var stars;
var nebulae;

function get_body(body, local_observer) {
  const now = new Date;
  const observer = new Astronomy.Observer(local_observer.latitude, local_observer.longitude, local_observer.altitude);
  const equ_ofdate = Astronomy.Equator(body, now, observer, true, true);
  const hor = Astronomy.Horizon(now, observer, equ_ofdate.ra, equ_ofdate.dec, "normal");
  const illumination = Astronomy.Illumination(body, now);
  const name = body;
  body = {}
  body.ra = equ_ofdate.ra;
  body.dec = equ_ofdate.dec;
  body.alt = hor.altitude;
  body.az = hor.azimuth;
  body.body_name = name;
  body.mag = illumination.mag;
  body.dist = equ_ofdate.dist;
  return body;
}
function draw_clock(sky_view, rc, gc, bc) {
  const now = new Date;
  const observer = new Astronomy.Observer(local_observer.latitude, local_observer.longitude, local_observer.altitude);
  const sun = get_body("Sun", local_observer);
  const alt = sun.alt;
  const az = sun.az;
  var mercury = Astronomy.Equator("Mercury", now, observer, true, true);
  var matrix = Astronomy.Rotation_HOR_EQD(now, observer);
  var spherical = {lat:alt, lon:az, dist:mercury.dist};
  var in_vector = Astronomy.VectorFromHorizon(spherical, now, "normal");
  var out_vector = Astronomy.RotateVector(matrix, in_vector);
  var equator = Astronomy.EquatorFromVector(out_vector);
  var size = 10;
  const width = sky_view.offsetWidth;
  const height = sky_view.offsetHeight;
  const top = height - (90 - alt) / 180 * height - (size / 2);
  const left = width - (az / 360 * width - (size / 2));
  const symbol = document.getElementById("Clock");
  symbol.dataset.ra = equator.ra;
  symbol.dataset.dec = equator.dec;
  symbol.dataset.alt = alt;
  symbol.dataset.az = az;
  symbol.dataset.type = "clock";
  symbol.style.position = "absolute";
  symbol.style.left = left;
  symbol.style.top = top;
  svg = '<svg width="{0}" height="{0}"><circle cx="{1}" cy="{1}" r="{1}" stroke="rgb({2},{3},{4})" stroke-width="1" fill="rgb({2},{3},{4})"/></svg>';
  symbol.innerHTML = string_format(svg, size, size / 2, rc, gc, bc);
}
function draw_body(sky_view, body, rc, gc, bc) {
  var size = 20;
  const m = (41.3 + (body.mag - 14.5)) * 4;
  if (m > 1) {size = size * 75 / m}
  if (m > 100) {size = 10}
  const width = sky_view.offsetWidth;
  const height = sky_view.offsetHeight;
  const top = height - (90 + body.alt) / 180 * height - (size / 2);
  const left = body.az / 360 * width - (size / 2);
  const symbol = document.getElementById(body.body_name);
  symbol.dataset.ra = body.ra;
  symbol.dataset.dec = body.dec;
  symbol.dataset.alt = body.alt;
  symbol.dataset.az = body.az;
  symbol.dataset.dist = body.dist;
  symbol.dataset.body_name = body.body_name;
  symbol.dataset.mag = Math.round(body.mag * 10) / 10;
  symbol.dataset.type = "body";
  symbol.style.position = "absolute";
  symbol.style.left = left;
  symbol.style.top = top;
  svg = '<svg width="{0}" height="{0}"><circle cx="{1}" cy="{1}" r="{1}" stroke="rgb({2},{3},{4})" stroke-width="1" fill="rgb({2},{3},{4})"/></svg>';
  if (body.body_name == "Moon") {
    symbol.innerHTML = string_format(svg, size, size / 2, rc, gc, bc);
  } else {
    symbol.innerHTML = string_format(svg, size, size / 2, rc - m, gc - m, bc - m);
  }
}
function draw_star(sky_view, star, initial) {
  var size = 4;
  if (star.mag > 2.5) {size = 2}
  if (star.mag <= 1.5) {size = 6}
  if (star.mag <= 0.5) {size = 8}
  const now = new Date;
  const observer = new Astronomy.Observer(local_observer.latitude, local_observer.longitude, local_observer.altitude);
  const hor = Astronomy.Horizon(now, observer, star.ra, star.dec, "normal");
  const width = sky_view.offsetWidth;
  const height = sky_view.offsetHeight;
  const top = height - (90 + hor.altitude) / 180 * height - (size / 2);
  const left = hor.azimuth / 360 * width - (size / 2);
  var symbol;
  if (initial) {
    symbol = document.createElement("div");
    symbol.id = star.id
    symbol.dataset.ra = star.ra;
    symbol.dataset.dec = star.dec;
    symbol.dataset.star_name = star.star_name;
