var Canvas = require('canvas'),
  fs = require('fs'),
  http = require('http'),
  https = require('https'),
  url = require('url'),
  Image = Canvas.Image;

var classifySkin = function(r, g, b) {
    var rgbClassifier = r > 95 && g > 40 && g < 100 && b > 20 && (Math.max(r, g, b) - Math.min(r, g, b)) > 15 && Math.abs(r - g) > 15 && r > g && r > b,
      nurgb = toNormalizedRgb(r, g, b),
      nr = nurgb[0],
      ng = nurgb[1],
      nb = nurgb[2],
      normRgbClassifier = (nr / ng) > 1.185 && (r * b / Math.pow(r + g + b, 2)) > 0.107 && (r * g / Math.pow(r + g + b, 2)) > 0.112,
      hsv = toHsvTest(r, g, b),
      h = hsv[0],
      s = hsv[1],
      hsvClassifier = h > 0 && h < 35 && s > 0.23 && s < 0.68;
    return rgbClassifier || normRgbClassifier || hsvClassifier;
  },
  toHsvTest = function(r, g, b) {
	  var h = 0,
	    mx = Math.max(r, g, b),
	    mn = Math.min(r, g, b),
	    dif = mx - mn;
	  if(mx == r)
		  h = (g - b) / dif;
	  else if(mx == g)
		  h = 2 + (g - r) / dif;
	  else
		  h = 4 + (r - g) / dif;
	  h *= 60;
	  if(h < 0)
		  h += 360;
	  return [h, 1 - 3 * (Math.min(r, g, b) / (r + g + b)), 1 / 3 * (r + g + b)];
  },
  toNormalizedRgb = function(r, g, b) {
	  var sum = r + g + b;
	  return [r / sum, g / sum, b / sum];
  };

var scan = function(data, callback) {
    var canvas = new Canvas(1, 1),
      ctx = canvas.getContext('2d'),
      img = new Image(),
      skinRegions = [],
      skinMap = [],
      detectedRegions = [],
      mergeRegions = [],
      detRegions = [],
      lastFrom = -1,
      lastTo = -1,
      totalSkin = 0,
      addMerge = function(from, to) {
        lastFrom = from;
        lastTo = to;
        var len = mergeRegions.length,
          fromIndex = -1,
          toIndex = -1,
          region,
          rlen;
        while(len--) {
          region = mergeRegions[len];
          rlen = region.length;
          while(rlen--) {
            if(region[rlen] == from)
              fromIndex = len;
            if(region[rlen] == to)
              toIndex = len;
          }
        }
        if(fromIndex != -1 && toIndex != -1 && fromIndex == toIndex)
          return;
        if(fromIndex == -1 && toIndex == -1)
          return mergeRegions.push([from, to]);
        if(fromIndex != -1 && toIndex == -1)
          return mergeRegions[fromIndex].push(to);
        if(fromIndex == -1 && toIndex != -1)
          return mergeRegions[toIndex].push(from);
        if(fromIndex != -1 && toIndex != -1 && fromIndex != toIndex) {
          mergeRegions[fromIndex] = mergeRegions[fromIndex].concat(mergeRegions[toIndex]);
          mergeRegions = [].concat(mergeRegions.slice(0, toIndex), mergeRegions.slice(toIndex + 1));
        }
      },
      totalPixels,
      imageData,
      length;
    img.src = data;
    canvas.width = img.width;
    canvas.height = img.height;
    totalPixels = canvas.width * canvas.height;
    try {
	    ctx.drawImage(img, 0, 0);
    } catch (e) {
	    console.log('unsupported image format');
    }
    imageData = ctx.getImageData(0, 0, canvas.width, canvas.height).data;
    length = imageData.length;
    for(var i = 0, u = 1; i < length; i += 4, u++) {
      var r = imageData[i],
        g = imageData[i + 1],
        b = imageData[i + 2],
        x = u > canvas.width ? u % canvas.width - 1 : u,
        y = u > canvas.width ? Math.ceil(u / canvas.width) - 1 : 1;
      if(classifySkin(r, g, b)) {
        skinMap.push({id: u, skin: true, region: 0, x: x, y: y, checked: false});
        var region = -1,
          checkIndexes = [u - 2, u - canvas.width - 2, u - canvas.width - 1, u - canvas.width],
          checker = false;
        for(var o = 0, index; o < 4; o++) {
          index = checkIndexes[o];
