import { IntrospectionTypeRef } from 'graphql'

export default function getTypescriptField(fieldName: string, type: IntrospectionTypeRef, {
	isNull,
	isList,
}: Props) {
	switch (type.kind) {
		case 'INPUT_OBJECT':
		case 'ENUM':
		case 'OBJECT':
		case 'INTERFACE':
		case 'SCALAR':
		case 'UNION':
			return buildField(fieldName, type.name, isNull, isList)

		case 'SCALAR':
			return buildField(fieldName, type.name, isNull, isList)

		case 'NON_NULL':
			return getTypescriptField(fieldName, type.ofType, { isList, isNull: true })

		case 'LIST':
			return getTypescriptField(fieldName, type.ofType, { isList: true, isNull })

		default:
			throw new Error(`UNKNOWN_TYPE_KIND`)
	}
}

const buildField = (fieldName, typeName, isNull, isList) => {
	const nullableSymbol = isNull ? '' : '?'
	const arraySymbol = isList ? '[]' : ''

	return `${fieldName}${nullableSymbol}: ${typeName}${arraySymbol}`
}
interface Props {
	isNull?: boolean
	isList?: boolean
}