const $rdf = require('rdflib')

const SOLID = $rdf.Namespace('http://www.w3.org/ns/solid/terms#')

const VCARD = $rdf.Namespace('http://www.w3.org/2006/vcard/ns#')

module.exports.getName = getName

module.exports.getWebId = getWebId

module.exports.isValidUsername = isValidUsername

async function getName (webId, fetchGraph) {

const graph = await fetchGraph(webId)

const nameNode = graph.any($rdf.sym(webId), VCARD('fn'))

return nameNode.value

}

async function getWebId (accountDirectory, accountUrl, suffixMeta, fetchData) {

const metaFilePath = `${accountDirectory}/${suffixMeta}`

const metaFileUri = `${accountUrl}${suffixMeta}`

const metaData = await fetchData(metaFilePath)

const metaGraph = $rdf.graph()

$rdf.parse(metaData, metaGraph, metaFileUri, 'text/turtle')

const webIdNode = metaGraph.any(undefined, SOLID('account'), $rdf.sym(accountUrl))

return webIdNode.value

}

function isValidUsername (username) {

return /^[a-z0-9]+(?:-[a-z0-9]+)*$/.test(username)

}