--[[ Copyright (c) 2017 Optera
 * Part of Logistics Train Network
 *
 * See LICENSE.md in the project directory for license information.
--]]


-- return true if stop, output, lamp are on same logic network
local function detectShortCircuit(checkStop)
  local scdetected = false
  local networks = {}
  local entities = {checkStop.entity, checkStop.output, checkStop.input}

  for k, entity in pairs(entities) do
    local greenWire = entity.get_circuit_network(defines.wire_type.green)
    if greenWire then
      if networks[greenWire.network_id] then
        scdetected = true
      else
        networks[greenWire.network_id] = entity.unit_number
      end
    end
    local redWire =  entity.get_circuit_network(defines.wire_type.red)
    if redWire then
      if networks[redWire.network_id] then
        scdetected = true
      else
        networks[redWire.network_id] = entity.unit_number
      end
    end
  end

  return scdetected
end

local function remove_available_train(trainID)
  if debug_log then log("(UpdateStop) removing available train "..tostring(trainID).." from depot." ) end
  global.Dispatcher.availableTrains_total_capacity = global.Dispatcher.availableTrains_total_capacity - global.Dispatcher.availableTrains[trainID].capacity
  global.Dispatcher.availableTrains_total_fluid_capacity = global.Dispatcher.availableTrains_total_fluid_capacity - global.Dispatcher.availableTrains[trainID].fluid_capacity
  global.Dispatcher.availableTrains[trainID] = nil
end

-- update stop input signals
function UpdateStop(stopID, stop)
  global.Dispatcher.Requests_by_Stop[stopID] = nil

  -- remove invalid stops
  if not stop or not stop.entity.valid or not stop.input.valid or not stop.output.valid or not stop.lamp_control.valid then
    if message_level >= 1 then printmsg({"ltn-message.error-invalid-stop", stopID}) end
    if debug_log then log(format("(UpdateStop) Removing invalid stop: [%d]", stopID )) end
    RemoveStop(stopID)
    return
  end

  -- remove invalid trains
  if stop.parked_train and not stop.parked_train.valid then
    global.LogisticTrainStops[stopID].parked_train = nil
    global.LogisticTrainStops[stopID].parked_train_id = nil
  end

  -- remove invalid active_deliveries -- shouldn't be necessary
  for i=#stop.active_deliveries, 1, -1 do
    if not global.Dispatcher.Deliveries[stop.active_deliveries[i]] then
      table.remove(stop.active_deliveries, i)
      if message_level >= 1 then printmsg({"ltn-message.error-invalid-delivery", stop.entity.backer_name}) end
      if debug_log then log("(UpdateStop) Removing invalid delivery from stop '"..tostring(stop.entity.backer_name).."': "..tostring(stop.active_deliveries[i])) end
    end
  end

  -- reset stop parameters in case something goes wrong
  stop.min_carriages = 0
  stop.max_carriages = 0
  stop.max_trains = 0
  stop.requesting_threshold = min_requested
  stop.requester_priority = 0
  stop.no_warnings = false
  stop.providing_threshold = min_provided
  stop.provider_priority = 0
  stop.locked_slots = 0
  stop.depot_priority = 0

  -- skip short circuited stops
  if detectShortCircuit(stop) then
    stop.error_code = 1
    if stop.parked_train_id and global.Dispatcher.availableTrains[stop.parked_train_id] then
      remove_available_train(stop.parked_train_id)
    end
    setLamp(stop, ErrorCodes[stop.error_code], 1)
    if debug_log then log("(UpdateStop) Short circuit error: "..stop.entity.backer_name) end
    return
  end

  -- skip deactivated stops
  local stopCB = stop.entity.get_control_behavior()
  if stopCB and stopCB.disabled then
    stop.error_code = 1
    if stop.parked_train_id and global.Dispatcher.availableTrains[stop.parked_train_id] then
      remove_available_train(stop.parked_train_id)
    end
    setLamp(stop, ErrorCodes[stop.error_code], 2)
    if debug_log then log("(UpdateStop) Circuit deactivated stop: "..stop.entity.backer_name) end
    return
  end

    -- initialize control signal values to defaults
  local is_depot = false
  local depot_priority = 0
  local network_id = default_network
  local min_carriages = 0
  local max_carriages = 0
  local max_trains = 0
  local requesting_threshold = min_requested
  local requesting_threshold_stacks = 0
  local requester_priority = 0
  local no_warnings = false
  local providing_threshold = min_provided
  local providing_threshold_stacks = 0
  local provider_priority = 0
  local locked_slots = 0

