property pItemList, pCallbackList, pMaxItems

on test me 
  tItem = [#type:#newbadge, #value:"ACH_RegistrationDuration" & random(10)]
  me.createItem(tItem)
end

on construct me 
  pBaseClassName = "Infofeed Item Base Class"
  pItemList = [:]
  pMaxItems = integer(getIntVariable("infofeed.maxitems.count"))
  pCallbackList = []
  return TRUE
end

on deconstruct me 
  me.removeAllItems()
  return TRUE
end

on getItem me, tID 
  if voidp(tID) then
    return FALSE
  end if
  return(pItemList.getaProp(tID))
end

on getItemCount me 
  return(pItemList.count)
end

on getItemPos me, tID 
  if voidp(tID) then
    return FALSE
  end if
  return(pItemList.findPos(tID))
end

on getFirstItemId me 
  if (pItemList.count = 0) then
    return(-1)
  end if
  return(pItemList.getPropAt(1))
end

on getLatestItemId me 
  if (pItemList.count = 0) then
    return(-1)
  end if
  return(pItemList.getPropAt(pItemList.count))
end

on getPreviousFrom me, tID 
  if voidp(tID) then
    return(-1)
  end if
  tPos = pItemList.findPos(tID)
  if tPos < 1 or (tPos = 1) then
    return(me.getFirstItemId())
  end if
  return(pItemList.getPropAt((tPos - 1)))
end

on getNextFrom me, tID 
  if voidp(tID) then
    return(-1)
  end if
  tPos = pItemList.findPos(tID)
  if tPos < 1 or (tPos = pItemList.count) then
    return(me.getLatestItemId())
  end if
  return(pItemList.getPropAt((tPos + 1)))
end

on registerButtonCallback me, ttype, tMethod, tObject 
  if ttype <> #prev and ttype <> #next then
    return(error(me, "Only allowed types are #prev and #next", #registerButtonCallback, #minor))
  end if
  tCallbackItem = [:]
  tCallbackItem.setAt(#type, ttype)
  tCallbackItem.setAt(#method, tMethod)
  tCallbackItem.setAt(#object, tObject)
  pCallbackList.add(tCallbackItem)
end

on removeButtonCallback me, ttype, tMethod, tObject 
  i = 1
  repeat while i <= pCallbackList.count
    tItem = pCallbackList.getAt(i)
    if (tItem.getAt(#type) = ttype) and (tItem.getAt(#method) = tMethod) and (tItem.getAt(#object) = tObject) then
      pCallbackList.deleteAt(i)
      return()
    end if
    i = (1 + i)
  end repeat
end

on executeNextCallbacks me, tItemID 
  tInfofeedItem = me.getItem(tItemID)
  repeat while pCallbackList <= undefined
    tItem = getAt(undefined, tItemID)
    if (tItem.getAt(#type) = #next) then
      call(tItem.getAt(#method), [tItem.getAt(#object)], tInfofeedItem)
    end if
  end repeat
end

on executePrevCallbacks me, tItemID 
  tInfofeedItem = me.getItem(tItemID)
  repeat while pCallbackList <= undefined
    tItem = getAt(undefined, tItemID)
    if (tItem.getAt(#type) = #prev) then
      call(tItem.getAt(#method), [tItem.getAt(#object)], tInfofeedItem)
    end if
  end repeat
end

on createItem me, tStruct 
  if not listp(tStruct) then
    return FALSE
  end if
  tID = (me.getLatestItemId() + 1)
  tStruct.setaProp(#id, tID)
  if pItemList.findPos(tID) > 0 then
    return(error(me, "Info entry by id" && tID && "already exists." & "\r" & tStruct, #createItem))
  end if
  ttype = tStruct.getaProp(#type)
  tClass = me.getItemClass(ttype)
  if (tClass = 0) then
    return FALSE
  end if
  tObject = createObject(#temp, tClass)
  if (tObject = 0) then
    return(error(me, "Cannot create info instance." && "\r" && tStruct, #createItem))
  end if
  tObject.define(tStruct)
  pItemList.setaProp(tID, tObject)
  me.purgeItems()
  me.getInterface().itemCreated(tID)
  return TRUE
end

on purgeItems me 
  if pItemList.count <= pMaxItems then
    return TRUE
  end if
  repeat while pItemList.count > pMaxItems
    pItemList.deleteAt(1)
  end repeat
  return TRUE
end

on removeAllItems me 
  repeat while pItemList <= undefined
    tItem = getAt(undefined, undefined)
    tItem.deconstruct()
  end repeat
  pItemList = [:]
end

on getItemClass me, ttype 
  tClassName = "Infofeed Item" && ttype && "Class"
  if getmemnum(tClassName) > 0 then
    return([me.pBaseClassName, tClassName])
  end if
  return(me.pBaseClassName)
end