--!nonstrict
--[[
	ConfigAdmin — headless logic for the Engine Config editor (issue #21). The generic sibling of
	StatAdmin: it edits the persisted `ReplicatedStorage.SurvivorCoreEngineConfig` instance the
	engine layers over every Config section at start()/startClient().

	The SCHEMA (sections → groups → typed fields) comes from the ENGINE — readSchema() requires
	ReplicatedStorage.SurvivorCore.shared.EngineConfig live, so plugin and engine can never
	disagree about fields, kinds or defaults. Writes are DELTAS-ONLY, same rule as StatAdmin:

	  • an attribute exists IFF the owner's value differs from the engine default
	  • typing the default back (or blanking the box) REMOVES the attribute
	  • unset fields keep following engine defaults across engine updates

	Instance shape: <instance>/<Section>/(attributes | <Group>/attributes). Field kinds:
	number | boolean | string | enum | color3 (native Color3 attribute) | font (attribute is an
	Enum.Font NAME string; the engine resolves it at apply time).
]]

local ReplicatedStorage = game:GetService("ReplicatedStorage")

local Field = require(script.Parent.Field)

local ConfigAdmin = {}

ConfigAdmin.INSTANCE_NAME = "SurvivorCoreEngineConfig"

-- ── Schema (live from the engine) ────────────────────────────────────────────

local function findEngineConfigModule(): ModuleScript?
	local engine = ReplicatedStorage:FindFirstChild("SurvivorCore")
	local shared = engine and engine:FindFirstChild("shared")
	local module = shared and shared:FindFirstChild("EngineConfig")
	if module and module:IsA("ModuleScript") then
		return module
	end
	return nil
end

-- Read the schema + per-section defaults from the live engine. Never errors:
-- { ok = true, source, sections, defaults } | { ok = false, reason, sections = {} }
function ConfigAdmin.readSchema(): any
	local module = findEngineConfigModule()
	if not module then
		return {
			ok = false,
			reason = "SurvivorCore engine not found in this place (expected"
				.. " ReplicatedStorage.SurvivorCore.shared.EngineConfig — sync/insert the engine, then Refresh).",
			sections = {},
		}
	end
	local ok, engineConfig = pcall(require, module)
	if not ok or typeof(engineConfig) ~= "table" or typeof(engineConfig.SECTIONS) ~= "table" then
		return {
			ok = false,
			reason = "Found the engine, but its EngineConfig module failed to load — is the engine"
				.. " up to date? (Engine Config needs SurvivorCore ≥ 0.8.)",
			sections = {},
		}
	end
	local defaults: { [string]: any } = {}
	for _, section in engineConfig.SECTIONS do
		defaults[section.id] = engineConfig.getDefaults(section.id)
	end
	return {
		ok = true,
		source = module:GetFullName(),
		sections = engineConfig.SECTIONS,
		defaults = defaults,
	}
end

-- ── Instance access (read-only vs ensure) ────────────────────────────────────

function ConfigAdmin.getNode(sectionId: string, groupName: string?): Instance?
	local instance = ReplicatedStorage:FindFirstChild(ConfigAdmin.INSTANCE_NAME)
	local section = instance and instance:FindFirstChild(sectionId)
	if groupName then
		return section and section:FindFirstChild(groupName)
	end
	return section
end

local function ensureConfiguration(parent: Instance, name: string): Instance
	local existing = parent:FindFirstChild(name)
	if existing then
		return existing
	end
	local node = Instance.new("Configuration")
	node.Name = name
	node.Parent = parent
	return node
end

function ConfigAdmin.ensureNode(sectionId: string, groupName: string?): Instance
	local instance = ReplicatedStorage:FindFirstChild(ConfigAdmin.INSTANCE_NAME)
	if not instance then
		instance = Instance.new("Configuration")
		instance.Name = ConfigAdmin.INSTANCE_NAME
		instance.Parent = ReplicatedStorage
	end
	local section = ensureConfiguration(instance, sectionId)
	if groupName then
		return ensureConfiguration(section, groupName)
	end
	return section
end

-- ── Effective values ─────────────────────────────────────────────────────────

-- The value the engine will use for a field: the instance override when present, else `default`.
function ConfigAdmin.readEffective(sectionId: string, groupName: string?, attr: string, default: any): any
	local node = ConfigAdmin.getNode(sectionId, groupName)
	local override = node and node:GetAttribute(attr)
	if override ~= nil then
		return { value = override, default = default, hasOverride = true }
	end
	return { value = default, default = default, hasOverride = false }
end

-- ── Coercion & default equality ──────────────────────────────────────────────

-- Parse a raw edit (usually TextBox text) per the field spec. Returns { ok, value } or
-- { ok = false, error }. A blank string is handled by setOverride (it means "reset").
function ConfigAdmin.coerce(field: any, raw: any): any
	return Field.coerce(field, raw)
end

-- Does a coerced value equal the engine default (→ store nothing)? Kind-aware: fonts compare
-- the stored NAME against the default Enum.Font; Color3 compares exactly (both sides come from
-- fromRGB construction); numbers use the relative epsilon.
function ConfigAdmin.equalsDefault(field: any, value: any, default: any): boolean
	return Field.equalsDefault(field, value, default)
end

-- Display formatting for effective values/defaults (what the TextBox shows).
function ConfigAdmin.formatValue(field: any, value: any): string
	return Field.format(field, value)
end

-- ── Writes (the deltas-only decision point) ──────────────────────────────────

-- Set (or clear) one field. Blank input = reset to default. Writes ONLY when the value differs
-- from the engine default; removes the attribute when it matches.
-- Returns { ok, action = "write"|"remove"|"noop", error? }.
function ConfigAdmin.setOverride(sectionId: string, groupName: string?, field: any, raw: any, default: any): any
	if typeof(raw) == "string" and string.match(raw, "^%s*$") then
		return ConfigAdmin.resetOverride(sectionId, groupName, field.attr)
	end
	local coerced = ConfigAdmin.coerce(field, raw)
	if not coerced.ok then
		return { ok = false, action = "noop", error = coerced.error }
	end
	if ConfigAdmin.equalsDefault(field, coerced.value, default) then
		return ConfigAdmin.resetOverride(sectionId, groupName, field.attr)
	end
	local node = ConfigAdmin.ensureNode(sectionId, groupName)
	node:SetAttribute(field.attr, coerced.value)
	return { ok = true, action = "write" }
end

function ConfigAdmin.resetOverride(sectionId: string, groupName: string?, attr: string): any
	local node = ConfigAdmin.getNode(sectionId, groupName)
	if node and node:GetAttribute(attr) ~= nil then
		node:SetAttribute(attr, nil)
		return { ok = true, action = "remove" }
	end
	return { ok = true, action = "noop" }
end

-- Remove every override in one section (all groups). Returns the number removed.
function ConfigAdmin.resetSection(section: any): number
	local removed = 0
	for _, group in section.groups do
		local node = ConfigAdmin.getNode(section.id, group.name)
		if node then
			for _, field in group.fields do
				if node:GetAttribute(field.attr) ~= nil then
					node:SetAttribute(field.attr, nil)
					removed += 1
				end
			end
		end
	end
	return removed
end

-- Count the overrides currently set in one section (drives the "n overridden" footer).
function ConfigAdmin.countOverrides(section: any): number
	local count = 0
	for _, group in section.groups do
		local node = ConfigAdmin.getNode(section.id, group.name)
		if node then
			for _, field in group.fields do
				if node:GetAttribute(field.attr) ~= nil then
					count += 1
				end
			end
		end
	end
	return count
end

return ConfigAdmin