import { isSemaEvent, isSemaEventLabel, isIntent, isIntentBinding } from './event'
import { SemaInvariantError } from './errors'
import { SEMA_FAMILY_POLICY, type SemaActionEvent, type IntentBinding } from './types'

export { SemaInvariantError } from './errors'

export function validateIntentBinding(binding: IntentBinding, ctx = 'sema.intent'): void {
	if (!isIntentBinding(binding)) {
		throw new SemaInvariantError(`${ctx} is not a valid IntentBinding`)
	}

	const supported = binding.supported ?? []
	if (supported.length === 0) return

	for (const intent of supported) {
		if (!isIntent(intent)) {
			throw new SemaInvariantError(`${ctx}: intent "${String(intent)}" is not a valid Intent`)
		}
	}

	if (!supported.includes(binding.default)) {
		throw new SemaInvariantError(
			`${ctx}: default intent "${binding.default}" must be included in supported intents`
		)
	}
}

export function validateSemaEvent(event: SemaActionEvent, ctx = 'sema.event'): void {
	if (isSemaEventLabel(event)) return

	if (!isSemaEvent(event)) {
		throw new SemaInvariantError(`${ctx} is not a valid canonical semantic event`)
	}

	const intent = 'intent' in event ? event.intent : undefined

	// Policy enforcement: families marked `intentRequirement: 'required'` MUST
	// declare intent.
	if (
		intent === undefined &&
		SEMA_FAMILY_POLICY[event.family].intentRequirement === 'required'
	) {
		throw new SemaInvariantError(
			`${ctx}: family "${event.family}" requires intent (intentRequirement: 'required')`
		)
	}

	// Bindings need structural validation; literals + absence are fine.
	if (intent === undefined || typeof intent === 'string') return

	validateIntentBinding(intent, `${ctx}.intent`)
}