  -- get circuit values 0.16.24
  local signals = stop.input.get_merged_signals()
  if not signals then return end -- either lamp and lampctrl are not connected or lampctrl has no output signal

  local signals_filtered = {}
  local signal_type_virtual = "virtual"
  local abs = math.abs

  for _,v in pairs(signals) do
    if v.signal.name and v.signal.type then
      if v.signal.type ~= signal_type_virtual then
        -- add item and fluid signals to new array
        signals_filtered[v.signal] = v.count
      elseif ControlSignals[v.signal.name] then
        -- read out control signals
        if v.signal.name == ISDEPOT and v.count > 0 then
          is_depot = true
        elseif v.signal.name == DEPOT_PRIORITY then
          depot_priority = v.count
        elseif v.signal.name == NETWORKID then
          network_id = v.count
        elseif v.signal.name == MINTRAINLENGTH and v.count > 0 then
          min_carriages = v.count
        elseif v.signal.name == MAXTRAINLENGTH and v.count > 0 then
          max_carriages = v.count
        elseif v.signal.name == MAXTRAINS and v.count > 0 then
          max_trains = v.count
        elseif v.signal.name == REQUESTED_THRESHOLD then
          requesting_threshold = abs(v.count)
        elseif v.signal.name == REQUESTED_STACK_THRESHOLD then
          requesting_threshold_stacks = abs(v.count)
        elseif v.signal.name == REQUESTED_PRIORITY then
          requester_priority = v.count
        elseif v.signal.name == NOWARN and v.count > 0 then
          no_warnings = true
        elseif v.signal.name == PROVIDED_THRESHOLD then
          providing_threshold = abs(v.count)
        elseif v.signal.name == PROVIDED_STACK_THRESHOLD then
          providing_threshold_stacks = abs(v.count)
        elseif v.signal.name == PROVIDED_PRIORITY then
          provider_priority = v.count
        elseif v.signal.name == LOCKEDSLOTS and v.count > 0 then
          locked_slots = v.count
        end
      end
    end
  end
  local network_id_string = format("0x%x", band(network_id))

  --update lamp colors when error_code or is_depot changed state
  if stop.error_code ~=0 or stop.is_depot ~= is_depot then
    stop.error_code = 0 -- we are error free here
    if is_depot then
      if stop.parked_train_id and stop.parked_train.valid then
        if global.Dispatcher.Deliveries[stop.parked_train_id] then
          setLamp(stop, "yellow", 1)
        else
          setLamp(stop, "blue", 1)
        end
      else
        setLamp(stop, "green", 1)
      end
    else
      if #stop.active_deliveries > 0 then
        if stop.parked_train_id and stop.parked_train.valid then
          setLamp(stop, "blue", #stop.active_deliveries)
        else
          setLamp(stop, "yellow", #stop.active_deliveries)
        end
      else
        setLamp(stop, "green", 1)
      end
    end
  end

  -- check if it's a depot
  if is_depot then
    stop.is_depot = true
    stop.depot_priority = depot_priority
    stop.network_id = network_id

    -- add parked train to available trains
    if stop.parked_train_id and stop.parked_train.valid then
      if global.Dispatcher.Deliveries[stop.parked_train_id] then
        if debug_log then log("(UpdateStop) "..stop.entity.backer_name.." {"..network_id_string.."}"..
          ", depot priority: ".. depot_priority..
          ", assigned train.id: "..stop.parked_train_id )
        end
      else
        if not global.Dispatcher.availableTrains[stop.parked_train_id] then
          -- full arrival handling in case ltn-depot signal was turned on with an already parked train
          TrainArrives(stop.parked_train)
        else
          -- update properties from depot
          global.Dispatcher.availableTrains[stop.parked_train_id].network_id = network_id
          global.Dispatcher.availableTrains[stop.parked_train_id].depot_priority = depot_priority
        end
        if debug_log then log("(UpdateStop) "..stop.entity.backer_name.." {"..network_id_string.."}"..
          ", depot priority: ".. depot_priority..
          ", available train.id: "..stop.parked_train_id )
        end
      end
    else
      if debug_log then log("(UpdateStop) "..stop.entity.backer_name.." {"..network_id_string.."}"..
        ", depot priority: ".. depot_priority..
        ", no available train" )
      end
    end

