(function() {
  const LANG_EXT_MAP = {
    actionscript:['actionscript', 'as'],
    apache:      ['httpd', 'conf', 'htaccess'],
    asciidoc:    ['asciidoc'],
    applescript: ['applescript'],
    aspectj:     ['aspectj', 'aj'],
    avrasm:      ['asm', 's'],
    bash:        ['sh', 'bash', 'zsh', 'shell'],
    brainfuck:   ['bf'],
    clojure:     ['clj'],
    coffeescript:['coffee'],
    cpp:         ['c', 'h', 'cc', 'cpp', 'cxx', 'c++', 'hpp', 'hxx', 'h++'],
    cs:          ['cs'],
    css:         ['css'],
    d:           ['d', 'dd', 'di'],
    dart:        ['dart'],
    delphi:      ['pas'],
    desktop:     ['desktop'],
    diff:        ['diff', 'patch'],
    dockerfile:  ['dockerfile'],
    dos:         ['bat', 'cmd'],
    elixir:      ['ex', 'exs'],
    erlang:      ['erl', 'erlang'],
    fortran:     ['f', 'for', 'f90', 'f95'],
    fsharp:      ['fs'],
    gherkin:     ['feature'],
    go:          ['go'],
    gradle:      ['gradle'],
    groovy:      ['groovy', 'gvy', 'gy', 'gsh'],
    haml:        ['haml'],
    handlebars:  ['hbs', 'handlebars'],
    haskell:     ['hs'],
    haxe:        ['hx', 'hxml'],
    http:        ['http'],
    ini:         ['ini'],
    java:        ['java', 'class', 'fx'],
    javascript:  ['js'],
    json:        ['json'],
    julia:       ['jl'],
    kotlin:      ['kt', 'kts'],
    less:        ['less'],
    lisp:        ['lsp', 'lisp', 'cl', 'el', 'scm'],
    livescript:  ['ls'],
    lua:         ['lua'],
    makefile:    ['Makefile'],
    markdown:    ['md', 'markdown'],
    nginx:       ['nginx'],
    objectivec:  ['m', 'mm'],
    ocaml:       ['ml'],
    perl:        ['pl', 'pm', 'perl'],
    php:         ['php', 'phtml', 'phps'],
    pig:         ['pig'],
    powershell:  ['ps1', 'psm1'],
    python:      ['py', 'pyc'],
    r:           ['r'],
    ruby:        ['rakefile', 'gemfile', 'rb'],
    scala:       ['scala', 'scl', 'sca', 'scb'],
    scss:        ['scss', 'sass'],
    smalltalk:   ['st', 'sm', 'sll'],
    sml:         ['sml'],
    sql:         ['sql'],
    stylus:      ['styl'],
    swift:       ['swift'],
    tex:         ['tex'],
    typescript:  ['ts'],
    vala:        ['vala', 'vapi'],
    vbnet:       ['vb'],
    vbscript:    ['vbs'],
    vhdl:        ['vhd', 'vhdl'],
    xml:         ['atom', 'rss', 'vsproj', 'csproj', 'build', 'wsdl', 'config', 'xsd', 'plist', 'xib'],
    yaml:        ['yaml']
  };

  const BROWSER_CONTENT = ['htm', 'html', 'xml', 'xhtml', 'shtml'];

  const OPTIONS_DEFAULTS = {
    theme: 'sunburst',
    font: 'Inconsolata',
    fontSize: 'medium',
    lineNumbers: true
  };

  const OPTIONS = Object.keys(OPTIONS_DEFAULTS);

  OPTIONS.forEach(function(option) {
    var value = localStorage.getItem(option) || OPTIONS_DEFAULTS[option];
    localStorage.setItem(option, value);
  });

  // Reverse index
  const EXT_LANG_MAP = {};
  for (var lang in LANG_EXT_MAP) {
    LANG_EXT_MAP[lang].forEach(function(ext) {
      EXT_LANG_MAP[ext] = lang;
    });
  }

  function getHeaderByName(headers, name) {
    var index, length = headers.length;
    for (index = 0; index < length; index++) {
      if (headers[index].name.toLowerCase() === name) {
        return headers[index].value;
      }
    }
    return null;
  }

  function getContentTypeFromHeaders(headers) {
    var contentType = getHeaderByName(headers, 'content-type');
    if (!contentType) {
      return null;
    }
    return contentType.split(';').shift().split('/').pop().trim();
  }

  function getFilenameFromUrl(url) {
    return url.split('/').pop().split('?').shift().toLowerCase();
  }

  function getExtensionFromFilename(filename) {
    return filename.split('.').pop();
  }

  function getFragmentFromUrl(url) {
    var fragment = /#ft=(\w+)/.exec(url);
    return fragment && fragment[1];
  }

  function detectLanguage(contentType, fragment, filename, extension) {
    if (BROWSER_CONTENT.indexOf(contentType) != -1) {
      return null;
    }
    return !!LANG_EXT_MAP[fragment] ?  fragment : EXT_LANG_MAP[contentType] ||
                                                  EXT_LANG_MAP[extension]   ||
                                                  EXT_LANG_MAP[filename];
  }

  function getHighlightingCode(font, fontSize, lineNumbers, language) {
    return 'document.body.style.fontFamily = "' + font + '";' +
      'document.body.style.fontSize = "' + fontSize + '";' +
      'var container = document.querySelector("pre");' +
      'container.classList.add("' + language + '");' +
      'hljs.configure({ lineNumbers: ' + lineNumbers + ' });' +
      'hljs.highlightBlock(container);' +
      'document.body.style.backgroundColor = getComputedStyle(container).backgroundColor;';
  }

  const JS_BEUTIFY_CODE =
    'var container = document.querySelector("pre");' +
    'var options = { indent_size: 2 };' +
    'container.textContent = js_beautify(container.textContent, options);';

  chrome.webRequest.onCompleted.addListener(function(details) {
    var contentType = getContentTypeFromHeaders(details.responseHeaders);
    var fragment = getFragmentFromUrl(details.url);
    var filename = getFilenameFromUrl(details.url);
    var extension = getExtensionFromFilename(filename);
    var language = detectLanguage(contentType, fragment, filename, extension);
    if (!language) {
      return;
    }

    var styles  = [
      { file: 'css/reset.css' },
      { file: 'css/main.css' },
      { file: 'css/' + localStorage.getItem('theme') + '.css' }
    ];

    var scripts = [
      { file: 'js/lib/highlight.js' },
      { file: 'js/languages/' + language + '.js' }
    ];

    if (/json/.test(language)) {
      scripts.push(
        { file: 'js/lib/beautify.js' },
        { code: JS_BEUTIFY_CODE }
      );
    }

    scripts.push({
      code: getHighlightingCode.apply(this, ['font', 'fontSize', 'lineNumbers'].
        map(localStorage.getItem.bind(localStorage)).concat(language))
    });

    for (var i = 0; i < styles.length; i++) {
      chrome.tabs.insertCSS(details.tabId, styles[i]);
    }

    (function chain(i) {
      if (i == scripts.length) { return; }
      chrome.tabs.executeScript(details.tabId, scripts[i], chain.bind(null, i+1));
    }(0))
  }, { urls: ['<all_urls>'], types: ['main_frame'] }, ['responseHeaders']);
}());