rskit-logging 0.1.0-alpha.1

//! Structured logging setup using the [`tracing`] ecosystem.
//!
//! # Usage
//!
//! ```ignore
//! use rskit_logging::init_logging;
//!
//! let _guard = init_logging(&config.service.logging)?;
//! // _guard must stay alive for the duration of the program
//! tracing::info!(service = "my-svc", "started");
//! ```
//!
//! # Design
//!
//! There is intentionally no global logger registry (unlike gokit's `logger.Get(name)`).
//! Callers use `tracing` directly and scope context via spans + `#[tracing::instrument]`.
//! `init_logging` installs a scoped default subscriber; the returned guard restores
//! the previous subscriber on drop.

#![warn(missing_docs)]

/// Span-level context helpers — component tagging, request enrichment.
pub mod context;
/// Error helpers for logging setup.
pub mod error;
/// Standard field name constants for the unified log schema.
pub mod fields;
/// Sensitive data masking for log output.
pub mod masking;
/// Per-module log level overrides from config.
pub mod module_levels;
/// OpenTelemetry Logs bridge with OTLP export.
#[cfg(feature = "otlp")]
pub mod otlp;
/// Rate-based log sampling layer.
pub mod sampling;

use std::collections::HashMap;
use std::fs::OpenOptions;
use std::sync::Arc;

use rskit_config::{LogFormat, LogOutput, LoggingConfig};
use tracing::dispatcher::DefaultGuard;
use tracing_subscriber::{EnvFilter, fmt, fmt::writer::BoxMakeWriter, layer::SubscriberExt};

pub use error::LoggingResult;
pub use masking::{DefaultMasker, Masker, MaskingConfig, MaskingMakeWriter};
pub use module_levels::{ModuleLevelsConfig, build_env_filter};
#[cfg(feature = "otlp")]
pub use otlp::{OtlpConfig, OtlpProvider};
pub use sampling::SamplingConfig;

/// Options for [`init_logging_full`].
#[cfg(feature = "otlp")]
pub struct LoggingSetup<'a> {
    /// Base logging configuration.
    pub config: &'a LoggingConfig,
    /// Optional rate-based sampling configuration.
    pub sampling: Option<&'a SamplingConfig>,
    /// Optional per-module level overrides.
    pub module_levels: Option<&'a HashMap<String, String>>,
    /// Optional sensitive data masking configuration.
    pub masking: Option<&'a MaskingConfig>,
    /// Optional OTLP exporter configuration.
    pub otlp: Option<&'a otlp::OtlpConfig>,
    /// Service name reported to OpenTelemetry.
    pub service_name: &'a str,
    /// Deployment environment reported to OpenTelemetry.
    pub environment: &'a str,
    /// Service version reported to OpenTelemetry.
    pub version: &'a str,
}

#[cfg(feature = "otlp")]
impl<'a> LoggingSetup<'a> {
    /// Create full logging setup options with no optional layers enabled.
    #[must_use]
    pub const fn new(
        config: &'a LoggingConfig,
        service_name: &'a str,
        environment: &'a str,
        version: &'a str,
    ) -> Self {
        Self {
            config,
            sampling: None,
            module_levels: None,
            masking: None,
            otlp: None,
            service_name,
            environment,
            version,
        }
    }

    /// Add rate-based sampling.
    #[must_use]
    pub const fn with_sampling(mut self, sampling: &'a SamplingConfig) -> Self {
        self.sampling = Some(sampling);
        self
    }

    /// Add per-module log level overrides.
    #[must_use]
    pub const fn with_module_levels(mut self, module_levels: &'a HashMap<String, String>) -> Self {
        self.module_levels = Some(module_levels);
        self
    }

    /// Add sensitive data masking.
    #[must_use]
    pub const fn with_masking(mut self, masking: &'a MaskingConfig) -> Self {
        self.masking = Some(masking);
        self
    }

    /// Add OTLP export.
    #[must_use]
    pub const fn with_otlp(mut self, otlp: &'a otlp::OtlpConfig) -> Self {
        self.otlp = Some(otlp);
        self
    }
}

