// Copyright 2020 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/>.

//! Interfaces, types and utils for benchmarking a FRAME runtime.

use codec::{Encode, Decode};
use sp_std::vec::Vec;
use sp_io::hashing::blake2_256;

/// An alphabet of possible parameters to use for benchmarking.
#[derive(codec::Encode, codec::Decode, Clone, Copy, PartialEq, Debug)]
#[allow(missing_docs)]
#[allow(non_camel_case_types)]
pub enum BenchmarkParameter {
	a, b, c, d, e, f, g, h, i, j, k, l, m, n, o, p, q, r, s, t, u, v, w, x, y, z,
}

/// Results from running benchmarks on a FRAME pallet.
/// Contains duration of the function call in nanoseconds along with the benchmark parameters
/// used for that benchmark result.
pub type BenchmarkResults = (Vec<(BenchmarkParameter, u32)>, u128, u128);

sp_api::decl_runtime_apis! {
	/// Runtime api for benchmarking a FRAME runtime.
	pub trait Benchmark {
		/// Dispatch the given benchmark.
		fn dispatch_benchmark(
			module: Vec<u8>,
			extrinsic: Vec<u8>,
			steps: Vec<u32>,
			repeat: u32,
		) -> Option<Vec<BenchmarkResults>>;
	}
}

/// Interface that provides functions for benchmarking the runtime.
#[sp_runtime_interface::runtime_interface]
pub trait Benchmarking {
	/// Get the number of nanoseconds passed since the UNIX epoch
	///
	/// WARNING! This is a non-deterministic call. Do not use this within
	/// consensus critical logic.
	fn current_time() -> u128 {
		std::time::SystemTime::now().duration_since(std::time::SystemTime::UNIX_EPOCH)
			.expect("Unix time doesn't go backwards; qed")
			.as_nanos()
	}

	/// Reset the trie database to the genesis state.
	fn wipe_db(&mut self) {
		self.wipe()
	}

	/// Commit pending storage changes to the trie database and clear the database cache.
	fn commit_db(&mut self) {
		self.commit()
	}
}

/// The pallet benchmarking trait.
pub trait Benchmarking<T> {
	/// Run the benchmarks for this pallet.
	///
	/// Parameters
	/// - `extrinsic`: The name of extrinsic function you want to benchmark encoded as bytes.
	/// - `steps`: The number of sample points you want to take across the range of parameters.
	/// - `repeat`: The number of times you want to repeat a benchmark.
	fn run_benchmark(extrinsic: Vec<u8>, steps: Vec<u32>, repeat: u32) -> Result<Vec<T>, &'static str>;
}

/// The required setup for creating a benchmark.
pub trait BenchmarkingSetup<T, Call, RawOrigin> {
	/// Return the components and their ranges which should be tested in this benchmark.
	fn components(&self) -> Vec<(BenchmarkParameter, u32, u32)>;

	/// Set up the storage, and prepare a call and caller to test in a single run of the benchmark.
	fn instance(&self, components: &[(BenchmarkParameter, u32)]) -> Result<(Call, RawOrigin), &'static str>;
}

/// Grab an account, seeded by a name and index.
pub fn account<AccountId: Decode + Default>(name: &'static str, index: u32, seed: u32) -> AccountId {
	let entropy = (name, index, seed).using_encoded(blake2_256);
	AccountId::decode(&mut &entropy[..]).unwrap_or_default()
}
