inventory API for ComputerCraft

--STUB needs to be implemented properly
function getStackSize(type)
  return 64
end


local function dropIn(inv,type,quantity)
  somePlaced=false
  for i=1,inv.numSlots,1 do
    if inv.slots[i].type==type then
      --how many can fit?
      if quantity+inv.slots[i].quantity <=64 then
        inv.slots[i].quantity=inv.slots[i].quantity+quantity
        somePlaced=true
        quantity=0
        break
      else
        quantity=quantity-(64-inv.slots[i].quantity)
        inv.slots[i].quantity=64
        somePlaced=true
      end
    elseif inv.slots[i].type==0 then
      inv.slots[i].type=type
      inv.slots[i].quantity=quantity
        quantity=0
      somePlaced=true
      break
    end
  end

  if inv.autoSave then
    save(inv)
  end
  return somePlaced, quantity
end


local function suckOut(inv)
  qtyTaken=0
  type=0
  for i=1,inv.numSlots,1 do
    if inv.slots[i].quantity~=0 then
      qtyTaken=inv.slots[i].quantity
      type=inv.slots[i].type
      inv.slots[i].type=0
      inv.slots[i].quantity=0
      if inv.autoSave then
        save(inv)
      end
      return type, qtyTaken
    end
  end
  return 0, 0
end


local function getQuantity(inv,type)
  count=0
  for n,slot in pairs(inv.slots) do
    if slot.type==type then
      count=count+slot.quantity
    end
  end
  return count
end

local function findSlot(inv,type,after)
  next=after and after+1 or 1
  for i=next,inv.numSlots,1 do
    if inv.slots[next].type==type then
      return next
    end
    next=next+1
  end
  return 0
end

function getNextUnknownType(inv)
  local i=1
  local type="unknown"
  while true do
    if inv:findSlot(type)==0 then
      return type
    end
    i=i+1
    type="unknown"..i
  end
end


function save(inv,filename)
  if filename==nil or filename=="" then
    filename=inv.fileName
  end
  if filename==nil or filename=="" then
    filename=".inventory"
    count=1
    while fs.exists(filename) do
      count=count+1
      filename=".inventory"..count
    end
  end

  inv.fileName=filename

  local file=fs.open(filename,"w")
  file.write("inv\n")
  file.write(inv.numSlots.."\n")
  for i=1,inv.numSlots,1 do
    file.write(inv.slots[i].quantity.." "..inv.slots[i].type.."\n")
  end
  file.close()
end


function load(filename)
  local inv=nil
  if not fs.exists(filename) then
    return nil
  end
  local file=fs.open(filename,"r")
  local header=file.readLine()
  if header=="inv" then
    local size=file.readLine()+0
    inv=inventory.create(inv,false)
    inv.fileName=filename
    for i=1,size,1 do
      local line=file.readLine()
      local spacePos=string.find(line," ")
      inv.slots[i].quantity=string.sub(line,1,spacePos-1)+0
      inv.slots[i].type=string.sub(line,spacePos+1)
    end
  end

  return inv

end


local function display(inv)
   str=""
   for i=1,inv.numSlots,1 do
     str=str..i.." - "..inv.slots[i].type.." x"..inv.slots[i].quantity.."\t"
   end
   print(str)
end

local function setType(inv, slot, type)
  prevType=inv.slots[slot].type
  inv.slots[slot].type=type

  --if prevtype was specified at all, get others identified as same
  if prevType~=0 then
    for i=1,inv.numSlots,1 do
      if inv.slots[i].type==prevType then
        inv.slots[i].type=type
      end
    end
  end

  if inv.autoSave then
    save(inv)
  end
end

inventoryTemplate= {
  dropIn=dropIn,
  suckOut=suckOut,
  getQuantity=getQuantity,
  display=display,
  findSlot=findSlot,
  setType=setType,
  getNextUnknownType=getNextUnknownType,

  autoSave=false,
  fileName=""
}


local function initializeTurtleInventory(inv)
  --everything will be unknown..
  unknownCount=0

  for i=1,inv.numSlots,1 do
    q=turtle.getItemCount(i)
    if q>0 then
      --compare to previous
      turtle.select(i)
      inv.slots[i].quantity=q
      for j=1,i-1,1 do
        if turtle.compareTo(j) then
          inv.slots[i].type=inv.slots[j].type
          break
        end
      end
      if inv.slots[i].type==0 then
        unknownCount=unknownCount+1
        inv.slots[i].type="unknown"..unknownCount
      end
    end
  end
end


function create(numSlots, isMe)
  newInv={}
  if numSlots==nil then
    numSlots=16 --assume minimum, for safety
  end

  newInv.numSlots=numSlots
  newInv.slots={}
  newInv.isMe=isMe and true or false

  for i=1,numSlots,1 do
    newInv.slots[i]={}
    newInv.slots[i].quantity=0
    newInv.slots[i].type=0
  end

  setmetatable(newInv,{__index=inventoryTemplate})
  --if it's an isMe, initialize automatically
  if isMe then
    initializeTurtleInventory(newInv)
  end

  return newInv

end