-- AD Flow Wagons
-- Flows ejer deres vogne, men traktor og vogn er ikke låst sammen: den vogn der hænger på en flow-traktor huskes
-- (run.wagons = {[traktorId] = vognId}). Starter flowet med en solo-traktor, henter den sin vogn ved "Connect <vognens
-- parkering>". Stoppes/slettes flowet, eller er dets bygning væk, sættes vognen på plads og traktoren kører hjem —
-- så er begge ledige i maskinpuljen (en stoppet flows vogn må lånes; en kørende flows aldrig).

ADFlowWagons = {}
ADFlowWagons.LOG_PREFIX = "ADSmartPickup: flow-vogne: "
ADFlowWagons.REMEMBER_MS = 10000     -- husk vogne / prøv ventende starter igen
ADFlowWagons.BUILDING_CHECK_MS = 60000
ADFlowWagons.MISSING_CHECKS = 2      -- så mange tjek i træk før en bygning regnes for væk

-- ---- ren logik ----

ADFlowWagons.serialize = function(wagons) return ADRuns.serializeWagons(wagons) end
ADFlowWagons.parse = function(text) return ADRuns.parseWagons(text) end

-- Husk traktorens vogn: ny tabel ved ændring, samme tabel når intet ændres.
function ADFlowWagons.remember(wagons, tractorId, wagonId)
    if (wagons or {})[tractorId] == wagonId then return wagons end
    local copy = ADRuns.copyWagons(wagons)
    copy[tractorId] = wagonId
    return copy
end

-- Må redskabet bag traktoren huskes som flowets vogn? Kun noget der kan rumme last — ikke plov/kultivator (ingen
-- plads) og ikke såmaskine (frøtank). s = {capacity, isSowingMachine}. in-game 30/9: 'Sell Slurry 2' huskede ploven.
function ADFlowWagons.isRememberableWagon(s)
    return (s.capacity or 0) > 0 and not s.isSowingMachine
end

-- s = {hasRear, wagonId, wagonExists, hasConnect, wagonAttached, wagonBusy} -> "start" | "fetch" | "wait"
function ADFlowWagons.startAction(s)
    -- lånt ud af puljen (markarbejde, marksilo, på hjemtur): vent til den er fri
    if s.tractorBusy then return "wait" end
    if s.hasRear or s.wagonId == nil or not s.wagonExists or not s.hasConnect then return "start" end
    if s.wagonAttached or s.wagonBusy then return "wait" end
    return "fetch"
end

-- Hent vogn fejlede: ét nyt forsøg når AD standsede undervejs (forbigående, fx spærret af en anden traktor);
-- ikke ved kobling der fejler ved markøren (den skal rettes).
ADFlowWagons.FETCH_RETRIES = 1
function ADFlowWagons.retryFetch(reason, retries)
    return tostring(reason):find("^stoppedAway") ~= nil and (retries or 0) < ADFlowWagons.FETCH_RETRIES
end

-- s = {flowRunning, ownWagon, adActive} -> start traktoren efter spillerens egen påkobling?
function ADFlowWagons.startAfterManualAttach(s)
    return s.flowRunning == true and s.ownWagon == true and not s.adActive
end

-- Husk vognen bag traktoren ved hjemtur? Kun når et KØRENDE flow stoppes (reason "stop") — ved oprydning efter
-- indlæsning ("afterLoad") kan traktoren have et puljeredskab på fra et lån (in-game 29/9).
function ADFlowWagons.shouldRememberOnHome(reason)
    return reason == "stop"
end

-- Påkobling uden ejer (hentet før genindlæsning, markopgaven tabt): s = {owned, idleMs} -> "home"|"wait"|"none"
ADFlowWagons.ORPHAN_MS = 120000
-- s.atOwnPark: traktoren holder på sin egen parkering = parkeret sæt, ikke forældreløs (vinmarks-REX, 29/9)
ADFlowWagons.OWN_PARK_M = 30
function ADFlowWagons.orphanAction(s)
    if s.owned or s.atOwnPark then return "none" end
    return (s.idleMs or 0) >= ADFlowWagons.ORPHAN_MS and "home" or "wait"
end

-- Hvorfor "wait" (til loggen). s som startAction.
function ADFlowWagons.waitReason(s)
    if s.tractorBusy then return "tractorBusy" end
    if s.wagonAttached then return "wagonAttached" end
    return "wagonReserved"
end

-- Ingen husket vogn: gæt ud fra parkeringsnavnet — en ledig vogn hvis parkering indeholder flowets navn, helst med
-- traktorens nummer til sidst ("Cow Food 3" -> "P Cow Food vogn 3"). candidates = {{id, parkName}}, taken = {[id]=true}
function ADFlowWagons.guessWagon(runName, tractorNumber, candidates, taken)
    local wanted = tostring(runName or ""):lower()
    if wanted == "" then return nil end
    local matching = {}
    for _, candidate in ipairs(candidates or {}) do
        local park = tostring(candidate.parkName or ""):lower()
        if not (taken or {})[candidate.id] and park:find(wanted, 1, true) ~= nil then table.insert(matching, candidate) end
    end
    table.sort(matching, function(a, b) return tostring(a.parkName) < tostring(b.parkName) end)
    for _, candidate in ipairs(matching) do
        if tractorNumber ~= nil and tostring(candidate.parkName):match("%s(%d+)$") == tostring(tractorNumber) then return candidate.id end
    end
    return matching[1] ~= nil and matching[1].id or nil
end

