/* eslint no-extend-native: 0 */

(function () {
  // Defining locale
  Date.shortMonths = ['Jan', 'Feb', 'Mar', 'Apr', 'May', 'Jun', 'Jul', 'Aug', 'Sep', 'Oct', 'Nov', 'Dec']
  Date.longMonths = ['January', 'February', 'March', 'April', 'May', 'June', 'July', 'August', 'September', 'October', 'November', 'December']
  Date.shortDays = ['Sun', 'Mon', 'Tue', 'Wed', 'Thu', 'Fri', 'Sat']
  Date.longDays = ['Sunday', 'Monday', 'Tuesday', 'Wednesday', 'Thursday', 'Friday', 'Saturday']
  // Defining patterns
  var replaceChars = {
    // Day
    d: function () { var d = this.getDate(); return (d < 10 ? '0' : '') + d },
    D: function () { return Date.shortDays[this.getDay()] },
    j: function () { return this.getDate() },
    l: function () { return Date.longDays[this.getDay()] },
    N: function () { var N = this.getDay(); return (N === 0 ? 7 : N) },
    S: function () { var S = this.getDate(); return (S % 10 === 1 && S !== 11 ? 'st' : (S % 10 === 2 && S !== 12 ? 'nd' : (S % 10 === 3 && S !== 13 ? 'rd' : 'th'))) },
    w: function () { return this.getDay() },
    z: function () { var d = new Date(this.getFullYear(), 0, 1); return Math.ceil((this - d) / 86400000) },
    // Week
    W: function () {
      var target = new Date(this.valueOf())
      var dayNr = (this.getDay() + 6) % 7
      target.setDate(target.getDate() - dayNr + 3)
      var firstThursday = target.valueOf()
      target.setMonth(0, 1)
      if (target.getDay() !== 4) {
        target.setMonth(0, 1 + ((4 - target.getDay()) + 7) % 7)
      }
      var retVal = 1 + Math.ceil((firstThursday - target) / 604800000)

      return (retVal < 10 ? '0' + retVal : retVal)
    },
    // Month
    F: function () { return Date.longMonths[this.getMonth()] },
    m: function () { var m = this.getMonth(); return (m < 9 ? '0' : '') + (m + 1) },
    M: function () { return Date.shortMonths[this.getMonth()] },
    n: function () { return this.getMonth() + 1 },
    t: function () {
      var year = this.getFullYear()
      var nextMonth = this.getMonth() + 1
      if (nextMonth === 12) {
        year = year++
        nextMonth = 0
      }
      return new Date(year, nextMonth, 0).getDate()
    },
    // Year
    L: function () { var L = this.getFullYear(); return (L % 400 === 0 || (L % 100 !== 0 && L % 4 === 0)) },
    o: function () { var d = new Date(this.valueOf()); d.setDate(d.getDate() - ((this.getDay() + 6) % 7) + 3); return d.getFullYear() },
    Y: function () { return this.getFullYear() },
    y: function () { return ('' + this.getFullYear()).substr(2) },
    // Time
    a: function () { return this.getHours() < 12 ? 'am' : 'pm' },
    A: function () { return this.getHours() < 12 ? 'AM' : 'PM' },
    B: function () { return Math.floor((((this.getUTCHours() + 1) % 24) + this.getUTCMinutes() / 60 + this.getUTCSeconds() / 3600) * 1000 / 24) },
    g: function () { return this.getHours() % 12 || 12 },
    G: function () { return this.getHours() },
    h: function () { var h = this.getHours(); return ((h % 12 || 12) < 10 ? '0' : '') + (h % 12 || 12) },
    H: function () { var H = this.getHours(); return (H < 10 ? '0' : '') + H },
    i: function () { var i = this.getMinutes(); return (i < 10 ? '0' : '') + i },
    s: function () { var s = this.getSeconds(); return (s < 10 ? '0' : '') + s },
    v: function () { var v = this.getMilliseconds(); return (v < 10 ? '00' : (v < 100 ? '0' : '')) + v },
    // Timezone
    e: function () { return Intl.DateTimeFormat().resolvedOptions().timeZone },
    I: function () {
      var DST = null
      for (var i = 0; i < 12; ++i) {
        var d = new Date(this.getFullYear(), i, 1)
        var offset = d.getTimezoneOffset()

        if (DST === null) DST = offset
        else if (offset < DST) { DST = offset; break } else if (offset > DST) break
      }
      return (this.getTimezoneOffset() === DST) | 0
    },
    O: function () { var O = this.getTimezoneOffset(); return (-O < 0 ? '-' : '+') + (Math.abs(O / 60) < 10 ? '0' : '') + Math.floor(Math.abs(O / 60)) + (Math.abs(O % 60) === 0 ? '00' : ((Math.abs(O % 60) < 10 ? '0' : '')) + (Math.abs(O % 60))) },
    P: function () { var P = this.getTimezoneOffset(); return (-P < 0 ? '-' : '+') + (Math.abs(P / 60) < 10 ? '0' : '') + Math.floor(Math.abs(P / 60)) + ':' + (Math.abs(P % 60) === 0 ? '00' : ((Math.abs(P % 60) < 10 ? '0' : '')) + (Math.abs(P % 60))) },
    T: function () { var tz = this.toLocaleTimeString(navigator.language, {timeZoneName: 'short'}).split(' '); return tz[tz.length - 1] },
    Z: function () { return -this.getTimezoneOffset() * 60 },
    // Full Date/Time
    c: function () { return this.format('Y-m-d\\TH:i:sP') },
    r: function () { return this.toString() },
    U: function () { return Math.floor(this.getTime() / 1000) }
  }

  // Simulates PHP's date function
  Date.prototype.format = function (format) {
    var date = this
    return format.replace(/(\\?)(.)/g, function (_, esc, chr) {
      return (esc === '' && replaceChars[chr]) ? replaceChars[chr].call(date) : chr
    })
  }
}).call(this)