-- PROTOTYPE (tickets "Probe vehicle data and native passing in game", "Can rebuilding a road segment move a passer
-- past its blocker?"): throwaway, lives only on branch prototype/vehicle-probe.
-- Every INTERVAL it dumps every player-owned road vehicle and groups them by street segment.
-- EXPERIMENT: when a player vehicle is within MAX_GAP behind another in the same lane of a two-way segment,
-- rebuild that segment (remove + re-add an identical BaseEdge) and log where both vehicles end up.
-- ponytail: module-local timer, not GameScriptState; fine for a probe (state resets between calls anyway).

local TAG = "[overtake_probe] "
local INTERVAL = 2.0
local MAX_GAP = 40.0
local MAX_REBUILDS = 0 -- off while testing the GUI-thread position flip (replaceSegment works, see vehicle-probe.md)
local MAX_SETLINES = 0 -- set-line disabled: lanes ahead get re-planned by the engine anyway, no forced lane change
local MAX_JUMPS = 0 -- dead: sendCommand(makeComponentExchangeCmd(...)) fails in engine state even without a callback
local JUMP_AHEAD = 15.0
local WATCH_TICKS = 150 -- ~30 s of game time at dt=0.2: log watched vehicles every update after a rebuild
local elapsed = 0.0
local ticks = 0

local function p(s : string)
	print(TAG .. s)
end

local function edgeAt(mp : Engine.Component.MovePath) : EdgeId, boolean
	-- path.edges is 1-based, elements are EdgeIdDir userdata (tealdef says {EdgeId, boolean})
	local e = (mp.path.edges as {any})[mp.dyn.pathPos.edgeIndex + 1] as UtilPathfinding.EdgeIdDir
	if e == nil then return nil, nil end
	return e.edgeId, e.dir
end

local function turnaround(edge : EdgeId) : integer
	local tn = api.engine.getComponent(edge.entity, api.type.ComponentType.TRANSPORT_NETWORK) as Engine.Component.TransportNetwork
	if tn == nil or tn.turnaroundEdges == nil then return nil end
	return tn.turnaroundEdges[edge.index + 1]
end

local record Car
	v : integer
	pos : number
	pos01 : number
	speed : number
	dir : boolean
end

local record ProbeState
	rebuilds : integer
	setlines : integer
	jumps : integer
	watch : {integer} -- vehicles involved in the last rebuild, flagged in later dumps
	watchLeft : integer -- updates left for per-tick logging of the watched vehicles
end

-- No edge objects (stops, signals),
-- because re-adding them is out of scope for this probe.
local function rebuildable(seg : integer) : boolean, string
	local be = api.engine.getComponent(seg, api.type.ComponentType.BASE_EDGE) as Engine.Component.BaseEdge
	if be == nil then return false, "no BaseEdge" end
	if #be.objects > 0 then return false, "has edge objects" end
	-- count BaseEdge lanes, not TransportNetwork edges (town roads split each lane into several edges).
	-- Sidewalks carry modes 0/1 only; driving lanes carry 2+ (observed: [2,3,4]).
	local driving = 0
	for _, lc in ipairs(be.laneConfigs) do
		for k, on in pairs(lc.transportModes) do
			if on and (tonumber(tostring(k)) or 0) >= 2 then driving = driving + 1 break end
		end
	end
	-- one lane per direction: 3 rebuilds there changed nothing (same gap, same lane), so trace multilane only
	if driving < 4 then return false, "driving lanes=" .. driving .. " (single-lane rebuilds showed no effect)" end
	return true, string.format("drivingLanes=%d template=%s length=%.1f", driving, tostring(be.roadTemplate), be.distance)
end

local function rebuild(seg : integer)
	-- same call the official campaign (mission 03 init.script.tl) uses to refresh a road segment in place
	local proposal = api.engine.util.proposal.replaceSegment(seg)
	api.cmd.sendCommand(api.cmd.makeWorldBuildProposalCmd(proposal, nil, true, true))
end