-- Ledige vogne til flow-guiden, bedste først: parkering med flowets navn, så "Disponibel", så resten (alfabetisk).
-- candidates = {{id, label}} -> ny sorteret liste.
function ADFlowWagons.rankWagons(runName, candidates)
    local wanted = tostring(runName or ""):lower()
    local function rank(wagon)
        local label = tostring(wagon.label or ""):lower()
        if wanted ~= "" and label:find(wanted, 1, true) ~= nil then return 1 end
        if label:find("disponibel", 1, true) ~= nil then return 2 end
        return 3
    end
    local ranked = {}
    for _, wagon in ipairs(candidates or {}) do table.insert(ranked, wagon) end
    table.sort(ranked, function(a, b)
        local ra, rb = rank(a), rank(b)
        if ra ~= rb then return ra < rb end
        return tostring(a.label) < tostring(b.label)
    end)
    return ranked
end

function ADFlowWagons.ownerOf(runs, wagonId)
    for _, run in ipairs(runs or {}) do
        for _, id in pairs(run.wagons or {}) do
            if id == wagonId then return run end
        end
    end
    return nil
end

-- Holdes vognen af et flow? Flowets vogn er flowets, også når flowet er stoppet — puljen, markarbejde og
-- marksilo må ikke låne den (in-game 29/9: marksilo lånte Cow Food-traktoren med vognen på efter stop).
function ADFlowWagons.isHeld(runs, wagonId)
    return ADFlowWagons.ownerOf(runs, wagonId) ~= nil
end

-- Et tjek af om bygningen mangler: -> ny tæller, væk?
function ADFlowWagons.missingStep(count, missingNow)
    if not missingNow then return 0, false end
    local next = (count or 0) + 1
    return next, next >= ADFlowWagons.MISSING_CHECKS
end

-- Flowets bygnings-id'er der ikke findes i exists = {[id] = true}. Kun bygninger der er set i denne session
-- (seen) tæller: et forældet id i et gammelt flow må ikke stoppe et flow der virker.
function ADFlowWagons.missingBuildings(run, exists, seen)
    local missing = {}
    for _, key in ipairs({"sourceBuildingIds", "targetBuildingIds", "storeBuildingIds"}) do
        for _, id in ipairs(run[key] or {}) do
            if not exists[id] and (seen or {})[id] then table.insert(missing, id) end
        end
    end
    return missing
end

-- Hvor læsset afleveres ved stop: AD's 2. markør kun hvis den er et af flowets mål — den kan være forældet
-- (gammel AD-tilstand) eller et Wait-punkt, Wait-logikken har skiftet til. Ellers flowets første mål; nil = silo.
function ADFlowWagons.emptyTarget(secondMarkerId, runTargetIds)
    local targets = runTargetIds or {}
    for _, id in ipairs(targets) do
        if id == secondMarkerId then return id end
    end
    return targets[1]
end

-- Tøm vognen før den parkeres (flowet stoppet): flowets mål -> silo/egen fabrik -> hjem.
-- stage: "start" | "target" | "dump"; s = {cargo, hasTarget, adActive, elapsedMs}
-- -> "home" | "target" | "dump" | "wait" | "giveUp"
ADFlowWagons.EMPTY_MIN_LITERS = 100
ADFlowWagons.EMPTY_TIMEOUT_MS = 600000
ADFlowWagons.EMPTY_STALL_MS = 45000     -- ved målet uden at læsset falder så længe = målet er fuldt
ADFlowWagons.EMPTY_NEAR_M = 40          -- m fra aflæsningsmarkøren tæller som "ved målet"
ADFlowWagons.MAX_DUMP_ATTEMPTS = 3      -- siloer der prøves før vognen parkeres med last

-- s = {nearTarget, sinceChangeMs}
function ADFlowWagons.isStalled(s)
    return s.nearTarget == true and (s.sinceChangeMs or 0) >= ADFlowWagons.EMPTY_STALL_MS
end

function ADFlowWagons.emptyStep(stage, s)
    local cargo = s.cargo or 0
    if stage == "start" then
        if cargo < ADFlowWagons.EMPTY_MIN_LITERS then return "home" end
        return s.hasTarget and "target" or "dump"
    end
    if (s.elapsedMs or 0) >= ADFlowWagons.EMPTY_TIMEOUT_MS then return "giveUp" end
    if s.stalled and cargo >= ADFlowWagons.EMPTY_MIN_LITERS then
        if stage == "target" then return "dump" end
        -- silo der ikke kunne tage imod: prøv den næste (op til MAX_DUMP_ATTEMPTS)
        return (s.dumpAttempts or 0) < ADFlowWagons.MAX_DUMP_ATTEMPTS and "dump" or "giveUp"
    end
    if s.adActive then return "wait" end
    if cargo < ADFlowWagons.EMPTY_MIN_LITERS then return "home" end
    if stage == "target" then return "dump" end
    return "giveUp"
end

