--[[
    Some functions that are needed multiple places in the code, to deal with player inventories.
]]
local invfuncs = {}

--Forcibly put an item in a backpack, you should check to make sure there's room first
invfuncs.PutItemInBackpack = function(backpack,x,y,item)
    backpack[1][x][y] = item
    for k = 1,#item.Shape do
        for i = 1,#(item.Shape[k]) do
            if k == 1 and i == 1 then continue end
            backpack[1][x + k - 1][y + i - 1] = item.Shape[k][i]
        end
    end
end

--Writes a backpack to the net stream
invfuncs.SerializeBackpack = function(backpack)
    net.WriteString(backpack[3]) --Name
    net.WriteUInt(backpack[2][1],16) --width
    net.WriteUInt(backpack[2][2],16) --height
    for k,v in pairs(backpack[1]) do
        for i,j in pairs(v) do
            if type(j) ~= "table" then continue end
            net.WriteString(j.Name)
            net.WriteUInt(k,16)
            net.WriteUInt(i,16)
            local data = j:Serialize()
            net.WriteUInt(#data,32)
            net.WriteData(data,#data)
        end
    end
    net.WriteString("END_ITEMS")
end

--Loads a backpack from the net stream
invfuncs.DeSerializeBackpack = function()
    local backpackname = net.ReadString()
    local width = net.ReadUInt(16)
    local height = net.ReadUInt(16)
    --Build the backpack
    local tb = {}
    tb[1] = {}
    tb[2] = {width,height}
    tb[3] = backpackname
    for x = 1,width do
        tb[1][x] = {}
        for y = 1,height do
            tb[1][x][y] = false
        end
    end

    local nitemname = net.ReadString()
    while nitemname ~= "END_ITEMS" do
        local xpos = net.ReadUInt(16)
        local ypos = net.ReadUInt(16)
        local data = net.ReadData(net.ReadUInt(32))
        local nitem = ART.GetItemByName(nitemname):DeSerialize(data)
        invfuncs.PutItemInBackpack(tb,xpos,ypos,nitem)
        nitemname = net.ReadString()
    end

    return tb

end

--Checks to see if an item can fit in the backpack at a certain position
invfuncs.CanFitInBackpack = function(backpack,x,y,item)
    for k,v in pairs(item.Shape) do
        for i,j in pairs(v) do
            if not j then continue end
            if backpack[1][x + k - 1] == nil then
                return false
            end
            if backpack[1][x + k - 1][y + i - 1] or backpack[1][x + k - 1][y + i - 1] == nil then
                return false
            end
        end
    end
    return true
end

--Creates a new backpack, this is NOT called when players join the server, even new ones.
invfuncs.CreateBackpack = function(name,width,height)
    local backpack = {}
    backpack[1] = {}
    backpack[2] = {width,height}
    backpack[3] = name
    for i = 1,width do --the width of the backpack.
      backpack[1][i] = {}
    end
    for k,v in pairs(backpack[1]) do
        for i = 1,height do --the height of the backpack.
            backpack[1][k][i] = false
        end
    end
    return backpack
end

--Displays a dropdown of options under the players mouse, if the option is clicked, does the function
--Requires a table of strings to functions, or strings to tables of strings to functions.
--Be careful not to make this a recursive table.
local function createMenuFor(menu, tbl)
  for k,v in pairs(tbl) do
    if(isfunction(v)) then --This is a dead-end, add the menu
      local thisoption = menu:AddOption(k,v)
    else --Otherwise it should be a table, recursively call to create
      local submenu = menu:AddSubMenu(k)
      createMenuFor(submenu,v)
    end
  end
end

--Draws a backpack on the dpanel, client side only
invfuncs.DrawBackpackOnDPanel = function(dp, backpack, backpacknum, tent)
    local width = ScrW()
    local height = ScrH()
    local slotsize = math.Round(width / 32)
    local backgrid = vgui.Create( "DGrid", dp )
    backgrid:SetPos( 10, 30 )
    backgrid:SetCols( backpack[2][1] )
    backgrid:SetColWide( backpack[2][2] )
    backgrid:Dock(FILL)
    for i = 1,#(backpack[1]) do
        for j = 1,#(backpack[1][i]) do
            local item = backpack[1][j][i]
            if type(backpack[1][j][i]) == "table" then
                local itemwidth = 0
                for _,l in pairs(item.Shape) do
                    itemwidth = math.Max(itemwidth,#l)
                end
                local itemheight = #item.Shape
                local invicon = vgui.Create( "DButton", dp )
                invicon:SetSize(slotsize * itemwidth, slotsize * itemheight)
                invicon:SetPos(slotsize * (i - 1), slotsize * (j - 1))
                invicon:SetText(item.Name)
                if item.Tooltip then
                    invicon:SetTooltip(item.Tooltip)
                end
                --invicon.Paint = function(self, w, h) draw.RoundedBox(4, 0,0,w,h,Color(0,100,0)) end
                invicon.DoClick = function()
                    if not item.GetOptions then return end
                    local menu = vgui.Create("DMenu")
        			createMenuFor(menu,item:GetOptions())
        			menu:Open()
                end
                invicon.Item = item
                invicon.invpos = {j,i}
                invicon.ent = tent
                invicon.backpacknum = backpacknum
                invicon:Droppable("Inventory")
            elseif not backpack[1][j][i] then
                local emptyslot = vgui.Create("DPanel", dp)
                emptyslot:SetSize(slotsize,slotsize)
                emptyslot:SetPos(slotsize * (i - 1), slotsize * (j - 1))
                --emptyslot.Paint = function(self, w, h) draw.RoundedBox(4, 0,0,w,h,Color(0,0,100)) end
                emptyslot:Receiver( "Inventory", function( receiver, tableOfDroppedPanels, isDropped, menuIndex, mouseX, mouseY )
                    if not isDropped then return end
                    local icon = tableOfDroppedPanels[1]
                    local item = icon.Item
                    local curpos = icon.invpos
                    --Set the shape it was at to false
                    if not icon.wasequiped and icon.ent == tent then
                        assert(curpos ~= nil, "print curpos was nil when not equiped")
                        for k = 1,#item.Shape do
                            for l = 1,#(item.Shape[k]) do
                                if k == 1 and l == 1 then continue end
                                backpack[1][curpos[1] + k - 1][curpos[2] + l - 1] = false
                            end
                        end
                        backpack[1][curpos[1]][curpos[2]] = false
                    end
                    if invfuncs.CanFitInBackpack(backpack,j,i,item) then
                        local fromtbl = icon.invpos
                        local wasequiped = icon.wasequiped
                        if wasequiped then
                            net.Start("unequipitem")
                            net.WriteString(wasequiped)
                            net.WriteUInt(backpacknum,16)
                            net.WriteUInt(i,16)
                            net.WriteUInt(j,16)
                            net.SendToServer()
                        else
                            net.Start("moveitem")
                            net.WriteEntity(icon.ent) -- from ent
                            net.WriteEntity(tent) -- to ent
                            net.WriteUInt(icon.backpacknum,16) -- from backpack number
                            net.WriteUInt(backpacknum,16) -- to backpack number
                            net.WriteUInt(fromtbl[1],16) -- From position
                            net.WriteUInt(fromtbl[2],16)
                            net.WriteUInt(j,16) -- To position
                            net.WriteUInt(i,16)
                            net.SendToServer()
                            if item.onEquip ~= nil then
                                item:onEquip(LocalPlayer())
                            end
                        end
                    end
                end, {} )
            end
        end
    end
end

return invfuncs