// This file is part of Substrate.

// Copyright (C) 2021-2022 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.

//! Types for transaction-payment RPC.

use codec::{Decode, Encode};
#[cfg(feature = "std")]
use serde::{Deserialize, Serialize};

use sp_runtime::traits::{AtLeast32BitUnsigned, Zero};
use sp_std::prelude::*;

use frame_support::dispatch::DispatchClass;

/// The base fee and adjusted weight and length fees constitute the _inclusion fee_.
#[derive(Encode, Decode, Clone, Eq, PartialEq)]
#[cfg_attr(feature = "std", derive(Debug, Serialize, Deserialize))]
#[cfg_attr(feature = "std", serde(rename_all = "camelCase"))]
pub struct InclusionFee<Balance> {
    /// This is the minimum amount a user pays for a transaction. It is declared
    /// as a base _weight_ in the runtime and converted to a fee using `WeightToFee`.
    pub base_fee: Balance,
    /// The length fee, the amount paid for the encoded length (in bytes) of the transaction.
    pub len_fee: Balance,
    ///
    /// - `targeted_fee_adjustment`: This is a multiplier that can tune the final fee based on the
    ///   congestion of the network.
    /// - `weight_fee`: This amount is computed based on the weight of the transaction. Weight
    /// accounts for the execution time of a transaction.
    ///
    /// adjusted_weight_fee = targeted_fee_adjustment * weight_fee
    pub adjusted_weight_fee: Balance,
}

impl<Balance: AtLeast32BitUnsigned + Copy> InclusionFee<Balance> {
    /// Returns the total of inclusion fee.
    ///
    /// ```ignore
    /// inclusion_fee = base_fee + len_fee + adjusted_weight_fee
    /// ```
    pub fn inclusion_fee(&self) -> Balance {
        self.base_fee
            .saturating_add(self.len_fee)
            .saturating_add(self.adjusted_weight_fee)
    }
}

/// The `FeeDetails` is composed of:
///   - (Optional) `inclusion_fee`: Only the `Pays::Yes` transaction can have the inclusion fee.
///   - `tip`: If included in the transaction, the tip will be added on top. Only signed
///     transactions can have a tip.
#[derive(Encode, Decode, Clone, Eq, PartialEq)]
#[cfg_attr(feature = "std", derive(Debug, Serialize, Deserialize))]
#[cfg_attr(feature = "std", serde(rename_all = "camelCase"))]
pub struct FeeDetails<Balance> {
    /// The minimum fee for a transaction to be included in a block.
    pub inclusion_fee: Option<InclusionFee<Balance>>,
    // Do not serialize and deserialize `tip` as we actually can not pass any tip to the RPC.
    #[cfg_attr(feature = "std", serde(skip))]
    pub tip: Balance,
}

impl<Balance: AtLeast32BitUnsigned + Copy> FeeDetails<Balance> {
    /// Returns the final fee.
    ///
    /// ```ignore
    /// final_fee = inclusion_fee + tip;
    /// ```
    pub fn final_fee(&self) -> Balance {
        self.inclusion_fee
            .as_ref()
            .map(|i| i.inclusion_fee())
            .unwrap_or_else(|| Zero::zero())
            .saturating_add(self.tip)
    }
}

/// Information related to a dispatchable's class, weight, and fee that can be queried from the
/// runtime.
#[derive(Eq, PartialEq, Encode, Decode, Default)]
#[cfg_attr(feature = "std", derive(Debug, Serialize, Deserialize))]
#[cfg_attr(feature = "std", serde(rename_all = "camelCase"))]
#[cfg_attr(
    feature = "std",
    serde(bound(serialize = "Balance: std::fmt::Display, Weight: Serialize"))
)]
#[cfg_attr(
    feature = "std",
    serde(bound(deserialize = "Balance: std::str::FromStr, Weight: Deserialize<'de>"))
)]
pub struct RuntimeDispatchInfo<Balance, Weight = frame_support::weights::Weight> {
    /// Weight of this dispatch.
    pub weight: Weight,
    /// Class of this dispatch.
    pub class: DispatchClass,
    /// The inclusion fee of this dispatch.
    ///
    /// This does not include a tip or anything else that
    /// depends on the signature (i.e. depends on a `SignedExtension`).
    #[cfg_attr(feature = "std", serde(with = "serde_balance"))]
    pub partial_fee: Balance,
}

#[cfg(feature = "std")]
mod serde_balance {
    use serde::{Deserialize, Deserializer, Serializer};

    pub fn serialize<S: Serializer, T: std::fmt::Display>(
        t: &T,
        serializer: S,
    ) -> Result<S::Ok, S::Error> {
        serializer.serialize_str(&t.to_string())
    }

    pub fn deserialize<'de, D: Deserializer<'de>, T: std::str::FromStr>(
        deserializer: D,
    ) -> Result<T, D::Error> {
        let s = String::deserialize(deserializer)?;
        s.parse::<T>()
            .map_err(|_| serde::de::Error::custom("Parse from string failed"))
    }
}

#[cfg(test)]
mod tests {
    use super::*;
    use frame_support::weights::Weight;

    #[test]
    fn should_serialize_and_deserialize_properly_with_string() {
        let info = RuntimeDispatchInfo {
            weight: Weight::from_ref_time(5),
            class: DispatchClass::Normal,
            partial_fee: 1_000_000_u64,
        };

        let json_str =
            r#"{"weight":{"ref_time":5,"proof_size":0},"class":"normal","partialFee":"1000000"}"#;

        assert_eq!(serde_json::to_string(&info).unwrap(), json_str);
        assert_eq!(
            serde_json::from_str::<RuntimeDispatchInfo<u64>>(json_str).unwrap(),
            info
        );

        // should not panic
        serde_json::to_value(&info).unwrap();
    }

    #[test]
    fn should_serialize_and_deserialize_properly_large_value() {
        let info = RuntimeDispatchInfo {
            weight: Weight::from_ref_time(5),
            class: DispatchClass::Normal,
            partial_fee: u128::max_value(),
        };

        let json_str = r#"{"weight":{"ref_time":5,"proof_size":0},"class":"normal","partialFee":"340282366920938463463374607431768211455"}"#;

        assert_eq!(serde_json::to_string(&info).unwrap(), json_str);
        assert_eq!(
            serde_json::from_str::<RuntimeDispatchInfo<u128>>(json_str).unwrap(),
            info
        );

        // should not panic
        serde_json::to_value(&info).unwrap();
    }
}
