rlist_vfs 0.1.1

Virtual File System for rList
Documentation 
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use std::time::SystemTime;
use rand::{Rng, thread_rng};
use crate::combinable::Combinable;
use crate::{VfsBasicMeta, VfsFileMeta};

/// The download link can be determined **when instance is created**.
pub trait StaticDownloadLinkFile: VfsBasicMeta {
    fn new(name: String, size: u64, last_modified: SystemTime, links: Vec<String>) -> Self;

    /// Get download links
    fn links(&self) -> &Vec<String>;

    /// Destructor, returns
    /// 1. name
    /// 2. size
    /// 3. last_modified
    /// 4. links
    fn destruct(self) -> (String, u64, SystemTime, Vec<String>);
}

impl<T: StaticDownloadLinkFile> Combinable for T {
    /// Combine **same** files which have different download links to one file.
    fn combine(from: Vec<Self>) -> Self {
        let destructed: Vec<(String, u64, SystemTime, Vec<String>)> = from.into_iter()
            .map(|x| x.destruct())
            .collect::<Vec<_>>();
        let new_name = destructed[0].0.clone();
        let new_size = destructed.iter().map(|x| x.1).sum();
        let new_last_modified = destructed.iter().map(|x| x.2).max().unwrap();
        let download_links: Vec<String> = destructed.iter().map(|x| x.3.clone()).flatten().collect();
        return Self::new(new_name, new_size, new_last_modified.clone(), download_links);
    }
}

impl<T> VfsFileMeta for T
where T: StaticDownloadLinkFile
{
    /// return a random link in list
    fn on_download(&self) -> String {
        let links = self.links();
        let index = thread_rng().gen_range(0..links.len());
        return links[index].clone()
    }
}

#[derive(Clone)]
/// minimal implementation of `StaticDownloadLinkFile`
pub struct StaticCombinableFile {
    pub name: String,
    pub size: u64,
    pub last_modified: SystemTime,
    pub links: Vec<String>,
}

impl VfsBasicMeta for StaticCombinableFile {
    fn name(&self) -> &str {
        self.name.as_str()
    }

    fn size(&self) -> u64 {
        self.size
    }

    fn last_modified(&self) -> SystemTime {
        self.last_modified
    }
}

impl StaticDownloadLinkFile for StaticCombinableFile {
    fn new(name: String, size: u64, last_modified: SystemTime, links: Vec<String>) -> Self {
        Self {
            name,
            size,
            last_modified,
            links,
        }
    }

    fn links(&self) -> &Vec<String> {
        &self.links
    }

    fn destruct(self) -> (String, u64, SystemTime, Vec<String>) {
        (self.name, self.size, self.last_modified, self.links)
    }
}