extends Node
## Hardware detection autoload for AI-Enhanced Dialogue (D-138, #646).
##
## Exposes classification methods for Layer 1 (RAM), Layer 2 (TPT benchmark),
## and Layer 3 (ongoing TPT degradation monitoring).
##
## Loaded as HardwareDetector autoload. Tests access via get_node("/root/HardwareDetector").
## Settings dialog reads classification strings to configure the toggle UI.

const RAM_PASS_THRESHOLD_MB    := 2000.0
const RAM_MARGINAL_THRESHOLD_MB := 1600.0
const TPT_GREEN_THRESHOLD      := 6.0   # tokens/sec — enable silently
const TPT_YELLOW_THRESHOLD     := 3.0   # tokens/sec — partial pre-voicing note
const TPT_DEGRADATION_THRESHOLD := 0.4  # fraction — >40% sustained drop → yellow

const BENCHMARK_CACHE_PATH := "user://ai-dialogue-config.json"


func _ready() -> void:
	load_ai_pref()


## Layer 1 — RAM classification.
## Accepts free MB as input; returns "pass" | "marginal" | "fail".
func classify_ram(free_mb: float) -> String:
	if free_mb >= RAM_PASS_THRESHOLD_MB:
		return "pass"
	elif free_mb >= RAM_MARGINAL_THRESHOLD_MB:
		return "marginal"
	else:
		return "fail"


## Layer 2 — TPT benchmark classification.
## Accepts tokens/sec as input; returns "green" | "yellow" | "red".
func classify_tpt(tps: float) -> String:
	if tps >= TPT_GREEN_THRESHOLD:
		return "green"
	elif tps >= TPT_YELLOW_THRESHOLD:
		return "yellow"
	else:
		return "red"


## Layer 3 — Ongoing degradation classification.
## D-138 §8: >40% sustained drop from baseline → yellow (not forced disable).
## Returns "ok" | "yellow".
func classify_degradation(baseline_tps: float, current_avg_tps: float) -> String:
	if baseline_tps <= 0.0:
		return "ok"
	var drop := (baseline_tps - current_avg_tps) / baseline_tps
	return "yellow" if drop > TPT_DEGRADATION_THRESHOLD else "ok"


## Query the OS for free RAM and return the classification plus the raw MB value.
## Returns: {classification: String, free_mb: float}
func check_ram() -> Dictionary:
	var mem := OS.get_memory_info()
	# "available" accounts for reclaimable pages (Linux MemAvailable / Windows ullAvailPhys).
	# Fall back to "free" on platforms that don't provide "available".
	var free_bytes: int = mem.get("available", mem.get("free", 0))
	var free_mb: float = float(free_bytes) / (1024.0 * 1024.0)
	return {"classification": classify_ram(free_mb), "free_mb": free_mb}


## Read the cached TPT benchmark result written by the server on first model load.
## Returns: {tps: float, classification: String} or null if no cache file exists.
func read_benchmark_cache() -> Variant:
	if not FileAccess.file_exists(BENCHMARK_CACHE_PATH):
		return null
	var f := FileAccess.open(BENCHMARK_CACHE_PATH, FileAccess.READ)
	if f == null:
		return null
	var json := JSON.new()
	if json.parse(f.get_as_text()) != OK:
		return null
	var data: Variant = json.get_data()
	if not data is Dictionary or not data.has("tps"):
		return null
	var tps: float = float(data["tps"])
	return {"tps": tps, "classification": classify_tpt(tps)}


## Load AI dialogue preference from settings.cfg and apply to GameState.
## Called from _ready() to restore the toggle state across session restarts.
## Spec: D-138 §8 — toggle persists via ConfigFile (client-local) + server SQLite (#627).
func load_ai_pref() -> void:
	var cfg := ConfigFile.new()
	if cfg.load("user://settings.cfg") != OK:
		return
	var enabled: Variant = cfg.get_value("ai_dialogue", "enabled", null)
	if enabled is bool:
		GameState.ai_enhanced_dialogue_enabled = enabled


## Compose a human-readable status message for the settings dialog.
## classification: "pass" | "marginal" | "fail" (RAM) or "green" | "yellow" | "red" (TPT).
## Returns empty string when no message is needed.
func status_message(ram_classification: String, tpt_classification: String, free_mb: float, tps: float) -> String:
	if ram_classification == "fail":
		return "AI-Enhanced Dialogue requires 2 GB of free memory. Your system currently has %.0f MB available. Close other applications and try again, or leave the setting off — the game is complete either way." % free_mb
	if ram_classification == "marginal":
		return "Only %.0f MB free — performance may vary. You can still enable it." % free_mb
	match tpt_classification:
		"yellow":
			return "Running at %.0f t/s — pre-voicing will work for main characters and key scenes. Background NPCs may show base text until the queue catches up." % tps
		"red":
			return "Running very slowly at %.0f t/s — we recommend leaving this off, but the choice is yours." % tps
	return ""