local failures = 0

local function expect(condition, message)
    if not condition then
        failures = failures + 1
        io.stderr:write("FAIL: " .. message .. "\n")
    end
end

package.path = table.concat({
    "42.20/media/lua/client/?.lua",
    "42.20/media/lua/shared/?.lua",
    package.path
}, ";")

isServer = function() return false end
isClient = function() return true end

local serverCommandCallbacks = {}
local enterVehicleCallbacks = {}
local spawnVehicleCallbacks = {}
local tickCallbacks = {}
Events = {
    OnServerCommand = {
        Add = function(callback)
            serverCommandCallbacks[#serverCommandCallbacks + 1] = callback
        end
    },
    OnEnterVehicle = {
        Add = function(callback)
            enterVehicleCallbacks[#enterVehicleCallbacks + 1] = callback
        end
    },
    OnSwitchVehicleSeat = { Add = function() end },
    OnSpawnVehicleEnd = {
        Add = function(callback)
            spawnVehicleCallbacks[#spawnVehicleCallbacks + 1] = callback
        end
    },
    OnTick = {
        Add = function(callback)
            tickCallbacks[#tickCallbacks + 1] = callback
        end
    }
}

local localPlayer = { vehicle = nil }
function localPlayer:getVehicle() return self.vehicle end

local attachmentIds = {
    trailer = true,
    trailerfront = true,
    towbarWreckerHookLow = true,
    towbarWreckerHookMid = true,
    towbarWreckerHookHigh = true
}

local function unlink(vehicleA, vehicleB)
    vehicleA.towing, vehicleA.towedBy = nil, nil
    vehicleB.towing, vehicleB.towedBy = nil, nil
end

local function link(vehicleA, vehicleB)
    vehicleA.towing, vehicleA.towedBy = vehicleB, nil
    vehicleB.towing, vehicleB.towedBy = nil, vehicleA
end

local function newVehicle(id, sqlId)
    local value = {
        id = id,
        sqlId = sqlId,
        modData = {},
        scriptName = "Base.DriverEntry" .. tostring(id),
        mass = 1000,
        brakingForce = 20,
        towing = nil,
        towedBy = nil,
        driver = nil,
        addCalls = 0,
        breakCalls = 0
    }

    local script = {
        getAttachmentById = function(_, attachmentId)
            return attachmentIds[attachmentId] and {} or nil
        end
    }

    function value:getId() return self.id end
    function value:getSqlId() return self.sqlId end
    function value:getModData() return self.modData end
    function value:transmitModData() end
    function value:getScript() return script end
    function value:getScriptName() return self.scriptName end
    function value:setScriptName(scriptName) self.scriptName = scriptName end
    function value:getMass() return self.mass end
    function value:setMass(mass) self.mass = mass end
    function value:getBrakingForce() return self.brakingForce end
    function value:setBrakingForce(force) self.brakingForce = force end
    function value:isParkingBrakeOn() return false end
    function value:setParkingBrakeOn() end
    function value:getParkingBrake() return false end
    function value:setParkingBrake() end
    function value:isHandbrake() return false end
    function value:setHandbrake() end
    function value:getVehicleTowing() return self.towing end
    function value:getVehicleTowedBy() return self.towedBy end
    function value:isDriver(player) return self.driver == player end
    function value:attachmentExist(attachmentId)
        return attachmentIds[attachmentId] == true
    end
    function value:addPointConstraint(_, other)
        self.addCalls = self.addCalls + 1
        link(self, other)
    end
    function value:breakConstraint()
        self.breakCalls = self.breakCalls + 1
        local other = self.towing or self.towedBy
        if other then unlink(self, other) end
    end

    return value
end

local portableTowing = newVehicle(101, 1001)
local portableTowed = newVehicle(102, 1002)
local wrecker = newVehicle(201, 2001)
local wreckerTarget = newVehicle(202, 2002)
local unrelated = newVehicle(301, 3001)
local allVehicles = {
    portableTowing,
    portableTowed,
    wrecker,
    wreckerTarget,
    unrelated
}
local vehiclesById = {}
for _, vehicle in ipairs(allVehicles) do vehiclesById[vehicle:getId()] = vehicle end

getPlayer = function() return localPlayer end
getVehicleById = function(id) return vehiclesById[tonumber(id)] end
getCell = function()
    return { getVehicles = function() return allVehicles end }
end

