use tracing::Level;
use tracing_subscriber::{Layer as _, layer::SubscriberExt as _, util::SubscriberInitExt as _};

pub const DEFAULT_LOG_LEVEL: Level = if cfg!(debug_assertions) {
    Level::DEBUG // debug builds
} else {
    Level::INFO // release builds
};

fn level_to_index(level: Level) -> u8 {
    match level {
        Level::TRACE => 0,
        Level::DEBUG => 1,
        Level::INFO => 2,
        Level::WARN => 3,
        Level::ERROR => 4,
    }
}

fn index_to_level(index: u8) -> Level {
    match index {
        0 => Level::TRACE,
        1 => Level::DEBUG,
        2 => Level::INFO,
        3 => Level::WARN,
        4.. => Level::ERROR,
    }
}

fn level_from_verbosity(verbosity: u8) -> Level {
    index_to_level(level_to_index(DEFAULT_LOG_LEVEL).saturating_sub(verbosity))
}

pub fn init_tracing(verbosity: u8) -> anyhow::Result<()> {
    let terminal_layer = tracing_subscriber::fmt::layer()
        .without_time()
        .compact()
        .boxed();

    let level = level_from_verbosity(verbosity);

    tracing_subscriber::registry()
        .with(terminal_layer)
        .with(
            tracing_subscriber::EnvFilter::builder()
                .with_default_directive(level.into())
                .from_env()?,
        )
        .init();

    tracing::info!("logging with level {level}");

    Ok(())
}