-- ---- spil ----

local waiting = setmetatable({}, {__mode = "k"})   -- traktor -> runId (venter på sin vogn)
local fetching = setmetatable({}, {__mode = "k"})  -- traktor -> runId (henter sin vogn)
local emptying = setmetatable({}, {__mode = "k"}) -- traktor -> {stage, since, fillType, runName}
local homing = setmetatable({}, {__mode = "k"})    -- traktor -> true (flowets hjemtur: vogn af, traktor hjem)
local fetchRetries = setmetatable({}, {__mode = "k"}) -- traktor -> antal nye hente-forsøg
local lastWaitText = setmetatable({}, {__mode = "k"}) -- traktor -> sidst loggede venteårsag (kun ændringer logges)
local orphans = setmetatable({}, {__mode = "k"})      -- traktor -> ms siden påkobling uden ejer
local missingCount = {}                            -- runId -> tjek i træk
local seenBuildings = {}                           -- bygnings-id'er set i denne session
local rememberTimer, buildingTimer = 0, 0

local function runs()
    return ADRunsController.store ~= nil and ADRunsController.store.runs or {}
end

local function findAnyVehicle(id)
    for _, vehicle in pairs(g_currentMission.vehicleSystem.vehicles) do
        if ADRunsController.getVehicleId(vehicle) == id then return vehicle end
    end
    return nil
end

local function connectOf(adEnv, wagon)
    local index = wagon.advd ~= nil and wagon.advd.parkDestination or nil
    local park = type(index) == "number" and index >= 1 and adEnv.ADGraphManager:getMapMarkerById(index) or nil
    if park == nil then return nil end
    local marker = ADPool.connectFor(park.name, adEnv.ADGraphManager:getMapMarkers())
    return marker ~= nil and marker.id or nil
end

-- Traktorer i stoppede flows er ledige i puljen; traktorer i kørende flows aldrig.
-- s = {hasRun, stopped, carriesFlowWagon, homeTrip} -> må puljen/markarbejde/marksilo låne traktoren?
function ADFlowWagons.tractorFree(s)
    if not s.hasRun then return true end
    return s.stopped == true and not s.carriesFlowWagon and not s.homeTrip
end

function ADFlowWagons.isFreeTractor(vehicle)
    local run = ADRunsController.getRunForVehicle(vehicle)
    local carries = false
    if run ~= nil then
        for _, implement in ipairs(ADHitch.rearImplementsOf(vehicle)) do
            local wagonId = ADRunsController.getVehicleId(implement.object)
            if wagonId ~= nil and ADFlowWagons.ownerOf(runs(), wagonId) ~= nil then carries = true end
        end
    end
    return ADFlowWagons.tractorFree({hasRun = run ~= nil, stopped = run ~= nil and run.stopped == true,
        carriesFlowWagon = carries, homeTrip = emptying[vehicle] ~= nil or homing[vehicle] ~= nil})
end

-- Holder flowet noget: en traktor henter/venter på sin vogn eller har en vogn bagpå (til Stop-knappen).
function ADFlowWagons.hasActivity(run, vehiclesById)
    for _, vehicleId in ipairs(run.vehicleIds or {}) do
        local vehicle = vehiclesById ~= nil and vehiclesById[vehicleId] or nil
        -- vogn bagpå tæller kun i et flow der er startet: et flow der aldrig kom i gang (fx 'ingen vogn', og spilleren
        -- har selv koblet på) skal vise Start, ikke Stop (in-game 29/9: Milk Store)
        local holdsWagon = vehicle ~= nil and ADRunsController.runningRuns[run.id] == true and #ADHitch.rearImplementsOf(vehicle) > 0
        if vehicle ~= nil and (waiting[vehicle] ~= nil or fetching[vehicle] ~= nil or holdsWagon) then
            return true
        end
    end
    return false
end

function ADFlowWagons.hasWagonFor(run, tractorId)
    return (run.wagons or {})[tractorId] ~= nil
end

function ADFlowWagons.isHeldWagon(wagonId)
    return ADFlowWagons.isHeld(runs(), wagonId)
end

-- Frakoblede vogne med parkering, som intet kørende flow holder, og som flowet ikke allerede har givet en traktor.
local function guessFor(adEnv, run, vehicle, tractorId)
    local taken = {}
    for _, id in pairs(run.wagons or {}) do taken[id] = true end
    local candidates = {}
    local farmId = g_currentMission:getFarmId()
    for _, any in pairs(g_currentMission.vehicleSystem.vehicles) do
        local index = any.advd ~= nil and any.advd.parkDestination or nil
        local attached = any.getAttacherVehicle ~= nil and any:getAttacherVehicle() ~= nil
        if any.spec_motorized == nil and any.spec_attachable ~= nil and not attached and type(index) == "number" and index >= 1
            and any.getOwnerFarmId ~= nil and any:getOwnerFarmId() == farmId then
            local id = ADRunsController.getVehicleId(any)
            local park = adEnv.ADGraphManager:getMapMarkerById(index)
            if id ~= nil and park ~= nil and not ADFlowWagons.isHeld(runs(), id) then
                table.insert(candidates, {id = id, parkName = park.name})
            end
        end
    end
    local number = nil
    for index, id in ipairs(run.vehicleIds or {}) do
        if id == tractorId then number = index end
    end
    local label = tostring(ADRuns.vehicleLabel(vehicle))
    number = tonumber(label:match("%s(%d+)$")) or number
    local wagonId = ADFlowWagons.guessWagon(run.name, number, candidates, taken)
    if wagonId ~= nil then
        Logging.info(ADFlowWagons.LOG_PREFIX .. "flow '%s': '%s' får vognen ved parkeringen der matcher flowets navn", tostring(run.name), label)
    end
    return wagonId
end

-- Flowet startes igen mens traktoren tømmer/kører hjem efter et stop: afbryd, så den kører videre med sin vogn.
-- Puljens egen hjemtur (fra markarbejde) røres ikke — der sidder et andet redskab bagpå.
-- s = {emptying, flowHoming, poolReturning} -> true = afbryd
function ADFlowWagons.abortHomeTripOnStart(s)
    return s.emptying == true or s.flowHoming == true
end

