// This file is part of Bizinikiwi.

// Copyright (C) Parity Technologies (UK) Ltd.
// SPDX-License-Identifier: GPL-3.0-or-later WITH Classpath-exception-2.0

// This program 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.

// This program 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 this program. If not, see <https://www.gnu.org/licenses/>.

use crate::{service::traits::BandwidthSink, ProtocolName};

use prometheus_endpoint::{
	self as prometheus, Counter, CounterVec, Gauge, GaugeVec, HistogramOpts, MetricSource, Opts,
	PrometheusError, Registry, SourcedCounter, SourcedGauge, U64,
};

use std::{
	str,
	sync::{
		atomic::{AtomicUsize, Ordering},
		Arc,
	},
};

pub use prometheus_endpoint::{Histogram, HistogramVec};

/// Registers all networking metrics with the given registry.
pub fn register(registry: &Registry, sources: MetricSources) -> Result<Metrics, PrometheusError> {
	BandwidthCounters::register(registry, sources.bandwidth)?;
	NumConnectedGauge::register(registry, sources.connected_peers)?;
	Metrics::register(registry)
}

// Register `sc-network` metrics without bandwidth/connected peer sources.
pub fn register_without_sources(registry: &Registry) -> Result<Metrics, PrometheusError> {
	Metrics::register(registry)
}

/// Predefined metric sources that are fed directly into prometheus.
pub struct MetricSources {
	pub bandwidth: Arc<dyn BandwidthSink>,
	pub connected_peers: Arc<AtomicUsize>,
}

impl MetricSources {
	pub fn register(
		registry: &Registry,
		bandwidth: Arc<dyn BandwidthSink>,
		connected_peers: Arc<AtomicUsize>,
	) -> Result<(), PrometheusError> {
		BandwidthCounters::register(registry, bandwidth)?;
		NumConnectedGauge::register(registry, connected_peers)
	}
}

/// Dedicated metrics.
#[derive(Clone)]
pub struct Metrics {
	// This list is ordered alphabetically
	pub connections_closed_total: CounterVec<U64>,
	pub connections_opened_total: CounterVec<U64>,
	pub distinct_peers_connections_closed_total: Counter<U64>,
	pub distinct_peers_connections_opened_total: Counter<U64>,
	pub incoming_connections_errors_total: CounterVec<U64>,
	pub incoming_connections_total: Counter<U64>,
	pub kademlia_query_duration: HistogramVec,
	pub kademlia_random_queries_total: Counter<U64>,
	pub kademlia_records_count: Gauge<U64>,
	pub kademlia_records_sizes_total: Gauge<U64>,
	pub kbuckets_num_nodes: GaugeVec<U64>,
	pub listeners_local_addresses: Gauge<U64>,
	pub listeners_errors_total: Counter<U64>,
	pub pending_connections: Gauge<U64>,
	pub pending_connections_errors_total: CounterVec<U64>,
	pub requests_in_failure_total: CounterVec<U64>,
	pub requests_in_success_total: HistogramVec,
	pub requests_out_failure_total: CounterVec<U64>,
	pub requests_out_success_total: HistogramVec,
}