    symbol.dataset.mag = star.mag;
    symbol.dataset.type = "star";
    symbol.style.position = "absolute";
  } else {
    symbol = document.getElementById(star.id);
  }
  symbol.dataset.alt = hor.altitude;
  symbol.dataset.az = hor.azimuth;
  symbol.style.left = left;
  symbol.style.top = top;
  var m, rc, gc, bc;
  if (star.mag < 2.5) {
    m = (symbol.dataset.mag - 2.5) * 40;
    rc = Math.min(100 - m, 255);
    gc = Math.min(100 - m, 255);
    bc = Math.min(100 - m, 255);
  } else {
    rc = 128;
    gc = 128;
    bc = 128;
  }
  if (initial) {
    svg = '<svg width="{0}" height="{0}"><circle cx="{1}" cy="{1}" r="{1}" stroke="rgb({2},{3},{4})" stroke-width="1" fill="rgb({2},{3},{4})"/></svg>';
    symbol.innerHTML = string_format(svg, size, size / 2, rc, gc, bc);
    sky_view.appendChild(symbol);
    symbol.addEventListener("mousemove", e => {
      show_nav_data(symbol);
    });
    symbol.addEventListener("mouseout", e => {
      hide_nav_data();
    });
    symbol.addEventListener("click", e => {
      mount_goto_body(symbol);
    });
  }
}
function draw_nebula(sky_view, nebula, initial) {
  var size = 6;
  const now = new Date;
  const observer = new Astronomy.Observer(local_observer.latitude, local_observer.longitude, local_observer.altitude);
  const hor = Astronomy.Horizon(now, observer, nebula.ra, nebula.dec, "normal");
  const width = sky_view.offsetWidth;
  const height = sky_view.offsetHeight;
  const top = height - (90 + hor.altitude) / 180 * height - (size / 2);
  const left = hor.azimuth / 360 * width - (size / 2);
  var symbol;
  if (initial) {
    symbol = document.createElement("div");
    symbol.id = nebula.id
    symbol.dataset.ra = nebula.ra;
    symbol.dataset.dec = nebula.dec;
    symbol.dataset.nebula_name = nebula.nebula_name;
    symbol.dataset.mag = nebula.mag;
    symbol.dataset.type = "nebula";
    symbol.dataset.dist = nebula.dist;
    symbol.dataset.VIEWING_SEASON = nebula.VIEWING_SEASON;
    symbol.style.position = "absolute";
  } else {
    symbol = document.getElementById(nebula.id);
  }
  if (symbol != null) {
    symbol.dataset.alt = hor.altitude;
    symbol.dataset.az = hor.azimuth;
    symbol.style.left = left;
    symbol.style.top = top;
    const rc = 200;
    const gc = 50;
    const bc = 50;
    if (initial) {
      svg = '<svg width="{0}" height="{0}"><circle cx="{1}" cy="{1}" r="{1}" stroke="rgb({2},{3},{4})" stroke-width="1" fill="rgb({2},{3},{4})"/></svg>';
      symbol.innerHTML = string_format(svg, size, size / 2, rc, gc, bc);
      sky_view.appendChild(symbol);
      symbol.addEventListener("mousemove", e => {
        show_nav_data(symbol);
      });
      symbol.addEventListener("mouseout", e => {
        hide_nav_data();
      });
      symbol.addEventListener("click", e => {
        mount_goto_body(symbol);
      });
    }
  }
}
function draw_mount(sky_view, color) {
  const width = sky_view.offsetWidth;
  const height = sky_view.offsetHeight;
  const top = height - (90 + mount.alt) / 180 * height - 10;
  const left = mount.az / 360 * width - 10;
  const symbol = document.getElementById("Mount");
  symbol.dataset.ra = mount.ra;
  symbol.dataset.dec = mount.dec;
  symbol.dataset.alt = mount.alt;
  symbol.dataset.az = mount.az;
  symbol.dataset.body_name = mount.body_name;
  symbol.dataset.type = "mount";
  symbol.style.position = "absolute";
  symbol.style.left = left;
  symbol.style.top = top;
  symbol.innerHTML = string_format('<svg width="20" height="20"><circle cx="10" cy="10" r="8" stroke="{0}" stroke-width="1" fill="#0000" /></svg>', color);
}
function equatorial_origin(local_observer) {
  const now = new Date;
  const observer = new Astronomy.Observer(local_observer.latitude, local_observer.longitude, local_observer.altitude);
  const horizon = Astronomy.Horizon(now, observer, 0, 0, false);
  const sky_view = document.getElementById("sky_view");
  const width = sky_view.offsetWidth;
  const height = sky_view.offsetHeight;
  const ra_line = document.getElementById("ra_line");
  // Vertical line moves east -> west.
