// This file is part of Substrate.

// Copyright (C) 2017-2020 Parity Technologies (UK) Ltd.
// SPDX-License-Identifier: Apache-2.0

// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// 	http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

// tag::description[]
//! Simple Ed25519 API.
// end::description[]

#[cfg(feature = "full_crypto")]
use sp_std::vec::Vec;

use crate::{hash::H256, hash::H512};
use codec::{Encode, Decode};

#[cfg(feature = "full_crypto")]
use blake2_rfc;
#[cfg(feature = "full_crypto")]
use core::convert::TryFrom;
#[cfg(feature = "full_crypto")]
use ed25519_dalek::{Signer as _, Verifier as _};
#[cfg(feature = "std")]
use substrate_bip39::seed_from_entropy;
#[cfg(feature = "std")]
use bip39::{Mnemonic, Language, MnemonicType};
#[cfg(feature = "full_crypto")]
use crate::crypto::{Pair as TraitPair, DeriveJunction, SecretStringError};
#[cfg(feature = "std")]
use crate::crypto::Ss58Codec;
#[cfg(feature = "std")]
use serde::{de, Serializer, Serialize, Deserializer, Deserialize};
use crate::crypto::{Public as TraitPublic, CryptoTypePublicPair, UncheckedFrom, CryptoType, Derive, CryptoTypeId};
use sp_runtime_interface::pass_by::PassByInner;
use sp_std::ops::Deref;

/// An identifier used to match public keys against ed25519 keys
pub const CRYPTO_ID: CryptoTypeId = CryptoTypeId(*b"ed25");

/// A secret seed. It's not called a "secret key" because ring doesn't expose the secret keys
/// of the key pair (yeah, dumb); as such we're forced to remember the seed manually if we
/// will need it later (such as for HDKD).
#[cfg(feature = "full_crypto")]
type Seed = [u8; 32];

/// A public key.
#[cfg_attr(feature = "full_crypto", derive(Hash))]
#[derive(PartialEq, Eq, PartialOrd, Ord, Clone, Copy, Encode, Decode, Default, PassByInner)]
pub struct Public(pub [u8; 32]);

/// A key pair.
#[cfg(feature = "full_crypto")]
pub struct Pair(ed25519_dalek::Keypair);

#[cfg(feature = "full_crypto")]
impl Clone for Pair {
	fn clone(&self) -> Self {
		Pair(ed25519_dalek::Keypair {
			public: self.0.public.clone(),
			secret: ed25519_dalek::SecretKey::from_bytes(self.0.secret.as_bytes())
				.expect("key is always the correct size; qed")
		})
	}
}

impl AsRef<[u8; 32]> for Public {
	fn as_ref(&self) -> &[u8; 32] {
		&self.0
	}
}

impl AsRef<[u8]> for Public {
	fn as_ref(&self) -> &[u8] {
		&self.0[..]
	}
}

impl AsMut<[u8]> for Public {
	fn as_mut(&mut self) -> &mut [u8] {
		&mut self.0[..]
	}
}

impl Deref for Public {
	type Target = [u8];

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

impl sp_std::convert::TryFrom<&[u8]> for Public {
	type Error = ();

	fn try_from(data: &[u8]) -> Result<Self, Self::Error> {
		if data.len() == 32 {
			let mut inner = [0u8; 32];
			inner.copy_from_slice(data);
			Ok(Public(inner))
		} else {
			Err(())
		}
	}
}

impl From<Public> for [u8; 32] {
	fn from(x: Public) -> Self {
		x.0
	}
}

#[cfg(feature = "full_crypto")]
impl From<Pair> for Public {
	fn from(x: Pair) -> Self {
		x.public()
	}
}

impl From<Public> for H256 {
	fn from(x: Public) -> Self {
		x.0.into()
	}
}

#[cfg(feature = "std")]
impl std::str::FromStr for Public {
	type Err = crate::crypto::PublicError;

	fn from_str(s: &str) -> Result<Self, Self::Err> {
		Self::from_ss58check(s)
	}
}

impl UncheckedFrom<[u8; 32]> for Public {
	fn unchecked_from(x: [u8; 32]) -> Self {
		Public::from_raw(x)
	}
}

impl UncheckedFrom<H256> for Public {
	fn unchecked_from(x: H256) -> Self {
		Public::from_h256(x)
	}
}

