bestool-alertd 6.0.0

use std::collections::HashMap;

use miette::Result;
use tera::Context as TeraCtx;
use tracing::{debug, error, info, warn};

use crate::{
	LogError,
	alert::{AlertDefinition, InternalContext},
	targets::{ExternalTarget, ResolvedTarget, determine_default_target},
};

/// Build the synthetic alert file used by event triggers and clears.
///
/// Embedding the entity key in the file stem keeps the canopy ref stable
/// across trigger and clear for the same logical entity (e.g. the same
/// failing alert), and distinct across different entities.
fn synthetic_alert_file(event_type: &EventType, entity_key: Option<&str>) -> std::path::PathBuf {
	match entity_key {
		Some(key) => format!("[internal:{}:{}]", event_type.as_str(), key).into(),
		None => format!("[internal:{}]", event_type.as_str()).into(),
	}
}

fn synthetic_alert(event_type: &EventType, entity_key: Option<&str>) -> AlertDefinition {
	AlertDefinition {
		file: synthetic_alert_file(event_type, entity_key),
		enabled: true,
		interval: "0 seconds".to_string(),
		interval_duration: std::time::Duration::from_secs(0),
		always_send: crate::alert::AlwaysSend::Boolean(false),
		when_changed: crate::alert::WhenChanged::default(),
		send: Vec::new(),
		// Synthesised internal-event alerts (e.g. source-error, definition-error)
		// aren't tied to a specific server kind — they run wherever the daemon
		// does. `None` means "any" (no filter).
		server_kind: None,
		source: crate::alert::TicketSource::Event {
			event: event_type.clone(),
		},
	}
}

/// Internal event types that can trigger alerts
#[derive(Debug, Clone, PartialEq, Eq, Hash, serde::Deserialize, serde::Serialize)]
#[serde(rename_all = "kebab-case")]
pub enum EventType {
	SourceError,
	DefinitionError,
	DatabaseDown,
}

impl EventType {
	pub fn as_str(&self) -> &'static str {
		match self {
			Self::SourceError => "source-error",
			Self::DefinitionError => "definition-error",
			Self::DatabaseDown => "database-down",
		}
	}
}

/// Context data for an event
#[derive(Debug, Clone)]
pub enum EventContext {
	SourceError {
		alert_file: String,
		error_message: String,
	},
	DefinitionError {
		alert_file: String,
		error_message: String,
	},
	DatabaseDown {
		database_url: String,
		error_message: String,
	},
}

impl EventContext {
	pub fn to_tera_context(&self) -> TeraCtx {
		let mut ctx = TeraCtx::new();
		match self {
			Self::SourceError {
				alert_file,
				error_message,
			} => {
				ctx.insert("alert_file", alert_file);
				ctx.insert("error_message", error_message);
			}
			Self::DefinitionError {
				alert_file,
				error_message,
			} => {
				ctx.insert("alert_file", alert_file);
				ctx.insert("error_message", error_message);
			}
			Self::DatabaseDown {
				database_url,
				error_message,
			} => {
				ctx.insert("database_url", database_url);
				ctx.insert("error_message", error_message);
			}
		}
		ctx
	}
}

/// Manages event-triggered alerts
#[derive(Clone)]
pub struct EventManager {
	/// Alerts that listen for specific events
	event_alerts: HashMap<EventType, Vec<(AlertDefinition, Vec<ResolvedTarget>)>>,
	/// Default target for fallback alerts
	default_target: Option<ResolvedTarget>,
}

impl EventManager {
	pub fn new(
		alerts: Vec<(AlertDefinition, Vec<ResolvedTarget>)>,
		external_targets: &HashMap<String, Vec<ExternalTarget>>,
	) -> Self {
		let mut event_alerts: HashMap<EventType, Vec<(AlertDefinition, Vec<ResolvedTarget>)>> =
			HashMap::new();

		debug!(total_alerts = alerts.len(), "initializing event manager");

		// Separate event-based alerts from regular alerts
		for (alert, targets) in alerts {
			if let crate::alert::TicketSource::Event { event } = &alert.source {
				debug!(
					file = ?alert.file,
					event = event.as_str(),
					targets = targets.len(),
					"registered event alert"
				);
				event_alerts
					.entry(event.clone())
					.or_default()
					.push((alert, targets));
			}
		}

		info!(
			event_types = ?event_alerts.keys().collect::<Vec<_>>(),
			total_event_alerts = event_alerts.values().map(|v| v.len()).sum::<usize>(),
			"event manager initialized"
		);

		let default_target = determine_default_target(external_targets).map(|t| ResolvedTarget {
			target_id: t.id.clone(),
			subject: None,
			template: String::new(),
			conn: t.conn.clone(),
		});
		if let Some(ref target) = default_target {
			let target_desc = match &target.conn {
				crate::targets::TargetConnection::Email(email) => email
					.addresses
					.first()
					.cloned()
					.unwrap_or_else(|| "unknown".into()),
				crate::targets::TargetConnection::Slack(slack) => {
					format!("slack:{}", slack.webhook.host_str().unwrap_or("unknown"))
				}
				crate::targets::TargetConnection::Canopy(_) => "canopy".to_string(),
			};
			info!(
				from = %target_desc,
				"determined default target for fallback alerts"
			);
		}

