use anyhow::{bail, Context, Result};
use hotspots_core::snapshot::{index_path, load_snapshot, Snapshot};
use hotspots_core::trainer::{train, RankerModel, TrainConfig};
use std::path::{Path, PathBuf};
pub(crate) struct TrainArgs {
pub path: PathBuf,
pub output: PathBuf,
pub label_window_days: u32,
pub n_estimators: usize,
pub max_depth: usize,
pub blame_labels: bool,
}
pub(crate) fn handle_train(args: TrainArgs) -> Result<()> {
let repo_root = args.path.canonicalize().context("resolve repo path")?;
let snapshot = load_latest_snapshot(&repo_root)?;
let output = if args.output.is_relative() {
repo_root.join(&args.output)
} else {
args.output.clone()
};
let args = TrainArgs { output, ..args };
let cfg = TrainConfig {
label_window_days: args.label_window_days,
n_estimators: args.n_estimators,
max_depth: args.max_depth,
blame_labels: args.blame_labels,
..Default::default()
};
let n_funcs = snapshot.functions.len();
let label_mode = if cfg.blame_labels {
"blame-based function labels"
} else {
"file-level labels"
};
eprintln!(
"hotspots train: {} functions in snapshot, scanning {} days of git history ({})…",
n_funcs, cfg.label_window_days, label_mode
);
match train(&snapshot, &repo_root, &cfg)? {
None => {
bail!(
"Not enough training signal: need ≥50 labelled functions, ≥5 positive and ≥10 negative. \
Try a larger --label-window or run `hotspots analyze` first to build a snapshot."
);
}
Some(model) => {
report_model(&model, n_funcs);
model.save(&args.output)?;
eprintln!("Model saved → {}", args.output.display());
}
}
Ok(())
}
fn load_latest_snapshot(repo_root: &Path) -> Result<Snapshot> {
let idx_path = index_path(repo_root);
if !idx_path.exists() {
bail!(
"No snapshot index found at {}. Run `hotspots analyze .` first.",
idx_path.display()
);
}
let json = std::fs::read_to_string(&idx_path)
.with_context(|| format!("read {}", idx_path.display()))?;
let index = hotspots_core::snapshot::Index::from_json(&json).context("parse index")?;
let entry = index
.commits
.last()
.context("snapshot index is empty — run `hotspots analyze .` first")?;
let sha = entry.sha.clone();
let snapshot = load_snapshot(repo_root, &sha)
.context("load snapshot")?
.with_context(|| format!("snapshot {} not found on disk", sha))?;
eprintln!("Loaded snapshot {}", &sha[..8.min(sha.len())]);
Ok(snapshot)
}
fn report_model(model: &RankerModel, n_funcs: usize) {
let m = &model.meta;
let base_rate = m.n_pos as f64 / m.n_samples as f64;
eprintln!(
"Trained: {} trees × depth {} | {} samples ({} pos, {} neg) | base rate {:.1}% | {} functions in repo",
m.n_estimators, m.max_depth,
m.n_samples, m.n_pos, m.n_neg,
base_rate * 100.0,
n_funcs,
);
}