// This file is part of Substrate.

// Copyright (C) 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.

//! Contains the [`MachineCmd`] as entry point for the node
//! and the core benchmarking logic.

pub mod hardware;

use std::{boxed::Box, fs, path::Path};

use clap::Parser;
use comfy_table::{Row, Table};
use log::{error, info, warn};

use sc_cli::{CliConfiguration, Result, SharedParams};
use sc_service::Configuration;
use sc_sysinfo::{
	benchmark_cpu, benchmark_disk_random_writes, benchmark_disk_sequential_writes,
	benchmark_memory, benchmark_sr25519_verify, ExecutionLimit,
};

use crate::shared::check_build_profile;
pub use hardware::{Metric, Requirement, Requirements, Throughput, SUBSTRATE_REFERENCE_HARDWARE};

/// Command to benchmark the hardware.
///
/// Runs multiple benchmarks and prints their output to console.
/// Can be used to gauge if the hardware is fast enough to keep up with a chain's requirements.
/// This command must be integrated by the client since the client can set compiler flags
/// which influence the results.
///
/// You can use the `--base-path` flag to set a location for the disk benchmarks.
#[derive(Debug, Parser)]
pub struct MachineCmd {
	#[allow(missing_docs)]
	#[clap(flatten)]
	pub shared_params: SharedParams,

	/// Do not return an error if any check fails.
	///
	/// Should only be used for debugging.
	#[clap(long)]
	pub allow_fail: bool,

	/// Set a fault tolerance for passing a requirement.
	///
	/// 10% means that the test would pass even when only 90% score was archived.
	/// Can be used to mitigate outliers of the benchmarks.
	#[clap(long, default_value = "10.0", value_name = "PERCENT")]
	pub tolerance: f64,

	/// Time limit for the verification benchmark.
	#[clap(long, default_value = "5.0", value_name = "SECONDS")]
	pub verify_duration: f32,

	/// Time limit for the hash function benchmark.
	#[clap(long, default_value = "5.0", value_name = "SECONDS")]
	pub hash_duration: f32,

	/// Time limit for the memory benchmark.
	#[clap(long, default_value = "5.0", value_name = "SECONDS")]
	pub memory_duration: f32,

	/// Time limit for each disk benchmark.
	#[clap(long, default_value = "5.0", value_name = "SECONDS")]
	pub disk_duration: f32,
}

/// Helper for the result of a concrete benchmark.
struct BenchResult {
	/// Did the hardware pass the benchmark?
	passed: bool,

	/// The absolute score that was archived.
	score: Throughput,

	/// The score relative to the minimal required score.
	///
	/// Is in range [0, 1].
	rel_score: f64,
}

/// Errors that can be returned by the this command.
#[derive(Debug, thiserror::Error)]
#[allow(missing_docs)]
pub enum Error {
	#[error("One of the benchmarks had a score that was lower than its requirement")]
	UnmetRequirement,

	#[error("The build profile is unfit for benchmarking: {0}")]
	BadBuildProfile(String),

	#[error("Benchmark results are off by at least factor 100")]
	BadResults,
}

impl MachineCmd {
	/// Execute the benchmark and print the results.
	pub fn run(&self, cfg: &Configuration, requirements: Requirements) -> Result<()> {
		self.validate_args()?;
		// Ensure that the dir exists since the node is not started to take care of it.
		let dir = cfg.database.path().ok_or("No DB directory provided")?;
		fs::create_dir_all(dir)?;

		info!("Running machine benchmarks...");
		let mut results = Vec::new();
		for requirement in &requirements.0 {
			let result = self.run_benchmark(requirement, &dir)?;
			results.push(result);
		}
		self.print_summary(requirements, results)
	}

	/// Benchmarks a specific metric of the hardware and judges the resulting score.
	fn run_benchmark(&self, requirement: &Requirement, dir: &Path) -> Result<BenchResult> {
		// Dispatch the concrete function from `sc-sysinfo`.
		let score = self.measure(&requirement.metric, dir)?;
		let rel_score = score.to_bs() / requirement.minimum.to_bs();