-- lanes of the next few path edges, to see whether a re-path changes the lane choice
local function lanesAhead(mp : Engine.Component.MovePath) : string
	local out : {string} = {}
	local edges = mp.path.edges as {any}
	for k = mp.dyn.pathPos.edgeIndex + 1, math.min(#edges, mp.dyn.pathPos.edgeIndex + 4) do
		local e = edges[k] as UtilPathfinding.EdgeIdDir
		table.insert(out, e.edgeId.entity .. ":" .. e.edgeId.index)
	end
	return table.concat(out, " ")
end

local function setLine(v : integer)
	local tv = api.engine.getComponent(v, api.type.ComponentType.TRANSPORT_VEHICLE) as Engine.Component.TransportVehicle
	p(string.format("SETLINE_TEST send veh=%d line=%s stopIndex=%s", v, tostring(tv.line), tostring(tv.stopIndex)))
	api.cmd.sendCommand(api.cmd.makeVehicleSetLineCmd(v, tv.line, tv.stopIndex))
end

-- returns false when the target doesn't fit on the current edge (we don't jump across edges)
local function jumpPast(follower : Car, leader : Car) : boolean, string
	if leader.pos01 <= 0 then return false, "leader pos01=0" end
	local len = leader.pos / leader.pos01
	local target = leader.pos + JUMP_AHEAD
	if target >= len then return false, string.format("target %.1f beyond edge length %.1f", target, len) end
	local mp = api.engine.getComponent(follower.v, api.type.ComponentType.MOVE_PATH) as Engine.Component.MovePath
	mp.dyn.pathPos.pos = target
	mp.dyn.pathPos.pos01 = target / len
	api.cmd.sendCommand(api.cmd.debug.makeComponentExchangeCmd(follower.v, mp as Engine.Component))
	return true, string.format("pos %.1f -> %.1f (leader %.1f, edge length %.1f)", follower.pos, target, leader.pos, len)
end

local function dump(dt : number, state : GameScriptState<ProbeState>)
	local st = state:get()
	st.rebuilds = st.rebuilds or 0
	st.setlines = st.setlines or 0
	st.jumps = st.jumps or 0
	st.watch = st.watch or {}
	local watched : {integer : boolean} = {}
	for _, w in ipairs(st.watch) do watched[w] = true end

	local player = api.engine.util.getPlayer()
	local vehicles = api.engine.getEntitiesWithComponent(api.type.ComponentType.TRANSPORT_VEHICLE, { requireOwnedByPlayer = player })
	p(string.format("tick=%d dt=%s playerVehicles=%d rebuilds=%d setlines=%d jumps=%d", ticks, tostring(dt), #vehicles, st.rebuilds, st.setlines, st.jumps))

	local byLane : {string : {Car}} = {}
	local laneSeg : {string : integer} = {}
	for _, v in ipairs(vehicles) do
		local lv = api.engine.getComponent(v, api.type.ComponentType.LAND_VEHICLE) as Engine.Component.LandVehicle
		local mp = api.engine.getComponent(v, api.type.ComponentType.MOVE_PATH) as Engine.Component.MovePath
		local tv = api.engine.getComponent(v, api.type.ComponentType.TRANSPORT_VEHICLE) as Engine.Component.TransportVehicle
		if lv ~= nil and not lv.isTram and mp ~= nil then
			local edge, dir = edgeAt(mp)
			local seg = edge and edge.entity or -1
			p(string.format(
				"%sveh=%d seg=%d lane=%s dir=%s turnaround=%s edgeIndex=%d/%d pos=%.1f speed=%.2f state=%s tvState=%s line=%s standing=%.1f",
				watched[v] and "WATCH " or "", v, seg, tostring(edge and edge.index), tostring(dir), tostring(edge and turnaround(edge)),
				mp.dyn.pathPos.edgeIndex, #(mp.path.edges as {any}), mp.dyn.pathPos.pos, mp.dyn.speed, tostring(mp.state),
				tostring(tv and tv.state), tostring(tv and tv.line), mp.dyn.timeStanding))
			if watched[v] then p("WATCH   lanesAhead veh=" .. v .. " " .. lanesAhead(mp)) end
			if edge ~= nil then
				local key = seg .. ":" .. edge.index
				byLane[key] = byLane[key] or {}
				laneSeg[key] = seg
				table.insert(byLane[key], { v = v, pos = mp.dyn.pathPos.pos, pos01 = mp.dyn.pathPos.pos01, speed = mp.dyn.speed, dir = dir })
			end
		end
	end

