// Copyright 2015-2020 Parity Technologies (UK) Ltd.
// This file is part of OpenEthereum.

// OpenEthereum is free software: you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.

// OpenEthereum 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 General Public License for more details.

// You should have received a copy of the GNU General Public License
// along with OpenEthereum.  If not, see <http://www.gnu.org/licenses/>.

//! Address Book Store

use std::{
    collections::HashMap,
    fmt, fs, hash, ops,
    path::{Path, PathBuf},
};

use ethkey::Address;
use log::{trace, warn};

use crate::AccountMeta;

/// Disk-backed map from Address to String. Uses JSON.
pub struct AddressBook {
    cache: DiskMap<Address, AccountMeta>,
}

impl AddressBook {
    /// Creates new address book at given directory.
    pub fn new(path: &Path) -> Self {
        let mut r = AddressBook {
            cache: DiskMap::new(path, "address_book.json"),
        };
        r.cache.revert(AccountMeta::read);
        r
    }

    /// Creates transient address book (no changes are saved to disk).
    pub fn transient() -> Self {
        AddressBook {
            cache: DiskMap::transient(),
        }
    }

    /// Get the address book.
    pub fn get(&self) -> HashMap<Address, AccountMeta> {
        self.cache.clone()
    }

    fn save(&self) {
        self.cache.save(AccountMeta::write)
    }

    /// Sets new name for given address.
    pub fn set_name(&mut self, a: Address, name: String) {
        {
            let x = self.cache.entry(a).or_insert_with(|| AccountMeta {
                name: Default::default(),
                meta: "{}".to_owned(),
                uuid: None,
            });
            x.name = name;
        }
        self.save();
    }

    /// Sets new meta for given address.
    pub fn set_meta(&mut self, a: Address, meta: String) {
        {
            let x = self.cache.entry(a).or_insert_with(|| AccountMeta {
                name: "Anonymous".to_owned(),
                meta: Default::default(),
                uuid: None,
            });
            x.meta = meta;
        }
        self.save();
    }

    /// Removes an entry
    pub fn remove(&mut self, a: Address) {
        self.cache.remove(&a);
        self.save();
    }
}

/// Disk-serializable HashMap
#[derive(Debug)]
struct DiskMap<K: hash::Hash + Eq, V> {
    path: PathBuf,
    cache: HashMap<K, V>,
    transient: bool,
}

impl<K: hash::Hash + Eq, V> ops::Deref for DiskMap<K, V> {
    type Target = HashMap<K, V>;
    fn deref(&self) -> &Self::Target {
        &self.cache
    }
}

impl<K: hash::Hash + Eq, V> ops::DerefMut for DiskMap<K, V> {
    fn deref_mut(&mut self) -> &mut Self::Target {
        &mut self.cache
    }
}

impl<K: hash::Hash + Eq, V> DiskMap<K, V> {
    pub fn new(path: &Path, file_name: &str) -> Self {
        let mut path = path.to_owned();
        path.push(file_name);
        trace!(target: "diskmap", "path={:?}", path);
        DiskMap {
            path: path,
            cache: HashMap::new(),
            transient: false,
        }
    }

    pub fn transient() -> Self {
        let mut map = DiskMap::new(&PathBuf::new(), "diskmap.json".into());
        map.transient = true;
        map
    }

    fn revert<F, E>(&mut self, read: F)
    where
        F: Fn(fs::File) -> Result<HashMap<K, V>, E>,
        E: fmt::Display,
    {
        if self.transient {
            return;
        }
        trace!(target: "diskmap", "revert {:?}", self.path);
        let _ = fs::File::open(self.path.clone())
            .map_err(|e| trace!(target: "diskmap", "Couldn't open disk map: {}", e))
            .and_then(|f| {
                read(f).map_err(|e| warn!(target: "diskmap", "Couldn't read disk map: {}", e))
            })
            .and_then(|m| {
                self.cache = m;
                Ok(())
            });
    }

    fn save<F, E>(&self, write: F)
    where
        F: Fn(&HashMap<K, V>, &mut fs::File) -> Result<(), E>,
        E: fmt::Display,
    {
        if self.transient {
            return;
        }
        trace!(target: "diskmap", "save {:?}", self.path);
        let _ = fs::File::create(self.path.clone())
            .map_err(|e| warn!(target: "diskmap", "Couldn't open disk map for writing: {}", e))
            .and_then(|mut f| {
                write(&self.cache, &mut f)
                    .map_err(|e| warn!(target: "diskmap", "Couldn't write to disk map: {}", e))
            });
    }
}

#[cfg(test)]
mod tests {
    use super::AddressBook;
    use crate::account_data::AccountMeta;
    use std::collections::HashMap;
    use tempdir::TempDir;

    #[test]
    fn should_save_and_reload_address_book() {
        let tempdir = TempDir::new("").unwrap();
        let mut b = AddressBook::new(tempdir.path());
        b.set_name(1.into(), "One".to_owned());
        b.set_meta(1.into(), "{1:1}".to_owned());
        let b = AddressBook::new(tempdir.path());
        assert_eq!(
            b.get(),
            vec![(
                1,
                AccountMeta {
                    name: "One".to_owned(),
                    meta: "{1:1}".to_owned(),
                    uuid: None
                }
            )]
            .into_iter()
            .map(|(a, b)| (a.into(), b))
            .collect::<HashMap<_, _>>()
        );
    }

    #[test]
    fn should_remove_address() {
        let tempdir = TempDir::new("").unwrap();
        let mut b = AddressBook::new(tempdir.path());

        b.set_name(1.into(), "One".to_owned());
        b.set_name(2.into(), "Two".to_owned());
        b.set_name(3.into(), "Three".to_owned());
        b.remove(2.into());

        let b = AddressBook::new(tempdir.path());
        assert_eq!(
            b.get(),
            vec![
                (
                    1,
                    AccountMeta {
                        name: "One".to_owned(),
                        meta: "{}".to_owned(),
                        uuid: None
                    }
                ),
                (
                    3,
                    AccountMeta {
                        name: "Three".to_owned(),
                        meta: "{}".to_owned(),
                        uuid: None
                    }
                ),
            ]
            .into_iter()
            .map(|(a, b)| (a.into(), b))
            .collect::<HashMap<_, _>>()
        );
    }
}