// This file is part of Substrate.

// 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/>.

//! Instrumentation implementation for substrate.
//!
//! This crate is unstable and the API and usage may change.
//!
//! # Usage
//!
//! See `sp-tracing` for examples on how to use tracing.
//!
//! Currently we only provide `Log` (default).

#![warn(missing_docs)]

pub mod block;
pub mod logging;

use rustc_hash::FxHashMap;
use serde::ser::{Serialize, SerializeMap, Serializer};
use sp_tracing::{WASM_NAME_KEY, WASM_TARGET_KEY, WASM_TRACE_IDENTIFIER};
use std::{
	fmt,
	time::{Duration, Instant},
};
use tracing::{
	event::Event,
	field::{Field, Visit},
	span::{Attributes, Id, Record},
	subscriber::Subscriber,
	Level,
};
use tracing_subscriber::{
	layer::{Context, Layer},
	registry::LookupSpan,
};

#[doc(hidden)]
pub use tracing;

const ZERO_DURATION: Duration = Duration::from_nanos(0);

/// Responsible for assigning ids to new spans, which are not re-used.
pub struct ProfilingLayer {
	targets: Vec<(String, Level)>,
	trace_handlers: Vec<Box<dyn TraceHandler>>,
}

/// Used to configure how to receive the metrics
#[derive(Debug, Clone)]
pub enum TracingReceiver {
	/// Output to logger
	Log,
}

impl Default for TracingReceiver {
	fn default() -> Self {
		Self::Log
	}
}

/// A handler for tracing `SpanDatum`
pub trait TraceHandler: Send + Sync {
	/// Process a `SpanDatum`.
	fn handle_span(&self, span: &SpanDatum);
	/// Process a `TraceEvent`.
	fn handle_event(&self, event: &TraceEvent);
}

/// Represents a tracing event, complete with values
#[derive(Debug, Clone)]
pub struct TraceEvent {
	/// Name of the event.
	pub name: String,
	/// Target of the event.
	pub target: String,
	/// Level of the event.
	pub level: Level,
	/// Values for this event.
	pub values: Values,
	/// Id of the parent tracing event, if any.
	pub parent_id: Option<Id>,
}

/// Represents a single instance of a tracing span
#[derive(Debug, Clone)]
pub struct SpanDatum {
	/// id for this span
	pub id: Id,
	/// id of the parent span, if any
	pub parent_id: Option<Id>,
	/// Name of this span
	pub name: String,
	/// Target, typically module
	pub target: String,
	/// Tracing Level - ERROR, WARN, INFO, DEBUG or TRACE
	pub level: Level,
	/// Line number in source
	pub line: u32,
	/// Time that the span was last entered
	pub start_time: Instant,
	/// Total duration of span while entered
	pub overall_time: Duration,
	/// Values recorded to this span
	pub values: Values,
}

/// Holds associated values for a tracing span
#[derive(Default, Clone, Debug)]
pub struct Values {
	/// FxHashMap of `bool` values
	pub bool_values: FxHashMap<String, bool>,
	/// FxHashMap of `i64` values
	pub i64_values: FxHashMap<String, i64>,
	/// FxHashMap of `u64` values
	pub u64_values: FxHashMap<String, u64>,
	/// FxHashMap of `String` values
	pub string_values: FxHashMap<String, String>,
}

impl Values {
	/// Returns a new instance of Values
	pub fn new() -> Self {
		Default::default()
	}

	/// Checks if all individual collections are empty
	pub fn is_empty(&self) -> bool {
		self.bool_values.is_empty() &&
			self.i64_values.is_empty() &&
			self.u64_values.is_empty() &&
			self.string_values.is_empty()
	}
}

impl Visit for Values {
	fn record_i64(&mut self, field: &Field, value: i64) {
		self.i64_values.insert(field.name().to_string(), value);
	}

	fn record_u64(&mut self, field: &Field, value: u64) {
		self.u64_values.insert(field.name().to_string(), value);
	}

	fn record_bool(&mut self, field: &Field, value: bool) {
		self.bool_values.insert(field.name().to_string(), value);
	}

	fn record_str(&mut self, field: &Field, value: &str) {
		self.string_values.insert(field.name().to_string(), value.to_owned());
	}

	fn record_debug(&mut self, field: &Field, value: &dyn std::fmt::Debug) {
		self.string_values.insert(field.name().to_string(), format!("{:?}", value));
	}
}

