class_name NewGame
extends RefCounted
## New-game construction. Reads three immutable inputs (origin, world, creation) and
## writes two products (CanonLog, GameState). Nothing flows back up — charter §2.
##
## Creation carries a SEED, not a stat block. construct() rebuilds the RNG and rolls
## the attributes ITSELF, so it never trusts a number handed to it (§2) and the same
## seed always yields the same character (§10 — "the difference between a bug you can
## reproduce and a bug you cannot"). The whole character is reproducible from four
## primitives: seed, race_id, calling_id, spend.
##
## `creation` stays a plain Dictionary: a saga (later) synthesizes one and skips the
## UI entirely, so the creation SCENE must never become the only thing that can make it.

const SPEND_POOL := 3


static func construct(origin: Dictionary, world: ContentDB, creation: Dictionary) -> Dictionary:
	var errors := _validate(origin, world, creation)
	if not errors.is_empty():
		return {"ok": false, "errors": errors, "log": null, "state": null}

	var rng := RandomNumberGenerator.new()
	rng.seed = int(creation.get("seed", 0))

	var state := GameState.new()
	var sheet := CharacterSheet.new()
	sheet.race_id = str(creation.get("race_id", ""))
	sheet.calling_id = str(creation.get("calling_id", ""))

	# The RNG ORDER is part of the contract: five attributes in a fixed order, then
	# Luck. Change the order and every existing seed produces a different character.
	# roll_attributes() is the ONE implementation — the creation screen calls the same
	# function to DISPLAY the roll, so what the player saw is what he gets (§2/§10).
	var attrs: Dictionary = _roll_five(rng)

	var bc: Dictionary = origin.get("build_constraints", {})
	state.luck_base = Luck.roll_base(rng, int(bc.get("luck_modifier", 0)))
	state.luck = state.luck_base

	var spend: Dictionary = creation.get("spend", {})
	for stat in spend:
		attrs[stat] = int(attrs[stat]) + int(spend[stat])
	sheet.attributes = attrs

	# Proficiencies: what the race grants + what the player picked + the human's bonus.
	# All land in one list, so is_proficient() has exactly one thing to read.
	var skills: Array = []
	skills.append_array(Races.granted_skills(sheet.race_id))
	skills.append_array(creation.get("skills", []))
	var bonus := str(creation.get("bonus_skill", ""))
	if bonus != "":
		skills.append(bonus)
		sheet.bonus_skill = bonus
	sheet.skills = skills

	sheet.hp = sheet.max_hp()   # the character starts whole
	sheet.mp = sheet.max_mp()
	state.sheet = sheet

	var log := CanonLog.new()
	log.player = LogPlayer.new(str(creation.get("name", "")), sheet.race_id,
		sheet.calling_id, state.luck_descriptor())

	var loc: Dictionary = world.location(origin["start_location_id"])
	log.set_location(loc.get("id", ""), loc.get("name", ""))

	var overrides: Dictionary = origin.get("disposition_overrides", {})
	var companion_ids := {}
	for c in world.companions():
		companion_ids[c["id"]] = true
		log.party.append(PartyMember.new(c["id"], c.get("name", ""), int(overrides.get(c["id"], 0))))
	for npc_id in overrides:
		if not companion_ids.has(npc_id):
			state.set_npc_disposition(npc_id, int(overrides[npc_id]))

	for line in origin.get("situation", []):
		log.push_event(line)
	for fact in origin.get("opening_facts", []):
		log.add_fact(fact)

	var quest_id: Variant = origin.get("start_quest_id", null)
	if quest_id != null:
		var qd: Dictionary = world.quest(quest_id)
		log.active_quests.append(Quest.new(qd.get("id", ""), qd.get("name", ""), "active",
			qd.get("objective", "")))

	# inventory grants -> game state (NOT the log). §2. grant() routes currency to the
	# purse; everything else to the inventory dict.
	for g in origin.get("inventory_grants", []):
		state.grant(g.get("item_id", ""), int(g.get("qty", 0)))

	return {"ok": true, "errors": [], "log": log, "state": state}


static func roll_attributes(character_seed: int) -> Dictionary:
	## PUBLIC and PURE. The creation screen calls this to SHOW the roll; construct
	## calls it to BUILD it. One implementation, so the two can never disagree.
	## NO DEFAULT PARAMETERS (traps.md #2) — a defaulted arg turns a wrong-arity
	## call into a silent miscompile that binds the wrong value into the wrong slot.
	var rng := RandomNumberGenerator.new()
	rng.seed = character_seed
	return _roll_five(rng)


static func _roll_five(rng: RandomNumberGenerator) -> Dictionary:
	var attrs: Dictionary = {}
	for stat in Attributes.IDS:
		attrs[stat] = _roll_attribute(rng)
	return attrs


