// Copyright 2015-2019 Parity Technologies (UK) Ltd.
// This file is part of Parity Ethereum.

// Parity Ethereum 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.

// Parity Ethereum 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 Parity Ethereum.  If not, see <http://www.gnu.org/licenses/>.

use super::{
    vault::{VaultDiskDirectory, VAULT_FILE_NAME},
    KeyDirectory, VaultKey, VaultKeyDirectory, VaultKeyDirectoryProvider,
};
use crate::{
    json::{self, Uuid},
    Error, SafeAccount,
};
use cfxkey::Password;
use log::warn;
use std::{
    collections::HashMap,
    fs,
    io::{self, Write},
    path::{Path, PathBuf},
};
use time;

const IGNORED_FILES: &[&str] = &[
    "thumbs.db",
    "address_book.json",
    "dapps_policy.json",
    "dapps_accounts.json",
    "dapps_history.json",
    "vault.json",
];

/// Find a unique filename that does not exist using four-letter random suffix.
pub fn find_unique_filename_using_random_suffix(
    parent_path: &Path, original_filename: &str,
) -> io::Result<String> {
    let mut path = parent_path.join(original_filename);
    let mut deduped_filename = original_filename.to_string();

    if path.exists() {
        const MAX_RETRIES: usize = 500;
        let mut retries = 0;

        while path.exists() {
            if retries >= MAX_RETRIES {
                return Err(io::Error::new(
                    io::ErrorKind::Other,
                    "Exceeded maximum retries when deduplicating filename.",
                ));
            }

            let suffix = crate::random::random_string(4);
            deduped_filename = format!("{}-{}", original_filename, suffix);
            path.set_file_name(&deduped_filename);
            retries += 1;
        }
    }

    Ok(deduped_filename)
}

/// Create a new file and restrict permissions to owner only. It errors if the
/// file already exists.
#[cfg(unix)]
pub fn create_new_file_with_permissions_to_owner(
    file_path: &Path,
) -> io::Result<fs::File> {
    use std::os::unix::fs::OpenOptionsExt;

    fs::OpenOptions::new()
        .write(true)
        .create_new(true)
        .mode((libc::S_IWUSR | libc::S_IRUSR) as u32)
        .open(file_path)
}

/// Create a new file and restrict permissions to owner only. It errors if the
/// file already exists.
#[cfg(not(unix))]
pub fn create_new_file_with_permissions_to_owner(
    file_path: &Path,
) -> io::Result<fs::File> {
    fs::OpenOptions::new()
        .write(true)
        .create_new(true)
        .open(file_path)
}

/// Create a new file and restrict permissions to owner only. It replaces the
/// existing file if it already exists.
#[cfg(unix)]
pub fn replace_file_with_permissions_to_owner(
    file_path: &Path,
) -> io::Result<fs::File> {
    use std::os::unix::fs::PermissionsExt;

    let file = fs::File::create(file_path)?;
    let mut permissions = file.metadata()?.permissions();
    permissions.set_mode((libc::S_IWUSR | libc::S_IRUSR) as u32);
    file.set_permissions(permissions)?;

    Ok(file)
}

/// Create a new file and restrict permissions to owner only. It replaces the
/// existing file if it already exists.
#[cfg(not(unix))]
pub fn replace_file_with_permissions_to_owner(
    file_path: &Path,
) -> io::Result<fs::File> {
    fs::File::create(file_path)
}

/// Root keys directory implementation
pub type RootDiskDirectory = DiskDirectory<DiskKeyFileManager>;

/// Disk directory key file manager
pub trait KeyFileManager: Send + Sync {
    /// Read `SafeAccount` from given key file stream
    fn read<T>(
        &self, filename: Option<String>, reader: T,
    ) -> Result<SafeAccount, Error>
    where T: io::Read;

    /// Write `SafeAccount` to given key file stream
    fn write<T>(
        &self, account: SafeAccount, writer: &mut T,
    ) -> Result<(), Error>
    where T: io::Write;
}

/// Disk-based keys directory implementation
pub struct DiskDirectory<T>
where T: KeyFileManager
{
    path: PathBuf,
    key_manager: T,
}

/// Keys file manager for root keys directory
#[derive(Default)]
pub struct DiskKeyFileManager {
    password: Option<Password>,
}

impl RootDiskDirectory {
    pub fn create<P>(path: P) -> Result<Self, Error>
    where P: AsRef<Path> {
        fs::create_dir_all(&path)?;
        Ok(Self::at(path))
    }

