const RESET = '\x1b[0m'
const BOLD = '\x1b[1m'
const DIM = '\x1b[2m'

const colors = {
  gray:    '\x1b[90m',
  green:   '\x1b[32m',
  yellow:  '\x1b[33m',
  red:     '\x1b[31m',
  cyan:    '\x1b[36m',
  magenta: '\x1b[35m',
  blue:    '\x1b[34m',
  white:   '\x1b[37m',
}

const LEVELS = {
  info:    { icon: '●', color: colors.cyan,    label: 'INFO ' },
  success: { icon: '✔', color: colors.green,   label: 'OK   ' },
  warn:    { icon: '▲', color: colors.yellow,  label: 'WARN ' },
  error:   { icon: '✖', color: colors.red,     label: 'ERROR' },
  debug:   { icon: '◆', color: colors.magenta, label: 'DEBUG' },
  llm:     { icon: '◈', color: colors.blue,    label: 'LLM  ' },
} as const

type Level = keyof typeof LEVELS

function timestamp(): string {
  const now = new Date()
  const dd = String(now.getDate()).padStart(2, '0')
  const mo = String(now.getMonth() + 1).padStart(2, '0')
  const hh = String(now.getHours()).padStart(2, '0')
  const mm = String(now.getMinutes()).padStart(2, '0')
  return `${DIM}${colors.gray}${dd}.${mo} ${hh}:${mm}${RESET}`
}

function formatTag(tag: string): string {
  return `${DIM}${colors.gray}[${tag}]${RESET}`
}

function formatArgs(args: unknown[]): string {
  return args
    .map((a) =>
      typeof a === 'object' && a !== null
        ? JSON.stringify(a, null, 2)
        : String(a),
    )
    .join(' ')
}

function print(level: Level, tag: string, args: unknown[]): void {
  const { icon, color, label } = LEVELS[level]
  const parts = [
    timestamp(),
    `${color}${BOLD}${icon} ${label}${RESET}`,
    formatTag(tag),
    `${color}${formatArgs(args)}${RESET}`,
  ]
  if (level === 'error') {
    process.stderr.write(parts.join(' ') + '\n')
  } else {
    process.stdout.write(parts.join(' ') + '\n')
  }
}

export function createLogger(tag: string) {
  return {
    info:    (...args: unknown[]) => print('info',    tag, args),
    ok:      (...args: unknown[]) => print('success', tag, args),
    warn:    (...args: unknown[]) => print('warn',    tag, args),
    error:   (...args: unknown[]) => print('error',   tag, args),
    debug:   (...args: unknown[]) => print('debug',   tag, args),
    llm:     (...args: unknown[]) => print('llm',     tag, args),
    divider: (label?: string) => {
      const line = '─'.repeat(58)
      const text = label
        ? `${DIM}${colors.gray}┌─ ${label} ${'─'.repeat(Math.max(0, 54 - label.length))}${RESET}`
        : `${DIM}${colors.gray}${line}${RESET}`
      process.stdout.write(text + '\n')
    },
  }
}

export type Logger = ReturnType<typeof createLogger>