/// Opaque guard — drop to restore the previous tracing subscriber.
///
/// Keep this alive for the lifetime of your service (e.g. bind it to a
/// variable in `main`). When OTLP export is enabled through `init_logging_full`,
/// the guard also owns the OTLP provider and shuts it
/// down on drop to flush pending records.
pub struct LoggingGuard {
    #[allow(dead_code)]
    guard: DefaultGuard,
    #[cfg(feature = "otlp")]
    otlp_provider: Option<otlp::OtlpProvider>,
}

impl LoggingGuard {
    fn new(guard: DefaultGuard) -> Self {
        Self {
            guard,
            #[cfg(feature = "otlp")]
            otlp_provider: None,
        }
    }

    #[cfg(feature = "otlp")]
    fn with_otlp_provider(guard: DefaultGuard, otlp_provider: Option<otlp::OtlpProvider>) -> Self {
        Self {
            guard,
            otlp_provider,
        }
    }
}

#[cfg(feature = "otlp")]
impl Drop for LoggingGuard {
    fn drop(&mut self) {
        if let Some(provider) = self.otlp_provider.take()
            && let Err(error) = provider.shutdown()
        {
            tracing::warn!(%error, "failed to shut down OTLP logging provider");
        }
    }
}

/// Initialize structured logging from a [`LoggingConfig`] with default masking.
///
/// - `LogFormat::Json` → newline-delimited JSON (production)
/// - `LogFormat::Console` → human-readable with colour (development)
///
/// Masking is **enabled by default** — sensitive fields are redacted before
/// reaching the output sink.  Use [`init_logging_with_options`] for full
/// control over masking, sampling, and per-module levels.
///
/// The `RUST_LOG` env var takes precedence over `cfg.level` when set.
///
/// # Errors
///
/// Returns an error when the configured file output cannot be opened.
pub fn init_logging(cfg: &LoggingConfig) -> LoggingResult<LoggingGuard> {
    init_logging_with_default_masking(cfg)
}

/// Initialize logging from `RUST_LOG` only (no config struct needed).
pub fn init_logging_env() -> LoggingGuard {
    let filter = EnvFilter::try_from_default_env().unwrap_or_else(|_| EnvFilter::new("info"));
    let layer = fmt::layer().pretty();
    let dispatcher = tracing_subscriber::registry()
        .with(filter)
        .with(layer)
        .into();
    LoggingGuard::new(tracing::dispatcher::set_default(&dispatcher))
}

fn init_logging_with_default_masking(cfg: &LoggingConfig) -> LoggingResult<LoggingGuard> {
    let filter = build_filter(&cfg.level, None);
    let masker: Arc<dyn masking::Masker> = Arc::new(masking::DefaultMasker::default());
    let writer = masking::MaskingMakeWriter::new(build_output_writer(&cfg.output)?, masker);

    let guard = match cfg.format {
        LogFormat::Json => {
            let layer = fmt::layer()
                .json()
                .with_current_span(true)
                .with_span_list(true)
                .with_writer(writer);
            let dispatcher = tracing_subscriber::registry()
                .with(filter)
                .with(layer)
                .into();
            tracing::dispatcher::set_default(&dispatcher)
        }
        _ => {
            let layer = fmt::layer().pretty().with_writer(writer);
            let dispatcher = tracing_subscriber::registry()
                .with(filter)
                .with(layer)
                .into();
            tracing::dispatcher::set_default(&dispatcher)
        }
    };

    Ok(LoggingGuard::new(guard))
}

/// Initialize logging with explicit masking configuration.
///
/// When `masking_cfg.enabled` is `true`, all log output passes through a
/// [`MaskingMakeWriter`] that redacts secrets and PII before they reach the
/// output sink.  When masking is disabled, logging goes directly to the
/// configured output.
pub fn init_logging_with_masking(
    cfg: &LoggingConfig,
    masking_cfg: &masking::MaskingConfig,
) -> LoggingResult<LoggingGuard> {
    let m = if masking_cfg.enabled {
        Some(masking_cfg)
    } else {
        None
    };
    init_logging_with_options(cfg, None, None, m)
}