static func validate(origin: Dictionary, world: ContentDB, creation: Dictionary) -> Array:
	## PUBLIC. The creation screen gates its CTA on this, so the player cannot press
	## his way into a rejection. construct() still calls it and still does not trust
	## its caller — the screen is a caller like any other. NO DEFAULT PARAMETERS.
	return _validate(origin, world, creation)


static func _roll_attribute(rng: RandomNumberGenerator) -> int:
	# 3d6 with a HARD FLOOR of 8. The floor clamps the die, not the player: straight
	# 3d6 puts ~9% on a primary the +3 pool cannot rescue, and a character who is bad
	# at the one thing he is FOR is not grit — it is the "fine" §7 forbids, paid for
	# twenty hours.
	var roll := rng.randi_range(1, 6) + rng.randi_range(1, 6) + rng.randi_range(1, 6)
	return maxi(8, roll)


static func _validate(origin: Dictionary, world: ContentDB, creation: Dictionary) -> Array:
	var errors: Array = []

	for ref in world.unresolved_refs(origin):
		errors.append("unresolved ref: %s" % ref)

	if str(creation.get("name", "")).strip_edges() == "":
		errors.append("player name is required")

	if not creation.has("seed") or typeof(creation["seed"]) != TYPE_INT:
		errors.append("seed is required and must be an integer")

	var race_id: String = str(creation.get("race_id", ""))
	if not Races.exists(race_id):
		errors.append("unknown race: %s" % race_id)

	var calling_id: String = str(creation.get("calling_id", ""))
	if not Callings.exists(calling_id):
		errors.append("unknown calling: %s" % calling_id)
	else:
		var allowed: Array = origin.get("build_constraints", {}).get("allowed_callings", [])
		if calling_id not in allowed:
			errors.append("calling not allowed by origin: %s" % calling_id)

	# Guard container SHAPES before any statically-typed call below touches them.
	# A JSON round-trip can hand back {"spend": null} or {"skills": "stealth"} —
	# without this check, assigning that into a typed Dictionary/Array parameter
	# throws a GDScript runtime error INSIDE construct() instead of landing in the
	# front-loaded {"ok": false, "errors": [...]} the spec promises.
	if typeof(creation.get("spend", {})) != TYPE_DICTIONARY:
		errors.append("spend must be an object")
	else:
		errors.append_array(_validate_spend(creation.get("spend", {})))

	if typeof(creation.get("skills", [])) != TYPE_ARRAY:
		errors.append("skills must be an array")
	elif Races.exists(race_id) and Callings.exists(calling_id):
		errors.append_array(_validate_skills(creation, race_id, calling_id))

	return errors


static func _validate_spend(spend: Dictionary) -> Array:
	var errors: Array = []
	var total := 0
	for stat in spend:
		# LCK is not merely hidden at creation — it is unspendable (§7).
		if not Attributes.exists(str(stat)):
			errors.append("cannot spend on '%s' — not an attribute" % stat)
			continue
		if typeof(spend[stat]) != TYPE_INT:
			errors.append("spend value for '%s' must be an integer" % stat)
			continue
		var v := int(spend[stat])
		if v < 0:
			errors.append("spend is additive only: %s is negative" % stat)
			continue
		total += v
	if total > SPEND_POOL:
		errors.append("spend exceeds the pool of %d (got %d)" % [SPEND_POOL, total])
	return errors


static func _validate_skills(creation: Dictionary, race_id: String, calling_id: String) -> Array:
	var errors: Array = []
	var picks: Array = creation.get("skills", [])
	var granted: Array = Races.granted_skills(race_id)
	var pool: Array = Callings.skill_pool(calling_id)
	var want := Callings.skill_count(calling_id)

	if picks.size() != want:
		errors.append("%s picks %d skills, got %d" % [calling_id, want, picks.size()])

	var seen := {}
	for s in picks:
		if s in seen:
			errors.append("duplicate skill pick: %s" % s)
		seen[s] = true
		if s not in pool:
			errors.append("%s is not in the %s pool" % [s, calling_id])
		if s in granted:
			errors.append("%s is already granted by %s — the pick buys nothing" % [s, race_id])

	var bonus := str(creation.get("bonus_skill", ""))
	if Races.wants_bonus_skill(race_id):
		if bonus == "":
			errors.append("%s must choose a bonus skill" % race_id)
		elif not Skills.exists(bonus):
			errors.append("unknown bonus skill: %s" % bonus)
		elif bonus in picks or bonus in granted:
			errors.append("bonus skill %s is already proficient" % bonus)
	elif bonus != "":
		errors.append("%s does not get a bonus skill" % race_id)

	return errors