import { mkdirSync } from 'fs';
import log4js from 'log4js';
import { resolve } from 'path';
import { env } from '../config/env';

const LOG_LEVELS = ['trace', 'debug', 'info', 'warn', 'error', 'fatal'] as const;
type LogLevel = (typeof LOG_LEVELS)[number];

function resolveLogLevel(): LogLevel {
  const raw = env.LOG_LEVEL.toLowerCase();
  return (LOG_LEVELS as readonly string[]).includes(raw) ? (raw as LogLevel) : 'info';
}

/** Resolves LOG_DIR from .env: absolute paths unchanged; relative paths from cwd. */
function resolveLogDir(raw: string): string {
  const trimmed = raw.trim();
  if (!trimmed) {
    return resolve('logs');
  }
  return resolve(trimmed);
}

function ensureLogDir(dir: string): void {
  try {
    mkdirSync(dir, { recursive: true });
  } catch (err) {
    const msg = err instanceof Error ? err.message : String(err);
    process.stderr.write(`[kord] Failed to create LOG_DIR "${dir}": ${msg}\n`);
    throw err;
  }
}

const logDir = resolveLogDir(env.LOG_DIR);
const level = resolveLogLevel();

ensureLogDir(logDir);

log4js.configure({
  appenders: {
    console: {
      type: 'stdout',
      layout: {
        type: 'pattern',
        pattern: '%[[%p]%] %m',
      },
    },
    file: {
      type: 'dateFile',
      filename: resolve(logDir, 'kord.log'),
      pattern: 'yyyy-MM-dd',
      alwaysIncludePattern: true,
      numBackups: 7,
      layout: {
        type: 'pattern',
        pattern: '%d{yyyy-MM-dd hh:mm:ss.SSS} [%p] %m',
      },
    },
  },
  categories: {
    default: { appenders: ['console', 'file'], level },
  },
});

process.on('exit', () => {
  try {
    log4js.shutdown();
  } catch {
    // ignore
  }
});

export const logger = log4js.getLogger();