class_name NetworkedMatch
extends GameMode

# Phase 2: server-authoritative simulation, dumb client (multiplayer-todo.md
# §7 Phase 2). The server runs the real physics for every ship — via
# RLShipController, fed by each connected player's forwarded input — and
# the ball, and broadcasts NetCodec snapshots at 60Hz. The client renders
# everything, including its own ship, from the interpolation buffer; there
# is no local prediction yet (that's Phase 4), so every body on the client
# is FREEZE_MODE_KINEMATIC and driven entirely by incoming snapshots.
#
# No HUD/Arena child in networked_match.tscn — both are built in code, once
# the arena is actually known (the server picks one; the client learns it
# from match_config), which is why this overrides _ready() completely
# rather than relying on GameMode's default (arena-required-synchronously)
# flow.

signal timer_updated(minutes: int, seconds: int)
signal score_changed(score: Dictionary)
signal match_ended(winning_team: int, score: Dictionary)
signal kickoff_countdown(count: int)
signal overtime_started

const NetCodec = preload("res://scripts/net_codec.gd")
const NetBodyState = preload("res://scripts/net_body_state.gd")
const NetInterpolator = preload("res://scripts/net_interpolator.gd")
const HUD_SCENE = preload("res://scenes/HUD.tscn")

# Minimum plausible interpolation delay even on a same-machine/LAN link —
# §4.6's INTERP_DELAY clamp floor. The full formula (one_way + snapshot
# interval*1.5 + 2.5*jitter_ewma) is simplified here to one_way + interval*1.5
# with no jitter term yet (no jitter EWMA is tracked before Phase 3) — close
# enough for Phase 2's "smooth, not exactly latency-optimal" bar.
const INTERP_DELAY_MIN_MS := 25.0
const INTERP_DELAY_MAX_MS := 200.0
const SNAPSHOT_INTERVAL_MS := 1000.0 / 60.0


class SlotInfo:
	var peer_id: int
	var team: int
	var spawn_index: int
	var ship: Ship
	var controller: RLShipController      # server only
	var interpolator := NetInterpolator.new()   # client only


var _slots: Array[SlotInfo] = []
var _my_slot: SlotInfo = null             # client only
var _ball_interpolator := NetInterpolator.new()   # client only
var _local_input_sampler := PlayerShipController.new()   # client only: reads local input each tick to forward; never added to a Ship, never in the tree — get_action() only touches the global Input singleton
var _input_seq := 0                       # client only
var _reset_gen := 0                       # server only: bumped on every kickoff/goal reset so the client hard-snaps instead of interpolating across the teleport


func _ready() -> void:
	add_to_group("game")
	Engine.max_physics_steps_per_frame = 4
	if kickoff_rng_seed == 0:
		_kickoff_rng.randomize()
	if multiplayer.is_server():
		_start_server()
	else:
		MatchSim.match_config_received.connect(_on_match_config_received)
		MatchSim.snapshot_received.connect(_on_snapshot_received)
		MatchSim.score_update_received.connect(_on_score_update_received)
		_request_match_config_until_received()


# The one-shot server broadcast in _start_server() is racy against however
# long this client's own scene load took to reach this line — it may have
# already fired into a MatchSim with no listener connected yet, or the
# server may not have even started the match yet. Keep asking until
# _on_match_config_received actually populates _slots.
func _request_match_config_until_received() -> void:
	while _slots.is_empty() and is_inside_tree():
		MatchSim.request_match_config()
		await get_tree().create_timer(0.5).timeout


func _owns_goal_logic() -> bool:
	return multiplayer.is_server()


func _owns_world_simulation() -> bool:
	return multiplayer.is_server()


