class_name ShipAIController
extends AIController3D

# Training-side bridge between godot_rl_agents and a ship. This is the only
# class that touches plugin types (AIController3D / the Sync node protocol) —
# everything else stays behind the ShipController seam: actions received from
# the trainer are written into an RLShipController, which the ship pulls like
# any other controller.
#
# Action space/layout is owned by ShipActionCodec (get_action_space/
# set_action just delegate to it) — see that file for the per-axis
# MultiDiscrete design and why. ShipAction axes are ship-local (body frame),
# so they need no team mirroring — only observations do (see
# ShipObservations.canon).

# Reward shaping weights. Dense terms accrue per physics tick (60 sim-ticks
# per sim-second); event terms fire once. Exported so tuning needs no code
# edits. Goal rewards are added by TrainingMode, which owns goal events.
@export var ball_touch_reward := 0.4
# Ball touches pay out at most once per this many physics ticks (1 sim-
# second at 60). Run07 lesson: body_entered re-fires on every micro-
# separation, so pinning the ball against a surface farmed ~2 touches/s —
# outearning every other term while the goal rate fell. The cooldown keeps
# touches a stepping-stone signal instead of the objective. Halved again
# after run01-vs-run02 eval (training/eval_history.json) came back 87.5%
# draws: even at 1 touch/s, a full episode's worth of touches could still
# outweigh TrainingMode's goal_reward, so scoring and ending the episode
# early was never worth it. See goal_reward's comment for the other half of
# this fix.
@export var ball_touch_cooldown_ticks := 60
# A touch pays out scaled by how goal-directed it was — full ball_touch_reward
# when the post-touch ball velocity points straight at the attack goal, down
# to this floor when it doesn't (0 = only goal-directed touches pay at all).
# Without this, any contact paid the same regardless of direction, so batting
# the ball anywhere counted the same as an actual shot on goal — reinforcing
# possession, not scoring. The floor keeps a purely defensive touch (e.g.
# clearing a shot away from your own goal) worth something as a stepping
# stone, matching ball_touch_cooldown_ticks's existing "stepping-stone, not
# the objective" framing.
@export_range(0.0, 1.0) var ball_touch_direction_floor := 0.3
@export var velocity_to_ball_weight := 0.02
@export var ball_velocity_to_goal_weight := 0.004
# Per-tick penalty scaled by distance to the ball (full value at the arena's
# far diagonal, 0 on top of the ball). Run04 lesson: with idling worth a flat
# 0, camping in a corner strictly dominated risking the wall/tilt penalties
# to chase the ball — this makes "do nothing far from the ball" the worst
# option instead of the safest. A penalty, not a proximity bonus, so orbiting
# the ball farms nothing.
@export var ball_distance_penalty := 0.002
# Per-tick penalty while pressed against a side wall, end wall, or the
# ceiling — NOT the floor (run03 lesson: taxing floor contact punishes the
# ship's natural low flight and drowns every other signal). At 60 ticks per
# sim-second this is -0.15/s. Halved for run05: the ball lives near walls,
# and the old -0.3/s made the productive region of the pitch aversive
# relative to the (then far weaker) ball-seeking shaping.
@export var wall_contact_penalty := 0.0025
# Per-tick penalty for not being upright, scaled by tilt: 0 when flat, full
# value when inverted. A penalty rather than an upright bonus so a flat, idle
# ship farms nothing. Lowered 4x for curriculum generation 4 (was 0.002,
# -0.12/s): a genuine aerial approach to a high ball requires pitching, and
# the old value quietly opposed the exact behaviour generation 4 is trying
# to teach. Not removed outright — an always-inverted bot still looks bad in
# a shipped game.
@export var tilt_penalty := 0.0005
# Per-tick bonus for own speed: 0 stationary, full value (+0.24/s) at
# max_speed. Run07 lesson: after the kickoff flurry both ships parked next to
# a cornered ball — with every other dense term near zero there, standing
# still was a rest state. Sized well below velocity_to_ball_weight so flying
# fast toward the ball still beats flying fast anywhere else.
@export var speed_reward_weight := 0.004
# Flat per-tick cost (-0.06/s, -1.8 over a full 30s episode) applied
# regardless of position or behaviour. Every other dense term can be farmed
# indefinitely by an episode that never ends in a goal; this one can't — it
# only stops accruing once the episode does, via a goal or the timeout. That
# makes running the clock out strictly worse than scoring as soon as a
# chance appears, instead of a free way to keep collecting dense reward.
@export var time_penalty := 0.001
# Per-tick penalty scaled by height above the floor (0 on the floor, full
# value at the arena's ceiling) — distinct from the locomotion mask, which
# only discards *thrust*-driven vertical/pitch-roll input; a masked ship can
# still be launched airborne by collisions (ball impacts, ship-vs-ship
# knockback, the wall/ceiling surface-pull field), and nothing previously
# penalized time spent up there. Default 0 (off) so ordinary runs are
# unaffected; the floor-lock curriculum stage turns it on.
@export var airborne_penalty := 0.0