-- Hvilken af isPoolBusy's grunde (til loggen).
function ADFlowWagons.busyWhy(vehicle, tractorId)
    if ADFieldJobs ~= nil and ADFieldJobs.state.assignments[tractorId] ~= nil then return "markopgave" end
    if ADFieldSilos ~= nil and ADFieldSilos.isLoaned(vehicle) then return "lånt af marksilo" end
    if ADPool ~= nil and ADPool.isReturning(vehicle) then return "sætter redskab af" end
    if ADCpBridge ~= nil and ADCpBridge.isWorking(vehicle) then return "Courseplay kører" end
    if emptying[vehicle] ~= nil then return "tømmer vognen" end
    return "?"
end

-- Lånt ud af puljen: markarbejde, marksilo-lån, på hjemtur eller Courseplay kører den.
function ADFlowWagons.isPoolBusy(vehicle, tractorId)
    return (ADFieldJobs ~= nil and ADFieldJobs.state.assignments[tractorId] ~= nil)
        or (ADFieldSilos ~= nil and ADFieldSilos.isLoaned(vehicle))
        or (ADPool ~= nil and ADPool.isReturning(vehicle))
        or (ADCpBridge ~= nil and ADCpBridge.isWorking(vehicle))
        or (ADFlowWagons.isEmptying ~= nil and ADFlowWagons.isEmptying(vehicle))
end

-- Før en flow-traktor startes: hent sin vogn / vent på den. -> håndteret, resultat (som startVehicle)
function ADFlowWagons.beforeStart(adEnv, run, vehicle)
    local tractorId = ADRunsController.getVehicleId(vehicle)
    if fetching[vehicle] ~= nil then return true, {vehicle = vehicle, ok = true, reason = "fetchingWagon"} end
    if ADFlowWagons.abortHomeTripOnStart({emptying = emptying[vehicle] ~= nil, flowHoming = homing[vehicle] ~= nil}) then
        Logging.info(ADFlowWagons.LOG_PREFIX .. "flow '%s': '%s' startet igen — tømning/hjemtur afbrudt, kører videre med vognen",
            tostring(run.name), tostring(ADRuns.vehicleLabel(vehicle)))
        emptying[vehicle] = nil
        if homing[vehicle] ~= nil then
            homing[vehicle] = nil
            ADHitch.cancel(vehicle)
        end
    end
    local wagonId = (run.wagons or {})[tractorId]
    if wagonId == nil and #ADHitch.rearImplementsOf(vehicle) == 0 then
        wagonId = guessFor(adEnv, run, vehicle, tractorId)
        if wagonId ~= nil then run.wagons = ADFlowWagons.remember(run.wagons, tractorId, wagonId) end
    end
    local wagon = wagonId ~= nil and findAnyVehicle(wagonId) or nil
    local connectId = wagon ~= nil and connectOf(adEnv, wagon) or nil
    local startState = {
        tractorBusy = ADFlowWagons.isPoolBusy(vehicle, tractorId),
        hasRear = #ADHitch.rearImplementsOf(vehicle) > 0, wagonId = wagonId, wagonExists = wagon ~= nil,
        hasConnect = connectId ~= nil,
        wagonAttached = wagon ~= nil and wagon.getAttacherVehicle ~= nil and wagon:getAttacherVehicle() ~= nil,
        wagonBusy = wagonId ~= nil and ADPool.isReserved(wagonId),
    }
    local action = ADFlowWagons.startAction(startState)
    if action == "start" then lastWaitText[vehicle] = nil return false end
    ADRunsController.runningRuns[run.id] = true
    if action == "wait" then
        local holder = wagon ~= nil and wagon.getAttacherVehicle ~= nil and wagon:getAttacherVehicle() or nil
        local waitText = ADFlowWagons.waitReason(startState) .. ": " .. (startState.tractorBusy and ADFlowWagons.busyWhy(vehicle, tractorId)
            or (holder ~= nil and ("sidder på " .. tostring(ADRuns.vehicleLabel(holder)))) or "reserveret af puljen")
        if lastWaitText[vehicle] ~= waitText then
            lastWaitText[vehicle] = waitText
            Logging.info(ADFlowWagons.LOG_PREFIX .. "flow '%s': '%s' venter på sin vogn (%s)", tostring(run.name),
                tostring(ADRuns.vehicleLabel(vehicle)), waitText)
        end
        waiting[vehicle] = run.id
        return true, {vehicle = vehicle, ok = true, reason = "waitingWagon"}
    end
    waiting[vehicle] = nil
    lastWaitText[vehicle] = nil
    fetching[vehicle] = run.id
    local runId = run.id
    local okFetch, errFetch = pcall(ADHitch.fetch, adEnv, vehicle, connectId, function(tractor, ok, detail)
        fetching[tractor] = nil
        local current = ADRuns.getRun(ADRunsController.store, runId)
        if current == nil or current.stopped then
            ADHitch.returnHome(adEnv, tractor)
            return
        end
        if ok then
            fetchRetries[tractor] = nil
            local result = ADRunsController.startVehicle(adEnv, current, tractor)
            if result ~= nil and not result.ok then
                -- flowet kan ikke startes (markør, bygning …): ikke efterladt ved Connect med vognen
                Logging.warning(ADFlowWagons.LOG_PREFIX .. "flow '%s': '%s' kunne ikke starte (%s) — vognen sættes tilbage",
                    tostring(current.name), tostring(ADRuns.vehicleLabel(tractor)), tostring(result.reason))
                ADHitch.returnHome(adEnv, tractor)
            end
        elseif ADFlowWagons.retryFetch(detail, fetchRetries[tractor]) then
            fetchRetries[tractor] = (fetchRetries[tractor] or 0) + 1
            waiting[tractor] = runId -- retryWaiting starter den igen om lidt
            Logging.warning(ADFlowWagons.LOG_PREFIX .. "flow '%s': '%s' kunne ikke hente sin vogn (%s) — prøver igen", tostring(current.name),
                tostring(ADRuns.vehicleLabel(tractor)), tostring(detail))
        else
            fetchRetries[tractor] = nil
            Logging.warning(ADFlowWagons.LOG_PREFIX .. "flow '%s': '%s' kunne ikke hente sin vogn (%s)", tostring(current.name),
                tostring(ADRuns.vehicleLabel(tractor)), tostring(detail))
        end
    end)
    if not okFetch then
        fetching[vehicle] = nil
        return true, {vehicle = vehicle, ok = false, reason = "error"}
    end
    Logging.info(ADFlowWagons.LOG_PREFIX .. "flow '%s': '%s' henter sin vogn", tostring(run.name), tostring(ADRuns.vehicleLabel(vehicle)))
    return true, {vehicle = vehicle, ok = true, reason = "fetchingWagon"}
end

