extends Node
## Persistent run progression across scene changes — which hub/level the player is in.
## The level scene is reloaded for every fight, so this state must outlive scene changes:
## genuinely global run state earns an autoload (`Run`).
##
## Flow: menu Play → start_new_run() → lobby hub → enter a gate → that level → win →
## return_to_lobby() (clearing a level opens its follow-on gates, e.g. clearing the arena
## unlocks the bear). Adding a level is a new LevelDef in the catalog plus a lobby gate.

signal run_started

# Every level loads the same reusable shell (player, camera, HUD, PS1 filter); the shell
# then instances the level's own `level_scene` module into its LevelRoot.
const _SHELL_SCENE := "res://levels/game_shell.tscn"
const _ARENA_LEVEL := preload("res://levels/arena_level.tscn")
const _BEAR_LEVEL := preload("res://levels/bear_level.tscn")
const _LOBBY_LEVEL := preload("res://levels/lobby_level.tscn")

## Debug override — when set, active_level() returns this regardless of run state.
## Set via the console `level` command; cleared on start_new_run().
var debug_level_override: LevelDef = null
## The lobby is the hub the run starts and returns to: a walk-around room whose gates lead
## into the fights. While set, active_level() serves the lobby; cleared once a gate is
## entered (choose_level) and set again on a win (return_to_lobby).
var enter_lobby: bool = false
## Level picked at a lobby gate and being fought now — active_level() serves it while
## enter_lobby is false. Null in the lobby itself.
var lobby_choice: LevelDef = null
## Ids of levels the player has cleared this run (StringName -> true). Drives which lobby
## gates are open: the bear gate stays shut until the arena is beaten.
var cleared: Dictionary = {}
## Run-long bonus health (yellow pips) earned from lobby rewards. Persists across level
## loads — the player reads it on spawn — and is capped so it can't stack past BONUS_HP_CAP.
var bonus_hp: int = 0
const BONUS_HP_CAP: int = 2
## True once start_new_run() has built a run. Lets ensure_run() avoid wiping an active run
## when the shell reloads for each fight.
var _run_active: bool = false

# Level catalog. Every level shares the shell scene; what changes is the level module
# (its geometry + spawners) and the opponent. The arena (matador wave, normal + boss
# flavours) and the bear (a lone boss enemy) live here. Future levels — china shop — slot
# in the same way: a new module + a LevelDef entry.
const _BEAR_SCENE := preload("res://actors/bear/bear.tscn")

var _arena: LevelDef
var _arena_boss: LevelDef
var _bear: LevelDef
var _lobby: LevelDef


func _ready() -> void:
	_arena = _make_level(&"arena", "The Arena", _ARENA_LEVEL)
	_arena_boss = _make_level(&"arena_boss", "Grand Arena", _ARENA_LEVEL)
	_bear = _make_level(&"bear", "Bear's Den", _BEAR_LEVEL)
	_bear.enemy_scene = _BEAR_SCENE
	# The lobby is a fightless hub — no enemy_scene, so no wave spawns and no win/lose.
	_lobby = _make_level(&"lobby", "Lobby", _LOBBY_LEVEL)
	# It's a roomy hub with nothing to fight — pull the camera back so more of it reads.
	_lobby.camera_zoom = 1.6


func _make_level(id: StringName, level_name: String, level_scene: PackedScene) -> LevelDef:
	var l := LevelDef.new()
	l.id = id
	l.display_name = level_name
	l.scene_path = _SHELL_SCENE
	l.level_scene = level_scene
	return l


## The level being served right now: debug override wins, then the lobby hub or the level
## picked at a gate, falling back to the plain arena for a direct scene launch.
func active_level() -> LevelDef:
	if debug_level_override != null:
		return debug_level_override
	if enter_lobby:
		return _lobby
	if lobby_choice != null:
		return lobby_choice
	return _arena


## Return a level by id, or null if unknown. Used by the debug console `level` command.
func get_level(id: StringName) -> LevelDef:
	match id:
		&"arena":      return _arena
		&"arena_boss": return _arena_boss
		&"bear":       return _bear
		&"lobby":      return _lobby
	return null


## All known level ids — shown by `level` in the console.
func level_ids() -> Array[StringName]:
	return [&"arena", &"arena_boss", &"bear", &"lobby"]


## Begin a fresh run: reset progression and open in the lobby hub. Called from the main-menu
## Play button, not from a level scene (which reloads for every fight).
func start_new_run() -> void:
	debug_level_override = null
	# The run opens in the lobby hub; its gates lead into the fights.
	enter_lobby = true
	lobby_choice = null
	cleared = {}
	bonus_hp = 0
	_run_active = true
	run_started.emit()


## Build a run if none is active — a safety net for entering a level directly (e.g. running
## game_shell.tscn straight from the editor) without coming through the menu. Guarded so the
## shell reloading for each fight doesn't wipe the run in progress.
func ensure_run() -> void:
	if not _run_active:
		start_new_run()


## Send the player to the lobby hub instead of a fight — active_level() serves the lobby
## until a gate is entered.
func go_to_lobby() -> void:
	enter_lobby = true
	lobby_choice = null


## Enter the fight behind a lobby gate: active_level() serves it until the player wins and
## returns to the lobby. Ignored for an unknown id.
func choose_level(id: StringName) -> void:
	var l := get_level(id)
	if l == null:
		return
	enter_lobby = false
	lobby_choice = l


## Land back in the lobby after a win, banking the cleared level so its follow-on gates
## open (clearing the arena unlocks the bear gate).
func return_to_lobby() -> void:
	if lobby_choice != null:
		cleared[lobby_choice.id] = true
	go_to_lobby()


## Whether the bear gate should be open — the arena must be cleared first.
func bear_gate_open() -> bool:
	return cleared.has(&"arena")


## Bank bonus health for the rest of the run, clamped to BONUS_HP_CAP. Returns how many
## pips were actually added (0 once the cap is reached) so the HUD only heals the bull when
## there's headroom — a repeat barrel clear still cheers but grants nothing.
func add_bonus_hp(amount: int) -> int:
	var before := bonus_hp
	bonus_hp = clampi(bonus_hp + amount, 0, BONUS_HP_CAP)
	return bonus_hp - before