  ra_line.style.position = "absolute";
  ra_line.style.top = height / 2 - 10;
  ra_line.style.left = horizon.azimuth / 360 * width;
  ra_line.style.display = "block";
  ra_line.dataset.az = horizon.azimuth;
  ra_line.dataset.type = "ra_line";
  const dec_line = document.getElementById("dec_line");
  // Horizontal line moves north to south.
  dec_line.style.position = "absolute";
  dec_line.style.top = height - (90 + horizon.altitude) / 180 * height;
  dec_line.style.left = width / 2 -10;
  dec_line.style.display = "block";
  dec_line.dataset.alt = horizon.altitude;
  dec_line.dataset.type = "dec_line";
}
function show_nav_data(e) {
  const nav = document.getElementById("nav");
  const nf22 = Intl.NumberFormat("en-IN", { minimumIntegerDigits: 2, minimumFractionDigits: 2, maximumFractionDigits: 2 });
  const nf2 = Intl.NumberFormat("en-IN", { minimumIntegerDigits: 2, minimumFractionDigits: 4, maximumFractionDigits: 4 });
  const nf3 = Intl.NumberFormat("en-IN", { minimumIntegerDigits: 3, minimumFractionDigits: 3, maximumFractionDigits: 3 });
  nav_data = "";
  if (e.dataset.type == "ra_line") {
    nav_data = "Right ascension of equatorial origin at azimuth: " + nf2.format(e.dataset.az);
  }
  if (e.dataset.type == "dec_line") {
    nav_data = "Declination of equatorial origin at altitude: " + nf2.format(e.dataset.alt);
  }
  if (e.dataset.type == "rise_line") {
    nav_data = "Sun rises at azimuth: " + nf2.format(e.dataset.az) + ", day time: " + Math.round(e.dataset.day_time * 100) + "%";
  }
  if (e.dataset.type == "set_line") {
    nav_data = "Sun sets at azimuth: " + nf2.format(e.dataset.az) + ", day time: " + Math.round(e.dataset.day_time * 100) + "%";
  }
  if (e.dataset.type == "top_line") {
    nav_data = "Sun is at it's highest at altitude: " + nf2.format(e.dataset.alt);
  }
  if (e.dataset.type == "mount") {
    nav_data = string_format("Alt: {0}, az: {1}, ra: {2}, dec: {3}, mag: {4}, name: {5}.",
                             nf2.format(e.dataset.alt), nf3.format(e.dataset.az), nf2.format(e.dataset.ra), nf3.format(e.dataset.dec),
                             e.dataset.mag, e.dataset.body_name);
  }
  if (e.dataset.type == "body") {
    nav_data = string_format("Alt: {0}, az: {1}, ra: {2}, dec: {3}, dist: {4} au, mag: {5}, name: {6}.",
                             nf2.format(e.dataset.alt), nf3.format(e.dataset.az), nf2.format(e.dataset.ra), nf3.format(e.dataset.dec),
                             nf22.format(e.dataset.dist), e.dataset.mag, e.dataset.body_name);
  }
  if (e.dataset.type == "star") {
    nav_data = string_format("Alt: {0}, az: {1}, ra: {2}, dec: {3}, mag: {4}, name: {5}.",
                             nf2.format(e.dataset.alt), nf3.format(e.dataset.az), nf2.format(e.dataset.ra), nf3.format(e.dataset.dec),
                             e.dataset.mag, e.dataset.star_name);
  }
  if (e.dataset.type == "nebula") {
    nav_data = string_format("Alt: {0}, az: {1}, ra: {2}, dec: {3}, mag: {4}, name: {5}, dist: {6} ly, viewing season: {7}.",
                             nf2.format(e.dataset.alt), nf3.format(e.dataset.az), nf2.format(e.dataset.ra), nf3.format(e.dataset.dec),
                             e.dataset.mag, e.dataset.nebula_name, e.dataset.dist.replaceAll(',', ''), e.dataset.VIEWING_SEASON);
  }
  if (e.dataset.type == "clock") {
    nav_data = string_format("Shadow from Earth is deepest in this direction.");
  }
  nav.innerHTML = nav_data;
}
function hide_nav_data(e) {
  const nav = document.getElementById("nav");
  nav.innerHTML = "";
}
function get_stars() {
  const xhttp = new XMLHttpRequest();
  xhttp.onload = function() {
    stars = JSON.parse(this.responseText);
    for(index in stars) {
      draw_star(sky_view, stars[index], true);
    }
  }
  xhttp.open("GET", "/get_stars?magnitude=" + 3.5, true);
  xhttp.send();
}
function get_nebulae() {
  const xhttp = new XMLHttpRequest();
  xhttp.onload = function() {
    nebulae = JSON.parse(this.responseText);
    for(index in nebulae) {
      draw_nebula(sky_view, nebulae[index], true);
    }
  }
  xhttp.open("GET", "/get_nebulae?VIEWING_DIFFICULTY=" + "Easy", true);
  xhttp.send();
}