-- Stop/slet/bygning væk: vognen tømmes (flowets mål, ellers silo/egen fabrik), sættes på plads, traktoren hjem.
local nowMs = 0

local function cargoOf(adEnv, vehicle)
    local level, fillType = 0, nil
    local ok, units = pcall(adEnv.AutoDrive.getAllDischargeableUnits, vehicle)
    for _, unit in ipairs(ok and units or {}) do
        local object, index = unit.object, unit.fillUnitIndex
        if object ~= nil and object.getFillUnitFillLevel ~= nil then
            local unitLevel = object:getFillUnitFillLevel(index) or 0
            if unitLevel > 0 then
                level = level + unitLevel
                fillType = fillType or object:getFillUnitFillType(index)
            end
        end
    end
    return level, fillType
end

local function goHome(adEnv, vehicle)
    emptying[vehicle] = nil
    homing[vehicle] = true
    local okHome, pooled = pcall(ADHitch.returnHome, adEnv, vehicle, function(tractor) homing[tractor] = nil end)
    if not (okHome and pooled) then
        homing[vehicle] = nil
        local park = ADFieldWork.parkMarkerId(adEnv, vehicle)
        if park ~= nil then pcall(ADFieldWork.startAd, adEnv, vehicle, adEnv.AutoDrive.MODE_DRIVETO, park, nil) end
    end
end

local function fillName(fillType)
    local desc = fillType ~= nil and g_fillTypeManager ~= nil and g_fillTypeManager:getFillTypeByIndex(fillType) or nil
    return desc ~= nil and (desc.title or desc.name) or tostring(fillType)
end

local function startDump(adEnv, vehicle, state)
    local cargo, fillType = cargoOf(adEnv, vehicle)
    local isReachable = function(markerId)
        return ADUnloadWait == nil or ADUnloadWait.hasRouteTo == nil or ADUnloadWait.hasRouteTo(adEnv, vehicle, markerId)
    end
    -- marksiloer er ikke tømmesteder (de er til markens høst); siloer der allerede fejlede springes over
    local okSet, fieldSilos = pcall(function() return ADFieldSilos ~= nil and ADFieldSilos.fieldSiloPlaceableSet(adEnv) or nil end)
    state.triedMarkers = state.triedMarkers or {}
    local ok, marker, why = pcall(ADLoadSwap.findDumpMarker, adEnv, vehicle, fillType, cargo, nil, isReachable,
        okSet and fieldSilos or nil, state.triedMarkers, true)
    if not ok or marker == nil then
        Logging.warning(ADFlowWagons.LOG_PREFIX .. "'%s' har stadig %d l %s — intet sted at aflæsse (%s); parkeres med last",
            tostring(ADRuns.vehicleLabel(vehicle)), math.floor(cargo), fillName(fillType), tostring(ok and why or marker))
        goHome(adEnv, vehicle)
        return
    end
    state.stage, state.since = "dump", nowMs
    state.markerId, state.markerName, state.lastCargo = marker.id, marker.name, nil
    state.dumpAttempts = (state.dumpAttempts or 0) + 1
    state.triedMarkers[marker.id] = true
    ADFieldWork.startAd(adEnv, vehicle, adEnv.AutoDrive.MODE_DELIVERTO, marker.id, nil, fillType)
    Logging.info(ADFlowWagons.LOG_PREFIX .. "'%s' aflæsser resten (%d l %s) ved %s før parkering",
        tostring(ADRuns.vehicleLabel(vehicle)), math.floor(cargo), fillName(fillType), tostring(marker.name))
end

-- Husk vognen bag traktoren som flowets (også når flowet lige er stoppet — rememberAll ser kun kørende flows).
-- in-game 29/9: Milk Store's tanke blev sat af ved Stop alt uden at være husket -> 'noTrailer' ved næste start.
local function isCargoWagon(object)
    local _, capacity = ADPool.cargoOf(object)
    return ADFlowWagons.isRememberableWagon({capacity = capacity, isSowingMachine = object.spec_sowingMachine ~= nil})
end

local function rememberWagonOf(vehicle)
    local run = ADRunsController.getRunForVehicle(vehicle)
    local rear = run ~= nil and ADHitch.rearImplementsOf(vehicle) or {}
    local tractorId = ADRunsController.getVehicleId(vehicle)
    local wagonId = rear[1] ~= nil and isCargoWagon(rear[1].object) and ADRunsController.getVehicleId(rear[1].object) or nil
    if wagonId == nil or tractorId == nil then return end
    local updated = ADFlowWagons.remember(run.wagons, tractorId, wagonId)
    if updated ~= run.wagons then
        run.wagons = updated
        Logging.info(ADFlowWagons.LOG_PREFIX .. "flow '%s': '%s' har vognen '%s'", tostring(run.name),
            tostring(ADRuns.vehicleLabel(vehicle)), tostring(ADRuns.vehicleLabel(rear[1].object)))
    end
end

