import { readIncomingType } from "../../bridge/incomingType.js"
import type { InvalidSandboxMessage } from "../../bridge/messages/invalidSandboxMessage.js"

export type InvalidSandboxMessageResponse = {
	incomingType: string | undefined
	nack?: InvalidSandboxMessage
}

export function getInvalidSandboxMessageResponse(
	data: unknown,
): InvalidSandboxMessageResponse {
	const incomingType = readIncomingType(data)
	if (
		incomingType === "invalidHostMessage" ||
		incomingType === "invalidSandboxMessage"
	) {
		return { incomingType }
	}
	return {
		incomingType,
		nack: {
			type: "invalidSandboxMessage",
			reason: nackReasonForInvalidSandboxMessage(incomingType),
		},
	}
}

function nackReasonForInvalidSandboxMessage(
	incomingType: string | undefined,
): string {
	if (incomingType === "ready") {
		return "Invalid manifest"
	}
	if (incomingType !== undefined) {
		return `Unsupported sandbox message of type "${incomingType}"`
	}
	return "Unsupported sandbox message (no `type` field or non-object payload)"
}