simple_logger.rs

simple_logger.rs

use std::env;
use std::process;
use std::io::{self, Write};

enum LogLevel {
    Error,
    Warn,
    Info,
    Debug,
}

struct SimpleLogger {
    level: LogLevel,
}

impl SimpleLogger {
    fn new() -> Self {
        let level = match env::var("MY_LOG_LEVEL").as_deref() {
            Ok("error") => LogLevel::Error,
            Ok("warn") => LogLevel::Warn,
            Ok("info") => LogLevel::Info,
            Ok("debug") => LogLevel::Debug,
            _ => LogLevel::Info, // Default to info
        };
        SimpleLogger { level }
    }

    fn log(&self, level: LogLevel, message: &str) {
        if self.should_log(&level) {
            let mut output = match level {
                LogLevel::Error => io::stderr(),
                _ => io::stderr(),
            };

            let level_str = match level {
                LogLevel::Error => "ERROR",
                LogLevel::Warn => "WARN",
                LogLevel::Info => "INFO",
                LogLevel::Debug => "DEBUG",
            };

            let _ = writeln!(output, "[{}] {}", level_str, message);
        }
    }

    fn should_log(&self, level: &LogLevel) -> bool {
        match self.level {
            LogLevel::Error => matches!(level, LogLevel::Error),
            LogLevel::Warn => matches!(level, LogLevel::Error | LogLevel::Warn),
            LogLevel::Info => matches!(level, LogLevel::Error | LogLevel::Warn | LogLevel::Info),
            LogLevel::Debug => matches!(level, LogLevel::Error | LogLevel::Warn | LogLevel::Info | LogLevel::Debug),
        }
    }

    fn error(&self, message: &str) {
        self.log(LogLevel::Error, message);
    }

    fn warn(&self, message: &str) {
        self.log(LogLevel::Warn, message);
    }

    fn info(&self, message: &str) {
        self.log(LogLevel::Info, message);
    }

    fn debug(&self, message: &str) {
        self.log(LogLevel::Debug, message);
    }
}

const VERSION: &'static str = "v0.0.1";

fn main() {

    let logger = SimpleLogger::new();

    logger.debug("This is a debug message.");
    logger.info("This is an info message.");
    logger.warn("This is a warning message.");
    logger.error("This is an error message.");

}