		Self {
			event_alerts,
			default_target,
		}
	}

	/// Trigger an event with the given context.
	///
	/// `entity_key` identifies the specific subject of the event (e.g. the
	/// erroring alert's file path). It's embedded in the synthetic alert file
	/// so canopy refs are stable across trigger and clear for the same
	/// subject, and distinct across different subjects. Pass `None` for
	/// events that have only one possible subject per host (e.g. the database).
	pub async fn trigger_event(
		&self,
		event_type: EventType,
		ctx: &InternalContext,
		email: Option<&crate::EmailConfig>,
		dry_run: bool,
		event_context: EventContext,
		entity_key: Option<&str>,
	) -> Result<()> {
		info!(
			event = event_type.as_str(),
			entity_key,
			has_alerts = self.event_alerts.contains_key(&event_type),
			has_default_target = self.default_target.is_some(),
			"triggering event"
		);

		// Check if there are explicit alerts for this event
		if let Some(alerts) = self.event_alerts.get(&event_type) {
			info!(count = alerts.len(), "executing event alerts");
			for (alert, targets) in alerts {
				let mut tera_ctx = crate::templates::build_context(alert, jiff::Timestamp::now());
				// Merge event context
				tera_ctx.extend(event_context.to_tera_context());

				for target in targets {
					if let Err(err) = target.send(alert, &mut tera_ctx, email, ctx, dry_run).await {
						error!(file = ?alert.file, "failed to send event alert: {}", LogError(&err));
					}
				}
			}
		} else if let Some(ref default_target) = self.default_target {
			// No explicit alert, use default target with event-specific template
			info!(
				event = event_type.as_str(),
				"using default target for event (no explicit alert configured)"
			);

			let (subject_template, body_template) = default_event_template(&event_type);

			let default_target_for_event = ResolvedTarget {
				target_id: default_target.target_id.clone(),
				subject: Some(subject_template),
				template: body_template,
				conn: default_target.conn.clone(),
			};

			let alert = synthetic_alert(&event_type, entity_key);

			let mut tera_ctx = crate::templates::build_context(&alert, jiff::Timestamp::now());
			tera_ctx.extend(event_context.to_tera_context());

			if let Err(err) = default_target_for_event
				.send(&alert, &mut tera_ctx, email, ctx, dry_run)
				.await
			{
				error!("failed to send default event alert: {}", LogError(&err));
			}
		} else {
			warn!(
				event = event_type.as_str(),
				"no alerts or default target for event, skipping notification"
			);
		}

		Ok(())
	}

	/// Send a clearing notification for an event.
	///
	/// Mirrors `trigger_event`, but calls `send_clear` on each target so
	/// stateful sinks (canopy) flip the corresponding issue to `active=false`.
	/// Non-stateful sinks (email, slack) return immediately — that's the same
	/// behaviour as SQL-alert clears.
	///
	/// `entity_key` must match the value passed to the original
	/// `trigger_event` so the canopy ref lines up.
	pub async fn trigger_clear(
		&self,
		event_type: EventType,
		ctx: &InternalContext,
		dry_run: bool,
		entity_key: Option<&str>,
	) -> Result<()> {
		info!(
			event = event_type.as_str(),
			entity_key,
			has_alerts = self.event_alerts.contains_key(&event_type),
			has_default_target = self.default_target.is_some(),
			"clearing event"
		);

		if let Some(alerts) = self.event_alerts.get(&event_type) {
			info!(count = alerts.len(), "clearing event alerts");
			for (alert, targets) in alerts {
				for target in targets {
					if let Err(err) = target.send_clear(alert, ctx, dry_run).await {
						error!(file = ?alert.file, "failed to clear event alert: {}", LogError(&err));
					}
				}
			}
		} else if let Some(ref default_target) = self.default_target {
			info!(
				event = event_type.as_str(),
				"clearing default target for event"
			);

			let default_target_for_event = ResolvedTarget {
				target_id: default_target.target_id.clone(),
				subject: None,
				template: String::new(),
				conn: default_target.conn.clone(),
			};

			let alert = synthetic_alert(&event_type, entity_key);

			if let Err(err) = default_target_for_event
				.send_clear(&alert, ctx, dry_run)
				.await
			{
				error!("failed to clear default event alert: {}", LogError(&err));
			}
		} else {
			debug!(
				event = event_type.as_str(),
				"no alerts or default target for event, skipping clear"
			);
		}

