var usedRotatedBannerPositions = new Array();
var currentLang = "ja";

function renderBanners(lang) {
  if (lang == null) {
    lang = 'ja';
  }
  currentLang = lang;
  renderRandomBanners(lang);
}

function renderAllBanners() {
  var result = "";
  var bannerAreas = bannerSettings.bannerAreas;
  for (var i=0; i<bannerAreas.length; i++) {
    result += buildBannerAreaForAll(bannerAreas[i]);
  }
  document.write(result);
}

function renderRandomBanners(lang) {
  var result = "";
  var bannerAreas = bannerSettings[lang].bannerAreas;
  for (var i=0; i<bannerAreas.length; i++) {
    result += buildBannerArea(bannerAreas[i]);
  }
  document.write(result);
}

function buildBannerArea(bannerArea) {
  var banners = bannerArea.banners;
  if (banners.length <= 0) {
    return "";
  }
  var rnd = Math.floor(Math.random() * banners.length);
  return buildBanner(banners[rnd]);
}

function buildBannerAreaForAll(bannerArea) {
  var banners = bannerArea.banners;
  var result = "";
  for (var i=0; i<banners.length; i++) {
    result += buildBanner(banners[i]);
  }
  return result;
}

function buildBanner(banner) {
  if (currentLang == "econ") {
	return doBuildBannerEcon(banner);
  } else {
	return doBuildBanner(banner);
  }
}

function doBuildBanner(banner) {
  var target = getTargetAttr(banner)
  var aTag = '<a href="' + banner.link + '" ' + target + '>';

  var result = "";
  result += '<div class="banner">';

  result += '<div class="img">';
  result += aTag;
  result += '<img src="' + banner.image + '" alt="" border="0" />';
  result += '</a>';
  result += '</div>';

  result += '<div class="lead">';
  result += aTag;
  result += banner.name;
  result += '</a>';
  result += '<br />';
  result += banner.description;
  result += '</div>';

  result += '</div>';

  return result;
}

function doBuildBannerEcon(banner) {

  var target = getTargetAttr(banner)
  var aTag = '<a href="' + banner.link + '" ' + target + '>';

  var result = "";
  result += '<div class="banner">';
  result += '<div class="img">';
  result += aTag;
  result += '<img src="' + banner.image + '" width="48" height="48" alt="" border="0" />';
  result += '</a>';
  result += '</div>';
  result += '<div class="lead">';
  result += '<p>';
  result += aTag + '<span class="title">' + banner.name + '</span><br />' + banner.description + '</a>';
  result += '</p>';
  result += '</div>';
  result += '</div>';
  return result;
}

function getTargetAttr(banner) {
  if (banner.openBlank == true) {
    return 'target="_blank"';
  } else {
    return "";
  }
}

String.prototype.startsWith = function(prefix) {
  if (prefix.length > this.length) return false;
  return prefix == this.substring(0, prefix.length);
}