impl Serialize for Values {
	fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error>
	where
		S: Serializer,
	{
		let len = self.bool_values.len() +
			self.i64_values.len() +
			self.u64_values.len() +
			self.string_values.len();
		let mut map = serializer.serialize_map(Some(len))?;
		for (k, v) in &self.bool_values {
			map.serialize_entry(k, v)?;
		}
		for (k, v) in &self.i64_values {
			map.serialize_entry(k, v)?;
		}
		for (k, v) in &self.u64_values {
			map.serialize_entry(k, v)?;
		}
		for (k, v) in &self.string_values {
			map.serialize_entry(k, v)?;
		}
		map.end()
	}
}

impl fmt::Display for Values {
	fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
		let bool_iter = self.bool_values.iter().map(|(k, v)| format!("{}={}", k, v));
		let i64_iter = self.i64_values.iter().map(|(k, v)| format!("{}={}", k, v));
		let u64_iter = self.u64_values.iter().map(|(k, v)| format!("{}={}", k, v));
		let string_iter = self.string_values.iter().map(|(k, v)| format!("{}=\"{}\"", k, v));
		let values = bool_iter
			.chain(i64_iter)
			.chain(u64_iter)
			.chain(string_iter)
			.collect::<Vec<String>>()
			.join(", ");
		write!(f, "{}", values)
	}
}

/// Trace handler event types.
#[derive(Debug)]
pub enum TraceHandlerEvents {
	/// An event.
	Event(TraceEvent),
	/// A span.
	Span(SpanDatum),
}

impl ProfilingLayer {
	/// Takes a `TracingReceiver` and a comma separated list of targets,
	/// either with a level: "pallet=trace,frame=debug"
	/// or without: "pallet,frame" in which case the level defaults to `trace`.
	/// wasm_tracing indicates whether to enable wasm traces
	pub fn new(receiver: TracingReceiver, targets: &str) -> Self {
		match receiver {
			TracingReceiver::Log => Self::new_with_handler(Box::new(LogTraceHandler), targets),
		}
	}

	/// Allows use of a custom TraceHandler to create a new instance of ProfilingSubscriber.
	/// Takes a comma separated list of targets,
	/// either with a level, eg: "pallet=trace"
	/// or without: "pallet" in which case the level defaults to `trace`.
	/// wasm_tracing indicates whether to enable wasm traces
	pub fn new_with_handler(trace_handler: Box<dyn TraceHandler>, targets: &str) -> Self {
		let targets: Vec<_> = targets.split(',').map(parse_target).collect();
		Self { targets, trace_handlers: vec![trace_handler] }
	}

	/// Attach additional handlers to allow handling of custom events/spans.
	pub fn add_handler(&mut self, trace_handler: Box<dyn TraceHandler>) {
		self.trace_handlers.push(trace_handler);
	}

	fn check_target(&self, target: &str, level: &Level) -> bool {
		for t in &self.targets {
			if target.starts_with(t.0.as_str()) && level <= &t.1 {
				return true
			}
		}
		false
	}

	/// Sequentially dispatch a trace event to all handlers.
	fn dispatch_event(&self, event: TraceHandlerEvents) {
		match &event {
			TraceHandlerEvents::Span(span_datum) => {
				self.trace_handlers.iter().for_each(|handler| handler.handle_span(span_datum));
			},
			TraceHandlerEvents::Event(event) => {
				self.trace_handlers.iter().for_each(|handler| handler.handle_event(event));
			},
		}
	}
}

// Default to TRACE if no level given or unable to parse Level
// We do not support a global `Level` currently
fn parse_target(s: &str) -> (String, Level) {
	match s.find('=') {
		Some(i) => {
			let target = s[0..i].to_string();
			if s.len() > i {
				let level = s[i + 1..].parse::<Level>().unwrap_or(Level::TRACE);
				(target, level)
			} else {
				(target, Level::TRACE)
			}
		},
		None => (s.to_string(), Level::TRACE),
	}
}

impl<S> Layer<S> for ProfilingLayer
where
	S: Subscriber + for<'span> LookupSpan<'span>,
{
	fn new_span(&self, attrs: &Attributes<'_>, id: &Id, ctx: Context<S>) {
		if let Some(span) = ctx.span(id) {
			let mut extension = span.extensions_mut();
			let parent_id = attrs.parent().cloned().or_else(|| {
				if attrs.is_contextual() {
					ctx.lookup_current().map(|span| span.id())
				} else {
					None
				}
			});

