/obj/item/weapon/gun/launcher/pneumatic
	name = "pneumatic cannon"
	desc = "A large gas-powered cannon."
	icon = 'icons/obj/gun.dmi'
	icon_state = "pneumatic"
	item_state = "pneumatic"
	w_class = 5.0
	flags =  FPRINT | TABLEPASS | CONDUCT
	fire_sound_text = "a loud whoosh of moving air"
	fire_delay = 50
	fire_sound = 'sound/weapons/tablehit1.ogg'

	var/fire_pressure                                   // Used in fire checks/pressure checks.
	var/max_w_class = 3                                 // Hopper intake size.
	var/max_combined_w_class = 20                       // Total internal storage size.
	var/obj/item/weapon/tank/tank = null                // Tank of gas for use in firing the cannon.
	var/obj/item/weapon/storage/tank_container  // Something to hold the tank item so we don't accidentally fire it.
	var/pressure_setting = 10                           // Percentage of the gas in the tank used to fire the projectile.
	var/possible_pressure_amounts = list(5,10,20,25,50) // Possible pressure settings.
	var/minimum_tank_pressure = 10                      // Minimum pressure to fire the gun.
	var/force_divisor = 400                             // Force equates to speed. Speed/5 equates to a damage multiplier for whoever you hit.
	                                                    // For reference, a fully pressurized oxy tank at 50% gas release firing a health
	                                                    // analyzer with a force_divisor of 10 hit with a damage multiplier of 3000+.
/obj/item/weapon/gun/launcher/pneumatic/New()
	..()
	tank_container = new(src)
	tank_container.tag = "gas_tank_holder"

/obj/item/weapon/gun/launcher/pneumatic/verb/set_pressure() //set amount of tank pressure.

	set name = "Set Valve Pressure"
	set category = "Object"
	set src in range(0)
	var/N = input("Percentage of tank used per shot:","[src]") as null|anything in possible_pressure_amounts
	if (N)
		pressure_setting = N
		usr << "You dial the pressure valve to [pressure_setting]%."

/obj/item/weapon/gun/launcher/pneumatic/verb/eject_tank() //Remove the tank.

	set name = "Eject Tank"
	set category = "Object"
	set src in range(0)

	if(tank)
		usr << "You twist the valve and pop the tank out of [src]."
		tank.loc = usr.loc
		tank = null
		icon_state = "pneumatic"
		item_state = "pneumatic"
		if (ismob(src.loc))
			var/mob/M = src.loc
			M.update_icons()
	else
		usr << "There's no tank in [src]."

/obj/item/weapon/gun/launcher/pneumatic/attackby(obj/item/W as obj, mob/user as mob)
	if(!tank && istype(W,/obj/item/weapon/tank))
		user.drop_item()
		tank = W
		tank.loc = src.tank_container
		user.visible_message("[user] jams [W] into [src]'s valve and twists it closed.","You jam [W] into [src]'s valve and twist it closed.")
		icon_state = "pneumatic-tank"
		item_state = "pneumatic-tank"
		user.update_icons()
	else if(W.w_class <= max_w_class)

		var/total_stored = 0
		for(var/obj/item/O in src.contents)
			total_stored += O.w_class
		if(total_stored + W.w_class <= max_combined_w_class)
			user.drop_item(W)
			W.loc = src
			user << "You shove [W] into the hopper."
		else
			user << "That won't fit into the hopper - it's full."
		return
	else
		user << "That won't fit into the hopper."

/obj/item/weapon/gun/launcher/pneumatic/attack_self(mob/user as mob)

	if(contents.len > 0)
		var/obj/item/removing = contents[contents.len]
		if(removing == in_chamber)
			in_chamber = null

		removing.loc = get_turf(src)
		user.put_in_hands(removing)
		user << "You remove [removing] from the hopper."
	else
		user << "There is nothing to remove in \the [src]."
	return

/obj/item/weapon/gun/launcher/pneumatic/load_into_chamber()
	if(!contents.len)
		return 0

	in_chamber = contents[1]
	return !isnull(in_chamber)

/obj/item/weapon/gun/launcher/pneumatic/examine(mob/user)
	if(!..(user, 2))
		return
	user << "The valve is dialed to [pressure_setting]%."
	if(tank)
		user << "The tank dial reads [tank.air_contents.return_pressure()] kPa."
	else
		user << "Nothing is attached to the tank valve!"

