use codec::{Decode, Encode, MaxEncodedLen};
use scale_info::TypeInfo;
use sp_arithmetic::traits::{BaseArithmetic, Unsigned, Zero};
use sp_core::U256;
use sp_runtime::{FixedU128, RuntimeDebug};
use sp_std::prelude::*;

#[derive(Clone, Encode, Decode, PartialEq, RuntimeDebug, MaxEncodedLen, TypeInfo)]
pub struct PricingParameters<Balance> {
	/// ETH/DOT exchange rate
	pub exchange_rate: FixedU128,
	/// Relayer rewards
	pub rewards: Rewards<Balance>,
	/// Ether (wei) fee per gas unit
	pub fee_per_gas: U256,
	/// Fee multiplier
	pub multiplier: FixedU128,
}

#[derive(Clone, Encode, Decode, PartialEq, RuntimeDebug, MaxEncodedLen, TypeInfo)]
pub struct Rewards<Balance> {
	/// Local reward in DOT
	pub local: Balance,
	/// Remote reward in ETH (wei)
	pub remote: U256,
}

#[derive(RuntimeDebug)]
pub struct InvalidPricingParameters;

impl<Balance> PricingParameters<Balance>
where
	Balance: BaseArithmetic + Unsigned + Copy,
{
	pub fn validate(&self) -> Result<(), InvalidPricingParameters> {
		if self.exchange_rate == FixedU128::zero() {
			return Err(InvalidPricingParameters)
		}
		if self.fee_per_gas == U256::zero() {
			return Err(InvalidPricingParameters)
		}
		if self.rewards.local.is_zero() {
			return Err(InvalidPricingParameters)
		}
		if self.rewards.remote.is_zero() {
			return Err(InvalidPricingParameters)
		}
		if self.multiplier == FixedU128::zero() {
			return Err(InvalidPricingParameters)
		}
		Ok(())
	}
}

/// Holder for fixed point number implemented in <https://github.com/PaulRBerg/prb-math>
#[derive(Clone, Encode, Decode, RuntimeDebug, TypeInfo)]
#[cfg_attr(feature = "std", derive(PartialEq))]
pub struct UD60x18(U256);

impl From<FixedU128> for UD60x18 {
	fn from(value: FixedU128) -> Self {
		// Both FixedU128 and UD60x18 have 18 decimal places
		let inner: u128 = value.into_inner();
		UD60x18(inner.into())
	}
}

impl UD60x18 {
	pub fn into_inner(self) -> U256 {
		self.0
	}
}