# ============================================================
# Server
# ============================================================

func _start_server() -> void:
	var arena_path := ArenaRegistry.random_path()
	arena = (load(arena_path) as PackedScene).instantiate()
	add_child(arena)
	for goal in arena.get_goals():
		goal.goal_scored.connect(_handle_goal_scored)

	spawn_ball()

	var peer_ids := PackedInt32Array()
	var teams := PackedInt32Array()
	var spawn_indices := PackedInt32Array()
	var team_counts := {0: 0, 1: 0}
	var sorted_peer_ids: Array = MatchNet.roster.keys()
	sorted_peer_ids.sort()
	for peer_id in sorted_peer_ids:
		var info: MatchNet.PlayerInfo = MatchNet.roster[peer_id]
		var spawn_index: int = team_counts.get(info.team, 0)
		team_counts[info.team] = spawn_index + 1
		var slot := SlotInfo.new()
		slot.peer_id = peer_id
		slot.team = info.team
		slot.spawn_index = spawn_index
		slot.controller = RLShipController.new()
		slot.ship = spawn_ship(info.team, spawn_index, slot.controller)
		_slots.append(slot)
		peer_ids.append(peer_id)
		teams.append(info.team)
		spawn_indices.append(spawn_index)

	MatchSim.send_match_config(arena_path, peer_ids, teams, spawn_indices)
	MatchSim.input_received.connect(_on_input_received)


func _on_input_received(peer_id: int, decoded: Dictionary) -> void:
	for slot in _slots:
		if slot.peer_id == peer_id:
			var actions: Array = decoded["actions"]
			# Newest-first; no redundancy handling yet (task 3.x) — just take
			# the newest one every time a packet arrives.
			if not actions.is_empty():
				slot.controller.action = actions[0]
			return


func _on_goal_registered(conceding_team: int) -> void:
	_record_goal(1 - conceding_team)
	MatchSim.send_score_update(score.duplicate())


func _on_goal_scored(_conceding_team: int) -> void:
	_reset_gen = (_reset_gen + 1) % 256
	reset_ball()
	reset_ships()


func _broadcast_snapshot() -> void:
	var server_tick := Engine.get_physics_frames()
	var bodies: Array[NetBodyState] = []
	for slot in _slots:
		if is_instance_valid(slot.ship):
			bodies.append(_ship_to_net_body_state(slot.ship))
	if is_instance_valid(ball):
		bodies.append(_ball_to_net_body_state(ball))
	var segment := NetCodec.pack_snapshot_body_segment(server_tick, 0, _reset_gen, bodies)
	# Per-client header fields (last_input_seq/input_buffer_depth/echo) aren't
	# tracked yet — that's the jitter-buffer work in Phase 3 (tasks 3.1-3.2).
	# Building the shared body segment once and reusing it per peer (rather
	# than re-encoding per client) is the whole reason §2.4 splits the wire
	# format into a per-client header + a shared body segment in the first
	# place — see pack_snapshot_body_segment's own doc comment.
	# "No ship is ever despawned" (§6.4) means _slots outlives a disconnect —
	# a real one will be handled by Phase 5's reconnect/controller-swap
	# logic, but sending an RPC to a peer_id ENet no longer knows about
	# (found via the smoke test: a client that exits mid-match spammed
	# "Attempt to call RPC with unknown peer ID" every tick for the rest of
	# the host's run) throws instead of silently no-op'ing. Guard against it.
	var connected_peers := multiplayer.get_peers()
	for slot in _slots:
		if connected_peers.has(slot.peer_id):
			MatchSim.send_snapshot(slot.peer_id, NetCodec.pack_snapshot(0, 0, 0, segment))


func _ship_to_net_body_state(ship: Ship) -> NetBodyState:
	var s := NetBodyState.new()
	s.position = ship.global_position
	s.rotation = ship.global_transform.basis.get_rotation_quaternion()
	s.linear_velocity = ship.linear_velocity
	s.angular_velocity = ship.angular_velocity
	s.frozen = false
	s.turbo = ship.is_turbo_active()
	# Matches Ship._update_movement_vfx's own read of thrust.z: only positive
	# forward thrust drives the visible flame (see task 2.6).
	s.thrust_z = clampf(maxf(ship.controller.get_action().thrust.z if ship.controller else 0.0, 0.0), 0.0, 1.0)
	s.avel_range = NetCodec.SHIP_AVEL_RANGE
	return s


