class_name Instance
extends RefCounted
## One live world on the server: the shared lobby hub, or one dungeon run for a
## party. Instances are cheap -- a [SimWorld] and a peer list -- so a single
## server process hosts the hub plus every concurrent dungeon.

enum State {
	## Dungeon is open for players to join from the hub.
	FORMING,
	## Fight in progress.
	ACTIVE,
	## Boss dead; players are being returned to the hub.
	CLEARED,
}

var id: int = 0
var kind: Protocol.InstanceKind = Protocol.InstanceKind.LOBBY
var world: SimWorld
var peers: Array[int] = []
var state: State = State.ACTIVE
var age: int = 0
var seed_value: int = 0
## Drives dungeon size and difficulty. The hub is always depth 0.
var depth: int = 0
## Which kind of run this is -- see [Dungeons]. Empty for the hub.
var dungeon_id: StringName = &""

## Dungeon progression. -1 is the pre-fight breather.
var stage: int = -1
var stage_delay: int = 0
var boss_id: StringName = &""
## Generated layout, used to place enemies room by room.
var rooms: Array[Rect2i] = []
## The rectangle each tunnel leg was carved over -- see MapGen. Overlaps the
## rooms at its ends, so _tunnel_tiles() decides what is actually tunnel.
var tunnels: Array[Rect2i] = []
var boss_spawn := Vector2.ZERO
var boss_room := Rect2i()


## Chance that any one tunnel leg has a group of enemies in it. Rolled per leg,
## and most legs are too short or too near the entrance to qualify anyway, so a
## depth-1 dungeon has a tunnel group about one run in three. Rare on purpose:
## tunnels are where you go between fights, and a tunnel that is usually empty
## is what makes the one that is not a surprise.
const TUNNEL_GROUP_CHANCE := 0.1
const TUNNEL_GROUP_MIN := 2
const TUNNEL_GROUP_MAX := 3
## Members stand within this many tiles of the group's centre, so a group reads
## as one encounter rather than a tunnel's worth of strays.
const TUNNEL_GROUP_SPREAD := 2


static func make_lobby(instance_id: int) -> Instance:
	var inst := Instance.new()
	inst.id = instance_id
	inst.kind = Protocol.InstanceKind.LOBBY
	inst.seed_value = 1
	inst.world = SimWorld.new(inst.seed_value)
	var built := MapGen.build(Protocol.InstanceKind.LOBBY, inst.seed_value, 0)
	inst.world.set_map(built["grid"])
	inst.world.portals = built["portals"]
	inst.world.upgrade_npc = built["npc"]
	inst.world.has_upgrade_npc = true
	inst.world.spawn_point = built["spawn"]
	# Nothing here to escape from, and completing the channel in the hub means
	# transferring to the hub -- see SimWorld.escape_enabled.
	inst.world.escape_enabled = false
	# The hub is where a run's damage is paid off. Arriving used to heal you to
	# full, which made health free between runs; ten seconds of standing here
	# does the same job at a price.
	inst.world.regen_percent_per_sec = SimConfig.LOBBY_HP_REGEN_PERCENT_PER_SEC
	inst.state = State.ACTIVE
	# A single inert practice target so players can feel out the gun before
	# committing to a run.
	inst.world.spawn_enemy(Content.dummy(), built["dummy"])
	return inst


## [param dungeon] picks the flavour of run. The map, the rooms, the enemies and
## the boss are the same whichever is chosen; only how much health they have and
## how freely they drop differs. See [Dungeons].
static func make_dungeon(instance_id: int, dungeon_seed: int, dungeon_depth: int = 1,
		dungeon: StringName = &"") -> Instance:
	var inst := Instance.new()
	inst.id = instance_id
	inst.kind = Protocol.InstanceKind.DUNGEON
	inst.seed_value = dungeon_seed
	inst.depth = maxi(dungeon_depth, 1)
	inst.dungeon_id = dungeon if not dungeon.is_empty() else Dungeons.default_id()
	inst.world = SimWorld.new(dungeon_seed)
	var flavour := Dungeons.get_or_default(inst.dungeon_id)
	var built := MapGen.build(Protocol.InstanceKind.DUNGEON, dungeon_seed,
		inst.depth, flavour.arena)
	inst.world.set_map(built["grid"])
	inst.rooms = built["rooms"]
	inst.tunnels = built["tunnels"]
	inst.boss_spawn = built["boss_pos"]
	inst.boss_room = built["boss_room"]
	inst.world.spawn_point = built["spawn"]
	# Arriving into a fight already in progress needs a moment of protection;
	# arriving in the hub does not.
	inst.world.spawn_grace_ticks = SimConfig.SPAWN_GRACE_TICKS
	inst.boss_id = built["boss_id"]
	inst.state = State.FORMING
	inst._populate()
	return inst


