var fs = require('fs'),
      util = require('util'),
      Canvas = require('canvas'),
      Image = Canvas.Image,
      Futures = require('futures'),
      Join = Futures.join;
  
  var maxSpriteWidth = 2048;
    
  function spriter(directory) { 
    var files = fs.readdirSync(directory),
        rowData = {},
        // Load all the images
        join = loadImages(directory,files,rowData);
   
    // Wait for the all images to load
    join.when(function() {
      // Get the dimensions of the output sprite map
      var dimensions = calculateSize(rowData),
          canvas = new Canvas(dimensions.width, dimensions.height);
  
      // Draw the images to the canvas and return the JSON data
      var jsonOutput = drawImages(rowData,canvas);
  
      // Write out both the sprites.png and sprites.json files
      fs.writeFileSync("mobile-game-ch08-spriter-sprites.png",canvas.toBuffer());
      fs.writeFileSync("mobile-game-ch08-spriter-sprites.json",JSON.stringify(jsonOutput));
      util.print("Wrote sprites.png and sprites.json\n");
    });
    
  }
  
  function loadImages(directory,files,rowData) {
    var fileRegex = /^(.*?)([0-9]+)\.[a-zA-Z]{3}$$/,
        join = Join();
  
    for(var i=0;i<files.length;i++) {
      (function(file) {
        var results = file.match(fileRegex),
            img = new Image();
  
        if(results) {
          var rowName = results[1],
              fileNum = parseInt(results[2],10);
  
          img.onload = join.add();
          img.onerror = function() { 
            util.print("Error loading: " + file + "\n"); process.exit(1); 
          }
  
          img.src = directory.replace(/\//,"") + "/" + file;
  
          rowData[rowName] = rowData[rowName] || [];
          rowData[rowName].push([fileNum,img]);
        }
      })(files[i]);
    }
  
    return join;
  
  }
  
  function calculateSize(rowData) {
    var maxWidth = 0,
        totalHeight = 0;
  
    for(var spriteName in rowData) {
      // Order by ascending number
      var row = rowData[spriteName],
      firstImage = row[0][1],
      width = firstImage.width * row.length,
      rows = 1;
  
      if(width > maxSpriteWidth) {
        rows = Math.ceil(width / maxSpriteWidth);
        width = maxSpriteWidth;
      }
  
      maxWidth = Math.max(width,maxWidth);
      totalHeight += firstImage.height * rows;
    }
  
    return { width: maxWidth, height: totalHeight };
  }
  
  function drawImages(rowData,canvas) {
      var ctx = canvas.getContext('2d'),
          curY = 0,
          jsonOutput = {};
  
      for(var spriteName in rowData) {
        // Order by ascending number
        var row = rowData[spriteName].sort(function(a,b) { return a[0] - b[0]; }),
            firstImage = row[0][1],
            imageWidth = firstImage.width,
            rowHeight = firstImage.height,
            rowWidth = Math.min(imageWidth * row.length, maxSpriteWidth),
            cols = Math.floor(rowWidth / imageWidth),
            rows = Math.ceil(row.length / cols);
  
            console.log(spriteName + " " + cols + " " + rows);
  
        jsonOutput[spriteName] = { sx: 0, sy: curY, cols: cols,
                                   tilew: imageWidth, tileh: rowHeight, 
                                   frames: row.length };
  
        for(var i =0;i<rows;i++) {
          for(var k=0;k<cols;k++) {
            if(row[k+i*cols])  {
              ctx.drawImage(row[k + i*cols ][1],k*imageWidth,curY);
            }
          }
          curY += rowHeight;
        }
      }
  
      return jsonOutput;
  
  }
  
  // Make the spriter method available
  module.exports = spriter;