c3_chart_internal_fn.generateColor = function () {

var $$ = this, config = $$.config, d3 = $$.d3,

colors = config.data_colors,

pattern = notEmpty(config.color_pattern) ? config.color_pattern : d3.scale.category10().range(),

callback = config.data_color,

ids = [];

return function (d) {

var id = d.id || (d.data && d.data.id) || d, color;

// if callback function is provided

if (colors[id] instanceof Function) {

color = colors[id](d);

}

// if specified, choose that color

else if (colors[id]) {

color = colors[id];

}

// if not specified, choose from pattern

else {

if (ids.indexOf(id) < 0) { ids.push(id); }

color = pattern[ids.indexOf(id) % pattern.length];

colors[id] = color;

}

return callback instanceof Function ? callback(color, d) : color;

};

};

c3_chart_internal_fn.generateLevelColor = function () {

var $$ = this, config = $$.config,

colors = config.color_pattern,

threshold = config.color_threshold,

asValue = threshold.unit === 'value',

values = threshold.values && threshold.values.length ? threshold.values : [],

max = threshold.max || 100;

return notEmpty(config.color_threshold) ? function (value) {

var i, v, color = colors[colors.length - 1];

for (i = 0; i < values.length; i++) {

v = asValue ? value : (value * 100 / max);

if (v < values[i]) {

color = colors[i];

break;

}

}

return color;

} : null;

};