path: root/lib/entry/libimagentryref/src/reference.rs

//
// imag - the personal information management suite for the commandline
// Copyright (C) 2015-2019 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
//

use std::path::Path;
use std::path::PathBuf;
use std::collections::BTreeMap;
use std::ops::Deref;

use libimagentryutil::isa::Is;
use libimagentryutil::isa::IsKindHeaderPathProvider;
use libimagerror::errors::ErrorMsg as EM;

use toml::Value;
use toml_query::read::TomlValueReadExt;
use toml_query::delete::TomlValueDeleteExt;
use toml_query::insert::TomlValueInsertExt;
use failure::Fallible as Result;
use failure::Error;
use failure::err_msg;
use failure::ResultExt;

use hasher::Hasher;

/// A configuration of "collection name" -> "collection path" mappings
///
/// Should be deserializeable from the configuration file right away, because we expect a
/// configuration like this in the config file:
///
/// ```toml
/// [ref.collections]
/// music = "/home/alice/music"
/// documents = "/home/alice/doc"
/// ```
///
/// for example.
#[derive(Serialize, Deserialize, Debug, Clone)]
pub struct Config(BTreeMap<String, PathBuf>);

impl Config {
    pub fn new(map: BTreeMap<String, PathBuf>) -> Self {
        Config(map)
    }
}

impl Deref for Config {
    type Target = BTreeMap<String, PathBuf>;

    fn deref(&self) -> &Self::Target {
        &self.0
    }
}

provide_kindflag_path!(pub IsRef, "ref.is_ref");

/// Fassade module
///
/// This module is necessary to build a generic fassade around the "entry with a (default) hasher to
/// represent the entry as a ref".
///
/// The module is for code-structuring only, all types in the module are exported publicly in the
/// supermodule.
pub mod fassade {
    use std::marker::PhantomData;

    use libimagstore::store::Entry;
    use libimagentryutil::isa::Is;

    use failure::Fallible as Result;
    use failure::Error;

    use hasher::sha1::Sha1Hasher;
    use hasher::Hasher;
    use super::IsRef;

    pub trait RefFassade {
        fn is_ref(&self)                                -> Result<bool>;
        fn as_ref_with_hasher<H: Hasher>(&self)         -> RefWithHasher<H>;
        fn as_ref_with_hasher_mut<H: Hasher>(&mut self) -> MutRefWithHasher<H>;
    }

    impl RefFassade for Entry {
        /// Check whether the underlying object is actually a ref
        fn is_ref(&self) -> Result<bool> {
            self.is::<IsRef>().map_err(Error::from)
        }

        fn as_ref_with_hasher<H: Hasher>(&self)     -> RefWithHasher<H> {
            RefWithHasher::new(self)
        }

        fn as_ref_with_hasher_mut<H: Hasher>(&mut self) -> MutRefWithHasher<H> {
            MutRefWithHasher::new(self)
        }

    }

    pub struct RefWithHasher<'a, H: Hasher = Sha1Hasher>(pub(crate) &'a Entry, PhantomData<H>);

    impl<'a, H> RefWithHasher<'a, H>
        where H: Hasher
    {
        fn new(entry: &'a Entry) -> Self {
            RefWithHasher(entry, PhantomData)
        }
    }

    pub struct MutRefWithHasher<'a, H: Hasher = Sha1Hasher>(pub(crate) &'a mut Entry, PhantomData<H>);

    impl<'a, H> MutRefWithHasher<'a, H>
        where H: Hasher
    {
        fn new(entry: &'a mut Entry) -> Self {
            MutRefWithHasher(entry, PhantomData)
        }
    }
}
pub use self::fassade::*;


pub trait Ref {

    /// Check whether the underlying object is actually a ref
    fn is_ref(&self) -> Result<bool>;

    /// Get the stored hash.
    fn get_path(&self) -> Result<PathBuf>;

    /// Get the stored hash.
    fn get_hash(&self) -> Result<&str>;

    /// Check whether the referenced file still matches its hash
    fn hash_valid(&self, config: &Config) -> Result<bool>;
}

impl<'a, H: Hasher> Ref for RefWithHasher<'a, H> {

    /// Check whether the underlying object is actually a ref
    fn is_ref(&self) -> Result<bool> {
        self.0.is::<IsRef>().map_err(Error::from)
    }

    fn get_hash(&self) -> Result<&str> {
        let header_path = format!("ref.hash.{}", H::NAME);
        self.0
            .get_header()
            .read(&header_path)
            .map_err(Error::from)?
            .ok_or_else(|| {
                Error::from(EM::EntryHeaderFieldMissing("ref.hash.<hash>"))
            })
            .and_then(|v| {
                v.as_str().ok_or_else(|| {
                    Error::from(EM::EntryHeaderTypeError2("ref.hash.<hash>", "string"))
                })
            })
    }

    fn get_path(&self) -> Result<PathBuf> {
        self.0
            .get_header()
            .read("ref.path")
            .map_err(Error::from)?
            .ok_or_else(|| Error::from(EM::EntryHeaderFieldMissing("ref.path")))
            .and_then(|v| {
                v.as_str()
                    .ok_or_else(|| EM::EntryHeaderTypeError2("ref.path", "string"))
                    .map_err(Error::from)
            })
            .map(PathBuf::from)
    }

    fn hash_valid(&self, config: &Config) -> Result<bool> {
        let ref_header = self.0
            .get_header()
            .read("ref")?
            .ok_or_else(|| err_msg("Header missing at 'ref'"))?;

        let collection_name = ref_header
            .read("collection")
            .map_err(Error::from)?
            .ok_or_else(|| err_msg("Header missing at 'ref.collection'"))?
            .as_str()
            .ok_or_else(|| Error::from(EM::EntryHeaderTypeError2("ref.hash.<hash>", "string")))?;

        let path = ref_header
            .read("path")
            .map_err(Error::from)?
            .ok_or_else(|| err_msg("Header missing at 'ref.path'"))?
            .as_str()
            .map(PathBuf::from)
            .ok_or_else(|| Error::from(EM::EntryHeaderTypeError2("ref.hash.<hash>", "string")))?;


        let file_path = get_file_path(config, collection_name.as_ref(), &path)?;

        ref_header
            .read(H::NAME)
            .map_err(Error::from)?
            .ok_or_else(|| format_err!("Header missing at 'ref.{}'", H::NAME))
            .and_then(|v| {
                v.as_str().ok_or_else(|| {
                    Error::from(EM::EntryHeaderTypeError2("ref.hash.<hash>", "string"))
                })
            })
            .and_then(|hash| H::hash(file_path).map(|h| h == hash))
    }

}

pub trait MutRef {
    fn remove_ref(&mut self) -> Result<()>;

    /// Make a ref out of a normal (non-ref) entry.
    ///
    /// If the entry is already a ref, this fails if `force` is false
    fn make_ref<P, Coll>(&mut self, path: P, collection_name: Coll, config: &Config, force: bool)
        -> Result<()>
        where P: AsRef<Path>,
              Coll: AsRef<str>;
}


impl<'a,