Revert "Removes material exports"

code/modules/cargo/exports.dm

@@ -126,7 +126,10 @@ Credit dupes that require a lot of manual work shouldn't be removed, unless they
 	var/the_cost = get_cost(O)
 	var/amount = get_amount(O)
 	total_cost += the_cost
-	total_amount += amount
+	if(istype(O, /datum/export/material))
+		total_amount += amount*MINERAL_MATERIAL_AMOUNT
+	else
+		total_amount += amount
 
 	cost *= GLOB.E**(-1*k_elasticity*amount)		//marginal cost modifier
 	SSblackbox.record_feedback("nested tally", "export_sold_cost", 1, list("[O.type]", "[the_cost]"))

code/modules/cargo/exports/materials.dm

@@ -0,0 +1,94 @@
+/datum/export/material
+	cost = 5 // Cost per MINERAL_MATERIAL_AMOUNT, which is 2000cm3 as of April 2016.
+	message = "cm3 of developer's tears. Please, report this on github"
+	var/material_id = null
+	export_types = list(
+		/obj/item/stack/sheet/mineral, /obj/item/stack/tile/mineral,
+		/obj/item/ore, /obj/item/coin)
+// Yes, it's a base type containing export_types.
+// But it has no material_id, so any applies_to check will return false, and these types reduce amount of copypasta a lot
+
+/datum/export/material/get_amount(obj/O)
+	if(!material_id)
+		return 0
+	if(!isitem(O))
+		return 0
+	var/obj/item/I = O
+	if(!(material_id in I.materials))
+		return 0
+
+	var/amount = I.materials[material_id]
+
+	if(istype(I, /obj/item/stack))
+		var/obj/item/stack/S = I
+		amount *= S.amount
+	else if(istype(I, /obj/item/ore))
+		amount *= 0.8 // Station's ore redemption equipment is really goddamn good.
+
+	return round(amount/MINERAL_MATERIAL_AMOUNT)
+
+// Materials. Nothing but plasma is really worth selling. Better leave it all to RnD and sell some plasma instead.
+
+// Bananium. Exporting it makes the clown cry. Priceless.
+/datum/export/material/bananium
+	cost = 5000
+	material_id = MAT_BANANIUM
+	message = "cm3 of bananium"
+
+// Diamonds. Rare and expensive.
+/datum/export/material/diamond
+	cost = 2500
+	material_id = MAT_DIAMOND
+	message = "cm3 of diamonds"
+
+// Plasma. The oil of 26 century. The reason why you are here.
+/datum/export/material/plasma
+	cost = 300
+	k_elasticity = 0
+	material_id = MAT_PLASMA
+	message = "cm3 of plasma"
+
+// Uranium. Still useful for both power generation and nuclear annihilation.
+/datum/export/material/uranium
+	cost = 400
+	material_id = MAT_URANIUM
+	message = "cm3 of uranium"
+
+// Gold. Used in electronics and corrosion-resistant plating.
+/datum/export/material/gold
+	cost = 250
+	material_id = MAT_GOLD
+	message = "cm3 of gold"
+
+// Silver.
+/datum/export/material/silver
+	cost = 100
+	material_id = MAT_SILVER
+	message = "cm3 of silver"
+
+// Titanium.
+/datum/export/material/titanium
+	cost = 250
+	material_id = MAT_TITANIUM
+	message = "cm3 of titanium"
+
+// Plastitanium.
+/datum/export/material/plastitanium
+	cost = 550
+	material_id = MAT_TITANIUM // code can only check for one material_id; plastitanium is half plasma, half titanium, so ((250 x 250) + (250 x 500)) / 250
+	message = "cm3 of plastitanium"
+
+// Metal. Common building material.
+/datum/export/material/metal
+	message = "cm3 of metal"
+	material_id = MAT_METAL
+	export_types = list(
+		/obj/item/stack/sheet/metal, /obj/item/stack/tile/plasteel,
+		/obj/item/stack/rods, /obj/item/ore, /obj/item/coin)
+
+// Glass. Common building material.
+/datum/export/material/glass
+	message = "cm3 of glass"
+	material_id = MAT_GLASS
+	export_types = list(/obj/item/stack/sheet/glass, /obj/item/ore,
+		/obj/item/shard)