#[cfg(feature = "std")]
impl std::fmt::Display for Public {
	fn fmt(&self, f: &mut std::fmt::Formatter) -> std::fmt::Result {
		write!(f, "{}", self.to_ss58check())
	}
}

impl sp_std::fmt::Debug for Public {
	#[cfg(feature = "std")]
	fn fmt(&self, f: &mut sp_std::fmt::Formatter) -> sp_std::fmt::Result {
		let s = self.to_ss58check();
		write!(f, "{} ({}...)", crate::hexdisplay::HexDisplay::from(&self.0), &s[0..8])
	}

	#[cfg(not(feature = "std"))]
	fn fmt(&self, _: &mut sp_std::fmt::Formatter) -> sp_std::fmt::Result {
		Ok(())
	}
}

#[cfg(feature = "std")]
impl Serialize for Public {
	fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error> where S: Serializer {
		serializer.serialize_str(&self.to_ss58check())
	}
}

#[cfg(feature = "std")]
impl<'de> Deserialize<'de> for Public {
	fn deserialize<D>(deserializer: D) -> Result<Self, D::Error> where D: Deserializer<'de> {
		Public::from_ss58check(&String::deserialize(deserializer)?)
			.map_err(|e| de::Error::custom(format!("{:?}", e)))
	}
}

/// A signature (a 512-bit value).
#[derive(Encode, Decode, PassByInner)]
pub struct Signature(pub [u8; 64]);

impl sp_std::convert::TryFrom<&[u8]> for Signature {
	type Error = ();

	fn try_from(data: &[u8]) -> Result<Self, Self::Error> {
		if data.len() == 64 {
			let mut inner = [0u8; 64];
			inner.copy_from_slice(data);
			Ok(Signature(inner))
		} else {
			Err(())
		}
	}
}

#[cfg(feature = "std")]
impl Serialize for Signature {
	fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error> where S: Serializer {
		serializer.serialize_str(&hex::encode(self))
	}
}

#[cfg(feature = "std")]
impl<'de> Deserialize<'de> for Signature {
	fn deserialize<D>(deserializer: D) -> Result<Self, D::Error> where D: Deserializer<'de> {
		let signature_hex = hex::decode(&String::deserialize(deserializer)?)
			.map_err(|e| de::Error::custom(format!("{:?}", e)))?;
		Ok(Signature::try_from(signature_hex.as_ref())
			.map_err(|e| de::Error::custom(format!("{:?}", e)))?)
	}
}

impl Clone for Signature {
	fn clone(&self) -> Self {
		let mut r = [0u8; 64];
		r.copy_from_slice(&self.0[..]);
		Signature(r)
	}
}

impl Default for Signature {
	fn default() -> Self {
		Signature([0u8; 64])
	}
}

impl PartialEq for Signature {
	fn eq(&self, b: &Self) -> bool {
		self.0[..] == b.0[..]
	}
}

impl Eq for Signature {}

impl From<Signature> for H512 {
	fn from(v: Signature) -> H512 {
		H512::from(v.0)
	}
}

impl From<Signature> for [u8; 64] {
	fn from(v: Signature) -> [u8; 64] {
		v.0
	}
}

impl AsRef<[u8; 64]> for Signature {
	fn as_ref(&self) -> &[u8; 64] {
		&self.0
	}
}

impl AsRef<[u8]> for Signature {
	fn as_ref(&self) -> &[u8] {
		&self.0[..]
	}
}

impl AsMut<[u8]> for Signature {
	fn as_mut(&mut self) -> &mut [u8] {
		&mut self.0[..]
	}
}

impl sp_std::fmt::Debug for Signature {
	#[cfg(feature = "std")]
	fn fmt(&self, f: &mut sp_std::fmt::Formatter) -> sp_std::fmt::Result {
		write!(f, "{}", crate::hexdisplay::HexDisplay::from(&self.0))
	}

