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imag/lib/entry/libimagentrylink/src/external.rs

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Rust
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//
// imag - the personal information management suite for the commandline
// Copyright (C) 2015, 2016 Matthias Beyer <mail@beyermatthias.de> and contributors
//
// This library is free software; you can redistribute it and/or
// modify it under the terms of the GNU Lesser General Public
// License as published by the Free Software Foundation; version
// 2.1 of the License.
//
// This library is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
// Lesser General Public License for more details.
//
// You should have received a copy of the GNU Lesser General Public
// License along with this library; if not, write to the Free Software
// Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
//
/// External linking is a complex implementation to be able to serve a clean and easy-to-use
/// interface.
///
/// Internally, there are no such things as "external links" (plural). Each Entry in the store can
/// only have _one_ external link.
///
/// This library does the following therefor: It allows you to have several external links with one
/// entry, which are internally one file in the store for each link, linked with "internal
/// linking".
///
/// This helps us greatly with deduplication of URLs.
///
use std::ops::DerefMut;
use std::collections::BTreeMap;
use std::fmt::Debug;
use libimagstore::store::Entry;
use libimagstore::store::Store;
use libimagstore::storeid::StoreId;
use libimagstore::storeid::IntoStoreId;
use libimagutil::debug_result::*;
use toml_query::read::TomlValueReadExt;
use toml_query::read::TomlValueReadTypeExt;
use toml_query::insert::TomlValueInsertExt;
use error::LinkErrorKind as LEK;
use error::Result;
use internal::InternalLinker;
use module_path::ModuleEntryPath;
use error::ResultExt;
use self::iter::*;
use toml::Value;
use url::Url;
use crypto::sha1::Sha1;
use crypto::digest::Digest;
pub trait Link {
fn get_link_uri_from_filelockentry(&self) -> Result<Option<Url>>;
fn get_url(&self) -> Result<Option<Url>>;
}
impl Link for Entry {
fn get_link_uri_from_filelockentry(&self) -> Result<Option<Url>> {
self.get_header()
.read_string("links.external.content.url")
.chain_err(|| LEK::EntryHeaderReadError)
.and_then(|opt| match opt {
None => Ok(None),
Some(ref s) => {
debug!("Found url, parsing: {:?}", s);
Url::parse(&s[..]).chain_err(|| LEK::InvalidUri).map(Some)
},
})
}
fn get_url(&self) -> Result<Option<Url>> {
match self.get_header().read_string("links.external.url")? {
None => Ok(None),
Some(ref s) => Url::parse(&s[..])
.map(Some)
.chain_err(|| LEK::EntryHeaderReadError),
}
}
}
pub trait ExternalLinker : InternalLinker {
/// Get the external links from the implementor object
fn get_external_links<'a>(&self, store: &'a Store) -> Result<UrlIter<'a>>;
/// Set the external links for the implementor object
fn set_external_links(&mut self, store: &Store, links: Vec<Url>) -> Result<()>;
/// Add an external link to the implementor object
fn add_external_link(&mut self, store: &Store, link: Url) -> Result<()>;
/// Remove an external link from the implementor object
fn remove_external_link(&mut self, store: &Store, link: Url) -> Result<()>;
}
pub mod iter {
//! Iterator helpers for external linking stuff
//!
//! Contains also helpers to filter iterators for external/internal links
//!
//!
//! # Warning
//!
//! This module uses `internal::Link` as link type, so we operate on _store ids_ here.
//!
//! Not to confuse with `external::Link` which is a real `FileLockEntry` under the hood.
//!
use libimagutil::debug_result::*;
use libimagstore::store::Store;
use internal::Link;
use internal::iter::LinkIter;
use error::Result;
use url::Url;
/// Helper for building `OnlyExternalIter` and `NoExternalIter`
///
/// The boolean value defines, how to interpret the `is_external_link_storeid()` return value
/// (here as "pred"):
///
/// pred | bool | xor | take?
/// ---- | ---- | --- | ----
/// 0 | 0 | 0 | 1
/// 0 | 1 | 1 | 0
/// 1 | 0 | 1 | 0
/// 1 | 1 | 0 | 1
///
/// If `bool` says "take if return value is false", we take the element if the `pred` returns
/// false... and so on.
