Connor Johnstone
58 lines
1.6 KiB
Rust
58 lines
1.6 KiB
Rust
use std::collections::BTreeMap;
|
|
|
|
use rand::prelude::*;
|
|
|
|
use crate::types::Candidate;
|
|
|
|
/// Reorder tracks so that artists are evenly spread out.
|
|
/// Greedily picks from the artist with the most remaining tracks,
|
|
/// avoiding back-to-back repeats when possible.
|
|
/// Ported faithfully from drift's interleave_artists().
|
|
pub fn interleave_artists(tracks: Vec<Candidate>) -> Vec<Candidate> {
|
|
let mut rng = rand::rng();
|
|
|
|
let mut by_artist: BTreeMap<String, Vec<Candidate>> = BTreeMap::new();
|
|
for track in tracks {
|
|
by_artist
|
|
.entry(track.artist.clone())
|
|
.or_default()
|
|
.push(track);
|
|
}
|
|
for group in by_artist.values_mut() {
|
|
group.shuffle(&mut rng);
|
|
}
|
|
|
|
let mut result = Vec::new();
|
|
let mut last_artist: Option<String> = None;
|
|
|
|
while !by_artist.is_empty() {
|
|
let mut artists: Vec<String> = by_artist.keys().cloned().collect();
|
|
artists.sort_by(|a, b| by_artist[b].len().cmp(&by_artist[a].len()));
|
|
|
|
let pick = artists
|
|
.iter()
|
|
.find(|a| last_artist.as_ref() != Some(a))
|
|
.or(artists.first())
|
|
.cloned()
|
|
.unwrap();
|
|
|
|
let group = by_artist.get_mut(&pick).unwrap();
|
|
let track = group.pop().unwrap();
|
|
if group.is_empty() {
|
|
by_artist.remove(&pick);
|
|
}
|
|
|
|
last_artist = Some(pick);
|
|
result.push(track);
|
|
}
|
|
|
|
result
|
|
}
|
|
|
|
/// Full random shuffle.
|
|
pub fn shuffle(mut tracks: Vec<Candidate>) -> Vec<Candidate> {
|
|
let mut rng = rand::rng();
|
|
tracks.shuffle(&mut rng);
|
|
tracks
|
|
}
|