	#[cfg(not(feature = "std"))]
	fn fmt(&self, _: &mut sp_std::fmt::Formatter) -> sp_std::fmt::Result {
		Ok(())
	}
}

#[cfg(feature = "full_crypto")]
impl sp_std::hash::Hash for Signature {
	fn hash<H: sp_std::hash::Hasher>(&self, state: &mut H) {
		sp_std::hash::Hash::hash(&self.0[..], state);
	}
}

impl Signature {
	/// A new instance from the given 64-byte `data`.
	///
	/// NOTE: No checking goes on to ensure this is a real signature. Only use it if
	/// you are certain that the array actually is a signature. GIGO!
	pub fn from_raw(data: [u8; 64]) -> Signature {
		Signature(data)
	}

	/// A new instance from the given slice that should be 64 bytes long.
	///
	/// NOTE: No checking goes on to ensure this is a real signature. Only use it if
	/// you are certain that the array actually is a signature. GIGO!
	pub fn from_slice(data: &[u8]) -> Self {
		let mut r = [0u8; 64];
		r.copy_from_slice(data);
		Signature(r)
	}

	/// A new instance from an H512.
	///
	/// NOTE: No checking goes on to ensure this is a real signature. Only use it if
	/// you are certain that the array actually is a signature. GIGO!
	pub fn from_h512(v: H512) -> Signature {
		Signature(v.into())
	}
}

/// A localized signature also contains sender information.
#[cfg(feature = "std")]
#[derive(PartialEq, Eq, Clone, Debug, Encode, Decode)]
pub struct LocalizedSignature {
	/// The signer of the signature.
	pub signer: Public,
	/// The signature itself.
	pub signature: Signature,
}

/// An error type for SS58 decoding.
#[cfg(feature = "std")]
#[derive(Clone, Copy, Eq, PartialEq, Debug, thiserror::Error)]
pub enum PublicError {
	/// Bad alphabet.
	#[error("Base 58 requirement is violated")]
	BadBase58,
	/// Bad length.
	#[error("Length is bad")]
	BadLength,
	/// Unknown version.
	#[error("Unknown version")]
	UnknownVersion,
	/// Invalid checksum.
	#[error("Invalid checksum")]
	InvalidChecksum,
}

impl Public {
	/// A new instance from the given 32-byte `data`.
	///
	/// NOTE: No checking goes on to ensure this is a real public key. Only use it if
	/// you are certain that the array actually is a pubkey. GIGO!
	pub fn from_raw(data: [u8; 32]) -> Self {
		Public(data)
	}

	/// A new instance from an H256.
	///
	/// NOTE: No checking goes on to ensure this is a real public key. Only use it if
	/// you are certain that the array actually is a pubkey. GIGO!
	pub fn from_h256(x: H256) -> Self {
		Public(x.into())
	}

	/// Return a slice filled with raw data.
	pub fn as_array_ref(&self) -> &[u8; 32] {
		self.as_ref()
	}
}

impl TraitPublic for Public {
	/// A new instance from the given slice that should be 32 bytes long.
	///
	/// NOTE: No checking goes on to ensure this is a real public key. Only use it if
	/// you are certain that the array actually is a pubkey. GIGO!
	fn from_slice(data: &[u8]) -> Self {
		let mut r = [0u8; 32];
		r.copy_from_slice(data);
		Public(r)
	}

	fn to_public_crypto_pair(&self) -> CryptoTypePublicPair {
		CryptoTypePublicPair(CRYPTO_ID, self.to_raw_vec())
	}
}

impl Derive for Public {}

impl From<Public> for CryptoTypePublicPair {
	fn from(key: Public) -> Self {
		(&key).into()
	}
}

impl From<&Public> for CryptoTypePublicPair {
	fn from(key: &Public) -> Self {
		CryptoTypePublicPair(CRYPTO_ID, key.to_raw_vec())
	}
}