/// Enhanced logging init with optional sampling, per-module levels, and masking.
///
/// This is the primary initialisation entry point.  All other `init_logging*`
/// functions delegate here.
///
/// - **Sampling** — when `sampling` is `Some` and enabled, a [`sampling::SamplingLayer`]
///   is added to drop events exceeding per-level rate limits.
/// - **Module levels** — when `module_levels` is `Some`, per-module filter directives
///   are merged into the [`EnvFilter`].
/// - **Masking** — when `masking_cfg` is `Some` and enabled, a [`MaskingMakeWriter`]
///   wraps the configured output to redact secrets.  Pass `None` to disable
///   masking entirely.
///
/// # Errors
///
/// Returns an error when a custom masking regex pattern is invalid, when the
/// configured file output cannot be opened, or when the configured output
/// variant is unsupported by this crate version.
pub fn init_logging_with_options(
    cfg: &LoggingConfig,
    sampling_cfg: Option<&SamplingConfig>,
    module_levels: Option<&HashMap<String, String>>,
    masking_cfg: Option<&MaskingConfig>,
) -> LoggingResult<LoggingGuard> {
    let filter = build_filter(&cfg.level, module_levels);

    let sampling_layer = sampling_cfg
        .filter(|s| s.enabled)
        .map(sampling::SamplingLayer::new);
    let writer = build_output_writer(&cfg.output)?;

    if let Some(m) = masking_cfg.filter(|m| m.enabled) {
        let masker: Arc<dyn masking::Masker> = Arc::new(masking::DefaultMasker::new(m)?);
        let writer = masking::MaskingMakeWriter::new(writer, masker);

        let guard = match cfg.format {
            LogFormat::Json => {
                let layer = fmt::layer()
                    .json()
                    .with_current_span(true)
                    .with_span_list(true)
                    .with_writer(writer);
                let dispatcher = tracing_subscriber::registry()
                    .with(filter)
                    .with(sampling_layer)
                    .with(layer)
                    .into();
                tracing::dispatcher::set_default(&dispatcher)
            }
            _ => {
                let layer = fmt::layer().pretty().with_writer(writer);
                let dispatcher = tracing_subscriber::registry()
                    .with(filter)
                    .with(sampling_layer)
                    .with(layer)
                    .into();
                tracing::dispatcher::set_default(&dispatcher)
            }
        };
        return Ok(LoggingGuard::new(guard));
    }

    let guard = match cfg.format {
        LogFormat::Json => {
            let layer = fmt::layer()
                .json()
                .with_current_span(true)
                .with_span_list(true)
                .with_writer(writer);
            let dispatcher = tracing_subscriber::registry()
                .with(filter)
                .with(sampling_layer)
                .with(layer)
                .into();
            tracing::dispatcher::set_default(&dispatcher)
        }
        _ => {
            let layer = fmt::layer().pretty().with_writer(writer);
            let dispatcher = tracing_subscriber::registry()
                .with(filter)
                .with(sampling_layer)
                .with(layer)
                .into();
            tracing::dispatcher::set_default(&dispatcher)
        }
    };

    Ok(LoggingGuard::new(guard))
}

/// Build an [`EnvFilter`] from the configured level and optional module overrides.
fn build_filter(level: &str, module_levels: Option<&HashMap<String, String>>) -> EnvFilter {
    match module_levels {
        Some(levels) if !levels.is_empty() => module_levels::build_env_filter(level, levels),
        _ => EnvFilter::try_from_default_env().unwrap_or_else(|_| EnvFilter::new(level)),
    }
}

fn build_output_writer(output: &LogOutput) -> LoggingResult<BoxMakeWriter> {
    let writer = match output {
        LogOutput::Stdout => BoxMakeWriter::new(std::io::stdout),
        LogOutput::Stderr => BoxMakeWriter::new(std::io::stderr),
        LogOutput::File { path } => {
            let file = OpenOptions::new()
                .create(true)
                .append(true)
                .open(path)
                .map_err(|err| error::log_file_open(path.clone(), err))?;
            BoxMakeWriter::new(Arc::new(file))
        }
        _ => return Err(error::unsupported_output()),
    };

