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//! A logger that prints all messages with a readable output format.

#[cfg(windows)]
extern crate atty;
#[cfg(feature = "chrono")]
extern crate chrono;
#[cfg(feature = "colored")]
extern crate colored;
extern crate log;
#[cfg(windows)]
extern crate winapi;

#[cfg(feature = "chrono")]
use chrono::Local;
#[cfg(feature = "colored")]
use colored::*;
use log::{Level, Log, Metadata, Record, SetLoggerError};

struct SimpleLogger {
    level: Level,
}

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

    fn log(&self, record: &Record) {
        if self.enabled(record.metadata()) {
            let level_string = {
                #[cfg(feature = "colored")]
                {
                    match record.level() {
                        Level::Error => record.level().to_string().red(),
                        Level::Warn => record.level().to_string().yellow(),
                        Level::Info => record.level().to_string().cyan(),
                        Level::Debug => record.level().to_string().purple(),
                        Level::Trace => record.level().to_string().normal(),
                    }
                }
                #[cfg(not(feature = "colored"))]
                {
                    record.level().to_string()
                }
            };
            let target = if record.target().len() > 0 {
                record.target()
            } else {
                record.module_path().unwrap_or_default()
            };
            #[cfg(feature = "chrono")] {
                println!(
                    "{} {:<5} [{}] {}",
                    Local::now().format("%Y-%m-%d %H:%M:%S,%3f"),
                    level_string,
                    target,
                    record.args());
            }
            #[cfg(not(feature = "chrono"))] {
                println!(
                    "{:<5} [{}] {}",
                    level_string,
                    target,
                    record.args());
            }
        }
    }

    fn flush(&self) {}
}

#[cfg(windows)]
fn set_up_color_terminal() {
    use atty::Stream;

    if atty::is(Stream::Stdout) {
        unsafe {
            use winapi::um::consoleapi::*;
            use winapi::um::handleapi::*;
            use winapi::um::processenv::*;
            use winapi::um::winbase::*;
            use winapi::um::wincon::*;

            let stdout = GetStdHandle(STD_OUTPUT_HANDLE);

            if stdout == INVALID_HANDLE_VALUE {
                return;
            }

            let mut mode: winapi::shared::minwindef::DWORD = 0;

            if GetConsoleMode(stdout, &mut mode) == 0 {
                return;
            }

            SetConsoleMode(stdout, mode | ENABLE_VIRTUAL_TERMINAL_PROCESSING);
        }
    }
}

/// Initializes the global logger with a SimpleLogger instance with
/// `max_log_level` set to a specific log level.
///
/// ```
/// # #[macro_use] extern crate log;
/// # extern crate simple_logger;
/// #
/// # fn main() {
/// simple_logger::init_with_level(log::Level::Warn).unwrap();
///
/// warn!("This is an example message.");
/// info!("This message will not be logged.");
/// # }
/// ```
pub fn init_with_level(level: Level) -> Result<(), SetLoggerError> {
    #[cfg(all(windows, feature = "colored"))]
    set_up_color_terminal();

    let logger = SimpleLogger { level };
    log::set_boxed_logger(Box::new(logger))?;
    log::set_max_level(level.to_level_filter());
    Ok(())
}

/// Initializes the global logger with a SimpleLogger instance with
/// `max_log_level` set to `LogLevel::Trace`.
///
/// ```
/// # #[macro_use] extern crate log;
/// # extern crate simple_logger;
/// #
/// # fn main() {
/// simple_logger::init().unwrap();
/// warn!("This is an example message.");
/// # }
/// ```
pub fn init() -> Result<(), SetLoggerError> {
    init_with_level(Level::Trace)
}


/// A macro for simulating env_logger behavior, which enables the user to choose log level by
/// setting a `RUST_LOG` environment variable. The `RUST_LOG` is not set or its value is not
/// recognized as one of the log levels, this function with use the `Error` level by default.
/// ```
/// # #[macro_use] extern crate log;
/// # #[macro_use] extern crate simple_logger;
/// #
/// # fn main() {
/// simple_logger::init_by_env();
/// warn!("This is an example message.");
/// # }
/// ```
pub fn init_by_env() {
    match std::env::var("RUST_LOG") {
        Ok(x) => {
            match x.to_lowercase().as_str() {
                "trace" => init_with_level(log::Level::Trace).unwrap(),
                "debug" => init_with_level(log::Level::Debug).unwrap(),
                "info" => init_with_level(log::Level::Info).unwrap(),
                "warn" => init_with_level(log::Level::Warn).unwrap(),
                _ => init_with_level(log::Level::Error).unwrap(),
            }
        }
        _ =>
            init_with_level(log::Level::Error).unwrap(),
    }
}