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use serde::{Deserialize, Serialize};
use std::fs;
use std::path::{Path, PathBuf};
use crate::utils::now;
use crate::Error;
#[derive(Debug, Clone, PartialEq, Serialize, Deserialize)]
pub(crate) struct Meta {
pub(crate) resource: String,
pub(crate) resource_path: PathBuf,
pub(crate) meta_path: PathBuf,
pub(crate) etag: Option<String>,
pub(crate) expires: Option<f64>,
pub(crate) creation_time: f64,
}
impl Meta {
pub(crate) fn new(
resource: String,
resource_path: PathBuf,
etag: Option<String>,
freshness_lifetime: Option<u64>,
) -> Meta {
let mut expires: Option<f64> = None;
let creation_time = now();
if let Some(lifetime) = freshness_lifetime {
expires = Some(creation_time + (lifetime as f64));
}
let meta_path = Meta::meta_path(&resource_path);
Meta {
resource,
resource_path,
meta_path,
etag,
expires,
creation_time,
}
}
pub(crate) fn meta_path(resource_path: &Path) -> PathBuf {
let mut meta_path = PathBuf::from(resource_path);
let resource_file_name = meta_path.file_name().unwrap().to_str().unwrap();
let meta_file_name = format!("{}.meta", resource_file_name);
meta_path.set_file_name(&meta_file_name[..]);
meta_path
}
pub(crate) fn get_extraction_path(&self) -> PathBuf {
let dirname = format!(
"{}-extracted",
self.resource_path.file_name().unwrap().to_str().unwrap()
);
self.resource_path.parent().unwrap().join(dirname)
}
pub(crate) fn to_file(&self) -> Result<(), Error> {
let serialized = serde_json::to_string(self).unwrap();
fs::write(&self.meta_path, &serialized[..])?;
Ok(())
}
pub(crate) fn from_cache(resource_path: &Path) -> Result<Self, Error> {
let meta_path = Meta::meta_path(resource_path);
Meta::from_path(&meta_path)
}
pub(crate) fn from_path(path: &Path) -> Result<Self, Error> {
if !path.is_file() {
return Err(Error::CacheCorrupted(format!("missing meta at {:?}", path)));
}
let serialized = fs::read_to_string(path)?;
let meta: Meta = serde_json::from_str(&serialized[..])
.map_err(|e| Error::CacheCorrupted(format!("invalid meta at {:?}: {:?}", path, e)))?;
Ok(meta)
}
pub(crate) fn is_fresh(&self, freshness_lifetime: Option<u64>) -> bool {
if let Some(lifetime) = freshness_lifetime {
let expiration_time = self.creation_time + (lifetime as f64);
expiration_time > now()
} else if let Some(expiration_time) = self.expires {
expiration_time > now()
} else {
false
}
}
}