas_fuel || used_fuel <= FIRE_GAS_MIN_BURNRATE*group_multiplier))
				return 0


		//*** Remove fuel and oxidizer, add carbon dioxide and heat

		//remove and add gasses as calculated
		var/used_gas_fuel = min(max(0.25, used_fuel*(gas_reaction_progress/total_reaction_progress)), gas_fuel) //remove in proportion to the relative reaction progress
		var/used_liquid_fuel = min(max(0.25, used_fuel-used_gas_fuel), liquid_fuel)

		//remove_by_flag() and adjust_gas() handle the group_multiplier for us.
		remove_by_flag(XGM_GAS_OXIDIZER, used_oxidizers)
		remove_by_flag(XGM_GAS_FUEL, used_gas_fuel)
		adjust_gas("carbon_dioxide", used_oxidizers)

		if(zone)
			zone.remove_liquidfuel(used_liquid_fuel, !check_combustability())

		//calculate the energy produced by the reaction and then set the new temperature of the mix
		temperature = (starting_energy + vsc.fire_fuel_energy_release * (used_gas_fuel + used_liquid_fuel)) / heat_capacity()
		
		#ifdef FIREDBG
		log_debug("used_gas_fuel = [used_gas_fuel]; used_liquid_fuel = [used_liquid_fuel]; total = [used_fuel]")
		log_debug("new temperature = [temperature]")
		#endif

		update_values()
		return firelevel

datum/gas_mixture/proc/check_recombustability(list/fuel_objs)
	. = 0
	for(var/g in gas)
		if(gas_data.flags[g] & XGM_GAS_OXIDIZER && gas[g] >= 0.1)
			. = 1
			break

	if(!.)
		return 0

	if(fuel_objs && fuel_objs.len)
		return 1

	. = 0
	for(var/g in gas)
		if(gas_data.flags[g] & XGM_GAS_FUEL && gas[g] >= 0.1)
			. = 1
			break

/datum/gas_mixture/proc/check_combustability(obj/effect/decal/cleanable/liquid_fuel/liquid=null)
	. = 0
	for(var/g in gas)
		if(gas_data.flags[g] & XGM_GAS_OXIDIZER && QUANTIZE(gas[g] * vsc.fire_consuption_rate) >= 0.1)
			. = 1
			break

	if(!.)
		return 0

	if(liquid)
		return 1

	. = 0
	for(var/g in gas)
		if(gas_data.flags[g] & XGM_GAS_FUEL && QUANTIZE(gas[g] * vsc.fire_consuption_rate) >= 0.005)
			. = 1
			break

//returns a value between 0 and vsc.fire_firelevel_multiplier
/datum/gas_mixture/proc/calculate_firelevel(total_fuel, total_oxidizers, reaction_limit)
	//Calculates the firelevel based on one equation instead of having to do this multiple times in different areas.
	var/firelevel = 0

	var/total_combustables = (total_fuel + total_oxidizers)

	if(total_combustables > 0)
		//slows down the burning when the concentration of the reactants is low
		var/dampening_multiplier = min(1, reaction_limit / (total_moles/group_multiplier))
		
		//calculates how close the mixture of the reactants is to the optimum
		//fires burn better when there is more oxidizer -- too much fuel will choke them out a bit, reducing firelevel.
		var/mix_multiplier = 1 / (1 + (5 * ((total_fuel / total_combustables) ** 2)))
		
		#ifdef FIREDBG
		ASSERT(dampening_multiplier <= 1)
		ASSERT(mix_multiplier <= 1)
		#endif
		
		//toss everything together -- should produce a value between 0 and fire_firelevel_multiplier
		firelevel = vsc.fire_firelevel_multiplier * mix_multiplier * dampening_multiplier

	return max( 0, firelevel)


/mob/living/proc/FireBurn(var/firelevel, var/last_temperature, var/pressure)
	var/mx = 5 * firelevel/vsc.fire_firelevel_multiplier * min(pressure / ONE_ATMOSPHERE, 1)
	apply_damage(2.5*mx, BURN)


/mob/living/carbon/human/FireBurn(var/firelevel, var/last_temperature, var/pressure)
	//Burns mobs due to fire. Respects heat transfer coefficients on various body parts.
	//Due to TG reworking how fireprotection works, this is kinda less meaningful.

	var/head_exposure = 1
	var/chest_exposure = 1
	var/groin_exposure = 1
	var/legs_exposure = 1
	var/arms_exposure = 1

	//Get heat transfer coefficients for clothing.

	for(var/obj/item/clothing/C in src)
		if(l_hand == C || r_hand == C)
			continue

		if( C.max_heat_protection_temperature >= last_temperature )
			if(C.body_parts_covered & HEAD)
				head_exposure = 0
			if(C.body_parts_covered & UPPER_TORSO)
				chest_exposure = 0
			if(C.body_parts_covered & LOWER_TORSO)
				groin_exposure = 0
			if(C.body_parts_covered & LEGS)
				legs_exposure = 0
			if(C.body_parts_covered & ARMS)
				arms_exposure = 0
	//minimize this for low-pressure enviroments
	var/mx = 5 * firelevel/vsc.fire_firelevel_multiplier * min(pressure / ONE_ATMOSPHERE, 1)

	//Always check these damage procs first if fire damage isn't working. They're probably what's wrong.

	apply_damage(2.5*mx*head_exposure, BURN, "head", 0, 0, "Fire")
	apply_damage(2.5*mx*chest_exposure, BURN, "chest", 0, 0, "Fire")
	apply_damage(2.0*mx*groin_exposure, BURN, "groin", 0, 0, "Fire")
	apply_damage(0.6*mx*legs_exposure, BURN, "l_leg", 0, 0, "Fire")
	apply_damage(0.6*mx*legs_exposure, BURN, "r_leg", 0, 0, "Fire")
	apply_damage(0.4*mx*arms_exposure, BURN, "l_arm", 0, 0, "Fire")
	apply_damage(0.4*mx*arms_exposure, BURN, "r_arm", 0, 0, "Fire")