/// Derive a single hard junction.
#[cfg(feature = "full_crypto")]
fn derive_hard_junction(secret_seed: &Seed, cc: &[u8; 32]) -> Seed {
	("Ed25519HDKD", secret_seed, cc).using_encoded(|data| {
		let mut res = [0u8; 32];
		res.copy_from_slice(blake2_rfc::blake2b::blake2b(32, &[], data).as_bytes());
		res
	})
}

/// An error when deriving a key.
#[cfg(feature = "full_crypto")]
pub enum DeriveError {
	/// A soft key was found in the path (and is unsupported).
	SoftKeyInPath,
}

#[cfg(feature = "full_crypto")]
impl TraitPair for Pair {
	type Public = Public;
	type Seed = Seed;
	type Signature = Signature;
	type DeriveError = DeriveError;

	/// Generate new secure (random) key pair and provide the recovery phrase.
	///
	/// You can recover the same key later with `from_phrase`.
	#[cfg(feature = "std")]
	fn generate_with_phrase(password: Option<&str>) -> (Pair, String, Seed) {
		let mnemonic = Mnemonic::new(MnemonicType::Words12, Language::English);
		let phrase = mnemonic.phrase();
		let (pair, seed) = Self::from_phrase(phrase, password)
			.expect("All phrases generated by Mnemonic are valid; qed");
		(
			pair,
			phrase.to_owned(),
			seed,
		)
	}

	/// Generate key pair from given recovery phrase and password.
	#[cfg(feature = "std")]
	fn from_phrase(phrase: &str, password: Option<&str>) -> Result<(Pair, Seed), SecretStringError> {
		let big_seed = seed_from_entropy(
			Mnemonic::from_phrase(phrase, Language::English)
				.map_err(|_| SecretStringError::InvalidPhrase)?.entropy(),
			password.unwrap_or(""),
		).map_err(|_| SecretStringError::InvalidSeed)?;
		let mut seed = Seed::default();
		seed.copy_from_slice(&big_seed[0..32]);
		Self::from_seed_slice(&big_seed[0..32]).map(|x| (x, seed))
	}

	/// Make a new key pair from secret seed material.
	///
	/// You should never need to use this; generate(), generate_with_phrase
	fn from_seed(seed: &Seed) -> Pair {
		Self::from_seed_slice(&seed[..]).expect("seed has valid length; qed")
	}

	/// Make a new key pair from secret seed material. The slice must be 32 bytes long or it
	/// will return `None`.
	///
	/// You should never need to use this; generate(), generate_with_phrase
	fn from_seed_slice(seed_slice: &[u8]) -> Result<Pair, SecretStringError> {
		let secret = ed25519_dalek::SecretKey::from_bytes(seed_slice)
			.map_err(|_| SecretStringError::InvalidSeedLength)?;
		let public = ed25519_dalek::PublicKey::from(&secret);
		Ok(Pair(ed25519_dalek::Keypair { secret, public }))
	}

	/// Derive a child key from a series of given junctions.
	fn derive<Iter: Iterator<Item=DeriveJunction>>(&self,
		path: Iter,
		_seed: Option<Seed>,
	) -> Result<(Pair, Option<Seed>), DeriveError> {
		let mut acc = self.0.secret.to_bytes();
		for j in path {
			match j {
				DeriveJunction::Soft(_cc) => return Err(DeriveError::SoftKeyInPath),
				DeriveJunction::Hard(cc) => acc = derive_hard_junction(&acc, &cc),
			}
		}
		Ok((Self::from_seed(&acc), Some(acc)))
	}

	/// Get the public key.
	fn public(&self) -> Public {
		let mut r = [0u8; 32];
		let pk = self.0.public.as_bytes();
		r.copy_from_slice(pk);
		Public(r)
	}

	/// Sign a message.
	fn sign(&self, message: &[u8]) -> Signature {
		let r = self.0.sign(message).to_bytes();
		Signature::from_raw(r)
	}

	/// Verify a signature on a message. Returns true if the signature is good.
	fn verify<M: AsRef<[u8]>>(sig: &Self::Signature, message: M, pubkey: &Self::Public) -> bool {
		Self::verify_weak(&sig.0[..], message.as_ref(), pubkey)
	}

