tari_core 0.8.1

// Copyright 2019. The Tari Project
//
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// following conditions are met:
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// 1. Redistributions of source code must retain the above copyright notice, this list of conditions and the following
// disclaimer.
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// 2. Redistributions in binary form must reproduce the above copyright notice, this list of conditions and the
// following disclaimer in the documentation and/or other materials provided with the distribution.
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// 3. Neither the name of the copyright holder nor the names of its contributors may be used to endorse or promote
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// INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
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use crate::{
    consensus::{KERNEL_WEIGHT, WEIGHT_PER_INPUT, WEIGHT_PER_OUTPUT},
    transactions::{tari_amount::*, transaction::MINIMUM_TRANSACTION_FEE},
};

pub struct Fee {}

impl Fee {
    /// Computes the absolute transaction fee given the fee-per-gram, and the size of the transaction
    pub fn calculate(fee_per_gram: MicroTari, num_kernels: usize, num_inputs: usize, num_outputs: usize) -> MicroTari {
        (Fee::calculate_weight(num_kernels, num_inputs, num_outputs) * u64::from(fee_per_gram)).into()
    }

    /// Computes the absolute transaction fee using `calculate`, but the resulting fee will always be at least the
    /// minimum network transaction fee.
    pub fn calculate_with_minimum(
        fee_per_gram: MicroTari,
        num_kernels: usize,
        num_inputs: usize,
        num_outputs: usize,
    ) -> MicroTari
    {
        let fee = Fee::calculate(fee_per_gram, num_kernels, num_inputs, num_outputs);
        if fee < MINIMUM_TRANSACTION_FEE {
            MINIMUM_TRANSACTION_FEE
        } else {
            fee
        }
    }

    /// Calculate the weight of a transaction based on the number of inputs and outputs
    pub fn calculate_weight(num_kernels: usize, num_inputs: usize, num_outputs: usize) -> u64 {
        KERNEL_WEIGHT * num_kernels as u64 +
            WEIGHT_PER_INPUT * num_inputs as u64 +
            WEIGHT_PER_OUTPUT * num_outputs as u64
    }
}