var fs = require('fs');
var path = require('path');

var IMGDIR = dir = path.join(__dirname, '/../www-root/img/');

function existsSync(filename) {
  try {
    fs.accessSync(filename);
    return true;
  } catch(ex) {
    return false;
  }
}

module.exports = function(set, app, data, scriptMethods) {
  var keys = Object.keys(set.generators);
  var cache = {};
  var fileNames = {};

  for(var i = 0; i < keys.length; ++i) {
    var fileName = "bg_" + keys[i].split('/').join('_') + ".png";

    if(existsSync(IMGDIR + fileName)) {
      fileName = "/img/" + fileName;
    } else {
      fileName = "bg_" + keys[i].split('/')[0] + ".png";

      if(existsSync(IMGDIR + fileName)) {
        fileName = "/img/" + fileName;
      } else {
        fileName = null;
      }
    }

    var binding = {'json': JSON.stringify(fileName), 'fileName': fileName};
    app.get('/b/' + keys[i], (function (req, res) {
      var agent = req.headers['user-agent'];

      res.header("Content-Type", "application/json; charset=utf-8");
      if(agent.indexOf('curl/') != -1) {
        res.end(this.fileName);
      } else {
        res.end(this.json);
      }
    }).bind(binding));

    console.log('[INFO] bg for "'+keys[i]+'" = "'+fileName+'"');

    fileNames[keys[i]] = fileName;
  }

  scriptMethods.getBackgroundFromCookie = function(cookies) {
    var key;

    if(Object.prototype.hasOwnProperty.call(cookies, 'last_generator')) {
      key = cookies['last_generator'];
    } else {
      key = scriptMethods.getDefaultDataKey();
    }

    return 'body { background-image: url(' + fileNames[key] + '); }'
  }
}