	/// Verify a signature on a message. Returns true if the signature is good.
	///
	/// This doesn't use the type system to ensure that `sig` and `pubkey` are the correct
	/// size. Use it only if you're coming from byte buffers and need the speed.
	fn verify_weak<P: AsRef<[u8]>, M: AsRef<[u8]>>(sig: &[u8], message: M, pubkey: P) -> bool {
		let public_key = match ed25519_dalek::PublicKey::from_bytes(pubkey.as_ref()) {
			Ok(pk) => pk,
			Err(_) => return false,
		};

		let sig = match ed25519_dalek::Signature::try_from(sig) {
			Ok(s) => s,
			Err(_) => return false
		};

		match public_key.verify(message.as_ref(), &sig) {
			Ok(_) => true,
			_ => false,
		}
	}

	/// Return a vec filled with raw data.
	fn to_raw_vec(&self) -> Vec<u8> {
		self.seed().to_vec()
	}
}

#[cfg(feature = "full_crypto")]
impl Pair {
	/// Get the seed for this key.
	pub fn seed(&self) -> &Seed {
		self.0.secret.as_bytes()
	}

	/// Exactly as `from_string` except that if no matches are found then, the the first 32
	/// characters are taken (padded with spaces as necessary) and used as the MiniSecretKey.
	#[cfg(feature = "std")]
	pub fn from_legacy_string(s: &str, password_override: Option<&str>) -> Pair {
		Self::from_string(s, password_override).unwrap_or_else(|_| {
			let mut padded_seed: Seed = [' ' as u8; 32];
			let len = s.len().min(32);
			padded_seed[..len].copy_from_slice(&s.as_bytes()[..len]);
			Self::from_seed(&padded_seed)
		})
	}
}

impl CryptoType for Public {
	#[cfg(feature = "full_crypto")]
	type Pair = Pair;
}

impl CryptoType for Signature {
	#[cfg(feature = "full_crypto")]
	type Pair = Pair;
}

#[cfg(feature = "full_crypto")]
impl CryptoType for Pair {
	type Pair = Pair;
}

#[cfg(test)]
mod test {
	use super::*;
	use hex_literal::hex;
	use crate::crypto::DEV_PHRASE;
	use serde_json;

	#[test]
	fn default_phrase_should_be_used() {
		assert_eq!(
			Pair::from_string("//Alice///password", None).unwrap().public(),
			Pair::from_string(&format!("{}//Alice", DEV_PHRASE), Some("password")).unwrap().public(),
		);
	}

	#[test]
	fn seed_and_derive_should_work() {
		let seed = hex!("9d61b19deffd5a60ba844af492ec2cc44449c5697b326919703bac031cae7f60");
		let pair = Pair::from_seed(&seed);
		assert_eq!(pair.seed(), &seed);
		let path = vec![DeriveJunction::Hard([0u8; 32])];
		let derived = pair.derive(path.into_iter(), None).ok().unwrap().0;
		assert_eq!(
			derived.seed(),
			&hex!("ede3354e133f9c8e337ddd6ee5415ed4b4ffe5fc7d21e933f4930a3730e5b21c")
		);
	}

	#[test]
	fn test_vector_should_work() {
		let pair = Pair::from_seed(
			&hex!("9d61b19deffd5a60ba844af492ec2cc44449c5697b326919703bac031cae7f60")
		);
		let public = pair.public();
		assert_eq!(public, Public::from_raw(
			hex!("d75a980182b10ab7d54bfed3c964073a0ee172f3daa62325af021a68f707511a")
		));
		let message = b"";
		let signature = hex!("e5564300c360ac729086e2cc806e828a84877f1eb8e5d974d873e065224901555fb8821590a33bacc61e39701cf9b46bd25bf5f0595bbe24655141438e7a100b");
		let signature = Signature::from_raw(signature);
		assert!(&pair.sign(&message[..]) == &signature);
		assert!(Pair::verify(&signature, &message[..], &public));
	}

