CHOMPStation2/code/ZAS/Fire.dm

/*

Making Bombs with ZAS:
Make burny fire with lots of burning
Draw off 5000K gas from burny fire
Separate gas into oxygen and plasma components
Obtain plasma 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.

*/


//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 < PLASMA_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

		if(! (locate(/obj/fire) in src))

			new /obj/fire(src,1000)

		//active_hotspot.just_spawned = (current_cycle < air_master.current_cycle)
		//remove just_spawned protection if no longer processing this cell

	return igniting

obj
	fire
		//Icon for fire on turfs.

		anchored = 1
		mouse_opacity = 0

		//luminosity = 3

		icon = 'fire.dmi'
		icon_state = "1"

		layer = TURF_LAYER

		var
			firelevel = 10000 //Calculated by gas_mixture.calculate_firelevel()

		process()
			. = 1
			
			//get location and check if it is in a proper ZAS zone
			var/turf/simulated/floor/S = loc
			if(!S.zone)
				del src
			
			if(!istype(S))
				del src
				
			var/datum/gas_mixture/air_contents = S.return_air()
			//get liquid fuels on the ground.
			var/obj/effect/decal/cleanable/liquid_fuel/liquid = locate() in S
			//and the volatile stuff from the air
			var/datum/gas/volatile_fuel/fuel = locate() in air_contents.trace_gases
			
			//since the air is processed in fractions, we need to make sure not to have any minuscle residue or
			//the amount of moles might get to low for some functions to catch them and thus result in wonky behaviour
			if(air_contents.oxygen < 0.001)
				air_contents.oxygen = 0
			if(air_contents.toxins < 0.001)
				air_contents.toxins = 0
			if(fuel)
				if(fuel.moles < 0.001)
					air_contents.trace_gases.Remove(fuel)
			
			//check if there is something to combust
			if(!air_contents.check_combustability(liquid))
				del src
			
			//get a firelevel and set the icon
			firelevel = air_contents.calculate_firelevel(liquid)
			
			if(firelevel > 6)
				icon_state = "3"
				SetLuminosity(7)
			else if(firelevel > 2.5)
				icon_state = "2"
				SetLuminosity(5)
			else
				icon_state = "1"
				SetLuminosity(3)
				
			//im not sure how to implement a version that works for every creature so for now monkeys are firesafe
			for(var/mob/living/carbon/human/M in loc)
				M.FireBurn(firelevel, air_contents.temperature, air_contents.return_pressure() ) //Burn the humans!

			
			//spread!
			for(var/direction in cardinal)
				if(S.air_check_directions&direction) //Grab all valid bordering tiles

					var/turf/simulated/enemy_tile = get_step(S, direction)

					if(istype(enemy_tile))
						//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(!(locate(/obj/fire) in enemy_tile))
							if( prob( 50 + 50 * (firelevel/vsc.fire_firelevel_multiplier) ) && S.CanPass(null, enemy_tile, 0,0) && enemy_tile.CanPass(null, S, 0,0))
								new/obj/fire(enemy_tile,firelevel)
			
			//seperate part of the present gas
			//this is done to prevent the fire burning all gases in a single pass
			var/datum/gas_mixture/flow = air_contents.remove_ratio(vsc.fire_consuption_rate)
			
///////////////////////////////// FLOW HAS BEEN CREATED /// DONT DELETE THE FIRE UNTIL IT IS MERGED BACK OR YOU WILL DELETE AIR ///////////////////////////////////////////////
			
			if(flow)
				if(flow.check_combustability(liquid))
					//Ensure flow temperature is higher than minimum fire temperatures.
						//this creates some energy ex nihilo but is necessary to get a fire started
						//lets just pretend this energy comes from the ignition source and dont mention this again
					//flow.temperature = max(PLASMA_MINIMUM_BURN_TEMPERATURE+0.1,flow.temperature)
					
					//burn baby burn!
					flow.zburn(liquid,1)
				
				//merge the air back
				S.assume_air(flow)

///////////////////////////////// FLOW HAS BEEN REMERGED /// feel free to delete the fire again from here on //////////////////////////////////////////////////////////////////

					
		New(newLoc,fl)
			..()

			if(!istype(loc, /turf))
				del src

			dir = pick(cardinal)
			SetLuminosity(3)
			firelevel = fl
			air_master.active_hotspots.Add(src)