	if st.rebuilds >= MAX_REBUILDS and st.setlines >= MAX_SETLINES and st.jumps >= MAX_JUMPS then return end
	for key, cars in pairs(byLane) do
		for i = 1, #cars do
			for j = 1, #cars do
				local a, b = cars[i], cars[j]
				-- ponytail: assumes pos grows in driving direction when dir=true (held so far in the logs)
				local ahead = (a.dir and b.pos > a.pos) or (not a.dir and b.pos < a.pos)
				-- leader must be moving, otherwise it's a queue at a stop or junction, not a slow vehicle
				if i ~= j and ahead and math.abs(b.pos - a.pos) < MAX_GAP and b.speed > 1.0 then
					local seg = laneSeg[key]
					if st.jumps < MAX_JUMPS then
						local ok, why = jumpPast(a, b)
						p(string.format("JUMP_TEST seg=%d follower=%d leader=%d sent=%s %s", seg, a.v, b.v, tostring(ok), why))
						if ok then
							st.jumps = st.jumps + 1
							st.watch = { a.v, b.v }
							state:set(st)
							return -- one experiment per dump
						end
					end
					if st.setlines < MAX_SETLINES then
						local amp = api.engine.getComponent(a.v, api.type.ComponentType.MOVE_PATH) as Engine.Component.MovePath
						p(string.format("SETLINE_TEST candidate seg=%d follower=%d (v=%.2f) leader=%d (v=%.2f) lanesAhead before: %s",
							seg, a.v, a.speed, b.v, b.speed, lanesAhead(amp)))
						setLine(a.v)
						st.setlines = st.setlines + 1
						st.watch = { a.v, b.v }
						state:set(st)
						return -- one experiment per dump
					end
					if st.rebuilds >= MAX_REBUILDS then return end
					local ok, why = rebuildable(seg)
					p(string.format("REBUILD_TEST candidate seg=%d follower=%d (pos=%.1f v=%.2f) leader=%d (pos=%.1f v=%.2f) ok=%s %s",
						seg, a.v, a.pos, a.speed, b.v, b.pos, b.speed, tostring(ok), why))
					if ok then
						rebuild(seg)
						st.rebuilds = st.rebuilds + 1
						st.watch = { a.v, b.v }
						st.watchLeft = WATCH_TICKS
						state:set(st)
						p(string.format("REBUILD_TEST sent #%d seg=%d", st.rebuilds, seg))
						return -- one rebuild per dump
					end
				end
			end
		end
	end
end

-- per-update trace of the watched vehicles, to catch the moment a lane changes
local function trace(state : GameScriptState<ProbeState>)
	local st = state:get()
	if (st.watchLeft or 0) <= 0 or st.watch == nil then return end
	for _, v in ipairs(st.watch) do
		local mp = api.engine.getComponent(v, api.type.ComponentType.MOVE_PATH) as Engine.Component.MovePath
		if mp ~= nil then
			local edge, _dir = edgeAt(mp)
			p(string.format("TRACE t=%d veh=%d seg=%s lane=%s pos=%.1f v=%.2f ahead=%s",
				WATCH_TICKS - st.watchLeft, v, tostring(edge and edge.entity), tostring(edge and edge.index),
				mp.dyn.pathPos.pos, mp.dyn.speed, lanesAhead(mp)))
		end
	end
	st.watchLeft = st.watchLeft - 1
	state:set(st)
end

-- EXPERIMENT (GUI thread, where sendCommand callbacks work): flip the positions of a follower and its leader by
-- exchanging their MovePath components (route + position) with api.cmd.debug.makeComponentExchangeCmd.
local MAX_FLIPS = 2
local FLIP_SCAN_FRAMES = 60 -- scan for a pair about once per second
local FLIP_TRACE_FRAMES = 600 -- then log both vehicles every 10 frames for ~10 s

local record GuiState
	frames : integer
	flips : integer
	traceLeft : integer
	a : integer
	b : integer
end

local function movePathOf(v : integer) : Engine.Component.MovePath
	return api.engine.getComponent(v, api.type.ComponentType.MOVE_PATH) as Engine.Component.MovePath
end

local function flipLine(v : integer) : string
	local mp = movePathOf(v)
	if mp == nil then return "veh=" .. v .. " no MovePath" end
	local edge, _dir = edgeAt(mp)
	return string.format("veh=%d seg=%s lane=%s pos=%.1f v=%.2f", v, tostring(edge and edge.entity), tostring(edge and edge.index), mp.dyn.pathPos.pos, mp.dyn.speed)
end

