// Copyright 2018-2021 the Deno authors. All rights reserved. MIT license.

use std::io::Write;
use std::sync::atomic::AtomicBool;
use std::sync::atomic::Ordering;
use std::sync::Arc;

lazy_static::lazy_static! {
  pub static ref LSP_DEBUG_FLAG: Arc<AtomicBool> = Arc::new(AtomicBool::new(false));
}

struct CliLogger(env_logger::Logger);

impl CliLogger {
  pub fn new(logger: env_logger::Logger) -> Self {
    Self(logger)
  }

  pub fn filter(&self) -> log::LevelFilter {
    self.0.filter()
  }
}

impl log::Log for CliLogger {
  fn enabled(&self, metadata: &log::Metadata) -> bool {
    if metadata.target() == "deno::lsp::performance"
      && metadata.level() == log::Level::Debug
    {
      LSP_DEBUG_FLAG.load(Ordering::Relaxed)
    } else {
      self.0.enabled(metadata)
    }
  }

  fn log(&self, record: &log::Record) {
    if self.enabled(record.metadata()) {
      self.0.log(record);
    }
  }

  fn flush(&self) {
    self.0.flush();
  }
}

pub(crate) fn init(maybe_level: Option<log::Level>) {
  let log_level = maybe_level.unwrap_or(log::Level::Info);
  let logger = env_logger::Builder::from_env(
    env_logger::Env::default()
      .default_filter_or(log_level.to_level_filter().to_string()),
  )
  // https://github.com/denoland/deno/issues/6641
  .filter_module("rustyline", log::LevelFilter::Off)
  // wgpu crates (gfx_backend), have a lot of useless INFO and WARN logs
  .filter_module("wgpu", log::LevelFilter::Error)
  .filter_module("gfx", log::LevelFilter::Error)
  // used to make available the lsp_debug which is then filtered out at runtime
  // in the cli logger
  .filter_module("deno::lsp::performance", log::LevelFilter::Debug)
  .format(|buf, record| {
    let mut target = record.target().to_string();
    if let Some(line_no) = record.line() {
      target.push(':');
      target.push_str(&line_no.to_string());
    }
    if record.level() <= log::Level::Info
      || (record.target() == "deno::lsp::performance"
        && record.level() == log::Level::Debug)
    {
      // Print ERROR, WARN, INFO and lsp_debug logs as they are
      writeln!(buf, "{}", record.args())
    } else {
      // Add prefix to DEBUG or TRACE logs
      writeln!(
        buf,
        "{} RS - {} - {}",
        record.level(),
        target,
        record.args()
      )
    }
  })
  .build();

  let cli_logger = CliLogger::new(logger);
  let max_level = cli_logger.filter();
  let r = log::set_boxed_logger(Box::new(cli_logger));
  if r.is_ok() {
    log::set_max_level(max_level);
  }
  r.expect("Could not install logger.");
}