	#[test]
	fn test_vector_by_string_should_work() {
		let pair = Pair::from_string(
			"0x9d61b19deffd5a60ba844af492ec2cc44449c5697b326919703bac031cae7f60",
			None
		).unwrap();
		let public = pair.public();
		assert_eq!(public, Public::from_raw(
			hex!("d75a980182b10ab7d54bfed3c964073a0ee172f3daa62325af021a68f707511a")
		));
		let message = b"";
		let signature = hex!("e5564300c360ac729086e2cc806e828a84877f1eb8e5d974d873e065224901555fb8821590a33bacc61e39701cf9b46bd25bf5f0595bbe24655141438e7a100b");
		let signature = Signature::from_raw(signature);
		assert!(&pair.sign(&message[..]) == &signature);
		assert!(Pair::verify(&signature, &message[..], &public));
	}

	#[test]
	fn generated_pair_should_work() {
		let (pair, _) = Pair::generate();
		let public = pair.public();
		let message = b"Something important";
		let signature = pair.sign(&message[..]);
		assert!(Pair::verify(&signature, &message[..], &public));
		assert!(!Pair::verify(&signature, b"Something else", &public));
	}

	#[test]
	fn seeded_pair_should_work() {
		let pair = Pair::from_seed(b"12345678901234567890123456789012");
		let public = pair.public();
		assert_eq!(public, Public::from_raw(
			hex!("2f8c6129d816cf51c374bc7f08c3e63ed156cf78aefb4a6550d97b87997977ee")
		));
		let message = hex!("2f8c6129d816cf51c374bc7f08c3e63ed156cf78aefb4a6550d97b87997977ee00000000000000000200d75a980182b10ab7d54bfed3c964073a0ee172f3daa62325af021a68f707511a4500000000000000");
		let signature = pair.sign(&message[..]);
		println!("Correct signature: {:?}", signature);
		assert!(Pair::verify(&signature, &message[..], &public));
		assert!(!Pair::verify(&signature, "Other message", &public));
	}

	#[test]
	fn generate_with_phrase_recovery_possible() {
		let (pair1, phrase, _) = Pair::generate_with_phrase(None);
		let (pair2, _) = Pair::from_phrase(&phrase, None).unwrap();

		assert_eq!(pair1.public(), pair2.public());
	}

	#[test]
	fn generate_with_password_phrase_recovery_possible() {
		let (pair1, phrase, _) = Pair::generate_with_phrase(Some("password"));
		let (pair2, _) = Pair::from_phrase(&phrase, Some("password")).unwrap();

		assert_eq!(pair1.public(), pair2.public());
	}

	#[test]
	fn password_does_something() {
		let (pair1, phrase, _) = Pair::generate_with_phrase(Some("password"));
		let (pair2, _) = Pair::from_phrase(&phrase, None).unwrap();

		assert_ne!(pair1.public(), pair2.public());
	}

	#[test]
	fn ss58check_roundtrip_works() {
		let pair = Pair::from_seed(b"12345678901234567890123456789012");
		let public = pair.public();
		let s = public.to_ss58check();
		println!("Correct: {}", s);
		let cmp = Public::from_ss58check(&s).unwrap();
		assert_eq!(cmp, public);
	}

	#[test]
	fn signature_serialization_works() {
		let pair = Pair::from_seed(b"12345678901234567890123456789012");
		let message = b"Something important";
		let signature = pair.sign(&message[..]);
		let serialized_signature = serde_json::to_string(&signature).unwrap();
		// Signature is 64 bytes, so 128 chars + 2 quote chars
		assert_eq!(serialized_signature.len(), 130);
		let signature = serde_json::from_str(&serialized_signature).unwrap();
		assert!(Pair::verify(&signature, &message[..], &pair.public()));
	}

	#[test]
	fn signature_serialization_doesnt_panic() {
		fn deserialize_signature(text: &str) -> Result<Signature, serde_json::error::Error> {
			Ok(serde_json::from_str(text)?)
		}
		assert!(deserialize_signature("Not valid json.").is_err());
		assert!(deserialize_signature("\"Not an actual signature.\"").is_err());
		// Poorly-sized
		assert!(deserialize_signature("\"abc123\"").is_err());
	}
}