		Ok(())
	}
}

fn default_event_template(event_type: &EventType) -> (String, String) {
	match event_type {
		EventType::SourceError => (
			"[bestool-alertd] {{ hostname }}: Failed alert: {{ alert_file }}".to_string(),
			"<pre>{{ error_message }}</pre>".to_string(),
		),
		EventType::DefinitionError => (
			"[bestool-alertd] {{ hostname }}: Invalid alert definition: {{ alert_file }}"
				.to_string(),
			"<pre>{{ error_message }}</pre>".to_string(),
		),
		EventType::DatabaseDown => (
			"[bestool-alertd] {{ hostname }}: Database unreachable".to_string(),
			"The PostgreSQL database is unreachable.\n\n\
			 Database URL: {{ database_url }}\n\
			 Error: <pre>{{ error_message }}</pre>\n\n\
			 All SQL-based alerts are non-functional until the database is restored."
				.to_string(),
		),
	}
}

#[cfg(test)]
mod tests {
	use super::*;

	#[test]
	fn test_event_type_parsing() {
		let yaml = "source-error";
		let event: EventType = serde_yaml::from_str(yaml).unwrap();
		assert_eq!(event, EventType::SourceError);
	}

	#[test]
	fn test_event_type_as_str() {
		assert_eq!(EventType::SourceError.as_str(), "source-error");
		assert_eq!(EventType::DefinitionError.as_str(), "definition-error");
		assert_eq!(EventType::DatabaseDown.as_str(), "database-down");
	}

	#[test]
	fn test_event_type_serialization() {
		let event = EventType::SourceError;
		let yaml = serde_yaml::to_string(&event).unwrap();
		assert!(yaml.contains("source-error"));
	}

	#[test]
	fn test_event_context_to_tera_source_error() {
		let ctx = EventContext::SourceError {
			alert_file: "/etc/alerts/test.yml".to_string(),
			error_message: "Something went wrong".to_string(),
		};

		let tera_ctx = ctx.to_tera_context();
		assert_eq!(
			tera_ctx.get("alert_file").unwrap().as_str().unwrap(),
			"/etc/alerts/test.yml"
		);
		assert_eq!(
			tera_ctx.get("error_message").unwrap().as_str().unwrap(),
			"Something went wrong"
		);
	}

	#[test]
	fn test_event_type_database_down() {
		let yaml = "database-down";
		let event: EventType = serde_yaml::from_str(yaml).unwrap();
		assert_eq!(event, EventType::DatabaseDown);
	}

	#[test]
	fn test_event_context_to_tera_database_down() {
		let ctx = EventContext::DatabaseDown {
			database_url: "postgresql://localhost/mydb".to_string(),
			error_message: "connection refused".to_string(),
		};

		let tera_ctx = ctx.to_tera_context();
		assert_eq!(
			tera_ctx.get("database_url").unwrap().as_str().unwrap(),
			"postgresql://localhost/mydb"
		);
		assert_eq!(
			tera_ctx.get("error_message").unwrap().as_str().unwrap(),
			"connection refused"
		);
	}

	#[test]
	fn test_event_type_definition_error() {
		let yaml = "definition-error";
		let event: EventType = serde_yaml::from_str(yaml).unwrap();
		assert_eq!(event, EventType::DefinitionError);
	}

	#[test]
	fn test_event_context_to_tera_definition_error() {
		let ctx = EventContext::DefinitionError {
			alert_file: "/etc/alerts/broken.yml".to_string(),
			error_message: "Invalid YAML syntax".to_string(),
		};

		let tera_ctx = ctx.to_tera_context();
		assert_eq!(
			tera_ctx.get("alert_file").unwrap().as_str().unwrap(),
			"/etc/alerts/broken.yml"
		);
		assert_eq!(
			tera_ctx.get("error_message").unwrap().as_str().unwrap(),
			"Invalid YAML syntax"
		);
	}

	#[test]
	fn synthetic_alert_file_without_entity_key() {
		let path = synthetic_alert_file(&EventType::DatabaseDown, None);
		assert_eq!(path.to_string_lossy(), "[internal:database-down]");
	}

	#[test]
	fn synthetic_alert_file_with_entity_key() {
		let path = synthetic_alert_file(&EventType::SourceError, Some("disk-full.yml"));
		assert_eq!(
			path.to_string_lossy(),
			"[internal:source-error:disk-full.yml]"
		);
	}

	#[test]
	fn synthetic_alert_file_distinguishes_entities() {
		let a = synthetic_alert_file(&EventType::DefinitionError, Some("a.yml"));
		let b = synthetic_alert_file(&EventType::DefinitionError, Some("b.yml"));
		assert_ne!(a, b);
	}

	#[test]
	fn synthetic_alert_file_stem_includes_entity_for_canopy_ref() {
		// build_ref uses file_stem() to form the canopy ref. Verify that
		// trigger and clear with the same entity key produce identical stems.
		let trigger = synthetic_alert_file(&EventType::SourceError, Some("my-alert"));
		let clear = synthetic_alert_file(&EventType::SourceError, Some("my-alert"));
		assert_eq!(trigger.file_stem(), clear.file_stem());

		// And distinct entities produce distinct stems so canopy treats them
		// as separate issues.
		let other = synthetic_alert_file(&EventType::SourceError, Some("other-alert"));
		assert_ne!(trigger.file_stem(), other.file_stem());
	}
}