-- Én traktor hjem (fra et stoppet/slettet flow): tøm først, så parkering.
-- reason: "stop" (et kørende flow stoppes: vognen huskes) | "afterLoad" (oprydning: intet huskes)
function ADFlowWagons.homeVehicle(adEnv, vehicle, runName, reason)
    waiting[vehicle] = nil
    if ADFlowWagons.shouldRememberOnHome(reason or "stop") then
        rememberWagonOf(vehicle) -- vognen sættes af nu: flowet skal kunne finde den igen ved næste start
    end
    ADHitch.stow(vehicle, "flowet stoppet")
    if fetching[vehicle] ~= nil then
        fetching[vehicle] = nil
        ADHitch.cancel(vehicle)
    end
    local module = vehicle.ad ~= nil and vehicle.ad.stateModule or nil
    local second = module ~= nil and module.getSecondMarker ~= nil and module:getSecondMarker() or nil
    local run = ADRunsController.getRunForVehicle(vehicle)
    local targetId = ADFlowWagons.emptyTarget(second ~= nil and second.id or nil, run ~= nil and run.targetWayPointIds or nil)
    local target = targetId ~= nil and adEnv.ADGraphManager:getMapMarkerByWayPointId(targetId) or nil
    local cargo, fillType = cargoOf(adEnv, vehicle)
    local action = ADFlowWagons.emptyStep("start", {cargo = cargo, hasTarget = target ~= nil})
    if action == "home" then return goHome(adEnv, vehicle) end
    local state = {stage = action, since = nowMs, runName = runName,
        markerId = target ~= nil and target.id or nil, markerName = target ~= nil and target.name or nil}
    emptying[vehicle] = state
    if action == "target" then
        ADFieldWork.startAd(adEnv, vehicle, adEnv.AutoDrive.MODE_DELIVERTO, target.id, nil, fillType)
        Logging.info(ADFlowWagons.LOG_PREFIX .. "'%s' afleverer sit læs (%d l %s) ved %s før parkering",
            tostring(ADRuns.vehicleLabel(vehicle)), math.floor(cargo), fillName(fillType), tostring(target.name))
    else
        startDump(adEnv, vehicle, state)
    end
end

-- ADHitch: spilleren har selv kørt traktoren til Connect og koblet på.
function ADFlowWagons.onManualAttach(adEnv, vehicle, wagon)
    local run = ADRunsController.getRunForVehicle(vehicle)
    orphans[vehicle] = 0 -- ryddes af tickOrphans når nogen ejer opgaven (flow, markopgave, AD, spilleren)
    if run == nil then return end
    local tractorId = ADRunsController.getVehicleId(vehicle)
    local wagonId = wagon ~= nil and ADRunsController.getVehicleId(wagon) or nil
    local remembered = (run.wagons or {})[tractorId]
    local module = vehicle.ad ~= nil and vehicle.ad.stateModule or nil
    -- ikke stoppet af spilleren = gælder også et flow hvis Start blev afvist ('ingen vogn') — det er derfor han henter vognen
    if not ADFlowWagons.startAfterManualAttach({flowRunning = not run.stopped,
        ownWagon = wagonId ~= nil and (remembered == nil or remembered == wagonId),
        adActive = module ~= nil and module:isActive()}) then return end
    fetchRetries[vehicle], waiting[vehicle], orphans[vehicle] = nil, nil, nil
    Logging.info(ADFlowWagons.LOG_PREFIX .. "flow '%s': '%s' har selv hentet sin vogn — startes", tostring(run.name), tostring(ADRuns.vehicleLabel(vehicle)))
    ADRunsController.startVehicle(adEnv, run, vehicle)
end

-- Traktorer der har koblet et redskab på uden ejer: efter ORPHAN_MS sættes redskabet tilbage og traktoren kører hjem.
local function tickOrphans(adEnv, elapsed)
    for vehicle, idle in pairs(orphans) do
        local id = ADRunsController.getVehicleId(vehicle)
        local run = ADRunsController.getRunForVehicle(vehicle)
        local module = vehicle.ad ~= nil and vehicle.ad.stateModule or nil
        local owned = (module ~= nil and module:isActive()) or (vehicle.getIsControlled ~= nil and vehicle:getIsControlled())
            or (run ~= nil and not run.stopped) or (ADFieldJobs ~= nil and id ~= nil and ADFieldJobs.state.assignments[id] ~= nil)
            or (ADCpBridge ~= nil and ADCpBridge.isWorking(vehicle)) or #ADHitch.rearImplementsOf(vehicle) == 0
        local atOwnPark = false
        local parkId = ADFieldWork ~= nil and ADFieldWork.parkMarkerId ~= nil and ADFieldWork.parkMarkerId(adEnv, vehicle) or nil
        local parkWp = parkId ~= nil and adEnv.ADGraphManager:getWayPointById(parkId) or nil
        if parkWp ~= nil and vehicle.rootNode ~= nil then
            local x, _, z = getWorldTranslation(vehicle.rootNode)
            atOwnPark = (x - parkWp.x) ^ 2 + (z - parkWp.z) ^ 2 <= ADFlowWagons.OWN_PARK_M ^ 2
        end
        local action = ADFlowWagons.orphanAction({owned = owned, atOwnPark = atOwnPark, idleMs = idle + elapsed})
        if action == "none" then
            orphans[vehicle] = nil
        elseif action == "home" then
            orphans[vehicle] = nil
            Logging.info(ADFlowWagons.LOG_PREFIX .. "'%s' har et redskab på uden opgave (hentet før genindlæsning?) — sættes tilbage og kører hjem",
                tostring(ADRuns.vehicleLabel(vehicle)))
            goHome(adEnv, vehicle)
        else
            orphans[vehicle] = idle + elapsed
        end
    end
end

