/*
 * NOTE FROM SOMEBODY WHO DID SOME HOUSEKEEPING AROUND THIS ASS-CODE
 * There's absolutely no documentation on most of this so I'd like to write this down to help you get a grasp of how this works and how redundant it all is.
 * Let's assume you live in a horrible horrible universe where nobody coded inventory datums yet. Damn. Now let's say you want your new mob to be able to wear a jumpsuit.
 *
 * First thing the mob needs is a variable for the inventory slot, like var/obj/item/w_uniform = null. Start by the most awful part and modify /obj/item/proc/mob_can_equip()
 * to account for your mob. It has a switch for every slot, and jumpsuits go in under slot_w_uniform, so probably just copypaste how monkeys do it.
 *
 * Good, now the item thinks the mob can equip it. Now the mob has to be ACTUALLY be able to equip it. Go and modify or create mob/your_mob/equip_to_slot(). Again, it's a switch of
 * all slots. You'll see that that proc also handles the icon refreshing, so you have to create mob/your_mob/update_inv_w_uniform() as well. Good luck there because iconcode is also ass.
 *
 * You can't do anything with the jumpsuit yet though, you need to add it to mob/your_mob/get_item_by_slot() for most things to work.
 * Small detail: Your mob cannot unequip their jumpsuit yet. You need to add it to mob/your_mob/u_equip()
 * Oh yeah, you need to add the new variable for the jumpsuit to mob/your_mob/get_all_slots(). I know, I know, this is why we need inventory datums.
 *
 * Okay, so your mob still has no HUD element for their inventory slot. That takes a /obj/abstract/screen/inventory... beats me how most of it works, but you do need to have it point to
 * slot_id = slot_w_uniform and define a new screen_loc for it. I would advise you to just look at code/_onclick/hud/monkey.dm and do the ol' monkey see, monkey do.
 * When you click on that obj/abstract/screen/inventory, it calls attack_ui() which by default will just call equip_to_slot_if_possible(item, slot_id)
 * At this point I think you need to handle some UI shitcode in mob/your_mob/update_inv_w_uniform(), something like w_uniform.screen_loc = the_screen_loc_you_defined_earlier
 *
 * For other players to be able to strip and forcibly put on the uniform on your mob, you need to give it a fancy mob/your_mob/show_inv(), and put HREF links that you'll pick up
 * in mob/your_mob/Topic() that finally point to handle_strip_slot(). If you search for (href_list["item"]) I'm sure you'll be able to figure this out.
 *
 * Good luck.
 *
 * So, a list of all methods used:
 * /obj/item/proc/mob_can_equip() -> mob/equip_to_slot() -> update_inv_[slot]()
 * get_item_by_slot(), u_equip(), get_all_slots()
 * obj/abstract/screen/inventory -> ??? -> attack_ui()? -> equip_to_slot_if_possible() -> ??????? -> update_inv_[slot]()?
 * show_inv() -> Topic() -> handle_strip_slot()
 */

#define is_valid_hand_index(index) ((index > 0) && (index <= held_items.len))

//These procs handle putting stuff in your hand. It's probably best to use these rather than setting l_hand = ...etc
//as they handle all relevant stuff like adding it to the player's screen and updating their overlays.

//Returns the thing in our active hand
/mob/proc/get_held_item_by_index(index)
	if(!is_valid_hand_index(index))
		return null

	return held_items[index]

/mob/proc/find_held_item_by_type(type) //Returns the list index
	if(!held_items.len)
		return 0

	for(var/i = 1 to held_items.len)
		if(istype(held_items[i], type))
			return i

	return 0

/mob/proc/is_holding_item(item)
	return held_items.Find(item)

/mob/proc/find_empty_hand_index()
	for(var/i = 1 to held_items.len)
		if(!held_items[i])
			return i

	return 0

/mob/proc/empty_hand_indexes_amount()
	. = 0

	for(var/i = 1 to held_items.len) //Go through all hand slots, increase return value by 1 for each empty slot
		if(!held_items[i])
			.++

/mob/proc/get_active_hand()
	return get_held_item_by_index(active_hand)

/mob/proc/get_held_item_ui_location(index)
	if(!is_valid_hand_index(index))
		return

	var/x_offset = -(index % 2) //Index is 1 -> one unit to the left
	var/y_offset = round((index-1) / 2) //Two slots per row, then go higher. Rounded down

	return "CENTER[x_offset ? x_offset : ""]:[WORLD_ICON_SIZE/2],SOUTH[y_offset ? "+[y_offset]" : ""]:[5*PIXEL_MULTIPLIER]"

	/*
	switch(index)
		if(1)
			return "CENTER-1:16,SOUTH:5"
		if(2)
			return "CENTER:16,SOUTH:5"
		if(3)
			return "CENTER-1:16,SOUTH+1:5"
		if(4)
			return "CENTER:16,SOUTH+1:5"
	*/

