ic-query 0.25.2

//! Module: cache_file::policy
//!
//! Responsibility: shared cache load/refresh decision helpers.
//! Does not own: command-specific cache keys, refresh requests, or report DTOs.
//! Boundary: centralizes silent missing-cache refresh policy for cache-backed reads.

use std::path::{Path, PathBuf};

///
/// CacheRefreshReason
///
/// Reason a shared cache policy requested an explicit refresh.
///

#[derive(Clone, Debug, Eq, PartialEq)]
#[cfg(feature = "host")]
pub enum CacheRefreshReason {
    Missing(PathBuf),
    Stale,
}

/// Load a cache, refresh it when the error represents a missing cache, then
/// load again.
pub fn load_or_refresh_missing_cache<T, Error>(
    mut load: impl FnMut() -> Result<T, Error>,
    missing_path: impl FnOnce(Error) -> Result<PathBuf, Error>,
    refresh: impl FnOnce(&Path) -> Result<(), Error>,
) -> Result<T, Error> {
    match load() {
        Ok(cached) => Ok(cached),
        Err(err) => {
            let path = missing_path(err)?;
            refresh(&path)?;
            load()
        }
    }
}

/// Load a cache, refresh it when missing or stale, then load the persisted
/// result again.
#[cfg(feature = "host")]
pub fn load_or_refresh_stale_cache<T, Error>(
    mut load: impl FnMut() -> Result<T, Error>,
    stale: impl FnOnce(&T) -> bool,
    missing_path: impl FnOnce(Error) -> Result<PathBuf, Error>,
    refresh: impl FnOnce(CacheRefreshReason) -> Result<(), Error>,
) -> Result<T, Error> {
    match load() {
        Ok(cached) if !stale(&cached) => Ok(cached),
        Ok(_) => {
            refresh(CacheRefreshReason::Stale)?;
            load()
        }
        Err(err) => {
            let path = missing_path(err)?;
            refresh(CacheRefreshReason::Missing(path))?;
            load()
        }
    }
}