local function sendFlip(gs : GuiState, follower : integer, leader : integer)
	local mpF, mpL = movePathOf(follower), movePathOf(leader)
	p("FLIP_TEST before " .. flipLine(follower) .. " | " .. flipLine(leader))
	local function done(label : string) : function(any, boolean)
		return function(res : any, success : boolean)
			p(string.format("FLIP_TEST result %s success=%s res=%s", label, tostring(success), tostring(res)))
		end
	end
	api.cmd.sendCommand(api.cmd.debug.makeComponentExchangeCmd(follower, mpL as Engine.Component), done("follower<-leader"))
	api.cmd.sendCommand(api.cmd.debug.makeComponentExchangeCmd(leader, mpF as Engine.Component), done("leader<-follower"))
	gs.flips = gs.flips + 1
	gs.traceLeft = FLIP_TRACE_FRAMES
	gs.a, gs.b = follower, leader
end

-- same pair rule as the engine-side probe: same segment + lane, follower < MAX_GAP behind a moving leader
local function findPair() : integer, integer
	local player = api.engine.util.getPlayer()
	local byLane : {string : {Car}} = {}
	for _, v in ipairs(api.engine.getEntitiesWithComponent(api.type.ComponentType.TRANSPORT_VEHICLE, { requireOwnedByPlayer = player })) do
		local lv = api.engine.getComponent(v, api.type.ComponentType.LAND_VEHICLE) as Engine.Component.LandVehicle
		local mp = movePathOf(v)
		if lv ~= nil and not lv.isTram and mp ~= nil then
			local edge, dir = edgeAt(mp)
			if edge ~= nil then
				local key = edge.entity .. ":" .. edge.index
				byLane[key] = byLane[key] or {}
				table.insert(byLane[key], { v = v, pos = mp.dyn.pathPos.pos, pos01 = mp.dyn.pathPos.pos01, speed = mp.dyn.speed, dir = dir })
			end
		end
	end
	for _, cars in pairs(byLane) do
		for i = 1, #cars do
			for j = 1, #cars do
				local a, b = cars[i], cars[j]
				local ahead = (a.dir and b.pos > a.pos) or (not a.dir and b.pos < a.pos)
				if i ~= j and ahead and math.abs(b.pos - a.pos) < MAX_GAP and b.speed > 1.0 then
					return a.v, b.v
				end
			end
		end
	end
	return nil, nil
end

local function guiStep(gsState : GameScriptState<GuiState>)
	local gs = gsState:get()
	gs.frames = (gs.frames or 0) + 1
	gs.flips = gs.flips or 0
	gs.traceLeft = gs.traceLeft or 0
	if gs.traceLeft > 0 then
		if gs.traceLeft % 10 == 0 then
			p(string.format("FLIP_TRACE f=%d %s | %s", FLIP_TRACE_FRAMES - gs.traceLeft, flipLine(gs.a), flipLine(gs.b)))
		end
		gs.traceLeft = gs.traceLeft - 1
	elseif gs.flips < MAX_FLIPS and gs.frames % FLIP_SCAN_FRAMES == 0 then
		local follower, leader = findPair()
		if follower ~= nil then sendFlip(gs, follower, leader) end
	end
	gsState:set(gs)
end

local ret : GameScriptWithGui<ProbeState, GuiState> = {
	update = function(_userParams : table, state : GameScriptState<ProbeState>, dt : number) : nil
		ticks = ticks + 1
		elapsed = elapsed + dt
		if dt > 0 then xpcall(trace, function(err : any) p("ERROR trace " .. tostring(err)) end, state) end
		if ticks == 1 then p("update running, first dt=" .. tostring(dt)) end
		if elapsed < INTERVAL then return end
		elapsed = 0.0
		xpcall(dump, function(err : any) p("ERROR " .. tostring(err)) end, dt, state)
	end,
	guiUpdate = function(_userParams : table, _state : GameScriptStateReadOnly<ProbeState>, guiState : GameScriptState<GuiState>)
		xpcall(guiStep, function(err : any) p("ERROR gui " .. tostring(err)) end, guiState)
	end,
}

return ret