		// Sanity check if the result is off by factor >100x.
		if rel_score >= 100.0 || rel_score <= 0.01 {
			self.check_failed(Error::BadResults)?;
		}
		let passed = rel_score >= (1.0 - (self.tolerance / 100.0));
		Ok(BenchResult { passed, score, rel_score })
	}

	/// Measures a metric of the hardware.
	fn measure(&self, metric: &Metric, dir: &Path) -> Result<Throughput> {
		let verify_limit = ExecutionLimit::from_secs_f32(self.verify_duration);
		let disk_limit = ExecutionLimit::from_secs_f32(self.disk_duration);
		let hash_limit = ExecutionLimit::from_secs_f32(self.hash_duration);
		let memory_limit = ExecutionLimit::from_secs_f32(self.memory_duration);

		let score = match metric {
			Metric::Blake2256 => Throughput::MiBs(benchmark_cpu(hash_limit) as f64),
			Metric::Sr25519Verify => Throughput::MiBs(benchmark_sr25519_verify(verify_limit)),
			Metric::MemCopy => Throughput::MiBs(benchmark_memory(memory_limit) as f64),
			Metric::DiskSeqWrite =>
				Throughput::MiBs(benchmark_disk_sequential_writes(disk_limit, dir)? as f64),
			Metric::DiskRndWrite =>
				Throughput::MiBs(benchmark_disk_random_writes(disk_limit, dir)? as f64),
		};
		Ok(score)
	}

	/// Prints a human-readable summary.
	fn print_summary(&self, requirements: Requirements, results: Vec<BenchResult>) -> Result<()> {
		// Use a table for nicer console output.
		let mut table = Table::new();
		table.set_header(["Category", "Function", "Score", "Minimum", "Result"]);
		// Count how many passed and how many failed.
		let (mut passed, mut failed) = (0, 0);
		for (requirement, result) in requirements.0.iter().zip(results.iter()) {
			if result.passed {
				passed += 1
			} else {
				failed += 1
			}

			table.add_row(result.to_row(requirement));
		}
		// Print the table and a summary.
		info!(
			"\n{}\nFrom {} benchmarks in total, {} passed and {} failed ({:.0?}% fault tolerance).",
			table,
			passed + failed,
			passed,
			failed,
			self.tolerance
		);
		// Print the final result.
		if failed != 0 {
			info!("The hardware fails to meet the requirements");
			self.check_failed(Error::UnmetRequirement)?;
		} else {
			info!("The hardware meets the requirements ");
		}
		// Check that the results were not created by a bad build profile.
		if let Err(err) = check_build_profile() {
			self.check_failed(Error::BadBuildProfile(err))?;
		}
		Ok(())
	}

	/// Returns `Ok` if [`self.allow_fail`] is set and otherwise the error argument.
	fn check_failed(&self, e: Error) -> Result<()> {
		if !self.allow_fail {
			error!("Failing since --allow-fail is not set");
			Err(sc_cli::Error::Application(Box::new(e)))
		} else {
			warn!("Ignoring error since --allow-fail is set: {:?}", e);
			Ok(())
		}
	}

	/// Validates the CLI arguments.
	fn validate_args(&self) -> Result<()> {
		if self.tolerance > 100.0 || self.tolerance < 0.0 {
			return Err("The --tolerance argument is out of range".into())
		}
		Ok(())
	}
}

impl BenchResult {
	/// Format [`Self`] as row that can be printed in a table.
	fn to_row(&self, req: &Requirement) -> Row {
		let passed = if self.passed { "✅ Pass" } else { "❌ Fail" };
		vec![
			req.metric.category().into(),
			req.metric.name().into(),
			format!("{}", self.score),
			format!("{}", req.minimum),
			format!("{} ({: >5.1?} %)", passed, self.rel_score * 100.0),
		]
		.into()
	}
}

// Boilerplate
impl CliConfiguration for MachineCmd {
	fn shared_params(&self) -> &SharedParams {
		&self.shared_params
	}
}