// 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/>.

use super::{Bytes, Error};
use serde::{
    de::{Error as SerdeError, Visitor},
    Deserialize, Deserializer, Serialize, Serializer,
};
use std::{fmt, num::NonZeroU32};

#[derive(Debug, PartialEq)]
pub enum KdfSer {
    Pbkdf2,
    Scrypt,
}

impl Serialize for KdfSer {
    fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error>
    where
        S: Serializer,
    {
        match *self {
            KdfSer::Pbkdf2 => serializer.serialize_str("pbkdf2"),
            KdfSer::Scrypt => serializer.serialize_str("scrypt"),
        }
    }
}

impl<'a> Deserialize<'a> for KdfSer {
    fn deserialize<D>(deserializer: D) -> Result<Self, D::Error>
    where
        D: Deserializer<'a>,
    {
        deserializer.deserialize_any(KdfSerVisitor)
    }
}

struct KdfSerVisitor;

impl<'a> Visitor<'a> for KdfSerVisitor {
    type Value = KdfSer;

    fn expecting(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
        write!(formatter, "a kdf algorithm identifier")
    }

    fn visit_str<E>(self, value: &str) -> Result<Self::Value, E>
    where
        E: SerdeError,
    {
        match value {
            "pbkdf2" => Ok(KdfSer::Pbkdf2),
            "scrypt" => Ok(KdfSer::Scrypt),
            _ => Err(SerdeError::custom(Error::UnsupportedKdf)),
        }
    }

    fn visit_string<E>(self, value: String) -> Result<Self::Value, E>
    where
        E: SerdeError,
    {
        self.visit_str(value.as_ref())
    }
}

#[derive(Debug, PartialEq)]
pub enum Prf {
    HmacSha256,
}

impl Serialize for Prf {
    fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error>
    where
        S: Serializer,
    {
        match *self {
            Prf::HmacSha256 => serializer.serialize_str("hmac-sha256"),
        }
    }
}

impl<'a> Deserialize<'a> for Prf {
    fn deserialize<D>(deserializer: D) -> Result<Self, D::Error>
    where
        D: Deserializer<'a>,
    {
        deserializer.deserialize_any(PrfVisitor)
    }
}

struct PrfVisitor;

impl<'a> Visitor<'a> for PrfVisitor {
    type Value = Prf;

    fn expecting(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
        write!(formatter, "a prf algorithm identifier")
    }

    fn visit_str<E>(self, value: &str) -> Result<Self::Value, E>
    where
        E: SerdeError,
    {
        match value {
            "hmac-sha256" => Ok(Prf::HmacSha256),
            _ => Err(SerdeError::custom(Error::InvalidPrf)),
        }
    }

    fn visit_string<E>(self, value: String) -> Result<Self::Value, E>
    where
        E: SerdeError,
    {
        self.visit_str(value.as_ref())
    }
}

#[derive(Debug, PartialEq, Serialize, Deserialize)]
pub struct Pbkdf2 {
    pub c: NonZeroU32,
    pub dklen: u32,
    pub prf: Prf,
    pub salt: Bytes,
}

#[derive(Debug, PartialEq, Serialize, Deserialize)]
pub struct Scrypt {
    pub dklen: u32,
    pub p: u32,
    pub n: u32,
    pub r: u32,
    pub salt: Bytes,
}

#[derive(Debug, PartialEq)]
pub enum KdfSerParams {
    Pbkdf2(Pbkdf2),
    Scrypt(Scrypt),
}

impl Serialize for KdfSerParams {
    fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error>
    where
        S: Serializer,
    {
        match *self {
            KdfSerParams::Pbkdf2(ref params) => params.serialize(serializer),
            KdfSerParams::Scrypt(ref params) => params.serialize(serializer),
        }
    }
}

impl<'a> Deserialize<'a> for KdfSerParams {
    fn deserialize<D>(deserializer: D) -> Result<Self, D::Error>
    where
        D: Deserializer<'a>,
    {
        use serde_json::{from_value, Value};

        let v: Value = Deserialize::deserialize(deserializer)?;

        from_value(v.clone())
            .map(KdfSerParams::Pbkdf2)
            .or_else(|_| from_value(v).map(KdfSerParams::Scrypt))
            .map_err(|_| D::Error::custom("Invalid KDF algorithm"))
    }
}

#[derive(Debug, PartialEq)]
pub enum Kdf {
    Pbkdf2(Pbkdf2),
    Scrypt(Scrypt),
}