import {
	IntrospectionField,
	IntrospectionType,
	IntrospectionObjectType,
	IntrospectionInterfaceType,
	IntrospectionTypeRef,
} from 'graphql'

export default function generateResultTypeFields(type: IntrospectionTypeRef, allTypes: IntrospectionType[]): string[] {

	switch (type.kind) {
		case 'ENUM':
		case 'SCALAR':
			return null

		case 'NON_NULL':
		case 'LIST':
			return generateResultTypeFields(type.ofType, allTypes)

		case 'INTERFACE':
			{
				const resultType = <IntrospectionInterfaceType>allTypes.find(x => x.name === type.name)
				if (!resultType) {
					return null
				}

				return resultType.fields
					.map(x => x.name)
			}

		case 'OBJECT':
			{
				const resultType = <IntrospectionObjectType>allTypes.find(x => x.name === type.name)
				if (!resultType) {
					return null
				}

				return resultType.fields
					.map(x => x.name)
			}

		default:
			console.log('MISSING RESULT TYPE', type.kind)
			return null
	}
}