// This file is part of Tetcore.

// Copyright (C) 2020-2021 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.

//! Metering tools for consensus

use prometheus_endpoint::{
	register, U64, Registry, PrometheusError, Opts, CounterVec, Histogram, HistogramVec, HistogramOpts
};

use tp_runtime::traits::{Block as BlockT, NumberFor};

use crate::import_queue::{BlockImportResult, BlockImportError};

/// Generic Prometheus metrics for common consensus functionality.
#[derive(Clone)]
pub(crate) struct Metrics {
	pub import_queue_processed: CounterVec<U64>,
	pub block_verification_time: HistogramVec,
	pub block_verification_and_import_time: Histogram,
	pub justification_import_time: Histogram,
}

impl Metrics {
	pub(crate) fn register(registry: &Registry) -> Result<Self, PrometheusError> {
		Ok(Self {
			import_queue_processed: register(
				CounterVec::new(
					Opts::new("import_queue_processed_total", "Blocks processed by import queue"),
					&["result"] // 'success or failure
				)?,
				registry,
			)?,
			block_verification_time: register(
				HistogramVec::new(
					HistogramOpts::new(
						"block_verification_time",
						"Time taken to verify blocks",
					),
					&["result"],
				)?,
				registry,
			)?,
			block_verification_and_import_time: register(
				Histogram::with_opts(
					HistogramOpts::new(
						"block_verification_and_import_time",
						"Time taken to verify and import blocks",
					),
				)?,
				registry,
			)?,
			justification_import_time: register(
				Histogram::with_opts(
					HistogramOpts::new(
						"justification_import_time",
						"Time taken to import justifications",
					),
				)?,
				registry,
			)?,
		})
	}

	pub fn report_import<B: BlockT>(
		&self,
		result: &Result<BlockImportResult<NumberFor<B>>, BlockImportError>,
	) {
		let label = match result {
			Ok(_) => "success",
			Err(BlockImportError::IncompleteHeader(_)) => "incomplete_header",
			Err(BlockImportError::VerificationFailed(_,_)) => "verification_failed",
			Err(BlockImportError::BadBlock(_)) => "bad_block",
			Err(BlockImportError::MissingState) => "missing_state",
			Err(BlockImportError::UnknownParent) => "unknown_parent",
			Err(BlockImportError::Cancelled) => "cancelled",
			Err(BlockImportError::Other(_)) => "failed",
		};

		self.import_queue_processed.with_label_values(
			&[label]
		).inc();
	}

	pub fn report_verification(&self, success: bool, time: std::time::Duration) {
		self.block_verification_time.with_label_values(
			&[if success { "success" } else { "verification_failed" }]
		).observe(time.as_secs_f64());
	}

	pub fn report_verification_and_import(&self, time: std::time::Duration) {
		self.block_verification_and_import_time.observe(time.as_secs_f64());
	}
}