  -- not a depot > check if the name is unique
  else
    stop.is_depot = false
    if stop.parked_train_id and global.Dispatcher.availableTrains[stop.parked_train_id] then
      remove_available_train(stop.parked_train_id)
    end

    for signal, count in pairs(signals_filtered) do
      local signal_type = signal.type
      local signal_name = signal.name
      local item = signal_type..","..signal_name

      for trainID, delivery in pairs (global.Dispatcher.Deliveries) do
        local deliverycount = delivery.shipment[item]
        if deliverycount then
          if stop.parked_train and stop.parked_train_id == trainID then
            -- calculate items +- train inventory
            local traincount = 0
            if signal_type == "fluid" then
              traincount = stop.parked_train.get_fluid_count(signal_name)
            else
              traincount = stop.parked_train.get_item_count(signal_name)
            end

            if delivery.to_id == stop.entity.unit_number then
              local newcount = count + traincount
              if newcount > 0 then newcount = 0 end --make sure we don't turn it into a provider
              if debug_log then log("(UpdateStop) "..stop.entity.backer_name.." {"..network_id_string.."} updating requested count with train "..trainID.." inventory: "..item.." "..count.."+"..traincount.."="..newcount) end
              count = newcount
            elseif delivery.from_id == stop.entity.unit_number then
              if traincount <= deliverycount then
                local newcount = count - (deliverycount - traincount)
                if newcount < 0 then newcount = 0 end --make sure we don't turn it into a request
                if debug_log then log("(UpdateStop) "..stop.entity.backer_name.." {"..network_id_string.."} updating provided count with train "..trainID.." inventory: "..item.." "..count.."-"..deliverycount - traincount.."="..newcount) end
                count = newcount
              else --train loaded more than delivery
                if debug_log then log("(UpdateStop) "..stop.entity.backer_name.." {"..network_id_string.."} updating delivery count with overloaded train "..trainID.." inventory: "..item.." "..traincount) end
                -- update delivery to new size
                global.Dispatcher.Deliveries[trainID].shipment[item] = traincount
              end
            end

          else
            -- calculate items +- deliveries
            if delivery.to_id == stop.entity.unit_number then
              local newcount = count + deliverycount
              if newcount > 0 then newcount = 0 end --make sure we don't turn it into a provider
              if debug_log then log("(UpdateStop) "..stop.entity.backer_name.." {"..network_id_string.."} updating requested count with delivery: "..item.." "..count.."+"..deliverycount.."="..newcount) end
              count = newcount
            elseif delivery.from_id == stop.entity.unit_number and not delivery.pickupDone then
              local newcount = count - deliverycount
              if newcount < 0 then newcount = 0 end --make sure we don't turn it into a request
              if debug_log then log("(UpdateStop) "..stop.entity.backer_name.." {"..network_id_string.."} updating provided count with delivery: "..item.." "..count.."-"..deliverycount.."="..newcount) end
              count = newcount
            end

          end
        end
      end -- for delivery

      local useProvideStackThreshold = false
      local useRequestStackThreshold = false
      local stack_count = 0

      if signal_type == "item" then
        useProvideStackThreshold = providing_threshold_stacks > 0
        useRequestStackThreshold = requesting_threshold_stacks > 0
        if game.item_prototypes[signal_name] then
          stack_count = count / game.item_prototypes[signal_name].stack_size
        end
      end