          if(skinMap[index] && skinMap[index].skin) {
            if(skinMap[index].region != region && region != -1 && lastFrom != region && lastTo != skinMap[index].region)
              addMerge(region, skinMap[index].region);
            region = skinMap[index].region;
            checker = true;
          }
        }
        if(!checker) {
          skinMap[u - 1].region = detectedRegions.length;
          detectedRegions.push([skinMap[u - 1]]);
          continue;
        }
        else
          if(region > -1) {
            if(!detectedRegions[region])
              detectedRegions[region] = [];
            skinMap[u - 1].region = region;
            detectedRegions[region].push(skinMap[u - 1]);
          }
      }
      else
        skinMap.push({ id: u, skin: false, region: 0, x: x, y: y, checked: false });
    }
    length = mergeRegions.length;
    while(length--) {
      region = mergeRegions[length];
      var rlen = region.length;
      if(!detRegions[length])
        detRegions[length] = [];
      while(rlen--) {
        index = region[rlen];
        detRegions[length] = detRegions[length].concat(detectedRegions[index]);
        detectedRegions[index] = [];
      }
    }
    length = detectedRegions.length;
    while(length--)
      if(detectedRegions[length].length > 0)
        detRegions.push(detectedRegions[length]);
    length = detRegions.length;
    for(var i = 0; i < length; i++)
      if(detRegions[i].length > 30)
        skinRegions.push(detRegions[i]);
    length = skinRegions.length;
    if(length < 3)
      return callback && callback(false);
    (function() {
      var sorted = false, temp;
      while(!sorted) {
        sorted = true;
        for(var i = 0; i < length-1; i++)
          if(skinRegions[i].length < skinRegions[i + 1].length) {
            sorted = false;
            temp = skinRegions[i];
            skinRegions[i] = skinRegions[i + 1];
            skinRegions[i + 1] = temp;
          }
      }
    })();
    while(length--)
      totalSkin += skinRegions[length].length;
    if((totalSkin / totalPixels) * 100 < 15)
      return callback && callback(false);
    if((skinRegions[0].length / totalSkin) * 100 < 35 && (skinRegions[1].length / totalSkin) * 100 < 30 && (skinRegions[2].length / totalSkin) * 100 < 30)
      return callback && callback(false);
    if((skinRegions[0].length / totalSkin) * 100 < 45)
      return callback && callback(false);
    if(skinRegions.length > 60)
      return callback && callback(false);
    return callback && callback(true);
  }
module.exports = {
  scanFile: function(src, callback){
    fs.readFile(src, function(err, data) {
      if (err) throw err;
      scan(data, callback);
    });
  },
  scanURL: function(src, callback){
    var data = [];
    var opts = url.parse(src);
    // opts.headers = {
	    // 'Content-Type': 'image/jpeg'
    // };
    if ( src.match( 'https' ) ) {
      https.request(opts, function(res) {
        res.setEncoding('binary');
        res.on('data', function(chunk) {
          data.push(chunk.toString('binary'));
        });
        res.on('error', function(err) {
          throw err;
        });
        res.on('end', function() {
          data = new Buffer(data.join(''), 'binary');
          scan(data, callback);
        });
      }).end();
    } else {
      http.request(opts, function(res) {
        res.setEncoding('binary');
        res.on('data', function(chunk) {
          data.push(chunk.toString('binary'));
        });
        res.on('error', function(err) {
          throw err;
        });
        res.on('end', function() {
          data = new Buffer(data.join(''), 'binary');
          scan(data, callback);
        });
      }).end();
    }
  },
};