/**
 * Tiny structured logger (JSON lines optional).
 */

const LEVELS = { debug: 10, info: 20, warn: 30, error: 40 }
const minLevel =
  LEVELS[String(process.env.LOG_LEVEL || 'info').toLowerCase()] ?? LEVELS.info

function emit(level, scope, message, fields) {
  if ((LEVELS[level] ?? 99) < minLevel) return
  const line = {
    ts: new Date().toISOString(),
    level,
    scope,
    msg: message,
    ...(fields && typeof fields === 'object' ? fields : {}),
  }
  const text = process.env.LOG_JSON === '1' ? JSON.stringify(line) : formatPretty(line)
  if (level === 'error') console.error(text)
  else if (level === 'warn') console.warn(text)
  else console.log(text)
}

function formatPretty(line) {
  const extra = { ...line }
  delete extra.ts
  delete extra.level
  delete extra.scope
  delete extra.msg
  const keys = Object.keys(extra)
  const tail = keys.length ? ' ' + JSON.stringify(extra) : ''
  return `${line.ts} [${line.level}] ${line.scope}: ${line.msg}${tail}`
}

function child(scope) {
  return {
    debug: (msg, fields) => emit('debug', scope, msg, fields),
    info: (msg, fields) => emit('info', scope, msg, fields),
    warn: (msg, fields) => emit('warn', scope, msg, fields),
    error: (msg, fields) => emit('error', scope, msg, fields),
    child: (sub) => child(`${scope}:${sub}`),
    banner(fields = {}) {
      const bar = '═'.repeat(56)
      console.log(bar)
      console.log(`  ${fields.title || 'Pear App Server'}`)
      for (const [k, v] of Object.entries(fields)) {
        if (k === 'title') continue
        console.log(`  ${k}: ${v}`)
      }
      console.log(bar)
    },
  }
}

const logger = child('app')
export default logger