var VERSION = "2.0";
var getCharDataUrl = char =>
  `https://cdn.jsdelivr.net/npm/hanzi-writer-data@${VERSION}/${char}.json`;

function loadData(char, onLoad, onError) {
  var xhr = new XMLHttpRequest();
  if (xhr.overrideMimeType) {
    xhr.overrideMimeType("application/json");
  }
  xhr.open("GET", getCharDataUrl(char), true);
  xhr.onreadystatechange = () => {
    if (xhr.readyState !== 4) return;
    if (xhr.status === 200) {
      onLoad(JSON.parse(xhr.responseText));
    } else if (onError) {
      onError(xhr);
    }
  };
  xhr.send(null);
}

function attr(elm, name, value) {
  elm.setAttributeNS(null, name, value);
}

function createElm(elmType) {
  return document.createElementNS("http://www.w3.org/2000/svg", elmType);
}

function getPathString(points) {
  const start = points[0];
  const remainingPoints = points.slice(1);
  let pathString = `M ${start[0]} ${start[1]}`;
  remainingPoints.forEach(point => {
    pathString += ` L ${point[0]} ${point[1]}`;
  });
  return pathString;
}

function renderCharacter(charData) {
  var target = document.querySelector("#target");
  document.body.classList.toggle("has-radical-data", !!charData.radStrokes);
  target.innerHTML = "";
  var svg = createElm("svg");
  attr(svg, "width", "100%");
  attr(svg, "height", "100%");
  target.appendChild(svg);
  var group = createElm("g");
  attr(
    group,
    "transform",
    "translate(0, 263.671875) scale(0.29296875, -0.29296875)"
  );
  svg.appendChild(group);
  charData.strokes.forEach((stroke, i) => {
    var isRadical = (charData.radStrokes || []).indexOf(i) > -1;
    var path = createElm("path");
    attr(path, "d", stroke);
    path.classList.toggle("radical-stroke", isRadical);
    group.appendChild(path);
  });
  charData.medians.forEach(median => {
    var path = createElm("path");
    attr(path, "d", getPathString(median));
    path.classList.add("median-stroke");
    group.appendChild(path);
  });
}

function updateClasses() {
  var target = document.querySelector("#target");
  var transparent = document.querySelector("#transparent").checked;
  var radical = document.querySelector("#radical").checked;
  var medians = document.querySelector("#medians").checked;
  target.classList.toggle("transparent-strokes", transparent);
  target.classList.toggle("color-radical", radical);
  target.classList.toggle("show-medians", medians);
}

document.querySelectorAll("input[type=checkbox]").forEach(function(node) {
  node.addEventListener("change", updateClasses);
});

function renderLoadPath(char) {
  var cdnTarget = document.querySelector("#cdn-path");
  var url = getCharDataUrl(char);
  cdnTarget.innerHTML = `<a href="${url}" target="blank">${url}</a>`;

  var npmTarget = document.querySelector("#npm-path");
  npmTarget.innerHTML = `var charData = require('hanzi-writer-data/${char}.json');`;
}

function loadAndRender() {
  var char = document.querySelector("#char-input").value;
  loadData(
    char,
    function(charData) {
      renderCharacter(charData);
      renderLoadPath(char);
      window.location.hash = char.codePointAt(0);
    },
    function(err) {
      console.error(err);
      alert(`Unable to load data for ${char}`);
    }
  );
}

function setCharFromHash(defaultChar) {
  var hashChar = defaultChar;
  if (window.location.hash) {
    var codePoint = parseInt(window.location.hash.slice(1));
    if (!isNaN(codePoint)) {
      hashChar = String.fromCodePoint(codePoint);
    }
  }
  if (hashChar) {
    document.querySelector("#char-input").value = hashChar;
  }
}

setCharFromHash("我");
window.addEventListener("hashchange", function() {
  setCharFromHash(null);
  loadAndRender();
});
document.querySelector("#update-char").addEventListener("click", loadAndRender);
updateClasses();
loadAndRender();