/**
 * Ah, JavaScript from 1998... when JS was still a pretty shitty language,
 * syntactically, and things that have simple utility APIs today still
 * required you to write out all the code yourself.
 *
 * Seriously: wtf, Adobe?
 **/

// First: functions that do what modern JS already does.

Array.prototype.map = function(f) {
  var retArr = [];
  for (var i = 0, e = this.length; i < e; i++) {
    retArr[i] = f(this[i], i);
  }
  return retArr;
};

Array.prototype.forEach = function(f) {
  this.map(f);
};

Array.from = function(iterable) {
  var retArr = [];
  for (var i = 0, e = iterable.length; i < e; i++) {
    retArr.push(iterable[i]);
  }
  return retArr;
}

//
// Also we'll need some custom objects.
//

var Point = function (kind, x, y) {
  this.kind = kind;
  this.x = x;
  this.y = y;
}

Point.prototype = {
  toString: function () {
    var base = [this.kind];
    if (this.in) {
      base = base.concat(['(', this.in.x, this.in.y, ')']);
    }
    base = base.concat([this.x, this.y]);
    if (this.out) {
      base = base.concat(['(', this.out.x, this.out.y, ')']);
    }
    return base.join(' ');
  }
}

var BBox = function () {
  this.mx = 9999999;
  this.my = 9999999;
  this.MX = -9999999;
  this.MY = -9999999;
};

BBox.prototype = {
  grow: function (p) {
    if (!p) return;
    if (p.x < this.mx) { this.mx = p.x; }
    if (p.y < this.my) { this.my = p.y; }
    if (p.x > this.MX) { this.MX = p.x; }
    if (p.y > this.MY) { this.MY = p.y; }
    this.grow(p.in);
    this.grow(p.out);
  }
}

//
// And with that out of the way, the actual script:
//

var pointTypes = {
  'PointKind.CORNERPOINT': 'P',
  'PointKind.SMOOTHPOINT': 'C'
};

// filewrite function
function writeToFile(data) {
  var path = '/';
  // can we get a file location from the current document?
  try { path = app.activeDocument.path; } catch (e) { }
  var dir = Folder(path);
  var file = dir.saveDlg('', '.svg', true);
  if (!file) return false;

  var mode = 'w';
  file.open(mode);
  file.write(data);
  file.close(mode);
  return file.toString();
}

// convert a PathPoint to a real object.
function improvePoint(point) {
  var kind = pointTypes[point.kind];
  var coord = point.anchor;
  var x = Math.round(coord[0]);
  var y = Math.round(coord[1]);
  var obj = new Point(kind, x, y);

  if (kind === 'C') {
    var d;
    if (point.leftDirection) {
      d = point.leftDirection.map(Math.round);
      obj.out = { x: d[0], y: d[1] };
    }
    if (point.rightDirection) {
      d = point.rightDirection.map(Math.round);
      obj.in = { x: d[0], y: d[1] };
    }
  }

  return obj;
}

// convert all points in a subpath to easier to parse form
function handleSubPath(subpath) {
  var pathPoints = Array.from(subpath.pathPoints);
  return pathPoints.map(improvePoint);
};

// convert all subpaths in a path to easier to walk form
function handlePath(path) {
  var subPaths = Array.from(path.subPathItems);
  return subPaths.map(handleSubPath);
};

// convert all paths in a document to easier to walk form.
function convertPaths(pathItems) {
  var paths = Array.from(pathItems);
  return paths.map(handlePath);
}

// turn a subpath of improved points into an SVG path
function formSVGpath(subpath, bbox) {
  var p0 = subpath[0];
  var path = ['M', p0.x, p0.y];
  // we want to close this path:
  subpath.push(p0);
  subpath.forEach(function (p, i) {
    if (i === 0) return;
    bbox.grow(p);

    if (p0.kind === 'P' && p.kind === 'P') {
      path = path.concat(['L', p.x, p.y]);
    }
    else if (p0.kind === 'P' && p.kind === 'C') {
      path = path.concat(['C', p0.x, p0.y, p.in.x, p.in.y, p.x, p.y]);
    }
    else if (p0.kind === 'C' && p.kind === 'P') {
      path = path.concat(['C', p0.out.x, p0.out.y, p.x, p.y, p.x, p.y]);
    }
    else if (p0.kind === 'C' && p.kind === 'C') {
      path = path.concat(['C', p0.out.x, p0.out.y, p.in.x, p.in.y, p.x, p.y]);
    }
    p0 = p;
  });
  path.push('z');
  return path.join(' ');
}

// Convert an improved path into an SVG string
function formPathCollectionSVG(pathCollection) {
  var svg = [];
  var bbox = new BBox();
  pathCollection.forEach(function (path) {
    var d = '';
    path.forEach(function (subpath) {
      d += formSVGpath(subpath, bbox);
    });
    svg.push('<path fill="black" stroke="black" fill-rule="evenodd" d="' + d + '"/>');
  });
  svg.push('</svg>');
  var w = bbox.MX - bbox.mx;
  var h = bbox.MY - bbox.my;
  var header = '<svg xmlns="http://www.w3.org/2000/svg" width="' + w + '" height="' + w + '" viewBox="' + [bbox.mx, bbox.my, w, h].join(' ') + '">';
  svg = [header].concat(svg);
  return svg.join('\n');;
}

// ===========================================
//
//           JS equivalent of main()
//
// ===========================================

#target photoshop

// switch to using pixels as unit, irrespective of what the document is set to
var activeDoc = app.activeDocument;
var origUnits = app.preferences.rulerUnits;
app.preferences.rulerUnits = Units.PIXELS;

// convert all paths and write them to file
var improved = convertPaths(activeDoc.pathItems);
var svg = formPathCollectionSVG(improved);
var filepath = writeToFile(svg);
if (!!filepath) alert("svg saved to " + filepath);

// switch back to the original document's units once we're done.
app.preferences.rulerUnits = origUnits;