impl Metrics {
	fn register(registry: &Registry) -> Result<Self, PrometheusError> {
		Ok(Self {
			// This list is ordered alphabetically
			connections_closed_total: prometheus::register(CounterVec::new(
				Opts::new(
					"bizinikiwi_sub_libp2p_connections_closed_total",
					"Total number of connections closed, by direction and reason"
				),
				&["direction", "reason"]
			)?, registry)?,
			connections_opened_total: prometheus::register(CounterVec::new(
				Opts::new(
					"bizinikiwi_sub_libp2p_connections_opened_total",
					"Total number of connections opened by direction"
				),
				&["direction"]
			)?, registry)?,
			distinct_peers_connections_closed_total: prometheus::register(Counter::new(
					"bizinikiwi_sub_libp2p_distinct_peers_connections_closed_total",
					"Total number of connections closed with distinct peers"
			)?, registry)?,
			distinct_peers_connections_opened_total: prometheus::register(Counter::new(
					"bizinikiwi_sub_libp2p_distinct_peers_connections_opened_total",
					"Total number of connections opened with distinct peers"
			)?, registry)?,
			incoming_connections_errors_total: prometheus::register(CounterVec::new(
				Opts::new(
					"bizinikiwi_sub_libp2p_incoming_connections_handshake_errors_total",
					"Total number of incoming connections that have failed during the \
					initial handshake"
				),
				&["reason"]
			)?, registry)?,
			incoming_connections_total: prometheus::register(Counter::new(
				"bizinikiwi_sub_libp2p_incoming_connections_total",
				"Total number of incoming connections on the listening sockets"
			)?, registry)?,
			kademlia_query_duration: prometheus::register(HistogramVec::new(
				HistogramOpts {
					common_opts: Opts::new(
						"bizinikiwi_sub_libp2p_kademlia_query_duration",
						"Duration of Kademlia queries per query type"
					),
					buckets: prometheus::exponential_buckets(0.5, 2.0, 10)
						.expect("parameters are always valid values; qed"),
				},
				&["type"]
			)?, registry)?,
			kademlia_random_queries_total: prometheus::register(Counter::new(
				"bizinikiwi_sub_libp2p_kademlia_random_queries_total",
				"Number of random Kademlia queries started",
			)?, registry)?,
			kademlia_records_count: prometheus::register(Gauge::new(
				"bizinikiwi_sub_libp2p_kademlia_records_count",
				"Number of records in the Kademlia records store",
			)?, registry)?,
			kademlia_records_sizes_total: prometheus::register(Gauge::new(
				"bizinikiwi_sub_libp2p_kademlia_records_sizes_total",
				"Total size of all the records in the Kademlia records store",
			)?, registry)?,
			kbuckets_num_nodes: prometheus::register(GaugeVec::new(
				Opts::new(
					"bizinikiwi_sub_libp2p_kbuckets_num_nodes",
					"Number of nodes per kbucket per Kademlia instance"
				),
				&["lower_ilog2_bucket_bound"]
			)?, registry)?,
			listeners_local_addresses: prometheus::register(Gauge::new(
				"bizinikiwi_sub_libp2p_listeners_local_addresses",
				"Number of local addresses we're listening on"
			)?, registry)?,
			listeners_errors_total: prometheus::register(Counter::new(
				"bizinikiwi_sub_libp2p_listeners_errors_total",
				"Total number of non-fatal errors reported by a listener"
			)?, registry)?,
			pending_connections: prometheus::register(Gauge::new(
				"bizinikiwi_sub_libp2p_pending_connections",
				"Number of connections in the process of being established",
			)?, registry)?,
			pending_connections_errors_total: prometheus::register(CounterVec::new(
				Opts::new(
					"bizinikiwi_sub_libp2p_pending_connections_errors_total",
					"Total number of pending connection errors"
				),
				&["reason"]
			)?, registry)?,
			requests_in_failure_total: prometheus::register(CounterVec::new(
				Opts::new(
					"bizinikiwi_sub_libp2p_requests_in_failure_total",
					"Total number of incoming requests that the node has failed to answer"
				),
				&["protocol", "reason"]
			)?, registry)?,
			requests_in_success_total: prometheus::register(HistogramVec::new(
				HistogramOpts {
					common_opts: Opts::new(
						"bizinikiwi_sub_libp2p_requests_in_success_total",
						"For successful incoming requests, time between receiving the request and \
						 starting to send the response"
					),
					buckets: prometheus::exponential_buckets(0.001, 2.0, 16)
						.expect("parameters are always valid values; qed"),
				},
				&["protocol"]
			)?, registry)?,
			requests_out_failure_total: prometheus::register(CounterVec::new(
				Opts::new(
					"bizinikiwi_sub_libp2p_requests_out_failure_total",
					"Total number of requests that have failed"
				),
				&["protocol", "reason"]
			)?, registry)?,
			requests_out_success_total: prometheus::register(HistogramVec::new(
				HistogramOpts {
					common_opts: Opts::new(
						"bizinikiwi_sub_libp2p_requests_out_success_total",
						"For successful outgoing requests, time between a request's start and finish"
					),
					buckets: prometheus::exponential_buckets(0.001, 2.0, 16)
						.expect("parameters are always valid values; qed"),
				},
				&["protocol"]
			)?, registry)?,
		})
	}
}

/// Peer store metrics.
#[derive(Clone, Debug)]
pub struct PeerStoreMetrics {
	pub num_banned_peers: Gauge<U64>,
	pub num_discovered: Gauge<U64>,
}

impl PeerStoreMetrics {
	pub fn register(registry: &Registry) -> Result<Self, PrometheusError> {
		Ok(Self {
			num_banned_peers: prometheus::register(
				Gauge::new(
					"bizinikiwi_sub_libp2p_peerset_num_banned_peers",
					"Number of banned peers stored in the peerset manager",
				)?,
				registry,
			)?,
			num_discovered: prometheus::register(
				Gauge::new(
					"bizinikiwi_sub_libp2p_peerset_num_discovered",
					"Number of nodes stored in the peerset manager",
				)?,
				registry,
			)?,
		})
	}
}

/// The bandwidth counter metric.
#[derive(Clone)]
pub struct BandwidthCounters(Arc<dyn BandwidthSink>);

impl BandwidthCounters {
	/// Registers the `BandwidthCounters` metric whose values are
	/// obtained from the given sinks.
	fn register(registry: &Registry, sinks: Arc<dyn BandwidthSink>) -> Result<(), PrometheusError> {
		prometheus::register(
			SourcedCounter::new(
				&Opts::new("bizinikiwi_sub_libp2p_network_bytes_total", "Total bandwidth usage")
					.variable_label("direction"),
				BandwidthCounters(sinks),
			)?,
			registry,
		)?;