## Enemies are placed once, per room, at generation -- not spawned in waves.
## A dungeon you explore has to be populated before you arrive in it: waves
## would make the map's contents depend on when you walk in rather than where,
## and aggro range would have nothing left to gate.
func _populate() -> void:
	var rng := RandomNumberGenerator.new()
	rng.seed = seed_value ^ 0x5eed
	var flavour := Dungeons.get_or_default(dungeon_id)
	var boss := world.spawn_boss(flavour.apply_to_boss(Content.boss(boss_id)))
	boss.pos = boss_spawn
	boss.room = _room_rect_world(boss_room)
	GameLog.info("instance", "BOSS_SPAWNED %s in instance %d" % [boss_id, id])
	if GameOpts.boss_rush:
		return  # dev switch: an empty dungeon with just the fight in it
	for i in rooms.size():
		# Room 0 holds the entrance; arriving into a fight you cannot see yet
		# is not a decision, it is an ambush.
		if i == 0:
			continue
		var r: Rect2i = rooms[i]
		var count := rng.randi_range(1, 3 + depth / 2)
		for _n in count:
			var def := flavour.apply_to_enemy(_pick_enemy(rng))
			var tx := rng.randi_range(r.position.x + 1, r.end.x - 2)
			var ty := rng.randi_range(r.position.y + 1, r.end.y - 2)
			var at := world.map.tile_centre(tx, ty)
			if world.map.circle_blocked(at, def.radius):
				continue
			world.spawn_enemy(def, at, rng.randi_range(0, 120))
	# After every room, so adding tunnel groups leaves each room's population
	# exactly what that seed always produced.
	_populate_tunnels(rng, flavour)


## Now and then, a group of enemies in a tunnel.
##
## Never within aggro range of the entrance, by the same reasoning room 0 is
## left empty: arriving into a fight you cannot see yet is not a decision, it
## is an ambush. And never a lone straggler -- if a leg cannot fit at least
## TUNNEL_GROUP_MIN, it gets nobody.
func _populate_tunnels(rng: RandomNumberGenerator, flavour: DungeonDef) -> void:
	var clear_of_spawn := _widest_aggro() + MapGrid.TILE * 2.0
	for leg in tunnels:
		# Every leg rolls the same three numbers whether or not it is used, so
		# one tunnel's dice never depend on another tunnel's shape.
		var roll := rng.randf()
		var pick := rng.randi()
		var size := rng.randi_range(TUNNEL_GROUP_MIN, TUNNEL_GROUP_MAX)
		if roll >= TUNNEL_GROUP_CHANCE:
			continue
		var open := _tunnel_tiles(leg)
		if open.size() < TUNNEL_GROUP_MAX * 2:
			continue
		var centre: Vector2i = open[pick % open.size()]
		var def := flavour.apply_to_enemy(_pick_enemy(rng))
		var spots: Array[Vector2] = []
		for t in open:
			if absi(t.x - centre.x) > TUNNEL_GROUP_SPREAD \
					or absi(t.y - centre.y) > TUNNEL_GROUP_SPREAD:
				continue
			var at := world.map.tile_centre(t.x, t.y)
			# Per member, not per group: members stand up to two tiles off the
			# centre, so a centre that clears the entrance does not mean every
			# member does.
			if at.distance_to(world.spawn_point) < clear_of_spawn:
				continue
			if not world.map.circle_blocked(at, def.radius):
				spots.append(at)
		if spots.size() < TUNNEL_GROUP_MIN:
			continue
		for i in range(spots.size() - 1, 0, -1):
			var j := rng.randi_range(0, i)
			var held := spots[i]
			spots[i] = spots[j]
			spots[j] = held
		for i in mini(size, spots.size()):
			# A fresh definition per member: apply_to_enemy mutates in place,
			# and sharing one object would scale it once per member.
			var member := def if i == 0 else flavour.apply_to_enemy(Content.enemy(def.id))
			world.spawn_enemy(member, spots[i], rng.randi_range(0, 120))


