import map from './map.js'
import wrapAsync from './internal/wrapAsync.js'
import awaitify from './internal/awaitify.js'
/**
* Sorts a list by the results of running each `coll` value through an async
* `iteratee`.
*
* @name sortBy
* @static
* @memberOf module:Collections
* @method
* @category Collection
* @param {Array|Iterable|AsyncIterable|Object} coll - A collection to iterate over.
* @param {AsyncFunction} iteratee - An async function to apply to each item in
* `coll`.
* The iteratee should complete with a value to use as the sort criteria as
* its `result`.
* Invoked with (item, callback).
* @param {Function} callback - A callback which is called after all the
* `iteratee` functions have finished, or an error occurs. Results is the items
* from the original `coll` sorted by the values returned by the `iteratee`
* calls. Invoked with (err, results).
* @returns {Promise} a promise, if no callback passed
* @example
*
* // bigfile.txt is a file that is 251100 bytes in size
* // mediumfile.txt is a file that is 11000 bytes in size
* // smallfile.txt is a file that is 121 bytes in size
*
* // asynchronous function that returns the file size in bytes
* function getFileSizeInBytes(file, callback) {
* fs.stat(file, function(err, stat) {
* if (err) {
* return callback(err);
* }
* callback(null, stat.size);
* });
* }
*
* // Using callbacks
* async.sortBy(['mediumfile.txt','smallfile.txt','bigfile.txt'], getFileSizeInBytes,
* function(err, results) {
* if (err) {
* console.log(err);
* } else {
* console.log(results);
* // results is now the original array of files sorted by
* // file size (ascending by default), e.g.
* // [ 'smallfile.txt', 'mediumfile.txt', 'bigfile.txt']
* }
* }
* );
*
* // By modifying the callback parameter the
* // sorting order can be influenced:
*
* // ascending order
* async.sortBy(['mediumfile.txt','smallfile.txt','bigfile.txt'], function(file, callback) {
* getFileSizeInBytes(file, function(getFileSizeErr, fileSize) {
* if (getFileSizeErr) return callback(getFileSizeErr);
* callback(null, fileSize);
* });
* }, function(err, results) {
* if (err) {
* console.log(err);
* } else {
* console.log(results);
* // results is now the original array of files sorted by
* // file size (ascending by default), e.g.
* // [ 'smallfile.txt', 'mediumfile.txt', 'bigfile.txt']
* }
* }
* );
*
* // descending order
* async.sortBy(['bigfile.txt','mediumfile.txt','smallfile.txt'], function(file, callback) {
* getFileSizeInBytes(file, function(getFileSizeErr, fileSize) {
* if (getFileSizeErr) {
* return callback(getFileSizeErr);
* }
* callback(null, fileSize * -1);
* });
* }, function(err, results) {
* if (err) {
* console.log(err);
* } else {
* console.log(results);
* // results is now the original array of files sorted by
* // file size (ascending by default), e.g.
* // [ 'bigfile.txt', 'mediumfile.txt', 'smallfile.txt']
* }
* }
* );
*
* // Error handling
* async.sortBy(['mediumfile.txt','smallfile.txt','missingfile.txt'], getFileSizeInBytes,
* function(err, results) {
* if (err) {
* console.log(err);
* // [ Error: ENOENT: no such file or directory ]
* } else {
* console.log(results);
* }
* }
* );
*
* // Using Promises
* async.sortBy(['mediumfile.txt','smallfile.txt','bigfile.txt'], getFileSizeInBytes)
* .then( results => {
* console.log(results);
* // results is now the original array of files sorted by
* // file size (ascending by default), e.g.
* // [ 'smallfile.txt', 'mediumfile.txt', 'bigfile.txt']
* }).catch( err => {
* console.log(err);
* });
*
* // Error handling
* async.sortBy(['mediumfile.txt','smallfile.txt','missingfile.txt'], getFileSizeInBytes)
* .then( results => {
* console.log(results);
* }).catch( err => {
* console.log(err);
* // [ Error: ENOENT: no such file or directory ]
* });
*
* // Using async/await
* (async () => {
* try {
* let results = await async.sortBy(['bigfile.txt','mediumfile.txt','smallfile.txt'], getFileSizeInBytes);
* console.log(results);
* // results is now the original array of files sorted by
* // file size (ascending by default), e.g.
* // [ 'smallfile.txt', 'mediumfile.txt', 'bigfile.txt']
* }
* catch (err) {
* console.log(err);
* }
* })();
*
* // Error handling
* async () => {
* try {
* let results = await async.sortBy(['missingfile.txt','mediumfile.txt','smallfile.txt'], getFileSizeInBytes);
* console.log(results);
* }
* catch (err) {
* console.log(err);
* // [ Error: ENOENT: no such file or directory ]
* }
* }
*
*/
function sortBy (coll, iteratee, callback) {
var _iteratee = wrapAsync(iteratee);
return map(coll, (x, iterCb) => {
_iteratee(x, (err, criteria) => {
if (err) return iterCb(err);
iterCb(err, {value: x, criteria});
});
}, (err, results) => {
if (err) return callback(err);
callback(null, results.sort(comparator).map(v => v.value));
});
function comparator(left, right) {
var a = left.criteria, b = right.criteria;
return a < b ? -1 : a > b ? 1 : 0;
}
}
export default awaitify(sortBy, 3)