func _ball_to_net_body_state(b: RigidBody3D) -> NetBodyState:
	var s := NetBodyState.new()
	s.position = b.global_position
	s.rotation = b.global_transform.basis.get_rotation_quaternion()
	s.linear_velocity = b.linear_velocity
	s.angular_velocity = b.angular_velocity
	s.avel_range = NetCodec.BALL_AVEL_RANGE
	return s


# ============================================================
# Client
# ============================================================

func _on_match_config_received(arena_path: String, peer_ids: PackedInt32Array, teams: PackedInt32Array, spawn_indices: PackedInt32Array) -> void:
	if not _slots.is_empty():
		# Not idempotent by accident: the original broadcast from
		# _start_server() and a reply to this client's own
		# request_match_config() (see _request_match_config_until_received)
		# can both legitimately arrive — the retry loop exists specifically
		# because either one alone isn't reliably delivered, so seeing both
		# is expected, not a protocol error. Processing this twice would
		# double-spawn the whole match (found via the two-process smoke
		# test: two arenas, two ships, two HUDs, _slots.size() == 2 instead
		# of 1). Once is enough.
		return
	var known := false
	for a in ArenaRegistry.ARENAS:
		if a["path"] == arena_path:
			known = true
			break
	if not known:
		push_error("NetworkedMatch: server sent unknown arena path '%s', refusing match_config" % arena_path)
		return

	arena = (load(arena_path) as PackedScene).instantiate()
	add_child(arena)
	# _owns_goal_logic() is false here, so GameMode's usual goal-signal wiring
	# never happens — a client's local (interpolated, laggy) Goal sensor must
	# never be allowed to decide a score, only the server's real one can.

	spawn_ball()
	ball.freeze = true
	ball.freeze_mode = RigidBody3D.FREEZE_MODE_KINEMATIC

	var my_id := multiplayer.get_unique_id()
	for i in peer_ids.size():
		var slot := SlotInfo.new()
		slot.peer_id = peer_ids[i]
		slot.team = teams[i]
		slot.spawn_index = spawn_indices[i]
		slot.ship = spawn_ship(slot.team, slot.spawn_index, null)
		slot.ship.freeze = true
		slot.ship.freeze_mode = RigidBody3D.FREEZE_MODE_KINEMATIC
		# §4.6: manual, per-render-frame $Visual updates must not fight
		# Godot's own built-in physics interpolation.
		if is_instance_valid(slot.ship.visual):
			slot.ship.visual.physics_interpolation_mode = Node.PHYSICS_INTERPOLATION_MODE_OFF
		_slots.append(slot)
		if slot.peer_id == my_id:
			_my_slot = slot

	_spawn_hud()
	if is_instance_valid(_my_slot) and is_instance_valid(_my_slot.ship):
		spawn_camera_rig(_my_slot.ship)


func _spawn_hud() -> void:
	hud = HUD_SCENE.instantiate()
	add_child(hud)


func _send_local_input() -> void:
	if _slots.is_empty():
		return   # match_config hasn't arrived yet
	var action := _local_input_sampler.get_action().copy()
	_input_seq += 1
	var bytes := NetCodec.pack_input(_input_seq, 0, Time.get_ticks_msec(), [action])
	MatchSim.send_input(bytes)


func _on_snapshot_received(decoded: Dictionary) -> void:
	var server_tick: int = decoded["server_tick"]
	var reset_gen: int = decoded["reset_gen"]
	var bodies: Array = decoded["bodies"]
	for i in _slots.size():
		if i < bodies.size():
			_slots[i].interpolator.add_sample(server_tick, bodies[i], reset_gen)
	if bodies.size() > _slots.size():
		_ball_interpolator.add_sample(server_tick, bodies[_slots.size()], reset_gen)


func _current_interp_delay_ms() -> float:
	var rtt := NetworkManager.rtt_ms
	var one_way := (rtt / 2.0) if rtt >= 0.0 else INTERP_DELAY_MIN_MS
	return clampf(one_way + SNAPSHOT_INTERVAL_MS * 1.5, INTERP_DELAY_MIN_MS, INTERP_DELAY_MAX_MS)