		Del()
			if (istype(loc, /turf/simulated))
				SetLuminosity(0)

				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


datum/gas_mixture/proc/zburn(obj/effect/decal/cleanable/liquid_fuel/liquid,force_burn)
	var/value = 0
	
	if((temperature > PLASMA_MINIMUM_BURN_TEMPERATURE || force_burn) && check_combustability(liquid) )
		var/total_fuel = 0 
		var/datum/gas/volatile_fuel/fuel = locate() in trace_gases

		total_fuel += toxins
		
		if(fuel)
		//Volatile Fuel
			total_fuel += fuel.moles

		if(liquid)
		//Liquid Fuel
			if(liquid.amount <= 0)
				del liquid
			else
				total_fuel += liquid.amount

		//Calculate the firelevel.
		var/firelevel = calculate_firelevel(liquid)

		//get the current inner 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 the amount of oxygen used
		var/total_oxygen = min(oxygen, 2 * total_fuel)
		
		//determine the amount of fuel actually used
		var/used_fuel_ratio = min(oxygen / 2 , total_fuel) / total_fuel
		total_fuel = total_fuel * used_fuel_ratio

		var/total_reactants = total_fuel + total_oxygen

		//determine the amount of reactants actually reacting
		var/used_reactants_ratio = min( max(total_reactants * firelevel / vsc.fire_firelevel_multiplier, 0.2), total_reactants) / total_reactants

		//remove and add gasses as calculated
		oxygen -= min(oxygen, total_oxygen * used_reactants_ratio )

		toxins -= min(toxins, toxins * used_fuel_ratio * used_reactants_ratio )

		carbon_dioxide += max(2 * total_fuel, 0)

		if(fuel)
			fuel.moles -= fuel.moles * used_fuel_ratio * used_reactants_ratio
			if(fuel.moles <= 0) del fuel

		if(liquid)
			liquid.amount -= liquid.amount * used_fuel_ratio * used_reactants_ratio
			if(liquid.amount <= 0) del liquid

		//calculate the energy produced by the reaction and then set the new temperature of the mix
		temperature = (starting_energy + vsc.fire_fuel_energy_release * total_fuel) / heat_capacity()
		
		update_values()
		value = total_reactants * used_reactants_ratio
	return value

datum/gas_mixture/proc/check_combustability(obj/effect/decal/cleanable/liquid_fuel/liquid)
	//this check comes up very often and is thus centralized here to ease adding stuff
	
	var/datum/gas/volatile_fuel/fuel = locate() in trace_gases	
	var/value = 0
	
	if(oxygen && (toxins || fuel || liquid))
		value = 1
	
	return value

datum/gas_mixture/proc/calculate_firelevel(obj/effect/decal/cleanable/liquid_fuel/liquid)
	//Calculates the firelevel based on one equation instead of having to do this multiple times in different areas.
	
	var/datum/gas/volatile_fuel/fuel = locate() in trace_gases
	var/total_fuel = 0
	var/firelevel = 0
	
	if(check_combustability(liquid))
	
		total_fuel += toxins

		if(liquid)
			total_fuel += liquid.amount

		if(fuel)
			total_fuel += fuel.moles

		var/total_combustables = (total_fuel + oxygen)
		
		if(total_fuel > 0 && oxygen > 0)
			
			//slows down the burning when the concentration of the reactants is low
			var/dampening_multiplier = total_combustables / (total_combustables + nitrogen + carbon_dioxide)
			//calculates how close the mixture of the reactants is to the optimum
			var/mix_multiplier = 1 / (1 + (5 * ((oxygen / total_combustables) ^2)))
			//toss everything together
			firelevel = vsc.fire_firelevel_multiplier * mix_multiplier * dampening_multiplier
			
	return max( 0, firelevel)


/mob/living/carbon/human/proc/FireBurn(var/firelevel, var/last_temperature, var/pressure)
// mostly using the old proc from Sky until I can think of something better
	//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
		chest_exposure = 1
		groin_exposure = 1
		legs_exposure = 1
		arms_exposure = 1

	//determine the multiplier
	//minimize this for low-pressure enviroments
	var/mx = 5 * firelevel/vsc.fire_firelevel_multiplier * min(pressure / ONE_ATMOSPHERE, 1)

	//Get heat transfer coefficients for clothing.
	//skytodo: kill anyone who breaks things then orders me to fix them
	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

	//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")

	//flash_pain()