function ADFlowWagons.isEmptying(vehicle)
    return emptying[vehicle] ~= nil
end

function ADFlowWagons.sendHome(adEnv, run)
    for _, vehicleId in ipairs(run.vehicleIds or {}) do
        local vehicle = ADRunsController.findVehicleById(adEnv, vehicleId)
        if vehicle ~= nil then
            local ok, err = pcall(ADFlowWagons.homeVehicle, adEnv, vehicle, run.name)
            if not ok then
                Logging.warning(ADFlowWagons.LOG_PREFIX .. "hjem fejlede: %s", tostring(err))
                goHome(adEnv, vehicle)
            end
        end
    end
end

-- Står traktoren ved tømningens markør, uden at læsset er faldet i EMPTY_STALL_MS?
local function stalledAt(adEnv, vehicle, state, cargo)
    if state.lastCargo == nil or cargo < state.lastCargo - 1 then
        state.lastCargo, state.changedAt = cargo, nowMs
    end
    local wayPoint = state.markerId ~= nil and adEnv.ADGraphManager:getWayPointById(state.markerId) or nil
    local near = false
    if wayPoint ~= nil and vehicle.rootNode ~= nil then
        local x, _, z = getWorldTranslation(vehicle.rootNode)
        near = math.sqrt((x - wayPoint.x) ^ 2 + (z - wayPoint.z) ^ 2) <= ADFlowWagons.EMPTY_NEAR_M
    end
    return ADFlowWagons.isStalled({nearTarget = near, sinceChangeMs = nowMs - (state.changedAt or nowMs)})
end

local function tickEmptying(adEnv)
    local list = {}
    for vehicle, state in pairs(emptying) do table.insert(list, {vehicle = vehicle, state = state}) end
    for _, item in ipairs(list) do
        local vehicle, state = item.vehicle, item.state
        local module = vehicle.ad ~= nil and vehicle.ad.stateModule or nil
        local cargo, fillType = cargoOf(adEnv, vehicle)
        local controlled = vehicle.getIsControlled ~= nil and vehicle:getIsControlled()
        if controlled then
            emptying[vehicle] = nil -- spilleren har overtaget
        else
            local stalled = stalledAt(adEnv, vehicle, state, cargo)
            local action = ADFlowWagons.emptyStep(state.stage, {cargo = cargo, adActive = module ~= nil and module:isActive(),
                elapsedMs = nowMs - state.since, stalled = stalled, dumpAttempts = state.dumpAttempts})
            if stalled and action ~= "wait" then
                Logging.info(ADFlowWagons.LOG_PREFIX .. "'%s' kan ikke aflæsse ved %s (fuldt?) — videre", tostring(ADRuns.vehicleLabel(vehicle)),
                    tostring(state.markerName))
            end
            if action == "home" then
                goHome(adEnv, vehicle)
            elseif action == "dump" then
                startDump(adEnv, vehicle, state)
            elseif action == "giveUp" then
                Logging.warning(ADFlowWagons.LOG_PREFIX .. "'%s' kunne ikke tømme vognen (%d l %s tilbage) — parkeres med last",
                    tostring(ADRuns.vehicleLabel(vehicle)), math.floor(cargo), fillName(fillType))
                goHome(adEnv, vehicle)
            end
        end
    end
end

local function rememberAll(adEnv)
    for _, run in ipairs(runs()) do
        if not run.stopped then
            for _, vehicleId in ipairs(run.vehicleIds or {}) do
                local vehicle = ADRunsController.findVehicleById(adEnv, vehicleId)
                local rear = vehicle ~= nil and ADHitch.rearImplementsOf(vehicle) or {}
                local wagonId = rear[1] ~= nil and isCargoWagon(rear[1].object) and ADRunsController.getVehicleId(rear[1].object) or nil
                if wagonId ~= nil then
                    local updated = ADFlowWagons.remember(run.wagons, vehicleId, wagonId)
                    if updated ~= run.wagons then
                        run.wagons = updated
                        Logging.info(ADFlowWagons.LOG_PREFIX .. "flow '%s': '%s' har vognen '%s'", tostring(run.name),
                            tostring(ADRuns.vehicleLabel(vehicle)), tostring(ADRuns.vehicleLabel(rear[1].object)))
                    end
                end
            end
        end
    end
end

local function retryWaiting(adEnv)
    local list = {}
    for vehicle, runId in pairs(waiting) do table.insert(list, {vehicle = vehicle, runId = runId}) end
    for _, item in ipairs(list) do
        waiting[item.vehicle] = nil
        local run = ADRuns.getRun(ADRunsController.store, item.runId)
        if run ~= nil and not run.stopped then pcall(ADRunsController.startVehicle, adEnv, run, item.vehicle) end
    end
end

