Adds installing cells as part of mech construction and fixes some mech construction bugs.

code/datums/helper_datums/construction_datum.dm

@@ -1,3 +1,4 @@
+<<<<<<< HEAD
 #define FORWARD -1
 #define BACKWARD 1
 
@@ -101,3 +102,116 @@
 
 /datum/construction/reversible/custom_action(index, diff, used_atom, user)
 	return 1
+=======
+#define FORWARD -1
+#define BACKWARD 1
+
+/datum/construction
+	var/list/steps
+	var/atom/holder
+	var/result
+	var/list/steps_desc
+
+/datum/construction/New(atom)
+	..()
+	holder = atom
+	if(!holder) //don't want this without a holder
+		qdel(src)
+	set_desc(steps.len)
+	return
+
+/datum/construction/proc/next_step()
+	steps.len--
+	if(!steps.len)
+		spawn_result()
+	else
+		set_desc(steps.len)
+	return
+
+/datum/construction/proc/action(atom/used_atom,mob/user)
+	return
+
+/datum/construction/proc/check_step(atom/used_atom,mob/user) //check last step only
+	var/valid_step = is_right_key(used_atom)
+	if(valid_step)
+		if(custom_action(valid_step, used_atom, user))
+			next_step()
+			return 1
+	return 0
+
+/datum/construction/proc/is_right_key(atom/used_atom) // returns current step num if used_atom is of the right type.
+	var/list/L = steps[steps.len]
+	if(istype(used_atom, L["key"]))
+		return steps.len
+	return 0
+
+/datum/construction/proc/custom_action(step, used_atom, user)
+	return 1
+
+/datum/construction/proc/check_all_steps(atom/used_atom,mob/user) //check all steps, remove matching one.
+	for(var/i=1;i<=steps.len;i++)
+		var/list/L = steps[i];
+		if(istype(used_atom, L["key"]))
+			if(custom_action(i, used_atom, user))
+				steps[i]=null;//stupid byond list from list removal...
+				listclearnulls(steps);
+				if(!steps.len)
+					spawn_result()
+				return 1
+	return 0
+
+
+/datum/construction/proc/spawn_result()
+	if(result)
+		new result(get_turf(holder))
+		qdel(holder)
+	return
+
+/datum/construction/proc/spawn_mecha_result()
+	if(result)
+		var/obj/mecha/m = new result(get_turf(holder))
+		var/obj/item/oldcell = locate (/obj/item/stock_parts/cell) in m
+		QDEL_NULL(oldcell)
+		m.CheckParts(holder.contents)
+		QDEL_NULL(holder)
+
+/datum/construction/proc/set_desc(index as num)
+	var/list/step = steps[index]
+	holder.desc = step["desc"]
+	return
+
+/datum/construction/reversible
+	var/index
+
+/datum/construction/reversible/New(atom)
+	..()
+	index = steps.len
+	return
+
+/datum/construction/reversible/proc/update_index(diff as num)
+	index+=diff
+	if(index==0)
+		spawn_result()
+	else
+		set_desc(index)
+	return
+
+/datum/construction/reversible/is_right_key(atom/used_atom) // returns index step
+	var/list/L = steps[index]
+	if(istype(used_atom, L["key"]))
+		return FORWARD //to the first step -> forward
+	else if(L["backkey"] && istype(used_atom, L["backkey"]))
+		return BACKWARD //to the last step -> backwards
+	return 0
+
+/datum/construction/reversible/check_step(atom/used_atom,mob/user)
+	var/diff = is_right_key(used_atom)
+	if(diff)
+		if(custom_action(index, diff, used_atom, user))
+			update_index(diff)
+			return 1
+	return 0
+
+/datum/construction/reversible/custom_action(index, diff, used_atom, user)
+	return 1
+>>>>>>> e632dee... Adds installing cells as part of mech construction and fixes some mech construction bugs. (#30942)