function getEbookPages(callback) {
    chrome.runtime.sendMessage({type: "get"}, function(response) {
       callback(response.allPages);
    });
}

function saveEbookPages(pages) {
    chrome.runtime.sendMessage({type: "set", pages: pages}, function(response) {});
}

function removeEbook() {
    chrome.runtime.sendMessage({type: "remove"}, function(response) {});
}

/////

function getCurrentUrl() {
    var url = window.location.href;
    if (url.indexOf('?') > 0) {
        url = window.location.href.split('?')[0];
    }
    url = url.substring(0, url.lastIndexOf('/')+1);
    return url;
}

function getOriginUrl() {
    var originUrl = window.location.origin;
    if (!originUrl) {
        originUrl = window.location.protocol + "//" + window.location.host;
    }
    return originUrl;
}

function getFileExtension(fileName) {
    var tmpFileName = fileName.split('.').pop();
    if (tmpFileName.indexOf('?') > 0) {
        tmpFileName = tmpFileName.split('?')[0];
    }
    if (tmpFileName.trim() === '') {
        return 'jpg'; //TODO
    }
    return tmpFileName;
}

function getHref(hrefTxt) {
    if (!hrefTxt) {
        return '';
    }
    if (hrefTxt.indexOf('#') === 0) {
        hrefTxt = window.location.href + hrefTxt;
    }
    if (hrefTxt.indexOf('/') === 0) {
        hrefTxt = window.location.protocol + '//' + window.location.hostname + hrefTxt;
    }
    // hrefTxt = escape(hrefTxt); // TODO
    return hrefTxt;
}

function getImgDownloadUrl(imgSrc) {
    var baseUrl = getOriginUrl();
    if (imgSrc.indexOf('//') === 0) {
        return baseUrl.split('//')[0] + imgSrc;
    }
    if (imgSrc.indexOf('http') !== 0) {
        if (imgSrc.indexOf('/') === 0) {
            return baseUrl + imgSrc;
        }
        return baseUrl + '/' + imgSrc;
    }
    return imgSrc;
}

/////////

function base64ArrayBuffer(arrayBuffer) {
  var base64    = '';
  var encodings = 'ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/';

  var bytes         = new Uint8Array(arrayBuffer);
  var byteLength    = bytes.byteLength;
  var byteRemainder = byteLength % 3;
  var mainLength    = byteLength - byteRemainder;

  var a, b, c, d;
  var chunk;

  // Main loop deals with bytes in chunks of 3
  for (var i = 0; i < mainLength; i = i + 3) {
    // Combine the three bytes into a single integer
    chunk = (bytes[i] << 16) | (bytes[i + 1] << 8) | bytes[i + 2];

    // Use bitmasks to extract 6-bit segments from the triplet
    a = (chunk & 16515072) >> 18; // 16515072 = (2^6 - 1) << 18
    b = (chunk & 258048)   >> 12; // 258048   = (2^6 - 1) << 12
    c = (chunk & 4032)     >>  6; // 4032     = (2^6 - 1) << 6
    d = chunk & 63;               // 63       = 2^6 - 1

    // Convert the raw binary segments to the appropriate ASCII encoding
    base64 += encodings[a] + encodings[b] + encodings[c] + encodings[d];
  }

  // Deal with the remaining bytes and padding
  if (byteRemainder == 1) {
    chunk = bytes[mainLength];

    a = (chunk & 252) >> 2; // 252 = (2^6 - 1) << 2

    // Set the 4 least significant bits to zero
    b = (chunk & 3)   << 4; // 3   = 2^2 - 1

    base64 += encodings[a] + encodings[b] + '==';
  } else if (byteRemainder == 2) {
    chunk = (bytes[mainLength] << 8) | bytes[mainLength + 1];

    a = (chunk & 64512) >> 10; // 64512 = (2^6 - 1) << 10
    b = (chunk & 1008)  >>  4; // 1008  = (2^6 - 1) << 4

    // Set the 2 least significant bits to zero
    c = (chunk & 15)    <<  2; // 15    = 2^4 - 1

    base64 += encodings[a] + encodings[b] + encodings[c] + '=';
  }

  return base64;
}