## Floor tiles of [param leg] that are tunnel rather than room: clear of every
## room by a tile, so a group is never standing in a doorway, and outside the
## boss arena.
func _tunnel_tiles(leg: Rect2i) -> Array[Vector2i]:
	var out: Array[Vector2i] = []
	for ty in range(leg.position.y, leg.end.y):
		for tx in range(leg.position.x, leg.end.x):
			if world.map.at(tx, ty) != MapGrid.Kind.FLOOR:
				continue
			var here := Vector2i(tx, ty)
			if boss_room.has_point(here):
				continue
			var in_room := false
			for r in rooms:
				if r.grow(1).has_point(here):
					in_room = true
					break
			if not in_room:
				out.append(here)
	return out


## The furthest any enemy in the game notices a player from.
static func _widest_aggro() -> float:
	var widest := 0.0
	for id in Content.ALL_ENEMIES:
		widest = maxf(widest, Content.enemy(id).aggro_range)
	return widest


func _pick_enemy(rng: RandomNumberGenerator) -> EnemyDef:
	var roll := rng.randf()
	if roll < 0.4:
		return Content.drifter()
	if roll < 0.75:
		return Content.turret()
	return Content.stalker()


## Tile-space room rect to world space, for confining a boss to its arena.
func _room_rect_world(r: Rect2i) -> Rect2:
	if r.size == Vector2i.ZERO:
		return Rect2()
	var lo := world.map.tile_centre(r.position.x + 1, r.position.y + 1)
	var hi := world.map.tile_centre(r.end.x - 2, r.end.y - 2)
	return Rect2(lo, hi - lo)


func add_peer(peer_id: int, display_name: String) -> void:
	if not peers.has(peer_id):
		peers.append(peer_id)
	world.add_player(peer_id, display_name)


func remove_peer(peer_id: int) -> void:
	peers.erase(peer_id)
	world.remove_player(peer_id)


## Drop a peer from the send list but leave its player in the world. Used when a
## connection dies: the body stays behind, still killable, channelling its way
## out (see SimPlayer.linkdead), while we stop trying to send to a dead socket.
func detach_peer(peer_id: int) -> void:
	peers.erase(peer_id)
	var p: SimPlayer = world.players.get(peer_id)
	if p != null:
		p.linkdead = true


## Peers we still talk to. Linkdead bodies are not counted -- an instance whose
## only occupant has dropped should wind down, not wait on a ghost.
func is_empty() -> bool:
	return peers.is_empty()


## True while a dropped player is still resolving its escape channel. Keeps the
## instance alive just long enough for that to finish.
func has_linkdead() -> bool:
	for p in world.players.values():
		if p.linkdead:
			return true
	return false


## Whole seconds until a cleared dungeon returns its party, or
## Protocol.COUNTDOWN_NONE when that does not apply.
func exit_countdown_seconds() -> int:
	if state != State.CLEARED:
		return Protocol.COUNTDOWN_NONE
	return mini(int(ceil(float(stage_delay) / float(SimConfig.TICK_RATE))),
		Protocol.COUNTDOWN_NONE - 1)


## [param dungeon] has to match: walking into the Proving Grounds portal must
## never drop you into a standard run that happens to still be forming, however
## conveniently timed.
func accepts_new_party_member(dungeon: StringName) -> bool:
	return kind == Protocol.InstanceKind.DUNGEON \
		and dungeon_id == dungeon \
		and state == State.FORMING \
		and peers.size() < SimConfig.DUNGEON_PARTY_MAX


func step() -> void:
	age += 1
	world.step()
	if kind == Protocol.InstanceKind.DUNGEON:
		_step_dungeon()


## The dungeon is fully populated at generation, so all that is left to track
## is the party forming and the boss dying.
func _step_dungeon() -> void:
	if stage_delay > 0:
		stage_delay -= 1
		return
	if state == State.CLEARED:
		return

	if state == State.FORMING:
		if age >= SimConfig.DUNGEON_FORMING_TICKS or peers.size() >= SimConfig.DUNGEON_PARTY_MAX:
			state = State.ACTIVE
		return

	if world.boss != null and not world.boss.alive:
		state = State.CLEARED
		stage_delay = SimConfig.DUNGEON_CLEARED_EXIT_TICKS
		GameLog.info("instance", "instance %d CLEARED, returning party in %ds" % [
			id, SimConfig.DUNGEON_CLEARED_EXIT_TICKS / SimConfig.TICK_RATE])


func _live_enemy_count() -> int:
	var n := 0
	for e in world.enemies.values():
		if e.alive:
			n += 1
	return n