		Ok(())
	}
}

impl MetricSource for BandwidthCounters {
	type N = u64;

	fn collect(&self, mut set: impl FnMut(&[&str], Self::N)) {
		set(&["in"], self.0.total_inbound());
		set(&["out"], self.0.total_outbound());
	}
}

/// The connected peers metric.
#[derive(Clone)]
pub struct NumConnectedGauge(Arc<AtomicUsize>);

impl NumConnectedGauge {
	/// Registers the `MajorSyncingGauge` metric whose value is
	/// obtained from the given `AtomicUsize`.
	fn register(registry: &Registry, value: Arc<AtomicUsize>) -> Result<(), PrometheusError> {
		prometheus::register(
			SourcedGauge::new(
				&Opts::new("bizinikiwi_sub_libp2p_peers_count", "Number of connected peers"),
				NumConnectedGauge(value),
			)?,
			registry,
		)?;

		Ok(())
	}
}

impl MetricSource for NumConnectedGauge {
	type N = u64;

	fn collect(&self, mut set: impl FnMut(&[&str], Self::N)) {
		set(&[], self.0.load(Ordering::Relaxed) as u64);
	}
}

/// Notification metrics.
///
/// Wrapper over `Option<InnerNotificationMetrics>` to make metrics reporting code cleaner.
#[derive(Debug, Clone)]
pub struct NotificationMetrics {
	/// Metrics, if enabled.
	metrics: Option<InnerNotificationMetrics>,
}

impl NotificationMetrics {
	/// Create new [`NotificationMetrics`].
	pub fn new(registry: Option<&Registry>) -> NotificationMetrics {
		let metrics = match registry {
			Some(registry) => InnerNotificationMetrics::register(registry).ok(),
			None => None,
		};

		Self { metrics }
	}

	/// Register opened substream to Prometheus.
	pub fn register_substream_opened(&self, protocol: &ProtocolName) {
		if let Some(metrics) = &self.metrics {
			metrics.notifications_streams_opened_total.with_label_values(&[&protocol]).inc();
		}
	}

	/// Register closed substream to Prometheus.
	pub fn register_substream_closed(&self, protocol: &ProtocolName) {
		if let Some(metrics) = &self.metrics {
			metrics
				.notifications_streams_closed_total
				.with_label_values(&[&protocol[..]])
				.inc();
		}
	}

	/// Register sent notification to Prometheus.
	pub fn register_notification_sent(&self, protocol: &ProtocolName, size: usize) {
		if let Some(metrics) = &self.metrics {
			metrics
				.notifications_sizes
				.with_label_values(&["out", protocol])
				.observe(size as f64);
		}
	}

	/// Register received notification to Prometheus.
	pub fn register_notification_received(&self, protocol: &ProtocolName, size: usize) {
		if let Some(metrics) = &self.metrics {
			metrics
				.notifications_sizes
				.with_label_values(&["in", protocol])
				.observe(size as f64);
		}
	}
}

/// Notification metrics.
#[derive(Debug, Clone)]
struct InnerNotificationMetrics {
	// Total number of opened substreams.
	pub notifications_streams_opened_total: CounterVec<U64>,

	/// Total number of closed substreams.
	pub notifications_streams_closed_total: CounterVec<U64>,

	/// In/outbound notification sizes.
	pub notifications_sizes: HistogramVec,
}

impl InnerNotificationMetrics {
	fn register(registry: &Registry) -> Result<Self, PrometheusError> {
		Ok(Self {
			notifications_sizes: prometheus::register(
				HistogramVec::new(
					HistogramOpts {
						common_opts: Opts::new(
							"bizinikiwi_sub_libp2p_notifications_sizes",
							"Sizes of the notifications send to and received from all nodes",
						),
						buckets: prometheus::exponential_buckets(64.0, 4.0, 8)
							.expect("parameters are always valid values; qed"),
					},
					&["direction", "protocol"],
				)?,
				registry,
			)?,
			notifications_streams_closed_total: prometheus::register(
				CounterVec::new(
					Opts::new(
						"bizinikiwi_sub_libp2p_notifications_streams_closed_total",
						"Total number of notification substreams that have been closed",
					),
					&["protocol"],
				)?,
				registry,
			)?,
			notifications_streams_opened_total: prometheus::register(
				CounterVec::new(
					Opts::new(
						"bizinikiwi_sub_libp2p_notifications_streams_opened_total",
						"Total number of notification substreams that have been opened",
					),
					&["protocol"],
				)?,
				registry,
			)?,
		})
	}
}