// 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 serde::{
    de::{Error, Visitor},
    Deserialize, Deserializer,
};
use std::fmt;

use ethereum_types::H256;

/// Type of derivation
pub enum DerivationType {
    /// Soft - allow proof of parent
    Soft,
    /// Hard - does not allow proof of parent
    Hard,
}

/// Derivation request by hash
#[allow(dead_code)]
#[derive(Deserialize)]
pub struct DeriveHash {
    hash: H256,
    #[serde(rename = "type")]
    d_type: DerivationType,
}

/// Node propertoes in hierarchical derivation request
#[allow(dead_code)]
#[derive(Deserialize)]
pub struct DeriveHierarchicalItem {
    index: u64,
    #[serde(rename = "type")]
    d_type: DerivationType,
}

/// Hierarchical (index sequence) request
pub type DeriveHierarchical = Vec<DeriveHierarchicalItem>;

/// Generic derivate request
pub enum Derive {
    /// Hierarchical (index sequence) request
    Hierarchical(DeriveHierarchical),
    /// Hash request
    Hash(DeriveHash),
}

impl From<DeriveHierarchical> for Derive {
    fn from(d: DeriveHierarchical) -> Self {
        Derive::Hierarchical(d)
    }
}

impl From<DeriveHash> for Derive {
    fn from(d: DeriveHash) -> Self {
        Derive::Hash(d)
    }
}

/// Error converting request data
#[cfg(any(test, feature = "accounts"))]
#[derive(Debug)]
pub enum ConvertError {
    IndexOverlfow(u64),
}

impl Derive {
    /// Convert to account provider struct dealing with possible overflows
    #[cfg(any(test, feature = "accounts"))]
    pub fn to_derivation(self) -> Result<ethstore::Derivation, ConvertError> {
        Ok(match self {
            Derive::Hierarchical(drv) => ethstore::Derivation::Hierarchical({
                let mut members = Vec::<ethstore::IndexDerivation>::new();
                for h in drv {
                    if h.index > ::std::u32::MAX as u64 {
                        return Err(ConvertError::IndexOverlfow(h.index));
                    }
                    members.push(match h.d_type {
                        DerivationType::Soft => ethstore::IndexDerivation {
                            soft: true,
                            index: h.index as u32,
                        },
                        DerivationType::Hard => ethstore::IndexDerivation {
                            soft: false,
                            index: h.index as u32,
                        },
                    });
                }
                members
            }),
            Derive::Hash(drv) => match drv.d_type {
                DerivationType::Soft => ethstore::Derivation::SoftHash(drv.hash.into()),
                DerivationType::Hard => ethstore::Derivation::HardHash(drv.hash.into()),
            },
        })
    }
}

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

struct DerivationTypeVisitor;

impl<'a> Visitor<'a> for DerivationTypeVisitor {
    type Value = DerivationType;

    fn expecting(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
        write!(formatter, "'hard' or 'soft'")
    }

    fn visit_str<E>(self, value: &str) -> Result<Self::Value, E>
    where
        E: Error,
    {
        match value {
            "soft" => Ok(DerivationType::Soft),
            "hard" => Ok(DerivationType::Hard),
            v => Err(Error::custom(format!("invalid derivation type: {:?}", v))),
        }
    }

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