			let mut values = Values::default();
			attrs.record(&mut values);
			let span_datum = SpanDatum {
				id: id.clone(),
				parent_id,
				name: attrs.metadata().name().to_owned(),
				target: attrs.metadata().target().to_owned(),
				level: *attrs.metadata().level(),
				line: attrs.metadata().line().unwrap_or(0),
				start_time: Instant::now(),
				overall_time: ZERO_DURATION,
				values,
			};
			extension.insert(span_datum);
		}
	}

	fn on_record(&self, id: &Id, values: &Record<'_>, ctx: Context<S>) {
		if let Some(span) = ctx.span(id) {
			let mut extensions = span.extensions_mut();
			if let Some(s) = extensions.get_mut::<SpanDatum>() {
				values.record(&mut s.values);
			}
		}
	}

	fn on_event(&self, event: &Event<'_>, ctx: Context<S>) {
		if !self.check_target(event.metadata().target(), &event.metadata().level()) {
			return
		}

		let parent_id = event.parent().cloned().or_else(|| {
			if event.is_contextual() {
				ctx.lookup_current().map(|span| span.id())
			} else {
				None
			}
		});

		let mut values = Values::default();
		event.record(&mut values);
		let trace_event = TraceEvent {
			name: event.metadata().name().to_owned(),
			target: event.metadata().target().to_owned(),
			level: *event.metadata().level(),
			values,
			parent_id,
		};
		self.dispatch_event(TraceHandlerEvents::Event(trace_event));
	}

	fn on_enter(&self, span: &Id, ctx: Context<S>) {
		if let Some(span) = ctx.span(span) {
			let mut extensions = span.extensions_mut();
			if let Some(s) = extensions.get_mut::<SpanDatum>() {
				let start_time = Instant::now();
				s.start_time = start_time;
			}
		}
	}

	fn on_exit(&self, span: &Id, ctx: Context<S>) {
		if let Some(span) = ctx.span(span) {
			let end_time = Instant::now();
			let mut extensions = span.extensions_mut();
			if let Some(mut span_datum) = extensions.remove::<SpanDatum>() {
				span_datum.overall_time += end_time - span_datum.start_time;
				if span_datum.name == WASM_TRACE_IDENTIFIER {
					span_datum.values.bool_values.insert("wasm".to_owned(), true);
					if let Some(n) = span_datum.values.string_values.remove(WASM_NAME_KEY) {
						span_datum.name = n;
					}
					if let Some(t) = span_datum.values.string_values.remove(WASM_TARGET_KEY) {
						span_datum.target = t;
					}
					if self.check_target(&span_datum.target, &span_datum.level) {
						self.dispatch_event(TraceHandlerEvents::Span(span_datum));
					}
				} else {
					self.dispatch_event(TraceHandlerEvents::Span(span_datum));
				}
			}
		}
	}

	fn on_close(&self, _span: Id, _ctx: Context<S>) {}
}

/// TraceHandler for sending span data to the logger
pub struct LogTraceHandler;

fn log_level(level: Level) -> log::Level {
	match level {
		Level::TRACE => log::Level::Trace,
		Level::DEBUG => log::Level::Debug,
		Level::INFO => log::Level::Info,
		Level::WARN => log::Level::Warn,
		Level::ERROR => log::Level::Error,
	}
}

impl TraceHandler for LogTraceHandler {
	fn handle_span(&self, span_datum: &SpanDatum) {
		if span_datum.values.is_empty() {
			log::log!(
				log_level(span_datum.level),
				"{}: {}, time: {}, id: {}, parent_id: {:?}",
				span_datum.target,
				span_datum.name,
				span_datum.overall_time.as_nanos(),
				span_datum.id.into_u64(),
				span_datum.parent_id.as_ref().map(|s| s.into_u64()),
			);
		} else {
			log::log!(
				log_level(span_datum.level),
				"{}: {}, time: {}, id: {}, parent_id: {:?}, values: {}",
				span_datum.target,
				span_datum.name,
				span_datum.overall_time.as_nanos(),
				span_datum.id.into_u64(),
				span_datum.parent_id.as_ref().map(|s| s.into_u64()),
				span_datum.values,
			);
		}
	}

