/*
 *   Copyright (c) 2023 R3BL LLC
 *   All rights reserved.
 *
 *   Licensed under the Apache License, Version 2.0 (the "License");
 *   you may not use this file except in compliance with the License.
 *   You may obtain a copy of the License at
 *
 *   http://www.apache.org/licenses/LICENSE-2.0
 *
 *   Unless required by applicable law or agreed to in writing, software
 *   distributed under the License is distributed on an "AS IS" BASIS,
 *   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 *   See the License for the specific language governing permissions and
 *   limitations under the License.
 */

//! Module providing the CombinedLogger Implementation

use log::{set_boxed_logger,
          set_max_level,
          LevelFilter,
          Log,
          Metadata,
          Record,
          SetLoggerError};

use crate::{Config, SharedLogger};

/// The CombinedLogger struct. Provides a Logger implementation that proxies multiple Loggers as one.
///
/// The purpose is to allow multiple Loggers to be set globally
pub struct CombinedLogger {
    level: LevelFilter,
    logger: Vec<Box<dyn SharedLogger>>,
}

impl CombinedLogger {
    /// init function. Globally initializes the CombinedLogger as the one and only used log facility.
    ///
    /// Takes all used Loggers as a Vector argument. None of those Loggers should already be set globally.
    ///
    /// All loggers need to implement `log::Log` and `logger::SharedLogger` and need to provide a way to be
    /// initialized without calling `set_logger`. All loggers of this library provide a `new(..)`` method
    /// for that purpose.
    /// Fails if another logger is already set globally.
    ///
    /// # Examples
    /// ```
    /// # extern crate r3bl_simple_logger;
    /// # use r3bl_simple_logger::*;
    /// # use std::fs::File;
    /// # fn main() {
    /// let _ = CombinedLogger::init(
    ///             vec![
    ///                 TermLogger::new(LevelFilter::Info, Config::default(), TerminalMode::Mixed, ColorChoice::Auto),
    ///                 WriteLogger::new(LevelFilter::Info, Config::default(), File::create("my_rust_bin.log").unwrap())
    ///             ]
    ///         );
    /// # }
    /// ```
    pub fn init(logger: Vec<Box<dyn SharedLogger>>) -> Result<(), SetLoggerError> {
        let comblog = CombinedLogger::new(logger);
        set_max_level(comblog.level());
        set_boxed_logger(comblog)
    }

    /// allows to create a new logger, that can be independently used, no matter whats globally set.
    ///
    /// no macros are provided for this case and you probably
    /// dont want to use this function, but `init()`, if you dont want to build a `CombinedLogger`.
    ///
    /// Takes all used loggers as a Vector argument. The log level is automatically determined by the
    /// lowest log level used by the given loggers.
    ///
    /// All loggers need to implement log::Log.
    ///
    /// # Examples
    /// ```
    /// # extern crate r3bl_simple_logger;
    /// # use r3bl_simple_logger::*;
    /// # use std::fs::File;
    /// # fn main() {
    /// let combined_logger = CombinedLogger::new(
    ///             vec![
    ///                 TermLogger::new(LevelFilter::Debug, Config::default(), TerminalMode::Mixed, ColorChoice::Auto),
    ///                 WriteLogger::new(LevelFilter::Info, Config::default(), File::create("my_rust_bin.log").unwrap())
    ///             ]
    ///         );
    /// # }
    /// ```
    #[must_use]
    pub fn new(logger: Vec<Box<dyn SharedLogger>>) -> Box<CombinedLogger> {
        let mut log_level = LevelFilter::Off;
        for log in &logger {
            if log_level < log.level() {
                log_level = log.level();
            }
        }

        Box::new(CombinedLogger {
            level: log_level,
            logger,
        })
    }
}

impl Log for CombinedLogger {
    fn enabled(&self, metadata: &Metadata<'_>) -> bool { metadata.level() <= self.level }

    fn log(&self, record: &Record<'_>) {
        if self.enabled(record.metadata()) {
            for log in &self.logger {
                log.log(record);
            }
        }
    }

    fn flush(&self) {
        for log in &self.logger {
            log.flush();
        }
    }
}

impl SharedLogger for CombinedLogger {
    fn level(&self) -> LevelFilter { self.level }

    fn config(&self) -> Option<&Config> { None }

    fn as_log(self: Box<Self>) -> Box<dyn Log> { Box::new(*self) }
}
