require("../env");

require("../../d3");

var assert = require("assert");

module.exports = {

  topic: function() {

    var cb = this.callback,

        dd = [],

        ii = [],

        tt = [],

        vv = [];

    var s = d3.select("body").html("").append("div").selectAll("div")

        .data(["red", "green"])

      .enter().append("div")

        .attr("color", function(d) { return d3.rgb(d)+""; });

    var t = s.transition()

        .attrTween("color", tween);

    function tween(d, i, v) {

      dd.push(d);

      ii.push(i);

      vv.push(v);

      if (tt.push(this) >= 2) cb(null, {

        selection: s,

        transition: t,

        data: dd,

        index: ii,

        value: vv,

        context: tt

      });

      return i && d3.interpolateHsl(v, "blue");

    }

  },

  // The order here is a bit brittle: because the transition has zero delay,

  // it's invoking the start event immediately for all nodes, rather than

  // pushing each node onto the timer queue (which would reverse the order of

  // callbacks). The order in which tweens are invoked is undefined, so perhaps

  // we should sort the expected and actual values before comparing.

  "defines the corresponding attr tween": function(result) {

    assert.typeOf(result.transition.tween("attr.color"), "function");

  },

  "invokes the tween function": function(result) {

    assert.deepEqual(result.data, ["red", "green"], "expected data, got {actual}");

    assert.deepEqual(result.index, [0, 1], "expected data, got {actual}");

    assert.deepEqual(result.value, ["#ff0000", "#008000"], "expected value, got {actual}");

    assert.domEqual(result.context[0], result.selection[0][0], "expected this, got {actual}");

    assert.domEqual(result.context[1], result.selection[0][1], "expected this, got {actual}");

  },

  "end": {

    topic: function(result) {

      var cb = this.callback;

      result.transition.each("end", function(d, i) { if (i >= 1) cb(null, result); });

    },

    "uses the returned interpolator": function(result) {

      assert.equal(result.selection[0][1].getAttribute("color"), "#0000ff");

    },

    "does nothing if the interpolator is falsey": function(result) {

      assert.equal(result.selection[0][0].getAttribute("color"), "#ff0000");

    }

  }

};