# Collider time: present-time estimate, applied once per physics tick.
func _physics_process(_delta: float) -> void:
	# Automatic multiplayer polling is disabled project-wide (task 1.3) —
	# every scene that sends/receives RPCs has to poll manually, and this
	# one is no exception. Missing this meant NOTHING sent after entering
	# this scene ever actually reached the wire in either direction
	# (queued but never flushed) — found via the two-process smoke test,
	# not by inspection.
	NetworkManager.poll()
	if _owns_world_simulation():
		_respawn_escaped_bodies()
	if multiplayer.is_server():
		_broadcast_snapshot()
		return

	_send_local_input()
	var server_time_est := NetworkManager.get_server_time_estimate_ms()
	var collider_tick := NetInterpolator.to_tick(server_time_est)
	for slot in _slots:
		if is_instance_valid(slot.ship) and slot.interpolator.has_samples():
			_apply_collider_state(slot.ship, slot.interpolator.sample_at(collider_tick))
	if is_instance_valid(ball) and _ball_interpolator.has_samples():
		_apply_collider_state(ball, _ball_interpolator.sample_at(collider_tick))


# Visual time: present-minus-INTERP_DELAY, applied once per rendered frame —
# separate from the collider update above so a high-refresh client samples
# remote motion at true render rate instead of repeating the same 60Hz value
# several times in a row (§2.4's "240 distinct positions/s, not 60").
#
# Ball only gets the VFX half of this (trail speed), not a transform write:
# unlike Ship, Ball has no separate $Visual child to offset from its
# collider (task 0.2's Visual-node split was scoped to Ship only) — giving
# it one is a bigger structural change than Phase 2's remit, so for now the
# ball's rendered position is whatever _physics_process's present-time
# collider update leaves it at, one tick behind true dual-time smoothness.
func _process(_delta: float) -> void:
	# §7 task 1.3: poll for receive unconditionally at the top of both
	# _process and _physics_process, not just physics — a snapshot that
	# lands between ticks can be rendered immediately at high refresh rates
	# instead of waiting for the next physics step.
	NetworkManager.poll()
	if multiplayer.is_server() or _slots.is_empty():
		return
	var server_time_est := NetworkManager.get_server_time_estimate_ms()
	var visual_tick := NetInterpolator.to_tick(server_time_est - _current_interp_delay_ms())
	for slot in _slots:
		if is_instance_valid(slot.ship) and slot.interpolator.has_samples():
			_apply_ship_visual_state(slot.ship, slot.interpolator.sample_at(visual_tick))
	if is_instance_valid(ball) and _ball_interpolator.has_samples():
		var state := _ball_interpolator.sample_at(visual_tick)
		if state != null:
			(ball as Ball).set_visual_speed(state.linear_velocity.length())


func _apply_collider_state(body: RigidBody3D, state: NetBodyState) -> void:
	if state == null:
		return
	body.global_transform = Transform3D(Basis(state.rotation), state.position)


func _apply_ship_visual_state(ship: Ship, state: NetBodyState) -> void:
	if state == null:
		return
	if is_instance_valid(ship.visual):
		ship.visual.global_transform = Transform3D(Basis(state.rotation), state.position)
	ship.set_visual_action(state.thrust_z, state.turbo)


func _on_score_update_received(new_score: Dictionary) -> void:
	score = new_score.duplicate()
	score_changed.emit(score.duplicate())