///
/// As we can see, the operator between these two operants is `!(a ^ b)`.
pub struct ExternalFilterIter(LinkIter, bool);
impl Iterator for ExternalFilterIter {
type Item = Link;
fn next(&mut self) -> Option<Self::Item> {
use super::is_external_link_storeid;
while let Some(elem) = self.0.next() {
trace!("Check whether is external: {:?}", elem);
if !(self.1 ^ is_external_link_storeid(&elem)) {
trace!("Is external id: {:?}", elem);
return Some(elem);
}
}
None
}
}
/// Helper trait to be implemented on `LinkIter` to select or deselect all external links
///
/// # See also
///
/// Also see `OnlyExternalIter` and `NoExternalIter` and the helper traits/functions
/// `OnlyInteralLinks`/`only_internal_links()` and `OnlyExternalLinks`/`only_external_links()`.
pub trait SelectExternal {
fn select_external_links(self, b: bool) -> ExternalFilterIter;
}
impl SelectExternal for LinkIter {
fn select_external_links(self, b: bool) -> ExternalFilterIter {
ExternalFilterIter(self, b)
}
}
pub struct OnlyExternalIter(ExternalFilterIter);
impl OnlyExternalIter {
pub fn new(li: LinkIter) -> OnlyExternalIter {
OnlyExternalIter(ExternalFilterIter(li, true))
}
pub fn urls<'a>(self, store: &'a Store) -> UrlIter<'a> {
UrlIter(self, store)
}
}
impl Iterator for OnlyExternalIter {
type Item = Link;
fn next(&mut self) -> Option<Self::Item> {
self.0.next()
}
}
pub struct NoExternalIter(ExternalFilterIter);
impl NoExternalIter {
pub fn new(li: LinkIter) -> NoExternalIter {
NoExternalIter(ExternalFilterIter(li, false))
}
}
impl Iterator for NoExternalIter {
type Item = Link;
fn next(&mut self) -> Option<Self::Item> {
self.0.next()
}
}
pub trait OnlyExternalLinks : Sized {
fn only_external_links(self) -> OnlyExternalIter ;
fn no_internal_links(self) -> OnlyExternalIter {
self.only_external_links()
}
}
impl OnlyExternalLinks for LinkIter {
fn only_external_links(self) -> OnlyExternalIter {
OnlyExternalIter::new(self)
}
}
pub trait OnlyInternalLinks : Sized {
fn only_internal_links(self) -> NoExternalIter;
fn no_external_links(self) -> NoExternalIter {
self.only_internal_links()
}
}
impl OnlyInternalLinks for LinkIter {
fn only_internal_links(self) -> NoExternalIter {
NoExternalIter::new(self)
}
}
pub struct UrlIter<'a>(OnlyExternalIter, &'a Store);
impl<'a> Iterator for UrlIter<'a> {
type Item = Result<Url>;
fn next(&mut self) -> Option<Self::Item> {
use external::Link;
loop {
let next = self.0
.next()
.map(|id| {
debug!("Retrieving entry for id: '{:?}'", id);
self.1
.retrieve(id.clone())
.map_dbg_err(|_| format!("Retrieving entry for id: '{:?}' failed", id))
.map_err(From::from)
.and_then(|f| {
debug!("Store::retrieve({:?}) succeeded", id);
debug!("getting external link from file now");
f.get_link_uri_from_filelockentry()
.map_dbg_str("Error happened while getting link URI from FLE")
.map_dbg_err(|e| format!("URL -> Err = {:?}", e))
})
});
match next {
Some(Ok(Some(link))) => return Some(Ok(link)),
Some(Ok(None)) => continue,
Some(Err(e)) => return Some(Err(e)),
None => return None
}
}
}
}
}
/// Check whether the StoreId starts with `/link/external/`
pub fn is_external_link_storeid<A: AsRef<StoreId> + Debug>(id: A) -> bool {
debug!("Checking whether this is a 'links/external/': '{:?}'", id);
id.as_ref().local().starts_with("links/external")
}
/// Implement `ExternalLinker` for `Entry`, hiding the fact that there is no such thing as an external
/// link in an entry, but internal links to other entries which serve as external links, as one
/// entry in the store can only have one external link.
