Implement stack group transfers

storage/chest.lua

@@ -1,6 +1,7 @@
 local ItemStack = require("storage.itemstack")
+local Sentinel = require("storage.sentinel")
 
-local Chest = {}
+local Chest = Sentinel.tag({}, Sentinel.CHEST)
 Chest.__index = Chest
 
 -- Homogeneity allows chest scan to clone empty itemDetail slot to all empty slots in chest

storage/init.lua

@@ -1,5 +1,7 @@
 local Chest = require("storage.chest")
-local Storage = {}
+local Sentinel = require("storage.sentinel")
+
+local Storage = Sentinel.tag({}, Sentinel.STORAGE)
 Storage.__index = Storage
 
 function Storage.assumeHomogeneous(names)

storage/itemgroup.lua

@@ -1,4 +1,6 @@
-local ItemGroup = {}
+local Sentinel = require("storage.sentinel")
+
+local ItemGroup = Sentinel.tag({}, Sentinel.ITEMGROUP)
 ItemGroup.__index = ItemGroup
 
 --- Create a group of managed itemstacks
@@ -107,6 +109,52 @@ function ItemGroup:addStack(stack)
   return false
 end
 
+function ItemGroup:transferTo(target, itemCount)
+  local targetGroup = nil
+  if Sentinel:is(target, Sentinel.CHEST) or Sentinel:is(target, Sentinel.STORAGE) then
+    local identity = self:_getIdentityStack()
+    local find = target:find(function(stack) return identity:canTransfer(stack) end)
+    if #find == 0 then
+      return itemCount == nil or itemCount == 0, 0
+    end
+
+    targetGroup = ItemGroup:from(find[1])
+    for i=2,#find do
+      targetGroup:_addStack(find[i])
+    end
+  elseif Sentinel:is(target, Sentinel.ITEMSTACK) then
+    targetGroup = ItemGroup:from(target)
+  elseif Sentinel:is(target, Sentinel.ITEMGROUP) then
+    targetGroup = target
+  end
+
+  if targetGroup == nil then
+    error("Unexpected transfer target for ItemGroup:transferTo")
+  end
+
+  local targetCap = 0
+  for _,stack in targetGroup:_iterateStacks() do
+    targetCap = targetCap + (stack:getMaxCount() - stack:getCount())
+  end
+
+  -- TODO: Not efficient
+  local transferMax = math.min(itemCount or targetCap, targetCap, self:getItemCount())
+  local transfer = 0
+  for _,stack in targetGroup:_iterateStacks() do
+    local targetCount = math.min(target:getCount() + transferMax - transfer, stack:getMaxCount())
+    for _,from in self:_iterateStacks() do
+      if stack:getCount() == targetCount then
+        goto continue
+      end
+      local _, xfer = from:transferTo(stack)
+      transfer = transfer + xfer
+    end
+      ::continue::
+  end
+
+  return itemCount == nil or (itemCount == transfer), transfer
+end
+
 function ItemGroup:getItemCount()
   if self:_getIdentityStack():isEmpty() then
     return 0

storage/itemstack.lua

@@ -1,6 +1,7 @@
 local Inventory = require("storage.inventory")
+local Sentinel = require("storage.sentinel")
 
-local ItemStack = {}
+local ItemStack = Sentinel.tag({}, Sentinel.ITEMSTACK)
 ItemStack.__index = ItemStack
 
 function ItemStack:fromDetail(inv, detail, slot)

storage/sentinel.lua

@@ -0,0 +1,19 @@
+local TABLE_KEY = "!__SENTINEL"
+
+local Sentinel = {
+    CHEST = "CHEST",
+    ITEMSTACK = "ITEMSTACK",
+    ITEMGROUP = "ITEMGROUP",
+    STORAGE = "STORAGE"
+}
+
+function Sentinel:tag(table, sentinel)
+    table[TABLE_KEY] = sentinel
+    return table
+end
+
+function Sentinel:is(table, sentinel)
+    return table[TABLE_KEY] == sentinel
+end
+
+return Sentinel