class_name BossPhase
extends Resource
## One stage of a boss fight: a looping timeline of emitters, entered when the
## boss drops below [member enter_at_hp_fraction].

@export var name: String = "Phase"
## The phase becomes active once hp/max_hp is at or below this. Phases are
## evaluated in array order, so list them from 1.0 downwards.
@export_range(0.0, 1.0, 0.01) var enter_at_hp_fraction: float = 1.0
## The phase timeline wraps at this many ticks. Emitter [member start_tick] and
## [member end_tick] are relative to the start of each loop.
@export var loop_ticks: int = 600
## Ticks of no fire after entering the phase, so the transition is readable.
@export var telegraph_ticks: int = 45
## Damage taken while in this phase is scaled by this. Use < 1.0 for armoured
## phases rather than adding hit points, so the fight length stays predictable.
@export var damage_taken_mult: float = 1.0
@export var emitters: Array[BulletEmitter] = []

@export_group("Movement")
## How the boss moves during this phase. Movement is a property of the PHASE,
## not of the boss: a fight that stands still and then starts hunting you is
## one boss with two phases, and expressing it any other way would put a
## per-boss branch in the simulation.
@export var move: Move = Move.STATIC
## Units per second. Zero is equivalent to STATIC.
@export var move_speed: float = 0.0
## ORBIT: radius around the arena's centre. CHASE: the distance it tries to
## hold from you -- closing all the way would mean a boss you cannot see past.
@export var move_param: float = 120.0
## WAYPOINTS: points in the arena as fractions of it, so one phase works in any
## room. (0,0) is the top-left corner of the fightable area, (1,1) the bottom
## right.
@export var waypoints: Array[Vector2] = []
## Ticks spent standing at each waypoint before moving on.
@export var waypoint_dwell: int = 60

enum Move {
	## Never moves. Every phase written before bosses could move.
	STATIC,
	## Circles the centre of its arena at [member move_param] radius.
	ORBIT,
	## Closes on the nearest player, holding [member move_param] distance.
	CHASE,
	## Walks a fixed circuit of [member waypoints], pausing at each.
	WAYPOINTS,
}


## Whether this phase actually moves the boss. Derived rather than stored, so a
## phase cannot claim to move and then sit still.
func moves() -> bool:
	return move != Move.STATIC and move_speed > 0.0