impl ExternalLinker for Entry {
/// Get the external links from the implementor object
fn get_external_links<'a>(&self, store: &'a Store) -> Result<UrlIter<'a>> {
// Iterate through all internal links and filter for FileLockEntries which live in
// /link/external/<SHA> -> load these files and get the external link from their headers,
// put them into the return vector.
self.get_internal_links()
.map(|iter| {
debug!("Getting external links");
iter.only_external_links().urls(store)
})
}
/// Set the external links for the implementor object
fn set_external_links(&mut self, store: &Store, links: Vec<Url>) -> Result<()> {
// Take all the links, generate a SHA sum out of each one, filter out the already existing
// store entries and store the other URIs in the header of one FileLockEntry each, in
// the path /link/external/<SHA of the URL>
debug!("Iterating {} links = {:?}", links.len(), links);
for link in links { // for all links
let hash = {
let mut s = Sha1::new();
s.input_str(&link.as_str()[..]);
s.result_str()
};
let file_id =
ModuleEntryPath::new(format!("external/{}", hash)).into_storeid()
.map_dbg_err(|_| {
format!("Failed to build StoreId for this hash '{:?}'", hash)
})
?;
debug!("Link = '{:?}'", link);
debug!("Hash = '{:?}'", hash);
debug!("StoreId = '{:?}'", file_id);
// retrieve the file from the store, which implicitely creates the entry if it does not
// exist
let mut file = store
.retrieve(file_id.clone())
.map_dbg_err(|_| {
format!("Failed to create or retrieve an file for this link '{:?}'", link)
})?;
debug!("Generating header content!");
{
let hdr = file.deref_mut().get_header_mut();
let mut table = match hdr.read("links.external.content")? {
Some(&Value::Table(ref table)) => table.clone(),
Some(_) => {
warn!("There is a value at 'links.external.content' which is not a table.");
warn!("Going to override this value");
BTreeMap::new()
},
None => BTreeMap::new(),
};
let v = Value::String(link.into_string());
debug!("setting URL = '{:?}", v);
table.insert(String::from("url"), v);
let _ = hdr.insert("links.external.content", Value::Table(table))?;
debug!("Setting URL worked");
}
// then add an internal link to the new file or return an error if this fails
let _ = self.add_internal_link(file.deref_mut())?;
debug!("Error adding internal link");
}
debug!("Ready iterating");
Ok(())
}
/// Add an external link to the implementor object
fn add_external_link(&mut self, store: &Store, link: Url) -> Result<()> {
// get external links, add this one, save them
debug!("Getting links");
self.get_external_links(store)
.and_then(|links| {
// TODO: Do not ignore errors here
let mut links = links.filter_map(Result::ok).collect::<Vec<_>>();
debug!("Adding link = '{:?}' to links = {:?}", link, links);
links.push(link);
debug!("Setting {} links = {:?}", links.len(), links);
self.set_external_links(store, links)
})
}
/// Remove an external link from the implementor object
fn remove_external_link(&mut self, store: &Store, link: Url) -> Result<()> {
// get external links, remove this one, save them
self.get_external_links(store)
.and_then(|links| {
debug!("Removing link = '{:?}'", link);
let links = links
.filter_map(Result::ok)
.filter(|l| l.as_str() != link.as_str())
.collect::<Vec<_>>();
self.set_external_links(store, links)
})
}
}
#[cfg(test)]
mod tests {
use super::*;
use std::path::PathBuf;
use libimagstore::store::Store;
fn setup_logging() {
use env_logger;
let _ = env_logger::try_init();
}
pub fn get_store() -> Store {
use libimagstore::file_abstraction::InMemoryFileAbstraction;
let backend = Box::new(InMemoryFileAbstraction::new());
Store::new_with_backend(PathBuf::from("/"), &None, backend).unwrap()
}
#[test]
fn test_simple() {
setup_logging();
let store = get_store();
let mut e = store.retrieve(PathBuf::from("base-test_simple")).unwrap();
let url = Url::parse("http://google.de").unwrap();
assert!(e.add_external_link(&store, url.clone()).is_ok());
assert_eq!(1, e.get_external_links(&store).unwrap().count());
assert_eq!(url, e.get_external_links(&store).unwrap().next().unwrap().unwrap());
}
}
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