'use strict'
function tryStringify (o) {
  try { return JSON.stringify(o) } catch(e) { return '"[Circular]"' }
}

module.exports = format 

function format(f, args, opts) {
  var ss = (opts && opts.stringify) || tryStringify
  var offset = 1
  if (f === null) {
    f = args[0]
    offset = 0
  }
  if (typeof f === 'object' && f !== null) {
    var len = args.length + offset
    if (len === 1) return f
    var objects = new Array(len)
    objects[0] = ss(f)
    for (var index = 1; index < len; index++) {
      objects[index] = ss(args[index])
    }
    return objects.join(' ')
  }
  var argLen = args.length
  if (argLen === 0) return f
  var x = ''
  var str = ''
  var a = 1 - offset
  var lastPos = 0
  var flen = (f && f.length) || 0
  for (var i = 0; i < flen;) {
    if (f.charCodeAt(i) === 37 && i + 1 < flen) {
      switch (f.charCodeAt(i + 1)) {
        case 100: // 'd'
          if (a >= argLen)
            break
          if (lastPos < i)
            str += f.slice(lastPos, i)
          if (args[a] == null)  break
          str += Number(args[a])
          lastPos = i = i + 2
          break
        case 79: // 'O'
        case 111: // 'o'
        case 106: // 'j'
          if (a >= argLen)
            break
          if (lastPos < i)
            str += f.slice(lastPos, i)
          if (args[a] === undefined) break
          var type = typeof args[a]
          if (type === 'string') {
            str += '\'' + args[a] + '\''
            lastPos = i + 2
            i++
            break
          }
          if (type === 'function') {
            str += args[a].name || '<anonymous>'
            lastPos = i + 2
            i++
            break
          }
          str += ss(args[a])
          lastPos = i + 2
          i++
          break
        case 115: // 's'
          if (a >= argLen)
            break
          if (lastPos < i)
            str += f.slice(lastPos, i)
          str += String(args[a])
          lastPos = i + 2
          i++
          break
        case 37: // '%'
          if (lastPos < i)
            str += f.slice(lastPos, i)
          str += '%'
          lastPos = i + 2
          i++
          break
      }
      ++a
    }
    ++i
  }
  if (lastPos === 0)
    str = f
  else if (lastPos < flen) {
    str += f.slice(lastPos)
  }
  while (a < argLen) {
    x = args[a++]
    if (x === null || (typeof x !== 'object')) {
      str += ' ' + String(x)
    } else {
      str += ' ' + ss(x)
    }
  }

  return str
}