local function checkBuildings(adEnv)
    local exists = {}
    local placeables = g_currentMission.placeableSystem ~= nil and g_currentMission.placeableSystem.placeables or {}
    for _, placeable in pairs(placeables) do
        local id = ADBuildings.getId(placeable)
        if id ~= nil then exists[id] = true end
    end
    if next(exists) == nil then return end -- listen er ikke klar: sig intet
    for id in pairs(exists) do seenBuildings[id] = true end
    for _, run in ipairs(runs()) do
        if not run.stopped then
            local missing = ADFlowWagons.missingBuildings(run, exists, seenBuildings)
            local count, gone = ADFlowWagons.missingStep(missingCount[run.id], #missing > 0)
            missingCount[run.id] = count
            if gone then
                missingCount[run.id] = 0
                Logging.warning(ADFlowWagons.LOG_PREFIX .. "flow '%s': bygning findes ikke længere (%s) — stoppet, traktorer kørt hjem",
                    tostring(run.name), table.concat(missing, ", "))
                ADRunsController.stopRun(adEnv, run.id)
                if ADFieldJobs ~= nil and ADFieldJobs.notify ~= nil then
                    pcall(ADFieldJobs.notify, string.format("Flow '%s': bygning findes ikke længere — stoppet, traktorer kørt hjem", tostring(run.name)), true)
                end
            end
        end
    end
end

-- Én gang efter indlæsning: et stoppet flows traktor der holder stille med sin vogn (gemt midt i hjemturen — AD
-- kørte den færdig, men afkoblingen er glemt) køres hjem. Ikke løbende: spilleren kan selv have koblet på.
ADFlowWagons.AFTER_LOAD_MS = 120000
local sinceLoad, cleanedUp = 0, false

-- Efter indlæsning: traktorer uden for flows med et puljeredskab på (hentet før gemning, opgaven tabt) følges som
-- forældreløse — får de ingen opgave inden ORPHAN_MS, sættes redskabet tilbage (in-game 29/9: 3 læssevogne).
local function adoptOrphansAfterLoad(adEnv)
    for _, vehicle in ipairs(ADRunsController.getFarmVehicles(adEnv)) do
        local run = ADRunsController.getRunForVehicle(vehicle)
        if (run == nil or run.stopped) and vehicle.spec_attacherJoints ~= nil and #ADHitch.poolParkIds(adEnv, vehicle) > 0
            and not ADFlowWagons.isEmptying(vehicle) and not homing[vehicle] then
            orphans[vehicle] = orphans[vehicle] or 0
        end
    end
end

local function cleanupAfterLoad(adEnv)
    for _, run in ipairs(runs()) do
        if run.stopped then
            for _, vehicleId in ipairs(run.vehicleIds or {}) do
                local vehicle = ADRunsController.findVehicleById(adEnv, vehicleId)
                local module = vehicle ~= nil and vehicle.ad ~= nil and vehicle.ad.stateModule or nil
                local controlled = vehicle ~= nil and vehicle.getIsControlled ~= nil and vehicle:getIsControlled()
                if module ~= nil and not module:isActive() and not controlled and #ADHitch.poolParkIds(adEnv, vehicle) > 0
                    and not ADFlowWagons.isPoolBusy(vehicle, vehicleId) then
                    Logging.info(ADFlowWagons.LOG_PREFIX .. "flow '%s' er stoppet: '%s' tømmer og sætter sin vogn på plads", tostring(run.name),
                        tostring(ADRuns.vehicleLabel(vehicle)))
                    pcall(ADFlowWagons.homeVehicle, adEnv, vehicle, run.name, "afterLoad")
                end
            end
        end
    end
end

local emptyTimer = 0

function ADFlowWagons.tick(adEnv, dt)
    if adEnv == nil or ADRunsController.store == nil then return end
    if ADHitch ~= nil and ADHitch.onManualAttach == nil then ADHitch.onManualAttach = ADFlowWagons.onManualAttach end
    nowMs = nowMs + dt
    emptyTimer = emptyTimer + dt
    if emptyTimer >= 2000 then
        emptyTimer = 0
        local okOrphan, errOrphan = pcall(tickOrphans, adEnv, 2000)
        if not okOrphan then Logging.warning(ADFlowWagons.LOG_PREFIX .. "redskaber uden opgave: %s", tostring(errOrphan)) end
        local okEmpty, errEmpty = pcall(tickEmptying, adEnv)
        if not okEmpty then Logging.warning(ADFlowWagons.LOG_PREFIX .. "tømning: %s", tostring(errEmpty)) end
    end
    if not cleanedUp then
        sinceLoad = sinceLoad + dt
        if sinceLoad >= ADFlowWagons.AFTER_LOAD_MS then
            cleanedUp = true
            local ok, err = pcall(cleanupAfterLoad, adEnv)
            if not ok then Logging.warning(ADFlowWagons.LOG_PREFIX .. "oprydning efter indlæsning: %s", tostring(err)) end
            local okAdopt, errAdopt = pcall(adoptOrphansAfterLoad, adEnv)
            if not okAdopt then Logging.warning(ADFlowWagons.LOG_PREFIX .. "redskaber uden opgave efter indlæsning: %s", tostring(errAdopt)) end
            local okPrune, errPrune = pcall(ADRunsController.pruneMissingVehicles, adEnv)
            if not okPrune then Logging.warning(ADFlowWagons.LOG_PREFIX .. "oprydning af solgte traktorer: %s", tostring(errPrune)) end
        end
    end
    rememberTimer = rememberTimer + dt
    buildingTimer = buildingTimer + dt
    if rememberTimer >= ADFlowWagons.REMEMBER_MS then
        rememberTimer = 0
        rememberAll(adEnv)
        retryWaiting(adEnv)
    end
    if buildingTimer >= ADFlowWagons.BUILDING_CHECK_MS then
        buildingTimer = 0
        checkBuildings(adEnv)
    end
end