// Copyright 2019 Parity Technologies (UK) Ltd.
// This file is part of Substrate.

// Substrate 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.

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

/// Contains the inherents for the AURA module

use sp_timestamp::TimestampInherentData;
use inherents::{InherentIdentifier, InherentData, Error};
use rstd::result::Result;
use codec::Decode;

#[cfg(feature = "std")]
use inherents::{InherentDataProviders, ProvideInherentData};

/// The Aura inherent identifier.
pub const INHERENT_IDENTIFIER: InherentIdentifier = *b"auraslot";

/// The type of the Aura inherent.
pub type InherentType = u64;

/// Auxiliary trait to extract Aura inherent data.
pub trait AuraInherentData {
	/// Get aura inherent data.
	fn aura_inherent_data(&self) ->Result<InherentType, Error>;
	/// Replace aura inherent data.
	fn aura_replace_inherent_data(&mut self, new: InherentType);
}

impl AuraInherentData for InherentData {
	fn aura_inherent_data(&self) ->Result<InherentType, Error> {
		self.get_data(&INHERENT_IDENTIFIER)
			.and_then(|r| r.ok_or_else(|| "Aura inherent data not found".into()))
	}

	fn aura_replace_inherent_data(&mut self, new: InherentType) {
		self.replace_data(INHERENT_IDENTIFIER, &new);
	}
}

/// Provides the slot duration inherent data for `Aura`.
#[cfg(feature = "std")]
pub struct InherentDataProvider {
	slot_duration: u64,
}

#[cfg(feature = "std")]
impl InherentDataProvider {
	pub fn new(slot_duration: u64) -> Self {
		Self {
			slot_duration
		}
	}
}

#[cfg(feature = "std")]
impl ProvideInherentData for InherentDataProvider {
	fn on_register(
		&self,
		providers: &InherentDataProviders,
	) ->Result<(), Error> {
		if !providers.has_provider(&sp_timestamp::INHERENT_IDENTIFIER) {
			// Add the timestamp inherent data provider, as we require it.
			providers.register_provider(sp_timestamp::InherentDataProvider)
		} else {
			Ok(())
		}
	}

	fn inherent_identifier(&self) -> &'static InherentIdentifier {
		&INHERENT_IDENTIFIER
	}

	fn provide_inherent_data(
		&self,
		inherent_data: &mut InherentData,
	) ->Result<(), Error> {
		let timestamp = inherent_data.timestamp_inherent_data()?;
		let slot_num = timestamp / self.slot_duration;
		inherent_data.put_data(INHERENT_IDENTIFIER, &slot_num)
	}

	fn error_to_string(&self, error: &[u8]) -> Option<String> {
		inherents::Error::decode(&mut &error[..]).map(|e| e.into_string()).ok()
	}
}
