'use strict';

var svgReg = /<return svgReg.test(buffer);

}

var extractorRegExps = {

'root': /<svg\s[^>]+>/,
'width': /\bwidth=(['"])([^%]+?)\1/,
'height': /\bheight=(['"])([^%]+?)\1/,
'viewbox': /\bviewBox=(['"])(.+?)\1/

};

function parseViewbox (viewbox) {

var bounds = viewbox.split(' ');
return {
  'width': parseInt(bounds[2], 10),
  'height': parseInt(bounds[3], 10)
};

}

function parseAttributes (root) {

var width = root.match(extractorRegExps.width);
var height = root.match(extractorRegExps.height);
var viewbox = root.match(extractorRegExps.viewbox);
return {
  'width': width && parseInt(width[2], 10),
  'height': height && parseInt(height[2], 10),
  'viewbox': viewbox && parseViewbox(viewbox[2])
};

}

function calculateByDimensions (attrs) {

return {
  'width': attrs.width,
  'height': attrs.height
};

}

function calculateByViewbox (attrs) {

var ratio = attrs.viewbox.width / attrs.viewbox.height;
if (attrs.width) {
  return {
    'width': attrs.width,
    'height': Math.floor(attrs.width / ratio)
  };
}
if (attrs.height) {
  return {
    'width': Math.floor(attrs.height * ratio),
    'height': attrs.height
  };
}
return {
  'width': attrs.viewbox.width,
  'height': attrs.viewbox.height
};

}

function calculate (buffer) {

var root = buffer.toString('utf8').match(extractorRegExps.root);
if (root) {
  var attrs = parseAttributes(root[0]);
  if (attrs.width && attrs.height) {
    return calculateByDimensions(attrs);
  }
  if (attrs.viewbox) {
    return calculateByViewbox(attrs);
  }
}
throw new TypeError('invalid svg');

}

module.exports = {

'detect': isSVG,
'calculate': calculate

};