import { isSemaEvent, isSemaEventLabel, isSemaIntent, isSemaIntentBinding } from './event'
import type { SemaActionEvent, SemaIntentBinding } from './types'

export class SemaInvariantError extends Error {
	constructor(message: string) {
		super(message)
		this.name = 'SemaInvariantError'
	}
}

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

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

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

	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`)
	}

	if (!('intent' in event) || typeof event.intent === 'string') return

	validateSemaIntentBinding(event.intent, `${ctx}.intent`)
}