local me = peripheral.wrap("back")
local EXPORT_SIDE = "south"

local args = {...}

local function starts_with(str, start)
    return str:sub(1, #start) == start
end

local function ends_with(str, ending)
    return ending == "" or str:sub(-#ending) == ending
end

local function waitForEnter()
    print("Press [Enter] to continue.")
    io.read()
end

local function isAEOnline()
    local usage, err = me.getEnergyUsage()
    return usage ~= nil and usage > 0
end

local function fetchItemLists(url)
    local request = http.get(url)
    if request == nil then
        print("HTTP request failed. Please contact the administrator.")
        return nil
    end
    if request.getResponseCode() ~= 200 then
        print("HTTP error code " .. request.getResponseCode() .. " Your link is likely incorrect.")
        return nil
    end
    local itemListText = request.readAll()
    request.close()
    local itemLists, msg = textutils.unserializeJSON(itemListText)
    if not itemLists then
        print("Failed to parse item-list JSON: " .. msg)
        return nil
    end
    return itemLists
end

local function findItem(items, name)
    for _, item in pairs(items) do
        if item.name == name then
            return item
        end
    end
    return nil
end

local function attemptItemExport(name, count, side)
    local func = function()
        return me.exportItem(
            {
                name=name,
                count=count
            },
            side
        )
    end
    local success, result = pcall(func)
    if success then
        return result
    else
        return nil, result
    end
end

local function exportItem(name, count)
    print("Exporting " .. count .. "x " .. name)
    local totalTransferred = 0
    while totalTransferred < count do
        local amountToTransfer = count - totalTransferred
        local items = me.listItems()
        local item = findItem(items, name)
        if item ~= nil and item.amount > 0 then
            local count, err = attemptItemExport(name, amountToTransfer, EXPORT_SIDE)
            if count ~= nil then
                print("  Transferred " .. count .. " items.")
                totalTransferred = totalTransferred + count
                if count == 0 then
                    print("  Couldn't transfer any items. Please ensure there's space available for exporting.")
                    waitForEnter()
                end
            else
                print(" Transfer failed: " .. err)
                waitForEnter()
            end
        -- elseif craftableItem ~= nil and not startedCraftingRecently then
        --     print("  No more items in the system; would you like to attempt to auto-craft " .. amountToTransfer .. " more?[yes/no]")
        --     local response = io.read()
        --     if response == "yes" then
        --         me.craftItem({name=name, count=amountToTransfer})
        --         startedCraftingRecently = true
        --         while me.isItemCrafting({name=name}) do
        --             print("  Crafting in progress...")
        --             os.sleep(0.5)
        --         end
        --     end
        else
            print("  Item doesn't exist in the system. Please add " .. amountToTransfer .. " of this item to the system, or type\"skip\" to skip this item.")
            local response = io.read()
            if response == "skip" then
                -- "skip" by pretending the items were exported.
                totalTransferred = totalTransferred + amountToTransfer
            end
        end
    end
end

local function exportSchematic(schematic)
    print("Exporting schematic\n \"" .. schematic.__NAME__ .. "\"")
    for i = 1, schematic.__COUNT__ do
        print("Iteration " .. i .. "/" .. schematic.__COUNT__ .. ":")
        for name, count in pairs(schematic) do
            if not (starts_with(name, "__") and ends_with(name, "__")) then
                exportItem(name, count)
            end
        end
    end
end

local function exportItemList(itemList)
    print("Exporting items for schematic:\n\t" .. itemList.__NAME__)
    for name, count in pairs(itemList) do
        exportItem(name, count)
    end
    print("Done!")
end

-- MAIN SCRIPT
if not isAEOnline() then
    print("Could not connect to the AE system.")
    return
end
-- Check URL
if #args < 1 or not http.checkURL(args[1]) then
    print("Missing or invalid item-list URL.")
    return
end

local itemLists = fetchItemLists(args[1])
if itemLists == nil then
    print("Failed to retrieve item-list. Exiting.")
    return
end

for idx, itemList in pairs(itemLists) do
    exportSchematic(itemList)
end