GLOBAL_DATUM_INIT(fire_overlay, /mutable_appearance, mutable_appearance('icons/effects/fire.dmi', "fire", appearance_flags = RESET_COLOR|KEEP_APART))

/**
 * Component representing an atom being on fire.
 * Should not be used on mobs, they use the fire stacks status effects.
 * Can only be used on atoms that use the integrity system.
 */
/datum/component/burning
	/// Fire overlay appearance we apply
	var/fire_overlay
	/// Particle holder for fire particles, if any. Still utilized over shared holders because they're movable-only
	var/obj/effect/abstract/particle_holder/particle_effect
	/// Particle type we're using for cleaning up our shared holder
	var/particle_type

/datum/component/burning/Initialize(fire_overlay = GLOB.fire_overlay, fire_particles = /particles/smoke/burning)
	if(!isatom(parent))
		return COMPONENT_INCOMPATIBLE
	var/atom/atom_parent = parent
	if(!atom_parent.uses_integrity)
		stack_trace("Tried to add /datum/component/burning to an atom ([atom_parent.type]) that does not use atom_integrity!")
		return COMPONENT_INCOMPATIBLE

	// only flammable atoms should have this component, but it's not really an error if we try to apply this to a non flammable one
	if(!(atom_parent.resistance_flags & FLAMMABLE) || (atom_parent.resistance_flags & FIRE_PROOF))
		qdel(src)
		return

	src.fire_overlay = fire_overlay
	if (fire_particles)
		if(ismovable(parent))
			var/atom/movable/movable_parent = parent
			// burning particles look pretty bad when they stack on mobs, so that behavior is not wanted for items
			movable_parent.add_shared_particles(fire_particles, "[fire_particles]_[isitem(parent)]", isitem(parent) ? NONE : PARTICLE_ATTACH_MOB)
			particle_type = fire_particles
		else
			particle_effect = new(atom_parent, fire_particles)
	START_PROCESSING(SSburning, src)

/datum/component/burning/Destroy(force)
	STOP_PROCESSING(SSburning, src)
	fire_overlay = null
	if(particle_effect)
		QDEL_NULL(particle_effect)
	if (ismovable(parent) && particle_type)
		var/atom/movable/movable_parent = parent
		movable_parent.remove_shared_particles("[particle_type]_[isitem(parent)]")
	return ..()

/datum/component/burning/RegisterWithParent()
	RegisterSignal(parent, COMSIG_ATOM_ATTACK_HAND, PROC_REF(on_attack_hand))
	RegisterSignal(parent, COMSIG_ATOM_UPDATE_OVERLAYS, PROC_REF(on_update_overlays))
	RegisterSignal(parent, COMSIG_ATOM_EXAMINE, PROC_REF(on_examine))
	RegisterSignal(parent, COMSIG_ATOM_EXTINGUISH, PROC_REF(on_extinguish))
	var/atom/atom_parent = parent
	atom_parent.resistance_flags |= ON_FIRE
	atom_parent.update_appearance()

/datum/component/burning/UnregisterFromParent()
	UnregisterSignal(parent, list(
		COMSIG_ATOM_ATTACK_HAND,
		COMSIG_ATOM_UPDATE_OVERLAYS,
		COMSIG_ATOM_EXAMINE,
		COMSIG_ATOM_EXTINGUISH,
	))
	var/atom/atom_parent = parent
	if(!QDELETED(atom_parent))
		atom_parent.resistance_flags &= ~ON_FIRE
		atom_parent.update_appearance()

/datum/component/burning/process(seconds_per_tick)
	var/atom/atom_parent = parent
	// Check if the parent somehow became fireproof, remove component if so
	if(atom_parent.resistance_flags & FIRE_PROOF)
		atom_parent.extinguish()
		return
	atom_parent.take_damage(10 * seconds_per_tick, BURN, FIRE, FALSE)

/// Alerts any examiners that the parent is on fire (even though it should be rather obvious)
/datum/component/burning/proc/on_examine(atom/source, mob/user, list/examine_list)
	SIGNAL_HANDLER

	examine_list += span_danger("[source.p_Theyre()] burning!")

/// Handles searing the hand of anyone who tries to touch parent without protection.
/datum/component/burning/proc/on_attack_hand(atom/source, mob/living/carbon/user)
	SIGNAL_HANDLER

	if(!iscarbon(user) || user.can_touch_burning(source))
		to_chat(user, span_notice("You put out the fire on [source]."))
		source.extinguish()
		return COMPONENT_CANCEL_ATTACK_CHAIN

	user.apply_damage(5, BURN, user.get_active_hand())
	to_chat(user, span_userdanger("You burn your hand on [source]!"))
	INVOKE_ASYNC(user, TYPE_PROC_REF(/mob, emote), "scream")
	playsound(source, SFX_SEAR, 50, TRUE)
	return COMPONENT_CANCEL_ATTACK_CHAIN

/// Maintains the burning overlay on the parent atom
/datum/component/burning/proc/on_update_overlays(atom/source, list/overlays)
	SIGNAL_HANDLER

	//most likely means the component is being removed
	if(!(source.resistance_flags & ON_FIRE))
		return

	if(fire_overlay)
		overlays += fire_overlay

/// Deletes the component when the atom gets extinguished
/datum/component/burning/proc/on_extinguish(atom/source, list/overlays)
	SIGNAL_HANDLER

	qdel(src)