      -- update Dispatcher Storage
      -- Providers are used when above Provider Threshold
      -- Requests are handled when above Requester Threshold
      if (useProvideStackThreshold and stack_count >= providing_threshold_stacks) or
        (not useProvideStackThreshold and count >= providing_threshold) then
        global.Dispatcher.Provided[item] = global.Dispatcher.Provided[item] or {}
        global.Dispatcher.Provided[item][stopID] = count
        global.Dispatcher.Provided_by_Stop[stopID] = global.Dispatcher.Provided_by_Stop[stopID] or {}
        global.Dispatcher.Provided_by_Stop[stopID][item] = count
        if debug_log then
          local trainsEnRoute = "";
          for k,v in pairs(stop.active_deliveries) do
            trainsEnRoute=trainsEnRoute.." "..v
          end
          log("(UpdateStop) "..stop.entity.backer_name.." {"..network_id_string.."} provides "..item.." "..count.."("..providing_threshold..")".." stacks: "..stack_count.."("..providing_threshold_stacks..")"..", priority: "..provider_priority..", min length: "..min_carriages..", max length: "..max_carriages..", trains en route: "..trainsEnRoute)
        end
      elseif (useRequestStackThreshold and stack_count*-1 >= requesting_threshold_stacks) or
        (not useRequestStackThreshold and count*-1 >= requesting_threshold) then
        count = count * -1
        local ageIndex = item..","..stopID
        global.Dispatcher.RequestAge[ageIndex] = global.Dispatcher.RequestAge[ageIndex] or game.tick
        global.Dispatcher.Requests[#global.Dispatcher.Requests+1] = {age = global.Dispatcher.RequestAge[ageIndex], stopID = stopID, priority = requester_priority, item = item, count = count}
        global.Dispatcher.Requests_by_Stop[stopID] = global.Dispatcher.Requests_by_Stop[stopID] or {}
        global.Dispatcher.Requests_by_Stop[stopID][item] = count
        if debug_log then
          local trainsEnRoute = "";
          for k,v in pairs(stop.active_deliveries) do
            trainsEnRoute=trainsEnRoute.." "..v
          end
          log("(UpdateStop) "..stop.entity.backer_name.." {"..network_id_string.."} requests "..item.." "..count.."("..requesting_threshold..")".." stacks: "..tostring(stack_count*-1).."("..requesting_threshold_stacks..")"..", priority: "..requester_priority..", min length: "..min_carriages..", max length: "..max_carriages..", age: "..global.Dispatcher.RequestAge[ageIndex].."/"..game.tick..", trains en route: "..trainsEnRoute)
        end
      end

    end -- for circuitValues

    stop.network_id = network_id
    stop.providing_threshold = providing_threshold
    stop.providing_threshold_stacks = providing_threshold_stacks
    stop.provider_priority = provider_priority
    stop.requesting_threshold = requesting_threshold
    stop.requesting_threshold_stacks = requesting_threshold_stacks
    stop.requester_priority = requester_priority
    stop.min_carriages = min_carriages
    stop.max_carriages = max_carriages
    stop.max_trains = max_trains
    stop.locked_slots = locked_slots
    stop.no_warnings = no_warnings
  end
end



function setLamp(trainStop, color, count)
  -- skip invalid stops and colors
  if trainStop and trainStop.lamp_control.valid and ColorLookup[color] then
    trainStop.lamp_control.get_control_behavior().parameters = {{index = 1, signal = {type="virtual",name=ColorLookup[color]}, count = count }}
    return true
  end
  return false
end


function UpdateStopOutput(trainStop, ignore_existing_cargo)
  -- skip invalid stop outputs
  if not trainStop.output.valid then
    return
  end

  local signals = {}
  local index = 0

  if trainStop.parked_train and trainStop.parked_train.valid then
    -- get train composition
    local carriages = trainStop.parked_train.carriages
    local encoded_positions_by_name = {}
    local encoded_positions_by_type = {}
    local inventory = not(ignore_existing_cargo) and trainStop.parked_train.get_contents() or {}
    local fluidInventory = not(ignore_existing_cargo) and trainStop.parked_train.get_fluid_contents() or {}

    if #carriages < 32 then --prevent circuit network integer overflow error
      if trainStop.parked_train_faces_stop then --train faces forwards >> iterate normal
        for i=1, #carriages do
          local signal_type = format("ltn-position-any-%s", carriages[i].type)
          if game.virtual_signal_prototypes[signal_type] then
            if encoded_positions_by_type[signal_type] then
              encoded_positions_by_type[signal_type] = encoded_positions_by_type[signal_type] + 2^(i-1)
            else
              encoded_positions_by_type[signal_type] = 2^(i-1)
            end
          else
            if message_level >= 1 then printmsg({"ltn-message.error-invalid-position-signal", signal_type}) end
            log(format("Error: signal \"%s\" not found!", signal_type))
          end
          local signal_name = format("ltn-position-%s", carriages[i].name)
          if game.virtual_signal_prototypes[signal_name] then
            if encoded_positions_by_name[signal_name] then
              encoded_positions_by_name[signal_name] = encoded_positions_by_name[signal_name] + 2^(i-1)
            else
              encoded_positions_by_name[signal_name] = 2^(i-1)
            end
          else
            if message_level >= 1 then printmsg({"ltn-message.error-invalid-position-signal", signal_name}) end
            log(format("Error: signal \"%s\" not found!", signal_name))
          end
        end
      else --train faces backwards >> iterate backwards
        n = 0
        for i=#carriages, 1, -1 do
          local signal_type = format("ltn-position-any-%s", carriages[i].type)
          if game.virtual_signal_prototypes[signal_type] then
            if encoded_positions_by_type[signal_type] then
              encoded_positions_by_type[signal_type] = encoded_positions_by_type[signal_type] + 2^n
            else
              encoded_positions_by_type[signal_type] = 2^n
            end
          else
            if message_level >= 1 then printmsg({"ltn-message.error-invalid-position-signal", signal_type}) end
            log(format("Error: signal \"%s\" not found!", signal_type))
          end
          local signal_name = format("ltn-position-%s", carriages[i].name)
          if game.virtual_signal_prototypes[signal_name] then
            if encoded_positions_by_name[signal_name] then
              encoded_positions_by_name[signal_name] = encoded_positions_by_name[signal_name] + 2^n
            else
              encoded_positions_by_name[signal_name] = 2^n
            end
          else
            if message_level >= 1 then printmsg({"ltn-message.error-invalid-position-signal", signal_name}) end
            log(format("Error: signal \"%s\" not found!", signal_name))
          end
          n=n+1
        end
      end

