//! Resolve `{{<name>}}` model-path references to container-side HF cache paths.

use crate::config::{Config, Node};
use crate::docker::{command, shq};
use crate::ssh::run_ssh;
use anyhow::Result;
use std::path::Path;

/// Resolve a model path reference's full HF cache path on a specific node by
/// reading its `refs/main`: `<hf_cache>/hub/<model_cache_dir_name(repo)>/snapshots/<refs/main>[/<subfolder>]`.
/// `refs/main` always points at the latest commit, so the path survives
/// `huggingface-cli download` updates (no fragile symlink). If the repo or
/// subfolder is absent, returns an error pointing at `huggingface-cli download`
/// (the launcher never downloads).
///
/// The resolved path is substituted into the recipe args/env via `{{<name>}}`
/// — no bind-mount is created (the HF cache is already mounted at
/// `/root/.cache/huggingface`, so the path's symlinks resolve correctly).
pub(crate) async fn resolve_path_ref_on_node(
    config: &Config,
    node: &Node,
    spec: &command::PathRef,
    hf_cache: &Path,
) -> Result<String> {
    let model_dir = crate::config::model_cache_dir_name(&spec.repo);
    let sub = spec.subfolder.as_deref().unwrap_or("");
    let hub_dir = format!("{}/hub/{}", hf_cache.display(), model_dir);
    let refs_path = format!("{}/refs/main", hub_dir);
    // `cat refs/main` prints the current commit hash; trim trailing newline.
    // All literal path components are shell-quoted (a repo/subfolder with a
    // quote/space would otherwise break the command); `$ref` is our own
    // captured var, so it expands safely inside the printf double-quotes.
    let cmd = format!(
        "ref=\"$(cat {refs_q} 2>/dev/null)\" && test -n \"$ref\" && \
         dir=\"$(printf '%s/snapshots/%s/%s' {hub_q} \"$ref\" {sub_q})\" && \
         test -d \"$dir\" && printf '%s' \"$dir\"",
        refs_q = shq(&refs_path),
        hub_q = shq(&hub_dir),
        sub_q = shq(sub),
    );
    let resolved_path = run_ssh(config, node, cmd, false).await?;
    if resolved_path.trim().is_empty() {
        let hint = format!(
            "Model subfolder '{}' not found in HF cache on '{}': \
             repo '{}' is not downloaded there or 'refs/main' is missing. \
             Run `huggingface-cli download {}` on that node.",
            sub, node.name, spec.repo, spec.repo
        );
        anyhow::bail!(hint);
    }
    Ok(resolved_path.replace(&hf_cache.display().to_string(), "/root/.cache/huggingface"))
}