EPUBJS.Map = function(layout){
  this.layout = layout;
};

EPUBJS.Map.prototype.section = function(view) {
  var ranges = this.findRanges(view);
  var map = this.rangeListToCfiList(view, ranges);

  return map;
};

EPUBJS.Map.prototype.page = function(view, start, end) {
  var root = view.document.body;
  return this.rangePairToCfiPair(view.section, {
    start: this.findStart(root, start, end),
    end: this.findEnd(root, start, end)
  });
};

EPUBJS.Map.prototype.walk = function(root, func) {
  //var treeWalker = document.createTreeWalker(root, NodeFilter.SHOW_ELEMENT + NodeFilter.SHOW_TEXT, null, false);
  var treeWalker = document.createTreeWalker(root, NodeFilter.SHOW_TEXT, {
      acceptNode: function (node) {
          if ( node.data.trim().length > 0 ) {
            return NodeFilter.FILTER_ACCEPT;
          } else {
            return NodeFilter.FILTER_REJECT;
          }
      }
  }, false);
  var node;
  var result;
  while ((node = treeWalker.nextNode())) {
    result = func(node);
    if(result) break;
  }
  
  return result;
};

EPUBJS.Map.prototype.findRanges = function(view){
  var columns = [];
  var count = this.layout.count(view);
  var column = this.layout.column;
  var gap = this.layout.gap;
  var start, end;

  for (var i = 0; i < count.pages; i++) {
    start = (column + gap) * i;
    end = (column * (i+1)) + (gap * i);
    columns.push({
      start: this.findStart(view.document.body, start, end),
      end: this.findEnd(view.document.body, start, end)
    });
  };
  
  return columns;
};

EPUBJS.Map.prototype.findStart = function(root, start, end){
  var stack = [root];
  var $el;
  var found;
  var $prev;
  while (stack.length) {

    $el = stack.shift();

    found = this.walk($el, function(node){
      var left, right;
      var elPos
      var elRange;
      

      if(node.nodeType == Node.TEXT_NODE){
        elRange = document.createRange();
        elRange.selectNodeContents(node);
        elPos = elRange.getBoundingClientRect();
      } else {
        elPos = node.getBoundingClientRect();
      }

      left = elPos.left;
      right = elPos.right;

      if( left >= start && left <= end ) {
        return node; 
      } else if (right > start) {
        return node;
      } else {
        $prev = node;
        stack.push(node);
      }

    });

    if(found) {
      return this.findTextStartRange(found, start, end);
    }

  }

  // Return last element
  return this.findTextStartRange($prev, start, end);
};

EPUBJS.Map.prototype.findEnd = function(root, start, end){
  var stack = [root];
  var $el;
  var $prev;
  var found;

  while (stack.length) {

    $el = stack.shift();

    found = this.walk($el, function(node){
      
      var left, right;
      var elPos
      var elRange;
      
      
      if(node.nodeType == Node.TEXT_NODE){
        elRange = document.createRange();
        elRange.selectNodeContents(node);
        elPos = elRange.getBoundingClientRect();
      } else {
        elPos = node.getBoundingClientRect();
      }

      left = elPos.left;
      right = elPos.right;
      
      if(left > end && $prev) {
        return $prev
      } else if(right > end) {
        return node;
      } else {
        $prev = node;
        stack.push(node);
      }

    });


    if(found){
      return this.findTextEndRange(found, start, end);
    }
  
  }

  // end of chapter
  return this.findTextEndRange($prev, start, end);
};


EPUBJS.Map.prototype.findTextStartRange = function(node, start, end){
  var ranges = this.splitTextNodeIntoRanges(node);
  var prev;
  var range;
  var pos;

  for (var i = 0; i < ranges.length; i++) {
    range = ranges[i];

    pos = range.getBoundingClientRect();

    if( pos.left >= start ) {
      return range;
    }

    prev = range;

  };

  return ranges[0];
};

EPUBJS.Map.prototype.findTextEndRange = function(node, start, end){
  var ranges = this.splitTextNodeIntoRanges(node);
  var prev;
  var range;
  var pos;

  for (var i = 0; i < ranges.length; i++) {
    range = ranges[i];

    pos = range.getBoundingClientRect();
    
    if(pos.left > end) {
      return prev;
    } else if(pos.right > end) {
      return range;
    }
  
    prev = range;

  };

  // Ends before limit
  return ranges[ranges.length-1];

};

EPUBJS.Map.prototype.splitTextNodeIntoRanges = function(node, _splitter){
  var ranges = [];
  var text = node.textContent.trim();
  var range;
  var rect;
  var list;
  var doc = node.ownerDocument;
  var splitter = _splitter || " ";

  pos = text.indexOf(splitter);

  if(pos === -1) {
    range = doc.createRange();
    range.selectNodeContents(node);
    return [range];
  }

  range = doc.createRange();
  range.setStart(node, 0);
  range.setEnd(node, pos);
  ranges.push(range);
  range = false;

  while ( pos != -1 ) {

    pos = text.indexOf(splitter, pos + 1);
    if(pos > 0) {

      if(range) {
        range.setEnd(node, pos);
        ranges.push(range);
      }

      range = doc.createRange();
      range.setStart(node, pos+1);
    }
  }

  if(range) {
    range.setEnd(node, text.length);
    ranges.push(range);
  }

  return ranges;
};



EPUBJS.Map.prototype.rangePairToCfiPair = function(section, rangePair){

  var startRange = rangePair.start;
  var endRange = rangePair.end;

  startRange.collapse(true);
  endRange.collapse(true);

  startCfi = section.cfiFromRange(startRange);
  endCfi = section.cfiFromRange(endRange);

  return {
    start: startCfi,
    end: endCfi
  }

};

EPUBJS.Map.prototype.rangeListToCfiList = function(view, columns){
  var map = [];
  var rangePair, cifPair;

  for (var i = 0; i < columns.length; i++) {
    cifPair = this.rangePairToCfiPair(view.section, columns[i]);

    map.push(cifPair);

  };
  
  return map;
};