# Height above which a touch counts toward air_touch_fraction telemetry
# (see get_info) — not a reward term itself, see set_action/get_info's
# comments on why generation 4 deliberately does not add a standalone
# air-touch reward.
const AIR_TOUCH_HEIGHT := 5.0

# Contact normals with y above this are floor contact (exempt from the wall
# penalty); below it they read as wall (sideways) or ceiling (downward).
# Mirrors ShipObservations.FLOOR_NORMAL_MIN_Y (see that file's comment).
const FLOOR_NORMAL_MIN_Y := 0.7

# Longest possible ship-to-ball separation: the enclosure's interior diagonal.
# Normalizes ball_distance_penalty so its export is the worst-case per-tick cost.
const MAX_BALL_DISTANCE := sqrt(
	(2.0 * ArenaBoundary.INNER_HALF_X) ** 2
	+ (2.0 * ArenaBoundary.INNER_HALF_Z) ** 2
	+ ArenaBoundary.INNER_HEIGHT ** 2
)

var ship: Ship
var rl_controller: RLShipController
var ball: RigidBody3D
var teammates: Array[Ship] = []
var opponents: Array[Ship] = []
var attack_goal_position: Vector3

# Set directly by TrainingMode (_on_goal_scored / the timeout branch in
# _physics_process) at the same time as `done = true`. Deliberately NOT
# cleared in reset(): TrainingMode's _reset_episode() (which calls reset())
# runs synchronously, immediately after done is set, before the Sync node
# ever reads get_info()/get_done() for that terminal tick — clearing it here
# would wipe the value that read needs. Both call sites always overwrite
# (true on goal, false on timeout) rather than toggle, so no reset is needed.
var goal_scored_this_episode := false

# Set only in the timeout branch (TrainingMode._physics_process), never on a
# goal — a goal is a genuine terminal (V(s)=0 is correct there); a timeout
# is an artificial episode boundary the value function should be bootstrapped
# through instead (see get_info). Same "always overwritten by both call
# sites, never cleared in reset()" pattern as goal_scored_this_episode above,
# for the same reason.
var truncated_this_episode := false
var terminal_obs: Array = []

var _ticks_since_ball_touch := 1 << 30  # large so the first touch always pays

# Flight telemetry (see get_info) — leading indicators for whether the
# policy is actually using its vertical/pitch-roll authority, visible from
# the first rollout instead of only in a win-rate number measured a full
# training run later. Accumulated per-tick, reset() zeroes them each episode;
# get_info() reports the running fraction/mean so the *final* tick of an
# episode (the one VecMonitor's info_keywords captures) holds the whole
# episode's aggregate.
const AIRBORNE_ALTITUDE_THRESHOLD := 3.0
var _telemetry_ticks := 0
var _airborne_ticks := 0
var _altitude_sum := 0.0
var _thrust_y_sum := 0.0
var _touches := 0
var _air_touches := 0


