// TODO nice

function d3_time_scale(linear, methods, format) {

  function scale(x) {

    return linear(x);

  }

  scale.invert = function(x) {

    return d3_time_scaleDate(linear.invert(x));

  };

  scale.domain = function(x) {

    if (!arguments.length) return linear.domain().map(d3_time_scaleDate);

    linear.domain(x);

    return scale;

  };

  scale.ticks = function(m, k) {

    var extent = d3_time_scaleExtent(scale.domain());

    if (typeof m !== "function") {

      var span = extent[1] - extent[0],

          target = span / m,

          i = d3.bisect(d3_time_scaleSteps, target, 1, d3_time_scaleSteps.length - 1);

      if (Math.log(target / d3_time_scaleSteps[i - 1]) < Math.log(d3_time_scaleSteps[i] / target)) --i;

      m = methods[i];

      k = m[1];

      m = m[0];

    }

    return m(extent[0], extent[1], k);

  };

  scale.tickFormat = function() {

    return format;

  };

  scale.copy = function() {

    return d3_time_scale(linear.copy(), methods, format);

  };

  // TOOD expose d3_scale_linear_rebind?

  scale.range = d3.rebind(scale, linear.range);

  scale.rangeRound = d3.rebind(scale, linear.rangeRound);

  scale.interpolate = d3.rebind(scale, linear.interpolate);

  scale.clamp = d3.rebind(scale, linear.clamp);

  return scale;

}

// TODO expose d3_scaleExtent?

function d3_time_scaleExtent(domain) {

  var start = domain[0], stop = domain[domain.length - 1];

  return start < stop ? [start, stop] : [stop, start];

}

function d3_time_scaleDate(t) {

  return new Date(t);

}

function d3_time_scaleFormat(formats) {

  return function(date) {

    var i = formats.length - 1, f = formats[i];

    while (!f[1](date)) f = formats[--i];

    return f[0](date);

  };

}

var d3_time_scaleSteps = [

  1e3,    // 1-second

  5e3,    // 5-second

  15e3,   // 15-second

  3e4,    // 30-second

  6e4,    // 1-minute

  3e5,    // 5-minute

  9e5,    // 15-minute

  18e5,   // 30-minute

  36e5,   // 1-hour

  108e5,  // 3-hour

  216e5,  // 6-hour

  432e5,  // 12-hour

  864e5,  // 1-day

  1728e5, // 2-day

  6048e5, // 1-week

  1728e6, // 1-month

  7776e6, // 3-month

  31536e6 // 1-year

];

var d3_time_scaleLocalMethods = [

  [d3.time.seconds, 1],

  [d3.time.seconds, 5],

  [d3.time.seconds, 15],

  [d3.time.seconds, 30],

  [d3.time.minutes, 1],

  [d3.time.minutes, 5],

  [d3.time.minutes, 15],

  [d3.time.minutes, 30],

  [d3.time.hours, 1],

  [d3.time.hours, 3],

  [d3.time.hours, 6],

  [d3.time.hours, 12],

  [d3.time.days, 1],

  [d3.time.days, 2],

  [d3.time.weeks, 1],

  [d3.time.months, 1],

  [d3.time.months, 3],

  [d3.time.years, 1]

];

var d3_time_scaleLocalFormats = [

  [d3.time.format("%Y"), function(d) { return true; }],

  [d3.time.format("%B"), function(d) { return d.getMonth(); }],

  [d3.time.format("%b %d"), function(d) { return d.getDate() != 1; }],

  [d3.time.format("%a %d"), function(d) { return d.getDay() && d.getDate() != 1; }],

  [d3.time.format("%I %p"), function(d) { return d.getHours(); }],

  [d3.time.format("%I:%M"), function(d) { return d.getMinutes(); }],

  [d3.time.format(":%S"), function(d) { return d.getSeconds() || d.getMilliseconds(); }]

];

var d3_time_scaleLocalFormat = d3_time_scaleFormat(d3_time_scaleLocalFormats);

d3.time.scale = function() {

  return d3_time_scale(d3.scale.linear(), d3_time_scaleLocalMethods, d3_time_scaleLocalFormat);

};