// Copyright 2012 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

/* A little code to ease navigation of these documents.
 *
 * On window load we:
 *  + Generate a table of contents (generateTOC)
 *  + Bind foldable sections (bindToggles)
 *  + Bind links to foldable sections (bindToggleLinks)
 */

(function() {
  'use strict';

  var headerEl = document.querySelector('.js-header');
  var menuButtonEl = document.querySelector('.js-headerMenuButton');
  menuButtonEl.addEventListener('click', function(e) {
    e.preventDefault();
    headerEl.classList.toggle('is-active');
    menuButtonEl.setAttribute(
      'aria-expanded',
      headerEl.classList.contains('is-active')
    );
  });

  /* Generates a table of contents: looks for h2 and h3 elements and generates
   * links. "Decorates" the element with id=="nav" with this table of contents.
   */
  function generateTOC() {
    if ($('#manual-nav').length > 0) {
      return;
    }

    // For search, we send the toc precomputed from server-side.
    // TODO: Ideally, this should always be precomputed for all pages, but then
    // we need to do HTML parsing on the server-side.
    if (location.pathname === '/search') {
      return;
    }

    var nav = $('#nav');
    if (nav.length === 0) {
      return;
    }

    var toc_items = [];
    $(nav)
      .nextAll('h2, h3')
      .each(function() {
        var node = this;
        if (node.id == '') node.id = 'tmp_' + toc_items.length;
        var link = $('<a/>')
          .attr('href', '#' + node.id)
          .text($(node).text());
        var item;
        if ($(node).is('h2')) {
          item = $('<dt/>');
        } else {
          // h3
          item = $('<dd class="indent"/>');
        }
        item.append(link);
        toc_items.push(item);
      });
    if (toc_items.length <= 1) {
      return;
    }
    var dl1 = $('<dl/>');
    var dl2 = $('<dl/>');

    var split_index = toc_items.length / 2 + 1;
    if (split_index < 8) {
      split_index = toc_items.length;
    }
    for (var i = 0; i < split_index; i++) {
      dl1.append(toc_items[i]);
    }
    for (; /* keep using i */ i < toc_items.length; i++) {
      dl2.append(toc_items[i]);
    }

    var tocTable = $('<table class="unruled"/>').appendTo(nav);
    var tocBody = $('<tbody/>').appendTo(tocTable);
    var tocRow = $('<tr/>').appendTo(tocBody);

    // 1st column
    $('<td class="first"/>')
      .appendTo(tocRow)
      .append(dl1);
    // 2nd column
    $('<td/>')
      .appendTo(tocRow)
      .append(dl2);
  }

  function bindToggle(el) {
    $('.toggleButton', el).click(function() {
      if ($(this).closest('.toggle, .toggleVisible')[0] != el) {
        // Only trigger the closest toggle header.
        return;
      }

      if ($(el).is('.toggle')) {
        $(el)
          .addClass('toggleVisible')
          .removeClass('toggle');
      } else {
        $(el)
          .addClass('toggle')
          .removeClass('toggleVisible');
      }
    });
  }

  function bindToggles(selector) {
    $(selector).each(function(i, el) {
      bindToggle(el);
    });
  }

  function bindToggleLink(el, prefix) {
    $(el).click(function() {
      var href = $(el).attr('href');
      var i = href.indexOf('#' + prefix);
      if (i < 0) {
        return;
      }
      var id = '#' + prefix + href.slice(i + 1 + prefix.length);
      if ($(id).is('.toggle')) {
        $(id)
          .find('.toggleButton')
          .first()
          .click();
      }
    });
  }
  function bindToggleLinks(selector, prefix) {
    $(selector).each(function(i, el) {
      bindToggleLink(el, prefix);
    });
  }

  function setupInlinePlayground() {
    'use strict';
    // Set up playground when each element is toggled.
    $('div.play').each(function(i, el) {
      // Set up playground for this example.
      var setup = function() {
        var code = $('.code', el);
        playground({
          codeEl: code,
          outputEl: $('.output', el),
          runEl: $('.run', el),
          fmtEl: $('.fmt', el),
          shareEl: $('.share', el),
          shareRedirect: '//play.golang.org/p/',
        });

        // Make the code textarea resize to fit content.
        var resize = function() {
          code.height(0);
          var h = code[0].scrollHeight;
          code.height(h + 20); // minimize bouncing.
          code.closest('.input').height(h);
        };
        code.on('keydown', resize);
        code.on('keyup', resize);
        code.keyup(); // resize now.
      };

      // If example already visible, set up playground now.
      if ($(el).is(':visible')) {
        setup();
        return;
      }

      // Otherwise, set up playground when example is expanded.
      var built = false;
      $(el)
        .closest('.toggle')
        .click(function() {
          // Only set up once.
          if (!built) {
            setup();
            built = true;
          }
        });
    });
  }