# Wire up references after the ship is spawned. `attack_goal` is the goal
# this ship scores into (goal.team == the opposing team's team).
func setup(
	p_ship: Ship, p_rl_controller: RLShipController, p_ball: RigidBody3D,
	p_teammates: Array[Ship], p_opponents: Array[Ship], p_attack_goal_position: Vector3
) -> void:
	ship = p_ship
	rl_controller = p_rl_controller
	ball = p_ball
	teammates = p_teammates
	opponents = p_opponents
	attack_goal_position = p_attack_goal_position
	init(ship)

	# ship.contact_monitor is on unconditionally (see ship.gd) since
	# ShipObservations now reads it for every ship, not just training agents.
	ship.body_entered.connect(_on_ship_body_entered)


func get_obs() -> Dictionary:
	return {"obs": ShipObservations.build(ship, teammates, opponents, ball, attack_goal_position)}


func get_reward() -> float:
	return reward


# Symmetric across both self-play agents. "goal_scored": whether this
# episode ended in a goal at all (not which team) — a clean "goal rate"
# signal distinct from rollout/ep_rew_mean, which mixes this with dense
# shaping (ball chasing/touching); see train.py's GoalRateCallback.
# "truncated"/"terminal_obs": only present on a timeout tick — remapped by
# cosmic_env.py into SB3's expected "TimeLimit.truncated"/
# "terminal_observation" keys so PPO bootstraps V(s) through episode
# timeouts instead of treating every 30s draw as a true terminal state (a
# real, previously-unnoticed bug independent of the action-space work — see
# TRAINING.md). Flight telemetry fields are leading indicators for
# generation 4's core hypothesis (see train.py's FlightTelemetryCallback).
func get_info() -> Dictionary:
	# The four telemetry keys must ALWAYS be present (not just when their
	# denominator is nonzero) — VecMonitor's info_keywords does a bare
	# info[key] lookup on whatever info dict is attached to a completed
	# episode's terminal step (see train.py's VecMonitor(...,
	# info_keywords=(...))) and raises KeyError, crashing the whole training
	# run, if a key is ever missing. 0.0 is a reasonable default for "no
	# touches/no ticks yet" (in practice _telemetry_ticks is >0 by the time
	# any episode ends; _touches often legitimately is 0).
	var info := {"goal_scored": goal_scored_this_episode}
	if truncated_this_episode:
		info["truncated"] = true
		info["terminal_obs"] = terminal_obs
	info["airborne_fraction"] = float(_airborne_ticks) / _telemetry_ticks if _telemetry_ticks > 0 else 0.0
	info["mean_altitude"] = _altitude_sum / _telemetry_ticks if _telemetry_ticks > 0 else 0.0
	info["vertical_thrust_mean"] = _thrust_y_sum / _telemetry_ticks if _telemetry_ticks > 0 else 0.0
	info["air_touch_fraction"] = float(_air_touches) / _touches if _touches > 0 else 0.0
	return info


func get_action_space() -> Dictionary:
	return ShipActionCodec.action_space_dict()


func set_action(action) -> void:
	rl_controller.action = ShipActionCodec.apply_team_frame(
		ShipActionCodec.from_indices(action), ship.team
	)


func reset():
	super()
	_ticks_since_ball_touch = 1 << 30
	_telemetry_ticks = 0
	_airborne_ticks = 0
	_altitude_sum = 0.0
	_thrust_y_sum = 0.0
	_touches = 0
	_air_touches = 0


func _physics_process(delta):
	super(delta)
	if not is_instance_valid(ship) or not is_instance_valid(ball):
		return
	_ticks_since_ball_touch += 1

	# Flat time cost — see time_penalty.
	reward -= time_penalty

	# Dense shaping: own velocity toward the ball
	var to_ball := ball.global_position - ship.global_position
	if to_ball.length_squared() > 0.0001:
		var closing_speed := ship.linear_velocity.dot(to_ball.normalized())
		reward += velocity_to_ball_weight * closing_speed / ship.max_speed