    /// allows to read keyfiles with given password (needed for keyfiles w/o
    /// address)
    pub fn with_password(&self, password: Option<Password>) -> Self {
        DiskDirectory::new(&self.path, DiskKeyFileManager { password })
    }

    pub fn at<P>(path: P) -> Self
    where P: AsRef<Path> {
        DiskDirectory::new(path, DiskKeyFileManager::default())
    }
}

impl<T> DiskDirectory<T>
where T: KeyFileManager
{
    /// Create new disk directory instance
    pub fn new<P>(path: P, key_manager: T) -> Self
    where P: AsRef<Path> {
        DiskDirectory {
            path: path.as_ref().to_path_buf(),
            key_manager,
        }
    }

    fn files(&self) -> Result<Vec<PathBuf>, Error> {
        Ok(fs::read_dir(&self.path)?
            .flat_map(Result::ok)
            .filter(|entry| {
                let metadata = entry.metadata().ok();
                let file_name = entry.file_name();
                let name = file_name.to_string_lossy();
                // filter directories
                metadata.map_or(false, |m| !m.is_dir()) &&
					// hidden files
					!name.starts_with('.') &&
					// other ignored files
					!IGNORED_FILES.contains(&&*name)
            })
            .map(|entry| entry.path())
            .collect::<Vec<PathBuf>>())
    }

    pub fn files_hash(&self) -> Result<u64, Error> {
        use std::{collections::hash_map::DefaultHasher, hash::Hasher};

        let mut hasher = DefaultHasher::new();
        let files = self.files()?;
        for file in files {
            hasher.write(file.to_str().unwrap_or("").as_bytes())
        }

        Ok(hasher.finish())
    }

    fn last_modification_date(&self) -> Result<u64, Error> {
        use std::time::UNIX_EPOCH;
        let duration = fs::metadata(&self.path)?
            .modified()?
            .duration_since(UNIX_EPOCH)
            .unwrap_or_default();
        let timestamp = duration.as_secs() ^ (duration.subsec_nanos() as u64);
        Ok(timestamp)
    }

    /// all accounts found in keys directory
    fn files_content(&self) -> Result<HashMap<PathBuf, SafeAccount>, Error> {
        // it's not done using one iterator cause
        // there is an issue with rustc and it takes tooo much time to compile
        let paths = self.files()?;
        Ok(paths
            .into_iter()
            .filter_map(|path| {
                let filename = Some(
                    path.file_name()
                        .and_then(|n| n.to_str())
                        .expect("Keys have valid UTF8 names only.")
                        .to_owned(),
                );
                fs::File::open(path.clone())
                    .map_err(Into::into)
                    .and_then(|file| self.key_manager.read(filename, file))
                    .map_err(|err| {
                        warn!("Invalid key file: {:?} ({})", path, err);
                        err
                    })
                    .map(|account| (path, account))
                    .ok()
            })
            .collect())
    }

    /// insert account with given filename. if the filename is a duplicate of
    /// any stored account and dedup is set to true, a random suffix is
    /// appended to the filename.
    pub fn insert_with_filename(
        &self, account: SafeAccount, mut filename: String, dedup: bool,
    ) -> Result<SafeAccount, Error> {
        if dedup {
            filename = find_unique_filename_using_random_suffix(
                &self.path, &filename,
            )?;
        }

        // path to keyfile
        let keyfile_path = self.path.join(filename.as_str());

        // update account filename
        let original_account = account.clone();
        let mut account = account;
        account.filename = Some(filename);

        {
            // save the file
            let mut file = if dedup {
                create_new_file_with_permissions_to_owner(&keyfile_path)?
            } else {
                replace_file_with_permissions_to_owner(&keyfile_path)?
            };

            // write key content
            self.key_manager
                .write(original_account, &mut file)
                .map_err(|e| Error::Custom(format!("{:?}", e)))?;

            file.flush()?;
            file.sync_all()?;
        }

        Ok(account)
    }

    /// Get key file manager referece
    pub fn key_manager(&self) -> &T { &self.key_manager }
}

impl<T> KeyDirectory for DiskDirectory<T>
where T: KeyFileManager
{
    fn load(&self) -> Result<Vec<SafeAccount>, Error> {
        let accounts = self
            .files_content()?
            .into_iter()
            .map(|(_, account)| account)
            .collect();
        Ok(accounts)
    }

    fn update(&self, account: SafeAccount) -> Result<SafeAccount, Error> {
        // Disk store handles updates correctly iff filename is the same
        let filename = account_filename(&account);
        self.insert_with_filename(account, filename, false)
    }

    fn insert(&self, account: SafeAccount) -> Result<SafeAccount, Error> {
        let filename = account_filename(&account);
        self.insert_with_filename(account, filename, true)
    }

    fn remove(&self, account: &SafeAccount) -> Result<(), Error> {
        // enumerate all entries in keystore
        // and find entry with given address
        let to_remove =
            self.files_content()?.into_iter().find(|&(_, ref acc)| {
                acc.id == account.id && acc.address == account.address
            });