/mob/proc/get_direction_by_index(index)
	if(index % 2 == GRASP_RIGHT_HAND)
		return "right_hand"
	else
		return "left_hand"

/mob/proc/get_index_limb_name(var/index)
	if(!index)
		index = active_hand

	switch(index)
		if(GRASP_LEFT_HAND)
			return "left hand"
		if(GRASP_RIGHT_HAND)
			return "right hand"
		else
			return "hand"

/mob/proc/get_item_offset_by_index(index) //Return a list with x and y offsets depending on index. Example: list("x"=5, "y"=4)
	return list()

// Get the organ of the active hand
/mob/proc/get_active_hand_organ()
	if(!istype(src, /mob/living/carbon))
		return
	if (hasorgans(src))
		var/datum/organ/external/temp = find_organ_by_grasp_index(active_hand)
		return temp

/mob/proc/find_organ_by_grasp_index(index)
	return

//Returns the thing in our inactive hand
/mob/proc/get_inactive_hand()
	return get_held_item_by_index(get_inactive_hand_index())

// Because there's several different places it's stored.
/mob/proc/get_multitool(var/if_active=0)
	return null

/mob/proc/get_inactive_hand_index()
	var/new_index = active_hand - 1

	if(new_index < 1)
		new_index = held_items.len

	return new_index

/mob/proc/swap_hand()
	if(++active_hand > held_items.len)
		active_hand = 1

	if(!hud_used)
		return

	for(var/obj/abstract/screen/inventory/hand_hud_object in hud_used.hand_hud_objects)
		if(active_hand == hand_hud_object.hand_index)
			hand_hud_object.icon_state = "hand_active"
		else
			hand_hud_object.icon_state = "hand_inactive"

	return

/mob/proc/activate_hand(var/selhand)
	active_hand = selhand

	if(!hud_used)
		return

	for(var/obj/abstract/screen/inventory/hand_hud_object in hud_used.hand_hud_objects)
		if(active_hand == hand_hud_object.hand_index)
			hand_hud_object.icon_state = "hand_active"
		else
			hand_hud_object.icon_state = "hand_inactive"

/mob/proc/put_in_hand(index, obj/item/W)
	if(!is_valid_hand_index(index) || !is_valid_hand_index(active_hand))
		return 0

	if(!put_in_hand_check(W, index))
		return 0

	if(W.prepickup(src))
		return 0

	W.forceMove(src)
	held_items[index] = W
	W.hud_layerise()
	W.pixel_x = initial(W.pixel_x)
	W.pixel_y = initial(W.pixel_y)
	W.equipped(src, null, index)

	if(client)
		client.screen |= W
	if(pulling == W)
		stop_pulling()

	update_inv_hand(index)
	W.pickup(src)
	return 1

//Puts the item into your left hand if possible and calls all necessary triggers/updates. returns 1 on success.
/mob/proc/put_in_l_hand(var/obj/item/W)
	return put_in_hand(GRASP_LEFT_HAND, W)

//Puts the item into your right hand if possible and calls all necessary triggers/updates. returns 1 on success.
/mob/proc/put_in_r_hand(var/obj/item/W)
	return put_in_hand(GRASP_RIGHT_HAND, W)

/mob/proc/put_in_hand_check(var/obj/item/W, index)
	if(lying) //&& !(W.flags & ABSTRACT))
		return 0
	if(!isitem(W))
		return 0

	if(held_items[index])
		return 0

	if(W.flags & MUSTTWOHAND)
		if(!W.wield(src, 1))
			to_chat(src, "You need both hands to pick up \the [W].")
			return 0

	if(W.cant_drop) //if the item can't be dropped
		var/I = is_holding_item(W) //AND the item is currently being held in one of the mob's hands
		if(I)
			to_chat(src, "You can't pry \the [W] out of your [get_index_limb_name(I)]!")
			return 0

	return 1

//Puts the item into our active hand if possible. returns 1 on success.
/mob/proc/put_in_active_hand(var/obj/item/W)
	return put_in_hand(active_hand, W)

//Puts the item into our inactive hand if possible. returns 1 on success.
/mob/proc/put_in_inactive_hand(var/obj/item/W) // The technology has advanced, we can now handle lifeforms with more than 2 hands.
	for (var/i = held_items.len; i > 0; i--) // held_items.len returns us to the last available hand. We iterate until we come to 0.
		if (i != active_hand && put_in_hand(i, W))
			return 1
	return 0

