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getDatasetHelpers.js
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getDatasetHelpers.js
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const utils = require("./utils");
const sources = require("./sources");
const handleError = (res, clientMsg, serverMsg="") => {
res.statusMessage = clientMsg;
utils.warn(`${clientMsg} -- ${serverMsg}`);
return res.status(500).end();
};
const unauthorized = (req, res) => {
const user = req.user
? `user ${req.user.username}`
: `an anonymous user`;
utils.warn(`Denying ${user} access to ${req.originalUrl}`);
return res.status(404).end();
};
/* All of the logic for mapping a dataset or narratives URL ("prefix") to a
* source + path is intentionally encapsulated contained here. This function
* is essentially a router, and potentially should be refactored as such in the
* future.
*
* The inverse of splitPrefixIntoParts() is joinPartsIntoPrefix(), which should
* roundtrip losslessly.
*/
const splitPrefixIntoParts = (prefix) => {
/* This could be const, but use let to signal to the reader that we use
* modifying methods like shift() and splice().
*/
const prefixParts = prefix
.replace(/^\//, '')
.replace(/\/$/, '')
.split("/");
/* The first part of the prefix is an optional source name. The rest is the
* source path parts.
*/
let sourceName;
switch (prefixParts[0]) {
case "community":
case "staging":
sourceName = prefixParts.shift();
break;
case "groups":
prefixParts.shift();
sourceName = prefixParts.shift();
break;
default:
sourceName = "core";
break;
}
const isNarrative = prefixParts[0] === "narratives";
if (isNarrative) {
prefixParts.shift();
}
const Source = sources.get(sourceName);
let source;
switch (sourceName) {
// Community source requires an owner and repo name
case "community":
source = new Source(...prefixParts.splice(0, 2));
break;
default:
source = new Source();
}
return {source, prefixParts, isNarrative};
};
/* The inverse of splitPrefixIntoParts() above, intentionally written to mimic
* that function's structure and roundtrip losslessly.
*
* If we move to a real router-based approach, this would ideally be an
* automatically provided reverse URL-construction/interpolation function on
* the matched route.
*/
const joinPartsIntoPrefix = ({source, prefixParts, isNarrative = false}) => {
const leadingParts = [];
switch (source.name) {
case "core":
break;
case "community":
case "staging":
leadingParts.push(source.name);
break;
default:
leadingParts.push("groups", source.name);
}
if (isNarrative) {
leadingParts.push("narratives");
}
switch (source.name) {
// Community source requires an owner and repo name
case "community":
leadingParts.push(source.owner, source.repoNameWithBranch);
break;
// no default
}
return [...leadingParts, ...prefixParts.filter((x) => x.length)].join("/");
};
/* Given the prefix (split on "/") -- is there an exact match in
* the available datasets? If not, we use these to pick the
* "default" one.
*/
const correctPrefixFromAvailable = (sourceName, prefixParts) => {
// XXX FIXME: This should be consulting our source objects, not breaking
// encapsulation by accessing the global directly. Punting on that for now
// as this work is time-sensitive. I'll loop back around to it, though!
// -trs, 5 Sept 2019
//
if (!global.availableDatasets[sourceName]) {
utils.verbose("Can't compare against available datasets as there are none!");
return prefixParts;
}
const doesPathExist = (pathToCheck) =>
global.availableDatasets[sourceName]
.includes(pathToCheck);
let prefix = prefixParts.join("/");
if (doesPathExist(prefix)) {
return prefixParts;
}
/* if we are here, then the path doesn't match any available datasets exactly */
if (prefix in global.availableDatasets.defaults[sourceName]) {
prefix = `${prefix}/${global.availableDatasets.defaults[sourceName][prefix]}`;
const parts = prefix.split("/");
if (doesPathExist(prefix)) {
return parts;
}
return correctPrefixFromAvailable(sourceName, parts);
}
return prefixParts;
};
const guessTreeName = (prefixParts) => {
const guesses = ["HA", "NA", "PB1", "PB2", "PA", "NP", "NS", "MP", "L", "S"];
for (const part of prefixParts) {
if (guesses.indexOf(part.toUpperCase()) !== -1) return part;
}
return undefined;
};
/* Parse the prefix (normally URL) and decide which URLs to fetch etc
* The prefix is case sensitive
*/
const parsePrefix = (prefix, otherQueries) => {
const fetchUrls = {};
let {source, prefixParts} = splitPrefixIntoParts(prefix);
/* Does the URL specify two trees?
*
* If so, we need to extract the two tree names and massage the prefixParts
* to only include the first.
*/
let treeName, secondTreeName;
for (let i=0; i<prefixParts.length; i++) {
if (prefixParts[i].indexOf(":") !== -1) {
[treeName, secondTreeName] = prefixParts[i].split(":");
prefixParts[i] = treeName; // only use the first tree from now on
break;
}
}
if (!secondTreeName && otherQueries.deprecatedSecondTree) {
secondTreeName = otherQueries.deprecatedSecondTree;
}
// Expand partial prefixes. This would be cleaner if integerated into the
// Source classes.
prefixParts = correctPrefixFromAvailable(source.name, prefixParts);
if (!treeName) {
utils.verbose("Guessing tree name -- this should be improved");
treeName = guessTreeName(prefixParts);
}
// The URL to be displayed in Auspice, tweaked below if necessary
let auspiceDisplayUrl = joinPartsIntoPrefix({source, prefixParts});
// Get the server fetch URLs
const dataset = source.dataset(prefixParts);
fetchUrls.main = dataset.urlFor("main");
fetchUrls.tree = dataset.urlFor("tree");
fetchUrls.meta = dataset.urlFor("meta");
if (secondTreeName) {
const idxOfTree = prefixParts.indexOf(treeName);
const secondTreePrefixParts = prefixParts.slice();
secondTreePrefixParts[idxOfTree] = secondTreeName;
const secondDataset = source.dataset(secondTreePrefixParts);
fetchUrls.secondTree = secondDataset.urlFor("tree");
const re = new RegExp(`\\/${treeName}(/|$)`); // note the double escape for special char
auspiceDisplayUrl = auspiceDisplayUrl.replace(re, `/${treeName}:${secondTreeName}/`);
}
auspiceDisplayUrl = auspiceDisplayUrl.replace(/\/$/, ''); // remove any trailing slash
if (otherQueries.type) {
fetchUrls.additional = dataset.urlFor(otherQueries.type);
}
return ({fetchUrls, auspiceDisplayUrl, treeName, secondTreeName, source, dataset});
};
module.exports = {
splitPrefixIntoParts,
joinPartsIntoPrefix,
handleError,
unauthorized,
parsePrefix
};