Calculate Circadian sine

var sunrise = "06:00"; //Hard-coded sunrise
var sunset = "18:00"; //Hard-coded sunset

var color_min = 2700; // Color temp at sunrise and sunset
var color_max = 6500; // Color temp at noon

function map(x, in_min, in_max, out_min, out_max)
{
    return Math.round((x - in_min) * (out_max - out_min) / (in_max - in_min) + out_min);
}

//If light is operating in RGB, do not set the color_temp except if the the light
//has just been turned on.
if (msg.topic != "turn_on") {
    if (msg.payload.attributes.color_mode != "color_temp") {
        return;
    }
}

var today = new Date();
var today_date = today.getFullYear() + '-' + (today.getMonth()+1) + '-' + today.getDate();
var today_time = today.getHours() + ":" + String(today.getMinutes()).padStart(2, '0');

var unix_sunrise = new Date(today_date + ' ' + sunrise).getTime() / 1000;
var unix_sunset = new Date(today_date + ' ' + sunset).getTime() / 1000;
var unix_now = new Date().getTime() / 1000;
var brightness = ""

var color_temp = color_min;

var day_progress = (unix_now-unix_sunrise) / (unix_sunset-unix_sunrise);

if (unix_now >= unix_sunrise && unix_now <= unix_sunset)
{
    var color_sine = Math.sin(((360 * day_progress)-90) * (Math.PI/180));

    color_temp = map(color_sine, -1.0, 1.0, color_min, color_max);
}

day_progress = Math.round(day_progress * 100); //Round to a whole number
node.status({text: color_temp + "K @ " + today_time + " (" + day_progress + "%)" });

/*msg.payload = {domain: "light", service: "turn_on",
    data: {
        entity_id: msg.payload.entity_id,
        kelvin: color_temp,  }
    };
*/
    //msg.payload.domain = "light";
    //msg.payload.service = "turn_on";

    //msg.payload.data = msg.payload.data || {}
    msg.payload.data.kelvin = color_temp
return msg;