    Ok(writer)
}

/// Enhanced logging init with all options including OTLP export.
///
/// Layers the subscriber stack as follows:
///
/// 1. [`EnvFilter`] — base level + optional per-module overrides
/// 2. Optional [`sampling::SamplingLayer`] — rate-based log sampling
/// 3. Format layer (JSON or console)
/// 4. Optional [`otlp::OtlpProvider`] layer — bridges events to OTel Logs SDK
///
/// The returned [`LoggingGuard`] **must** be held for the lifetime of the
/// service.  When dropped it restores the previous subscriber and (when OTLP
/// is enabled) shuts down the provider, flushing pending logs.
///
/// # Errors
///
/// Returns an error if the OTLP provider cannot be created (e.g. invalid
/// endpoint or transport failure), or if a custom masking regex pattern is
/// invalid.
#[cfg(feature = "otlp")]
pub fn init_logging_full(setup: LoggingSetup<'_>) -> LoggingResult<LoggingGuard> {
    let filter = build_filter(&setup.config.level, setup.module_levels);

    let sampling_layer = setup
        .sampling
        .filter(|s| s.enabled)
        .map(sampling::SamplingLayer::new);
    let writer = build_output_writer(&setup.config.output)?;

    let otlp_provider = match setup.otlp {
        Some(oc) => {
            otlp::OtlpProvider::new(oc, setup.service_name, setup.environment, setup.version)?
        }
        None => None,
    };
    let otlp_layer = otlp_provider
        .as_ref()
        .map(|p| p.layer::<tracing_subscriber::Registry>());

    if let Some(m) = setup.masking.filter(|m| m.enabled) {
        let masker: Arc<dyn masking::Masker> = Arc::new(masking::DefaultMasker::new(m)?);
        let writer = masking::MaskingMakeWriter::new(writer, masker);

        let guard = match setup.config.format {
            LogFormat::Json => {
                let layer = fmt::layer()
                    .json()
                    .with_current_span(true)
                    .with_span_list(true)
                    .with_writer(writer);
                let dispatcher = tracing_subscriber::registry()
                    .with(filter)
                    .with(sampling_layer)
                    .with(layer)
                    .with(otlp_layer)
                    .into();
                tracing::dispatcher::set_default(&dispatcher)
            }
            _ => {
                let layer = fmt::layer().pretty().with_writer(writer);
                let dispatcher = tracing_subscriber::registry()
                    .with(filter)
                    .with(sampling_layer)
                    .with(layer)
                    .with(otlp_layer)
                    .into();
                tracing::dispatcher::set_default(&dispatcher)
            }
        };
        return Ok(LoggingGuard::with_otlp_provider(guard, otlp_provider));
    }

    let guard = match setup.config.format {
        LogFormat::Json => {
            let layer = fmt::layer()
                .json()
                .with_current_span(true)
                .with_span_list(true)
                .with_writer(writer);
            let dispatcher = tracing_subscriber::registry()
                .with(filter)
                .with(sampling_layer)
                .with(layer)
                .with(otlp_layer)
                .into();
            tracing::dispatcher::set_default(&dispatcher)
        }
        _ => {
            let layer = fmt::layer().pretty().with_writer(writer);
            let dispatcher = tracing_subscriber::registry()
                .with(filter)
                .with(sampling_layer)
                .with(layer)
                .with(otlp_layer)
                .into();
            tracing::dispatcher::set_default(&dispatcher)
        }
    };

    Ok(LoggingGuard::with_otlp_provider(guard, otlp_provider))
}

// Logging macros exposed by this crate.
pub use tracing::{debug, error, info, instrument, trace, warn};

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

    #[test]
    fn init_console_does_not_panic() {
        let cfg = LoggingConfig::default();
        let _guard = init_logging(&cfg).unwrap();
        tracing::info!("test log");
    }

    #[test]
    fn init_json_does_not_panic() {
        let cfg = LoggingConfig {
            format: rskit_config::LogFormat::Json,
            ..Default::default()
        };
        let _guard = init_logging(&cfg).unwrap();
        tracing::info!("test json log");
    }
}