	# Dense penalty: distance to the ball, so idling far away bleeds reward
	# instead of scoring a safe zero (see ball_distance_penalty).
	if ball_distance_penalty > 0.0:
		reward -= ball_distance_penalty * to_ball.length() / MAX_BALL_DISTANCE

	# Dense bonus: own speed, so hovering in place is never a rest state
	# (see speed_reward_weight).
	if speed_reward_weight > 0.0:
		reward += speed_reward_weight * ship.linear_velocity.length() / ship.max_speed

	# Dense shaping: ball velocity toward the goal we attack
	var ball_to_goal := attack_goal_position - ball.global_position
	if ball_to_goal.length_squared() > 0.0001:
		var ball_progress := ball.linear_velocity.dot(ball_to_goal.normalized())
		reward += ball_velocity_to_goal_weight * ball_progress / ShipObservations.BALL_SPEED_SCALE

	# Dense penalty: every tick spent pressed against a wall or the ceiling
	# (contact monitoring is already on for the ball-touch reward). Ships
	# bumping each other, the ball, or the floor is fine. The boundary is one
	# body, so the contact normal tells us which surface: floor contact
	# pushes the ship up (+Y), walls push sideways, the ceiling down.
	if wall_contact_penalty > 0.0 and _wall_or_ceiling_contact():
		reward -= wall_contact_penalty

	# Dense penalty: tilt away from upright (0 flat, max when inverted) —
	# discourages ending up on a side or roof without rewarding idleness.
	if tilt_penalty > 0.0:
		var uprightness: float = ship.global_transform.basis.y.dot(Vector3.UP)
		reward -= tilt_penalty * (1.0 - uprightness) * 0.5

	# Dense penalty: height above the floor (see airborne_penalty). The
	# floor sits at world y = 0 (see training_mode.gd's FIELD_MIN_Y/
	# _escaped bounds); normalized so the worst case is pinned at the
	# ceiling.
	if airborne_penalty > 0.0:
		var height := maxf(ship.global_position.y, 0.0)
		reward -= airborne_penalty * height / ArenaBoundary.INNER_HEIGHT

	# Flight telemetry accumulation (see get_info) — not reward, just
	# observation of what the policy is actually doing this tick.
	_telemetry_ticks += 1
	_altitude_sum += ship.global_position.y
	if ship.global_position.y > AIRBORNE_ALTITUDE_THRESHOLD:
		_airborne_ticks += 1
	_thrust_y_sum += rl_controller.action.thrust.y


func _wall_or_ceiling_contact() -> bool:
	return ShipObservations.contact_normal(ship) != Vector3.ZERO


func _on_ship_body_entered(body: Node) -> void:
	if not body.is_in_group("ball") or _ticks_since_ball_touch < ball_touch_cooldown_ticks:
		return
	# Contact-signal ordering means ball.linear_velocity here already reflects
	# the collision impulse from this touch, not the pre-touch velocity.
	var alignment := 0.0
	var to_goal := attack_goal_position - ball.global_position
	if to_goal.length_squared() > 0.0001 and ball.linear_velocity.length_squared() > 0.0001:
		alignment = clampf(ball.linear_velocity.normalized().dot(to_goal.normalized()), 0.0, 1.0)
	reward += ball_touch_reward * lerpf(ball_touch_direction_floor, 1.0, alignment)
	_ticks_since_ball_touch = 0

	# Telemetry only (see get_info's air_touch_fraction) — not a reward term.
	# Generation 4 deliberately doesn't reward high touches directly (see
	# TRAINING.md's "why no air-touch reward" note); this just measures
	# whether the air-drill state setter is producing genuine aerial
	# contests, so a future decision to add one is data-driven.
	_touches += 1
	if ball.global_position.y > AIR_TOUCH_HEIGHT:
		_air_touches += 1