	fn handle_event(&self, event: &TraceEvent) {
		log::log!(
			log_level(event.level),
			"{}, parent_id: {:?}, {}",
			event.target,
			event.parent_id.as_ref().map(|s| s.into_u64()),
			event.values,
		);
	}
}

impl From<TraceEvent> for sp_rpc::tracing::Event {
	fn from(trace_event: TraceEvent) -> Self {
		let data = sp_rpc::tracing::Data { string_values: trace_event.values.string_values };
		sp_rpc::tracing::Event {
			target: trace_event.target,
			data,
			parent_id: trace_event.parent_id.map(|id| id.into_u64()),
		}
	}
}

impl From<SpanDatum> for sp_rpc::tracing::Span {
	fn from(span_datum: SpanDatum) -> Self {
		let wasm = span_datum.values.bool_values.get("wasm").is_some();
		sp_rpc::tracing::Span {
			id: span_datum.id.into_u64(),
			parent_id: span_datum.parent_id.map(|id| id.into_u64()),
			name: span_datum.name,
			target: span_datum.target,
			wasm,
		}
	}
}

#[cfg(test)]
mod tests {
	use super::*;
	use parking_lot::Mutex;
	use std::sync::{
		mpsc::{Receiver, Sender},
		Arc,
	};
	use tracing_subscriber::layer::SubscriberExt;

	struct TestTraceHandler {
		spans: Arc<Mutex<Vec<SpanDatum>>>,
		events: Arc<Mutex<Vec<TraceEvent>>>,
	}

	impl TraceHandler for TestTraceHandler {
		fn handle_span(&self, sd: &SpanDatum) {
			self.spans.lock().push(sd.clone());
		}

		fn handle_event(&self, event: &TraceEvent) {
			self.events.lock().push(event.clone());
		}
	}

	fn setup_subscriber() -> (
		impl tracing::Subscriber + Send + Sync,
		Arc<Mutex<Vec<SpanDatum>>>,
		Arc<Mutex<Vec<TraceEvent>>>,
	) {
		let spans = Arc::new(Mutex::new(Vec::new()));
		let events = Arc::new(Mutex::new(Vec::new()));
		let handler = TestTraceHandler { spans: spans.clone(), events: events.clone() };
		let layer = ProfilingLayer::new_with_handler(Box::new(handler), "test_target");
		let subscriber = tracing_subscriber::fmt().with_writer(std::io::sink).finish().with(layer);
		(subscriber, spans, events)
	}

	#[test]
	fn test_span() {
		let (sub, spans, events) = setup_subscriber();
		let _sub_guard = tracing::subscriber::set_default(sub);
		let span = tracing::info_span!(target: "test_target", "test_span1");
		assert_eq!(spans.lock().len(), 0);
		assert_eq!(events.lock().len(), 0);
		let _guard = span.enter();
		assert_eq!(spans.lock().len(), 0);
		assert_eq!(events.lock().len(), 0);
		drop(_guard);
		drop(span);
		assert_eq!(spans.lock().len(), 1);
		assert_eq!(events.lock().len(), 0);
		let sd = spans.lock().remove(0);
		assert_eq!(sd.name, "test_span1");
		assert_eq!(sd.target, "test_target");
		let time: u128 = sd.overall_time.as_nanos();
		assert!(time > 0);
	}

	#[test]
	fn test_span_parent_id() {
		let (sub, spans, _events) = setup_subscriber();
		let _sub_guard = tracing::subscriber::set_default(sub);
		let span1 = tracing::info_span!(target: "test_target", "test_span1");
		let _guard1 = span1.enter();
		let span2 = tracing::info_span!(target: "test_target", "test_span2");
		let _guard2 = span2.enter();
		drop(_guard2);
		drop(span2);
		let sd2 = spans.lock().remove(0);
		drop(_guard1);
		drop(span1);
		let sd1 = spans.lock().remove(0);
		assert_eq!(sd1.id, sd2.parent_id.unwrap())
	}

