use anyhow::{Context, Result};
use std::{fs::OpenOptions, path::Path};
use time::{format_description::well_known::Rfc3339, UtcOffset};
use tracing_subscriber::{
    filter::LevelFilter,
    fmt::{self, time::OffsetTime},
    layer::SubscriberExt,
    util::SubscriberInitExt,
    Layer,
};

use crate::config;

/// Initializes the logger.
pub fn init_logger(data_dir: &Path, utc_offset: &config::UtcOffset) -> Result<()> {
    // Set UTC offset for time formatting.
    let timer = OffsetTime::new(
        UtcOffset::from_hms(utc_offset.hours, utc_offset.minutes, 0)
            .context("Failed to set the time offset from the given utc_hours_offset!")?,
        Rfc3339,
    );

    // Use the DEBUG level in debug builds.
    let stdout_level_filter = if cfg!(debug_assertions) {
        LevelFilter::DEBUG
    } else {
        LevelFilter::INFO
    };
    // Stdout logger.
    let stdout_layer = fmt::layer()
        .with_ansi(true)
        .with_timer(timer.clone())
        .with_filter(stdout_level_filter);

    // Log file.
    let log_file = {
        let mut buf = data_dir.to_path_buf();
        buf.push("log.txt");

        OpenOptions::new()
            .create(true)
            .append(true)
            .open(buf)
            .context("Failed to open the log file in append mode!")?
    };
    let file_layer = fmt::layer()
        .with_writer(log_file)
        .with_ansi(false)
        .with_timer(timer)
        .with_filter(LevelFilter::INFO);

    tracing_subscriber::registry()
        .with(stdout_layer.and_then(file_layer))
        .try_init()
        .context("Failed to initialize logging!")?;

    Ok(())
}