//Puts the item our active hand if possible. Failing that it tries our inactive hand. Returns 1 on success.
//If both fail it drops it on the floor and returns 0.
//This is probably the main one you need to know :)
/mob/proc/put_in_hands(var/obj/item/W)
	if(!W)
		return 0
	for (var/i = 1 to held_items.len)
		if (held_items[i] == W)
			return 0 // If it's already in your hands and you move it, it's in a superposition and breaks everything.
	if(put_in_active_hand(W))
		return 1
	else if(put_in_inactive_hand(W))
		return 1
	else
		W.forceMove(get_turf(src))
		W.reset_plane_and_layer()
		W.dropped()
		return 0

/mob/proc/set_hand_amount(new_amount)
	if(new_amount < held_items.len) //Decrease hand amount - drop items held in hands which will no longer exist!
		for(var/i = (new_amount+1) to held_items.len)
			var/obj/item/I = held_items[i]

			if(I)
				drop_item(I, force_drop = 1)
	if(new_amount < active_hand)
		active_hand = new_amount //Don't update the HUD - it'll be redrawn anyways

	held_items.len = new_amount

	if(hud_used)
		hud_used.update_hand_icons()

/mob/proc/drop_item_v()		//this is dumb.
	if(stat == CONSCIOUS && isturf(loc))
		return drop_item()
	return 0


/mob/proc/drop_from_inventory(var/obj/item/W) //I'm fairly sure the entirety of this proc is redundant and can be replaced by just u_equip(W,1)
	if(W)
		if(client)
			client.screen -= W
		u_equip(W,1)
		if(!W)
			return 1 // self destroying objects (tk, grabs)
		W.reset_plane_and_layer()
		W.forceMove(loc)

		//W.dropped(src)
		//update_icons() // Redundant as u_equip will handle updating the specific overlay
		return 1

// Drops all and only equipped items, including items in hand
/mob/proc/drop_all()
	for (var/obj/item/I in get_all_slots())
		drop_from_inventory(I)
	drop_hands()

//Drops the item in our hand - you can specify an item and a location to drop to

/mob/proc/drop_item(var/obj/item/to_drop, var/atom/Target, force_drop = 0) //Set force_drop to 1 to force the item to drop (even if it can't be dropped normally)

	if(!candrop) //can't drop items while etheral
		return 0

	if(!to_drop) //if we're not told to drop something specific
		to_drop = get_active_hand() //drop what we're currently holding

	if(!istype(to_drop)) //still nothing to drop?
		return 0 //bail

	if((to_drop.cant_drop > 0) && !force_drop)
		return 0

	if(!Target)
		Target = src.loc

	remove_from_mob(to_drop) //clean out any refs

	if(!to_drop)
		return 0

	to_drop.forceMove(Target) //calls the Entered procs
	if(ismob(Target))
		var/mob/M = Target
		if(iscarbon(M))
			var/mob/living/carbon/C = M
			C.stomach_contents.Add(to_drop)

	to_drop.dropped(src)

	if(to_drop && to_drop.loc)
		return 1
	return 0

/mob/proc/drop_hands(var/atom/Target, force_drop = 0) //drops both items
	for(var/obj/item/I in held_items)
		drop_item(I, Target, force_drop = force_drop)

//TODO: phase out this proc
/mob/proc/before_take_item(var/obj/item/W)	//TODO: what is this?
	W.forceMove(null)
	W.reset_plane_and_layer()
	u_equip(W,0)
	update_icons()


/mob/proc/u_equip(var/obj/item/W as obj, dropped = 1, var/slot = null)
	if(!W)
		return 0
	var/success = 0

	var/index = is_holding_item(W)
	if(index)
		held_items[index] = null
		success = 1
		update_inv_hand(index)
	else if (W == back)
		back = null
		success = 1
		update_inv_back()
	else if (W == wear_mask)
		wear_mask = null
		success = 1
		update_inv_wear_mask()
	else
		return 0

	if(success)
		if(client)
			client.screen -= W
		if(dropped)
			W.forceMove(loc)
			W.dropped(src)
		if(W)
			W.reset_plane_and_layer()
	return 1


//Attemps to remove an object on a mob.  Will not move it to another area or such, just removes from the mob.
/mob/proc/remove_from_mob(var/obj/O)
	src.u_equip(O,1)
	if (src.client)
		src.client.screen -= O
	if(!O)
		return
	O.reset_plane_and_layer()
	O.screen_loc = null
	return 1

/mob/proc/get_all_slots()
	return list(wear_mask, back) + held_items

//everything on the mob that it isn't holding
/mob/proc/get_equipped_items()
	var/list/equipped = get_all_slots()
	equipped -= list(get_active_hand(), get_inactive_hand())
	return equipped

//everything on the mob that is not in its pockets, hands and belt.
/mob/proc/get_clothing_items()
	var/list/equipped = get_all_slots()
	equipped -= list(get_active_hand(), get_inactive_hand())
	return equipped