        // remove it
        match to_remove {
            None => Err(Error::InvalidAccount),
            Some((path, _)) => fs::remove_file(path).map_err(From::from),
        }
    }

    fn path(&self) -> Option<&PathBuf> { Some(&self.path) }

    fn as_vault_provider(&self) -> Option<&dyn VaultKeyDirectoryProvider> {
        Some(self)
    }

    fn unique_repr(&self) -> Result<u64, Error> {
        self.last_modification_date()
    }
}

impl<T> VaultKeyDirectoryProvider for DiskDirectory<T>
where T: KeyFileManager
{
    fn create(
        &self, name: &str, key: VaultKey,
    ) -> Result<Box<dyn VaultKeyDirectory>, Error> {
        let vault_dir = VaultDiskDirectory::create(&self.path, name, key)?;
        Ok(Box::new(vault_dir))
    }

    fn open(
        &self, name: &str, key: VaultKey,
    ) -> Result<Box<dyn VaultKeyDirectory>, Error> {
        let vault_dir = VaultDiskDirectory::at(&self.path, name, key)?;
        Ok(Box::new(vault_dir))
    }

    fn list_vaults(&self) -> Result<Vec<String>, Error> {
        Ok(fs::read_dir(&self.path)?
            .filter_map(|e| e.ok().map(|e| e.path()))
            .filter_map(|path| {
                let mut vault_file_path = path.clone();
                vault_file_path.push(VAULT_FILE_NAME);
                if vault_file_path.is_file() {
                    path.file_name()
                        .and_then(|f| f.to_str())
                        .map(|f| f.to_owned())
                } else {
                    None
                }
            })
            .collect())
    }

    fn vault_meta(&self, name: &str) -> Result<String, Error> {
        VaultDiskDirectory::meta_at(&self.path, name)
    }
}

impl KeyFileManager for DiskKeyFileManager {
    fn read<T>(
        &self, filename: Option<String>, reader: T,
    ) -> Result<SafeAccount, Error>
    where T: io::Read {
        let key_file = json::KeyFile::load(reader)
            .map_err(|e| Error::Custom(format!("{:?}", e)))?;
        SafeAccount::from_file(key_file, filename, &self.password)
    }

    fn write<T>(
        &self, mut account: SafeAccount, writer: &mut T,
    ) -> Result<(), Error>
    where T: io::Write {
        // when account is moved back to root directory from vault
        // => remove vault field from meta
        account.meta = json::remove_vault_name_from_json_meta(&account.meta)
            .map_err(|err| Error::Custom(format!("{:?}", err)))?;

        let key_file: json::KeyFile = account.into();
        key_file
            .write(writer)
            .map_err(|e| Error::Custom(format!("{:?}", e)))
    }
}

fn account_filename(account: &SafeAccount) -> String {
    // build file path
    account.filename.clone().unwrap_or_else(|| {
        let timestamp = time::strftime("%Y-%m-%dT%H-%M-%S", &time::now_utc())
            .expect("Time-format string is valid.");
        format!("UTC--{}Z--{}", timestamp, Uuid::from(account.id))
    })
}

#[cfg(test)]
mod test {
    use super::{KeyDirectory, RootDiskDirectory, VaultKey};
    use crate::account::SafeAccount;
    use cfxkey::{Generator, Random};
    use std::{env, fs};
    use tempdir::TempDir;

    #[test]
    fn should_create_new_account() {
        // given
        let mut dir = env::temp_dir();
        dir.push("cfxstore_should_create_new_account");
        let keypair = Random.generate().unwrap();
        let password = "hello world".into();
        let directory = RootDiskDirectory::create(dir.clone()).unwrap();

        // when
        let account = SafeAccount::create(
            &keypair,
            [0u8; 16],
            &password,
            1024,
            "Test".to_owned(),
            "{}".to_owned(),
        );
        let res = directory.insert(account.unwrap());