/obj/item/weapon/gun/launcher/pneumatic/special_check(user)

	if (!tank)
		user << "There is no gas tank in [src]!"
		return 0

	fire_pressure = (tank.air_contents.return_pressure()/100)*pressure_setting
	if (fire_pressure < minimum_tank_pressure)
		user << "There isn't enough gas in the tank to fire [src]."
		return 0

	return 1

/obj/item/weapon/gun/launcher/pneumatic/update_release_force()
	if(!in_chamber) return
	release_force = ((fire_pressure*tank.volume)/in_chamber.w_class)/force_divisor //projectile speed.
	if(release_force >80) release_force = 80 //damage cap.

/obj/item/weapon/gun/launcher/pneumatic/Fire(atom/target as mob|obj|turf|area, mob/living/user as mob|obj, params, reflex = 0)

	if(!tank || !..()) return //Only do this on a successful shot.

	var/lost_gas_amount = tank.air_contents.total_moles*(pressure_setting/100)
	var/datum/gas_mixture/removed = tank.air_contents.remove(lost_gas_amount)
	user.loc.assume_air(removed)

//Constructable pneumatic cannon.

/obj/item/weapon/cannonframe
	name = "pneumatic cannon frame"
	desc = "A half-finished pneumatic cannon."
	icon_state = "pneumatic0"
	item_state = "pneumatic"

	var/buildstate = 0

/obj/item/weapon/cannonframe/update_icon()
	icon_state = "pneumatic[buildstate]"

/obj/item/weapon/cannonframe/examine(mob/user)
	..(user)
	switch(buildstate)
		if(1) user << "It has a pipe segment installed."
		if(2) user << "It has a pipe segment welded in place."
		if(3) user << "It has an outer chassis installed."
		if(4) user << "It has an outer chassis welded in place."
		if(5) user << "It has a transfer valve installed."

/obj/item/weapon/cannonframe/attackby(obj/item/W as obj, mob/user as mob)
	if(istype(W,/obj/item/pipe))
		if(buildstate == 0)
			user.drop_item()
			del(W)
			user << "\blue You secure the piping inside the frame."
			buildstate++
			update_icon()
			return
	else if(istype(W,/obj/item/stack/sheet/metal))
		if(buildstate == 2)
			var/obj/item/stack/sheet/metal/M = W
			if(M.use(5))
				user << "\blue You assemble a chassis around the cannon frame."
				buildstate++
				update_icon()
			else
				user << "\blue You need at least five metal sheets to complete this task."
			return
	else if(istype(W,/obj/item/device/transfer_valve))
		if(buildstate == 4)
			user.drop_item()
			del(W)
			user << "\blue You install the transfer valve and connect it to the piping."
			buildstate++
			update_icon()
			return
	else if(istype(W,/obj/item/weapon/weldingtool))
		if(buildstate == 1)
			var/obj/item/weapon/weldingtool/T = W
			if(T.remove_fuel(0,user))
				if(!src || !T.isOn()) return
				playsound(src.loc, 'sound/items/Welder2.ogg', 100, 1)
				user << "\blue You weld the pipe into place."
				buildstate++
				update_icon()
		if(buildstate == 3)
			var/obj/item/weapon/weldingtool/T = W
			if(T.remove_fuel(0,user))
				if(!src || !T.isOn()) return
				playsound(src.loc, 'sound/items/Welder2.ogg', 100, 1)
				user << "\blue You weld the metal chassis together."
				buildstate++
				update_icon()
		if(buildstate == 5)
			var/obj/item/weapon/weldingtool/T = W
			if(T.remove_fuel(0,user))
				if(!src || !T.isOn()) return
				playsound(src.loc, 'sound/items/Welder2.ogg', 100, 1)
				user << "\blue You weld the valve into place."
				new /obj/item/weapon/gun/launcher/pneumatic(get_turf(src))
				del(src)
		return
	else
		..()