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//! the log subsystem

use chrono::{DateTime, FixedOffset, Local, Utc};
use event::{Event, Receiver, Severity};
use std::sync::RwLock;

pub mod event;
pub mod output;

#[cfg(test)]
mod test;

/// centralized log handler service which receives log messages and dispatches them to receivers
#[derive(Default)]
pub struct Log {
    /// receivers to which events will be dispatched
    receivers: RwLock<Vec<RwLock<Box<dyn Receiver + Send + Sync>>>>,
}

impl Log {
    /// create a new log handler service
    pub fn new() -> Log {
        Default::default()
    }

    /// add a receiver to an existing log handler
    pub fn add_receiver(&self, receiver: Box<dyn Receiver + Send + Sync>) {
        self.receivers
            .write()
            .expect("receivers is poisoned")
            .push(RwLock::new(receiver));
    }

    /// create and notify a log event for the current instant
    pub fn now(&self, severity: Severity, context: &str, message: &str) {
        let event = Event::now(severity, context, message);
        self.notify(&event);
    }

    /// create and notify a log event for a given time in UTC
    pub fn with_utc_time(
        &self,
        time: DateTime<Utc>,
        severity: Severity,
        context: &str,
        message: &str,
    ) {
        let event = Event::with_utc_time(time, severity, context, message);
        self.notify(&event);
    }

    /// create and notify a log event for a given time in local time
    pub fn with_local_time(
        &self,
        time: DateTime<Local>,
        severity: Severity,
        context: &str,
        message: &str,
    ) {
        let event = Event::with_local_time(time, severity, context, message);
        self.notify(&event);
    }

    /// create and notify a log event for a given arbitrary time
    pub fn with_time(
        &self,
        time: DateTime<FixedOffset>,
        severity: Severity,
        context: &str,
        message: &str,
    ) {
        let event = Event::with_time(time, severity, context, message);
        self.notify(&event);
    }

    /// helper function for logging a debug message
    pub fn debug(&self, context: &str, message: &str) {
        self.now(Severity::Debug, context, message);
    }

    /// helper function for logging a verbose message
    pub fn verbose(&self, context: &str, message: &str) {
        self.now(Severity::Verbose, context, message);
    }

    /// helper function for logging an info message
    pub fn info(&self, context: &str, message: &str) {
        self.now(Severity::Info, context, message);
    }

    /// helper function for logging a warning message
    pub fn warning(&self, context: &str, message: &str) {
        self.now(Severity::Warning, context, message);
    }

    /// helper function for logging an error message
    pub fn error(&self, context: &str, message: &str) {
        self.now(Severity::Error, context, message);
    }

    /// helper function for logging a fatal error message
    pub fn fatal(&self, context: &str, message: &str) {
        self.now(Severity::Fatal, context, message);
    }

    /// notify all receivers of a log event
    pub fn notify(&self, event: &Event) {
        for receiver in self.receivers.read().expect("receivers is poisoned").iter() {
            receiver
                .write()
                .expect("receivers is poisoned")
                .notify(event);
        }
    }
}

impl Receiver for Log {
    /// notify all receivers of a log event
    fn notify(&mut self, event: &Event) {
        Log::notify(self, event);
    }
}