import winston from 'winston';
import path from 'path';
import fs from 'fs';

// ─── Helpers ────────────────────────────────────────────────────────────────

const getMonthFolder = (): string => {
  const now = new Date();
  const year = now.getFullYear();
  const month = String(now.getMonth() + 1).padStart(2, '0');
  return `${year}-${month}`;
};

const getDateFile = (): string => {
  const now = new Date();
  const yyyy = now.getFullYear();
  const mm = String(now.getMonth() + 1).padStart(2, '0');
  const dd = String(now.getDate()).padStart(2, '0');
  return `${yyyy}-${mm}-${dd}`;
};

const ensureDir = (dirPath: string): void => {
  if (!fs.existsSync(dirPath)) {
    fs.mkdirSync(dirPath, { recursive: true });
  }
};

// ─── Dynamic Transport Factory ───────────────────────────────────────────────

const createFileTransport = (level: 'combined' | 'error') => {
  return new winston.transports.DailyRotateFile({
    dirname: path.join(process.cwd(), 'logs', getMonthFolder()),
    filename: `${getDateFile()}-${level}-%DATE%.log`,
    datePattern: '',
    maxFiles: '90d',
    level: level === 'error' ? 'error' : undefined,
    format: winston.format.combine(
      winston.format.timestamp({ format: 'YYYY-MM-DD HH:mm:ss' }),
      winston.format.errors({ stack: true }),
      winston.format.json()
    ),
  });
};

// ─── Winston Logger ──────────────────────────────────────────────────────────

const logFormat = winston.format.combine(
  winston.format.timestamp({ format: 'YYYY-MM-DD HH:mm:ss' }),
  winston.format.errors({ stack: true }),
  winston.format.colorize({ all: true }),
  winston.format.printf(({ timestamp, level, message, stack, ...meta }) => {
    const metaStr = Object.keys(meta).length ? `\n${JSON.stringify(meta, null, 2)}` : '';
    return `[${timestamp}] ${level}: ${stack || message}${metaStr}`;
  })
);

const monthDir = path.join(process.cwd(), 'logs', getMonthFolder());
ensureDir(monthDir);

export const logger = winston.createLogger({
  level: process.env.NODE_ENV === 'production' ? 'warn' : 'debug',
  transports: [
    // Console output
    new winston.transports.Console({ format: logFormat }),

    // All logs → logs/YYYY-MM/YYYY-MM-DD-combined.log
    new winston.transports.File({
      filename: path.join(monthDir, `${getDateFile()}-combined.log`),
      format: winston.format.combine(
        winston.format.timestamp({ format: 'YYYY-MM-DD HH:mm:ss' }),
        winston.format.errors({ stack: true }),
        winston.format.json()
      ),
    }),

    // Error logs → logs/YYYY-MM/YYYY-MM-DD-error.log
    new winston.transports.File({
      filename: path.join(monthDir, `${getDateFile()}-error.log`),
      level: 'error',
      format: winston.format.combine(
        winston.format.timestamp({ format: 'YYYY-MM-DD HH:mm:ss' }),
        winston.format.errors({ stack: true }),
        winston.format.json()
      ),
    }),
  ],
  exceptionHandlers: [
    new winston.transports.File({
      filename: path.join(monthDir, `${getDateFile()}-exceptions.log`),
    }),
  ],
  rejectionHandlers: [
    new winston.transports.File({
      filename: path.join(monthDir, `${getDateFile()}-rejections.log`),
    }),
  ],
});