/*
   * ext-grid.js
   *
   * Licensed under the Apache License, Version 2
   *
   * Copyright(c) 2010 Redou Mine
   * Copyright(c) 2010 Alexis Deveria
   *
   */
  
  // Dependencies:
  // 1) units.js
  // 2) everything else
  
  svgEditor.addExtension("view_grid", function(s) {
  
      var svgdoc = document.getElementById("svgcanvas").ownerDocument,
  			svgns = "http://www.w3.org/2000/svg",
  			dims = svgEditor.curConfig.dimensions,
  			svgroot = s.svgroot;
  
  	var showGrid = false;
      var assignAttributes = svgCanvas.assignAttributes;
      
      var hcanvas = document.createElement('canvas');
      $(hcanvas).hide().appendTo('body');
  
      var canvasgrid = svgdoc.createElementNS(svgns, "svg");
      assignAttributes(canvasgrid, {
          'id': 'canvasGrid',
          'width': '100%',
          'height': '100%',
          'x': 0,
          'y': 0,
          'overflow': 'visible',
          'display': 'none'
      });
      
      var canvBG = $('#canvasBackground');
      canvBG.append(canvasgrid);
  
          // grid-pattern
          var gridPattern = svgdoc.createElementNS(svgns, "pattern");
          assignAttributes(gridPattern, {
              'id': 'gridpattern',
              'patternUnits': 'userSpaceOnUse',
              'x': 0, //-(value.strokeWidth / 2), // position for strokewidth
              'y': 0, //-(value.strokeWidth / 2), // position for strokewidth
              'width': 100,
              'height': 100
          });
          
          var gridimg = svgdoc.createElementNS(svgns, "image");
          assignAttributes(gridimg, {
              'x': 0,
              'y': 0,
              'width': 100,
              'height': 100
          });
          
          gridPattern.appendChild(gridimg);
          $('#svgroot defs').append(gridPattern);
  
          // grid-box
          var gridBox = svgdoc.createElementNS(svgns, "rect");
          assignAttributes(gridBox, {
              'width': '100%',
              'height': '100%',
              'x': 0,
              'y': 0,
              'stroke-width': 0,
              'stroke': 'none',
              'fill': 'url(#gridpattern)',
              'style': 'pointer-events: none; display:visible;'
          });
          $('#canvasGrid').append(gridBox);
  //     });
  
  	function updateGrid(zoom) {
  		// TODO: Try this with <line> elements, then compare performance difference
  	
  		var bgwidth = +canvBG.attr('width');
  		var bgheight = +canvBG.attr('height');
  		
  		var units = svgedit.units.getTypeMap();
  		var unit = units[svgEditor.curConfig.baseUnit]; // 1 = 1px
  		var r_intervals = [.01, .1, 1, 10, 100, 1000];
  	
  		var d = 0;
  		var is_x = (d === 0);
  		var dim = is_x ? 'x' : 'y';
  		var lentype = is_x?'width':'height';
  		var c_elem = svgCanvas.getContentElem();
  		var content_d = c_elem.getAttribute(dim)-0;
  		
  		var hcanv = hcanvas;
  		
  		var u_multi = unit * zoom;
  		
  		// Calculate the main number interval
  		var raw_m = 100 / u_multi;
  		var multi = 1;
  		for(var i = 0; i < r_intervals.length; i++) {
  			var num = r_intervals[i];
  			multi = num;
  			if(raw_m <= num) {
  				break;
  			}
  		}
  		
  		var big_int = multi * u_multi;
  
  		// Set the canvas size to the width of the container
  		hcanv.width = big_int;
  		hcanv.height = big_int;
  		var ctx = hcanv.getContext("2d");
  
  		var ruler_d = 0; 
  		var cur_d = .5;
  		
  		var part = big_int / 10;
  
  		ctx.globalAlpha = 0.2;
  		ctx.strokeStyle = "#000";
  		for(var i = 1; i < 10; i++) {
  			var sub_d = Math.round(part * i) + .5;
  // 					var line_num = (i % 2)?12:10;
  			var line_num = 0;
  			ctx.moveTo(sub_d, big_int);
  			ctx.lineTo(sub_d, line_num);
  			ctx.moveTo(big_int, sub_d);
  			ctx.lineTo(line_num ,sub_d);
  		}
  		ctx.stroke();
  		ctx.beginPath();  
  		ctx.globalAlpha = 0.5;
  		ctx.moveTo(cur_d, big_int);
  		ctx.lineTo(cur_d, 0);
  
  		ctx.moveTo(big_int, cur_d);
  		ctx.lineTo(0, cur_d);
  		ctx.stroke();
  
  		var datauri = hcanv.toDataURL('image/png');
  		gridimg.setAttribute('width', big_int);
  		gridimg.setAttribute('height', big_int);
  		gridimg.parentNode.setAttribute('width', big_int);
  		gridimg.parentNode.setAttribute('height', big_int);
  		svgCanvas.setHref(gridimg, datauri);
  	}
  
      return {
          name: "view_grid",
          svgicons: "extensions/grid-icon.xml",
  
          zoomChanged: function(zoom) {
              // update size
              if(showGrid) updateGrid(zoom);
          },
  
          buttons: [{
              id: "view_grid",
              type: "context",
              panel: "editor_panel",
              title: "Show/Hide Grid",
              events: {
                  'click': function() {
                      var gr = !$('#view_grid').hasClass('push_button_pressed');
                      if (gr) {
                          svgEditor.curConfig.showGrid = showGrid = true;
                          $('#view_grid').addClass('push_button_pressed').removeClass('tool_button');
                          $('#canvasGrid').attr('display', 'normal');
                          updateGrid(svgCanvas.getZoom());
                      }
                      else {
                          svgEditor.curConfig.showGrid = showGrid = false;
                          $('#view_grid').removeClass('push_button_pressed').addClass('tool_button');
                          $('#canvasGrid').attr('display', 'none');
                      }
                  }
              }
  }]
          };
      });