use std::{io::Error, path::PathBuf, str::FromStr};

use tracing_error::ErrorLayer;
use tracing_subscriber::{self, Layer, layer::SubscriberExt, util::SubscriberInitExt};

const LOG_FILE: &'static str = "equity-tracker.log";

const LOG_LEVEL: &'static str = "LOG_LEVEL";
const DEFAULT_LOG_LEVEL: &'static str = "DEBUG";

const LOG_DIRECTORY: &'static str = "LOG_DIRECTORY";
const DEFAULT_LOG_DIRECTORY: &'static str = "./target";

/// Either retrieves the environment variable or uses a default value
fn get_env_var(var_name: &'static str, default: &'static str) -> String {
    if let Ok(env_var) = std::env::var(var_name) {
        env_var
    } else {
        default.into()
    }
}

/// Provides a PathBuf of the configured log directory, or the target directory
fn get_log_directory() -> std::io::Result<PathBuf> {
    let env_dir = get_env_var(LOG_DIRECTORY, DEFAULT_LOG_DIRECTORY);
    let path = PathBuf::from_str(&env_dir).map_err(|e| Error::other(e))?;

    Ok(path)
}

/// Configure the logging through tracing
pub fn initialize_logging() -> std::io::Result<()> {
    let directory = get_log_directory()?;
    std::fs::create_dir_all(directory.clone())?;

    let log_path = directory.join(LOG_FILE);
    let log_file = std::fs::File::create(log_path)?;

    let log_filter = get_env_var(LOG_LEVEL, DEFAULT_LOG_LEVEL);
    let file_subscriber = tracing_subscriber::fmt::layer()
        .with_file(true)
        .with_line_number(true)
        .with_target(false)
        .with_ansi(false)
        .with_writer(log_file)
        .with_filter(tracing_subscriber::filter::EnvFilter::builder().parse_lossy(log_filter));

    tracing_subscriber::registry()
        .with(file_subscriber)
        .with(ErrorLayer::default())
        .init();

    Ok(())
}