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// This file is part of Substrate.

// Copyright (C) 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.

//! A logger that can be used to log from the runtime.
//!
//! See [`RuntimeLogger`] for more docs.

/// Runtime logger implementation - `log` crate backend.
///
/// The logger should be initialized if you want to display
/// logs inside the runtime that is not necessarily running natively.
pub struct RuntimeLogger;

impl RuntimeLogger {
	/// Initialize the logger.
	///
	/// This is a no-op when running natively (`std`).
	#[cfg(feature = "std")]
	pub fn init() {}

	/// Initialize the logger.
	///
	/// This is a no-op when running natively (`std`).
	#[cfg(not(feature = "std"))]
	pub fn init() {
		static LOGGER: RuntimeLogger = RuntimeLogger;
		let _ = log::set_logger(&LOGGER);

		// Use the same max log level as used by the host.
		log::set_max_level(sp_io::logging::max_level().into());
	}
}

impl log::Log for RuntimeLogger {
	fn enabled(&self, _: &log::Metadata) -> bool {
		// The final filtering is done by the host. This is not perfect, as we would still call into
		// the host for log lines that will be thrown away.
		true
	}

	fn log(&self, record: &log::Record) {
		use sp_std::fmt::Write;
		let mut w = sp_std::Writer::default();
		let _ = ::core::write!(&mut w, "{}", record.args());

		sp_io::logging::log(record.level().into(), record.target(), w.inner());
	}

	fn flush(&self) {}
}

#[cfg(test)]
mod tests {
	use sp_api::ProvideRuntimeApi;
	use std::{env, str::FromStr};
	use substrate_test_runtime_client::{
		runtime::TestAPI, DefaultTestClientBuilderExt, TestClientBuilder, TestClientBuilderExt,
	};

	#[test]
	fn ensure_runtime_logger_respects_host_max_log_level() {
		if env::var("RUN_TEST").is_ok() {
			sp_tracing::try_init_simple();
			log::set_max_level(log::LevelFilter::from_str(&env::var("RUST_LOG").unwrap()).unwrap());

			let client = TestClientBuilder::new().build();
			let runtime_api = client.runtime_api();
			runtime_api
				.do_trace_log(client.chain_info().genesis_hash)
				.expect("Logging should not fail");
		} else {
			for (level, should_print) in &[("trace", true), ("info", false)] {
				let executable = std::env::current_exe().unwrap();
				let output = std::process::Command::new(executable)
					.env("RUN_TEST", "1")
					.env("RUST_LOG", level)
					.args(&["--nocapture", "ensure_runtime_logger_respects_host_max_log_level"])
					.output()
					.unwrap();

				let output = String::from_utf8(output.stderr).unwrap();
				assert!(output.contains("Hey I'm runtime") == *should_print);
			}
		}
	}
}