        // then
        assert!(res.is_ok(), "Should save account succesfuly.");
        assert!(
            res.unwrap().filename.is_some(),
            "Filename has been assigned."
        );

        // cleanup
        let _ = fs::remove_dir_all(dir);
    }

    #[test]
    fn should_handle_duplicate_filenames() {
        // given
        let mut dir = env::temp_dir();
        dir.push("cfxstore_should_handle_duplicate_filenames");
        let keypair = Random.generate().unwrap();
        let password = "hello world".into();
        let directory = RootDiskDirectory::create(dir.clone()).unwrap();

        // when
        let account = SafeAccount::create(
            &keypair,
            [0u8; 16],
            &password,
            1024,
            "Test".to_owned(),
            "{}".to_owned(),
        )
        .unwrap();
        let filename = "test".to_string();
        let dedup = true;

        directory
            .insert_with_filename(account.clone(), "foo".to_string(), dedup)
            .unwrap();
        let file1 = directory
            .insert_with_filename(account.clone(), filename.clone(), dedup)
            .unwrap()
            .filename
            .unwrap();
        let file2 = directory
            .insert_with_filename(account.clone(), filename.clone(), dedup)
            .unwrap()
            .filename
            .unwrap();
        let file3 = directory
            .insert_with_filename(account, filename.clone(), dedup)
            .unwrap()
            .filename
            .unwrap();

        // then
        // the first file should have the original names
        assert_eq!(file1, filename);

        // the following duplicate files should have a suffix appended
        assert!(file2 != file3);
        assert_eq!(file2.len(), filename.len() + 5);
        assert_eq!(file3.len(), filename.len() + 5);

        // cleanup
        let _ = fs::remove_dir_all(dir);
    }

    #[test]
    fn should_manage_vaults() {
        // given
        let mut dir = env::temp_dir();
        dir.push("should_create_new_vault");
        let directory = RootDiskDirectory::create(dir.clone()).unwrap();
        let vault_name = "vault";
        let password = "password".into();

        // then
        assert!(directory.as_vault_provider().is_some());

        // and when
        let before_root_items_count = fs::read_dir(&dir).unwrap().count();
        let vault = directory
            .as_vault_provider()
            .unwrap()
            .create(vault_name, VaultKey::new(&password, 1024));

        // then
        assert!(vault.is_ok());
        let after_root_items_count = fs::read_dir(&dir).unwrap().count();
        assert!(after_root_items_count > before_root_items_count);

        // and when
        let vault = directory
            .as_vault_provider()
            .unwrap()
            .open(vault_name, VaultKey::new(&password, 1024));

        // then
        assert!(vault.is_ok());
        let after_root_items_count2 = fs::read_dir(&dir).unwrap().count();
        assert!(after_root_items_count == after_root_items_count2);

        // cleanup
        let _ = fs::remove_dir_all(dir);
    }

    #[test]
    fn should_list_vaults() {
        // given
        let temp_path = TempDir::new("").unwrap();
        let directory = RootDiskDirectory::create(&temp_path).unwrap();
        let vault_provider = directory.as_vault_provider().unwrap();
        vault_provider
            .create("vault1", VaultKey::new(&"password1".into(), 1))
            .unwrap();
        vault_provider
            .create("vault2", VaultKey::new(&"password2".into(), 1))
            .unwrap();

        // then
        let vaults = vault_provider.list_vaults().unwrap();
        assert_eq!(vaults.len(), 2);
        assert!(vaults.iter().any(|v| &*v == "vault1"));
        assert!(vaults.iter().any(|v| &*v == "vault2"));
    }

    #[test]
    fn hash_of_files() {
        let temp_path = TempDir::new("").unwrap();
        let directory = RootDiskDirectory::create(&temp_path).unwrap();

        let hash = directory
            .files_hash()
            .expect("Files hash should be calculated ok");
        assert_eq!(hash, 15_130_871_412_783_076_140);

        let keypair = Random.generate().unwrap();
        let password = "test pass".into();
        let account = SafeAccount::create(
            &keypair,
            [0u8; 16],
            &password,
            1024,
            "Test".to_owned(),
            "{}".to_owned(),
        );
        directory
            .insert(account.unwrap())
            .expect("Account should be inserted ok");

        let new_hash = directory
            .files_hash()
            .expect("New files hash should be calculated ok");

        assert!(new_hash != hash, "hash of the file list should change once directory content changed");
    }
}