	#[test]
	fn test_span_values() {
		let (sub, spans, _events) = setup_subscriber();
		let _sub_guard = tracing::subscriber::set_default(sub);
		let test_bool = true;
		let test_u64 = 1u64;
		let test_i64 = 2i64;
		let test_str = "test_str";
		let span = tracing::info_span!(
			target: "test_target",
			"test_span1",
			test_bool,
			test_u64,
			test_i64,
			test_str
		);
		let _guard = span.enter();
		drop(_guard);
		drop(span);
		let sd = spans.lock().remove(0);
		assert_eq!(sd.name, "test_span1");
		assert_eq!(sd.target, "test_target");
		let values = sd.values;
		assert_eq!(values.bool_values.get("test_bool").unwrap(), &test_bool);
		assert_eq!(values.u64_values.get("test_u64").unwrap(), &test_u64);
		assert_eq!(values.i64_values.get("test_i64").unwrap(), &test_i64);
		assert_eq!(values.string_values.get("test_str").unwrap(), &test_str.to_owned());
	}

	#[test]
	fn test_event() {
		let (sub, _spans, events) = setup_subscriber();
		let _sub_guard = tracing::subscriber::set_default(sub);
		tracing::event!(target: "test_target", tracing::Level::INFO, "test_event");
		let mut te1 = events.lock().remove(0);
		assert_eq!(
			te1.values.string_values.remove(&"message".to_owned()).unwrap(),
			"test_event".to_owned()
		);
	}

	#[test]
	fn test_event_parent_id() {
		let (sub, spans, events) = setup_subscriber();
		let _sub_guard = tracing::subscriber::set_default(sub);

		// enter span
		let span1 = tracing::info_span!(target: "test_target", "test_span1");
		let _guard1 = span1.enter();

		// emit event
		tracing::event!(target: "test_target", tracing::Level::INFO, "test_event");

		// exit span
		drop(_guard1);
		drop(span1);

		let sd1 = spans.lock().remove(0);
		let te1 = events.lock().remove(0);

		assert_eq!(sd1.id, te1.parent_id.unwrap());
	}

	#[test]
	fn test_parent_id_with_threads() {
		use std::{sync::mpsc, thread};

		if std::env::var("RUN_TEST_PARENT_ID_WITH_THREADS").is_err() {
			let executable = std::env::current_exe().unwrap();
			let mut command = std::process::Command::new(executable);

			let res = command
				.env("RUN_TEST_PARENT_ID_WITH_THREADS", "1")
				.args(&["--nocapture", "test_parent_id_with_threads"])
				.output()
				.unwrap()
				.status;
			assert!(res.success());
		} else {
			let (sub, spans, events) = setup_subscriber();
			let _sub_guard = tracing::subscriber::set_global_default(sub);
			let span1 = tracing::info_span!(target: "test_target", "test_span1");
			let _guard1 = span1.enter();

			let (tx, rx): (Sender<bool>, Receiver<bool>) = mpsc::channel();
			let handle = thread::spawn(move || {
				let span2 = tracing::info_span!(target: "test_target", "test_span2");
				let _guard2 = span2.enter();
				// emit event
				tracing::event!(target: "test_target", tracing::Level::INFO, "test_event1");
				let _ = rx.recv();
				// guard2 and span2 dropped / exited
			});

			// wait for Event to be dispatched and stored
			while events.lock().is_empty() {
				thread::sleep(Duration::from_millis(1));
			}

			// emit new event (will be second item in Vec) while span2 still active in other thread
			tracing::event!(target: "test_target", tracing::Level::INFO, "test_event2");

			// stop thread and drop span
			let _ = tx.send(false);
			let _ = handle.join();

			// wait for Span to be dispatched and stored
			while spans.lock().is_empty() {
				thread::sleep(Duration::from_millis(1));
			}
			let span2 = spans.lock().remove(0);
			let event1 = events.lock().remove(0);
			drop(_guard1);
			drop(span1);

			// emit event with no parent
			tracing::event!(target: "test_target", tracing::Level::INFO, "test_event3");

			let span1 = spans.lock().remove(0);
			let event2 = events.lock().remove(0);

			assert_eq!(event1.values.string_values.get("message").unwrap(), "test_event1");
			assert_eq!(event2.values.string_values.get("message").unwrap(), "test_event2");
			assert!(span1.parent_id.is_none());
			assert!(span2.parent_id.is_none());
			assert_eq!(span2.id, event1.parent_id.unwrap());
			assert_eq!(span1.id, event2.parent_id.unwrap());
			assert_ne!(span2.id, span1.id);

			let event3 = events.lock().remove(0);
			assert!(event3.parent_id.is_none());
		}
	}
}