// Copyright 2015-2018 Parity Technologies (UK) Ltd.
// This file is part of Parity.

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

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

const IGNORED_FILES: &'static [&'static 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 = ::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 libc;
	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 libc;
	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
pub struct DiskKeyFileManager;

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

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

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: 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;
		use std::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::{Duration, UNIX_EPOCH};
		let duration = fs::metadata(&self.path)?.modified()?.duration_since(UNIX_EPOCH).unwrap_or(Duration::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<&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<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<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)))?;
		Ok(SafeAccount::from_file(key_file, filename))
	}

	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 {
	extern crate tempdir;

	use std::{env, fs};
	use super::{KeyDirectory, RootDiskDirectory, VaultKey};
	use account::SafeAccount;
	use ethkey::{Random, Generator};
	use self::tempdir::TempDir;

	#[test]
	fn should_create_new_account() {
		// given
		let mut dir = env::temp_dir();
		dir.push("ethstore_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("ethstore_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.clone(), 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,
			15130871412783076140
		);

		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");
	}
}