//inventory slots which would be hidden by other clothing items. currently only used for humans because fuck you
/mob/proc/check_obscured_slots()
	return null

//currently only used for humans because fuck you
/mob/proc/has_organ(name)
	return TRUE

//currently only used for humans because fuck you
/mob/proc/has_organ_for_slot(slot)
	return TRUE

//Returns true if mob is wearing the item in any of the inventory slots (NOT hands). If slot is specified, only checks if the item is in that slot
//Item can be either an object or a path. In the second case, the proc checks if there is a worn item of that type (in that slot), and returns the item
/mob/proc/is_wearing_item(obj/item/I, slot = null)
	if(slot)
		if(ispath(I))
			var/obj/item/item = get_item_by_slot(slot)
			if(istype(item, I))
				return item
		return (get_item_by_slot(slot) == I)
	else
		if(ispath(I))
			return (locate(I) in get_equipped_items())
		return (I in get_equipped_items())

/mob/living/carbon/human/proc/equip_if_possible(obj/item/W, slot, act_on_fail = EQUIP_FAILACTION_DELETE) // since byond doesn't seem to have pointers, this seems like the best way to do this :/
	//warning: icky code
	var/equipped = 0
	switch(slot)
		if(slot_back)
			if(!src.back)
				src.back = W
				equipped = 1
		if(slot_wear_mask)
			if(!src.wear_mask)
				src.wear_mask = W
				equipped = 1
		if(slot_handcuffed)
			if(!src.handcuffed)
				src.handcuffed = W
				equipped = 1
		if(slot_belt)
			if(!src.belt && src.w_uniform)
				src.belt = W
				equipped = 1
		if(slot_wear_id)
			if(!src.wear_id && src.w_uniform)
				src.wear_id = W
				equipped = 1
		if(slot_ears)
			if(!src.ears)
				src.ears = W
				equipped = 1
		if(slot_glasses)
			if(!src.glasses)
				src.glasses = W
				equipped = 1
		if(slot_gloves)
			if(!src.gloves)
				src.gloves = W
				equipped = 1
		if(slot_head)
			if(!src.head)
				src.head = W
				equipped = 1
		if(slot_shoes)
			if(!src.shoes)
				src.shoes = W
				equipped = 1
		if(slot_wear_suit)
			if(!src.wear_suit)
				src.wear_suit = W
				equipped = 1
		if(slot_w_uniform)
			if(!src.w_uniform)
				src.w_uniform = W
				equipped = 1
		if(slot_l_store)
			if(!src.l_store && src.w_uniform)
				src.l_store = W
				equipped = 1
		if(slot_r_store)
			if(!src.r_store && src.w_uniform)
				src.r_store = W
				equipped = 1
		if(slot_s_store)
			if(!src.s_store && src.wear_suit)
				src.s_store = W
				equipped = 1
		if(slot_in_backpack)
			if (src.back && istype(src.back, /obj/item/weapon/storage/backpack))
				var/obj/item/weapon/storage/backpack/B = src.back
				if(B.contents.len < B.storage_slots && W.w_class <= B.fits_max_w_class)
					W.forceMove(B)
					equipped = 1

	if(equipped)
		W.hud_layerise()
		if(src.back && W.loc != src.back)
			W.forceMove(src)
	else
		switch(act_on_fail)
			if(EQUIP_FAILACTION_DELETE)
				qdel(W)
				W = null
			if(EQUIP_FAILACTION_DROP)
				W.forceMove(get_turf(src)) // I think.
	return equipped

/mob/proc/get_id_card()
	for(var/obj/item/I in src.get_all_slots())
		. = I.GetID()
		if(.)
			break

/mob/proc/slotID2slotname(slot_id)
	switch (slot_id)
		if (slot_back)
			return "back"
		if (slot_wear_mask)
			return "face"
		if (slot_handcuffed)
			return "hands"
		if (slot_belt)
			return "belt"
		if (slot_wear_id)
			return "jumpsuit"
		if (slot_ears)
			return "ears"
		if (slot_glasses)
			return "face"
		if (slot_gloves)
			return "hands"
		if (slot_head)
			return "head"
		if (slot_shoes)
			return "feet"
		if (slot_wear_suit)
			return "suit"
		if (slot_w_uniform)
			return "uniform"
		if (slot_l_store)
			return "left pocket"
		if (slot_r_store)
			return "right pocket"
		if (slot_s_store)
			return "suit storage"
		if (slot_in_backpack)
			return "backpack"
		if (slot_legcuffed)
			return "ankles"
		else
			return ""

//Returns 1 if the item is part of the mob's built-in modules, and thus shouldn't be dropped or recycled or whatever.
//Currently only used for silicons, but I guess you could use this for robot arms with built-in tools or something
/mob/proc/is_in_modules(var/obj/item/W)
	return 0