TowBarMod = {
    Utils = { updateAttachmentsForRigidTow = function() end },
    Hook = {
        applyFreeRollingTowState = function() end,
        setVehiclePostAttach = function() end,
        setVehicleScriptWithTowBarHidden = function(vehicle, scriptName)
            vehicle:setScriptName(scriptName)
            return true
        end,
        cleanupDetachedTowBar = function() end
    },
    Wrecker = {
        getWorldVehicles = function() return allVehicles end,
        getHeightAttachmentId = function(level)
            return ({
                [0] = "towbarWreckerHookLow",
                [1] = "towbarWreckerHookMid",
                [2] = "towbarWreckerHookHigh"
            })[tonumber(level) or 0]
        end
    }
}

-- Model a fully persisted portable pair whose transient sync cache was lost
-- during reload. The exact native relation is deliberately present: entry
-- must replace it with one fresh client-owned rigid constraint.
portableTowing.modData = {
    isTowingByTowBar = true,
    towed = false,
    towBarTowedVehicleId = portableTowed:getId(),
    towBarTowedVehicleSqlId = portableTowed:getSqlId(),
    towBarExpectedAttachment = "trailer"
}
portableTowed.modData = {
    isTowingByTowBar = true,
    towed = true,
    towBarTowingVehicleId = portableTowing:getId(),
    towBarTowingVehicleSqlId = portableTowing:getSqlId(),
    towBarExpectedAttachment = "trailerfront",
    towBarOriginalScriptName = portableTowed:getScriptName()
}
link(portableTowing, portableTowed)

-- Model the equivalent persisted wrecker pair, also without applied-level
-- cache state. Both members carry the reciprocal identity written by the
-- authoritative wrecker attach path.
wrecker.modData = {
    wreckerTowActive = true,
    wreckerTowedVehicleId = wreckerTarget:getId(),
    wreckerTowedVehicleSqlId = wreckerTarget:getSqlId(),
    wreckerTargetAttachment = "trailerfront",
    wreckerHeightLevel = 2
}
wreckerTarget.modData = {
    wreckerTowingVehicleId = wrecker:getId(),
    wreckerTowingVehicleSqlId = wrecker:getSqlId(),
    wreckerOriginalScriptName = wreckerTarget:getScriptName()
}
link(wrecker, wreckerTarget)

dofile("42.20/media/lua/client/TowBar/TowSyncClient.lua")
dofile("42.20/media/lua/client/TowBar/WreckerSyncClient.lua")

expect(next(TowBarMod.Sync.desiredPairs) == nil,
    "portable regression setup must not depend on transient desired-pair sync")
expect(next(TowBarMod.Sync.appliedPairs) == nil,
    "portable regression setup must begin without an applied-pair cache")
expect(next(TowBarMod.WreckerSync.appliedLevels) == nil,
    "wrecker regression setup must begin without an applied-level cache")

local function enterAsDriver(vehicle)
    for _, candidate in ipairs(allVehicles) do candidate.driver = nil end
    vehicle.driver = localPlayer
    localPlayer.vehicle = vehicle
    for i = 1, #enterVehicleCallbacks do
        enterVehicleCallbacks[i](localPlayer)
    end
end

enterAsDriver(portableTowing)
expect(portableTowing.breakCalls == 1 and portableTowing.addCalls == 1,
    "portable driver entry must force exactly one rebuild from persisted modData")
enterAsDriver(portableTowing)
expect(portableTowing.breakCalls == 2 and portableTowing.addCalls == 2,
    "each later portable driver entry must force one new rebuild, not remain cache-idempotent")

enterAsDriver(wrecker)
expect(wrecker.breakCalls == 1 and wrecker.addCalls == 1,
    "wrecker driver entry must force exactly one rebuild from persisted modData")
enterAsDriver(wrecker)
expect(wrecker.breakCalls == 2 and wrecker.addCalls == 2,
    "each later wrecker driver entry must force one new rebuild, not remain cache-idempotent")

local portableCounts = portableTowing.breakCalls + portableTowing.addCalls
local wreckerCounts = wrecker.breakCalls + wrecker.addCalls
enterAsDriver(unrelated)
expect(portableTowing.breakCalls + portableTowing.addCalls == portableCounts
        and wrecker.breakCalls + wrecker.addCalls == wreckerCounts,
    "entering an unrelated vehicle must not rebuild any persisted tow pair")
expect(#tickCallbacks == 0,
    "driver-entry recovery must remain event-driven and must not install a tick retry loop")

if failures > 0 then os.exit(1) end
print("PASS: driver entry force-reattaches persisted portable and wrecker pairs once")