  // fixFocus tries to put focus to #page so that keyboard navigation works.
  function fixFocus() {
    var page = $('#page');
    var topbar = $('div#topbar');
    page.css('outline', 0); // disable outline when focused
    page.attr('tabindex', -1); // and set tabindex so that it is focusable
    $(window)
      .resize(function(evt) {
        // only focus page when the topbar is at fixed position (that is, it's in
        // front of page, and keyboard event will go to the former by default.)
        // by focusing page, keyboard event will go to page so that up/down arrow,
        // space, etc. will work as expected.
        if (topbar.css('position') == 'fixed') page.focus();
      })
      .resize();
  }

  function toggleHash() {
    var id = window.location.hash.substring(1);
    // Open all of the toggles for a particular hash.
    var els = $(
      document.getElementById(id),
      $('a[name]').filter(function() {
        return $(this).attr('name') == id;
      })
    );

    while (els.length) {
      for (var i = 0; i < els.length; i++) {
        var el = $(els[i]);
        if (el.is('.toggle')) {
          el.find('.toggleButton')
            .first()
            .click();
        }
      }
      els = el.parent();
    }
  }

  function personalizeInstallInstructions() {
    var prefix = '?download=';
    var s = window.location.search;
    if (s.indexOf(prefix) != 0) {
      // No 'download' query string; detect "test" instructions from User Agent.
      if (navigator.platform.indexOf('Win') != -1) {
        $('.testUnix').hide();
        $('.testWindows').show();
      } else {
        $('.testUnix').show();
        $('.testWindows').hide();
      }
      return;
    }

    var filename = s.substr(prefix.length);
    var filenameRE = /^go1\.\d+(\.\d+)?([a-z0-9]+)?\.([a-z0-9]+)(-[a-z0-9]+)?(-osx10\.[68])?\.([a-z.]+)$/;
    var m = filenameRE.exec(filename);
    if (!m) {
      // Can't interpret file name; bail.
      return;
    }
    $('.downloadFilename').text(filename);
    $('.hideFromDownload').hide();

    var os = m[3];
    var ext = m[6];
    if (ext != 'tar.gz') {
      $('#tarballInstructions').hide();
    }
    if (os != 'darwin' || ext != 'pkg') {
      $('#darwinPackageInstructions').hide();
    }
    if (os != 'windows') {
      $('#windowsInstructions').hide();
      $('.testUnix').show();
      $('.testWindows').hide();
    } else {
      if (ext != 'msi') {
        $('#windowsInstallerInstructions').hide();
      }
      if (ext != 'zip') {
        $('#windowsZipInstructions').hide();
      }
      $('.testUnix').hide();
      $('.testWindows').show();
    }

    var download = '/dl/' + filename;

    var message = $(
      '<p class="downloading">' +
        'Your download should begin shortly. ' +
        'If it does not, click <a>this link</a>.</p>'
    );
    message.find('a').attr('href', download);
    message.insertAfter('#nav');

    window.location = download;
  }

  function updateVersionTags() {
    var v = window.goVersion;
    if (/^go[0-9.]+$/.test(v)) {
      $('.versionTag')
        .empty()
        .text(v);
      $('.whereTag').hide();
    }
  }

  function addPermalinks() {
    function addPermalink(source, parent) {
      var id = source.attr('id');
      if (id == '' || id.indexOf('tmp_') === 0) {
        // Auto-generated permalink.
        return;
      }
      if (parent.find('> .permalink').length) {
        // Already attached.
        return;
      }
      parent
        .append(' ')
        .append($("<a class='permalink'>&#xb6;</a>").attr('href', '#' + id));
    }

    $('#page .container')
      .find('h2[id], h3[id]')
      .each(function() {
        var el = $(this);
        addPermalink(el, el);
      });

    $('#page .container')
      .find('dl[id]')
      .each(function() {
        var el = $(this);
        // Add the anchor to the "dt" element.
        addPermalink(el, el.find('> dt').first());
      });
  }

  $('.js-expandAll').click(function() {
    if ($(this).hasClass('collapsed')) {
      toggleExamples('toggle');
      $(this).text('(Collapse All)');
    } else {
      toggleExamples('toggleVisible');
      $(this).text('(Expand All)');
    }
    $(this).toggleClass('collapsed');
  });

  function toggleExamples(className) {
    // We need to explicitly iterate through divs starting with "example_"
    // to avoid toggling Overview and Index collapsibles.
    $("[id^='example_']").each(function() {
      // Check for state and click it only if required.
      if ($(this).hasClass(className)) {
        $(this)
          .find('.toggleButton')
          .first()
          .click();
      }
    });
  }

  $(document).ready(function() {
    generateTOC();
    addPermalinks();
    bindToggles('.toggle');
    bindToggles('.toggleVisible');
    bindToggleLinks('.exampleLink', 'example_');
    bindToggleLinks('.overviewLink', '');
    bindToggleLinks('.examplesLink', '');
    bindToggleLinks('.indexLink', '');
    setupInlinePlayground();
    fixFocus();
    toggleHash();
    personalizeInstallInstructions();
    updateVersionTags();

    // site.html defines window.initFuncs in the <head> tag, and root.html and
    // codewalk.js push their on-page-ready functions to the list.
    // We execute those functions here, to avoid loading jQuery until the page
    // content is loaded.
    for (var i = 0; i < window.initFuncs.length; i++) window.initFuncs[i]();
  });
})();