      for k ,v in pairs (encoded_positions_by_type) do
        index = index+1
        table.insert(signals, {index = index, signal = {type="virtual",name=k}, count = v })
      end
      for k ,v in pairs (encoded_positions_by_name) do
        index = index+1
        table.insert(signals, {index = index, signal = {type="virtual",name=k}, count = v })
      end
    end

    if not trainStop.is_depot then
      -- Update normal stations
      local conditions = trainStop.parked_train.schedule.records[trainStop.parked_train.schedule.current].wait_conditions
      if conditions ~= nil then
        for _, c in pairs(conditions) do
          if c.condition and c.condition.first_signal then -- loading without mods can make first signal nil?
            if c.type == "item_count" then
              if (c.condition.comparator == "=" and c.condition.constant == 0) then
                --train expects to be unloaded of each of this item
                inventory[c.condition.first_signal.name] = nil
              elseif c.condition.comparator == "≥" then
                --train expects to be loaded to x of this item
                inventory[c.condition.first_signal.name] = c.condition.constant
              end
            elseif c.type == "fluid_count" then
              if (c.condition.comparator == "=" and c.condition.constant == 0) then
                --train expects to be unloaded of each of this fluid
                fluidInventory[c.condition.first_signal.name] = -1
              elseif c.condition.comparator == "≥" then
                --train expects to be loaded to x of this fluid
                fluidInventory[c.condition.first_signal.name] = c.condition.constant
              end
            end
          end
        end
      end

      -- output expected inventory contents
      for k,v in pairs(inventory) do
        index = index+1
        table.insert(signals, {index = index, signal = {type="item", name=k}, count = v})
      end
      for k,v in pairs(fluidInventory) do
        index = index+1
        table.insert(signals, {index = index, signal = {type="fluid", name=k}, count = v})
      end

    end -- not trainStop.is_depot

  end
  -- will reset if called with no parked train
  if index > 0 then
    -- log("[LTN] "..tostring(trainStop.entity.backer_name).. " displaying "..#signals.."/"..tostring(trainStop.output.get_control_behavior().signals_count).." signals.")

    while #signals > trainStop.output.get_control_behavior().signals_count do
      -- log("[LTN] removing signal "..tostring(signals[#signals].signal.name))
      table.remove(signals)
    end
    if index ~= #signals then
      if message_level >= 1 then printmsg({"ltn-message.error-stop-output-truncated", tostring(trainStop.entity.backer_name), tostring(trainStop.parked_train), trainStop.output.get_control_behavior().signals_count, index-#signals}, trainStop.entity.force) end
      if debug_log then log("(UpdateStopOutput) Inventory of train "..tostring(trainStop.parked_train.id).." at stop "..tostring(trainStop.entity.backer_name).." exceeds stop output limit of "..trainStop.output.get_control_behavior().signals_count.." by "..index-#signals.." signals.") end
    end
    trainStop.output.get_control_behavior().parameters = signals
    if debug_log then log("(UpdateStopOutput) Updating signals for "..tostring(trainStop.entity.backer_name)..": train "..tostring(trainStop.parked_train.id)..": "..index.." signals") end
  else
    trainStop.output.get_control_behavior().parameters = nil
    if debug_log then log("(UpdateStopOutput) Resetting signals for "..tostring(trainStop.entity.backer_name)..".") end
  end
end