// Enable expanding/folding folders in TracBrowser

var FOLDERID_COUNTER = 0;
var SUBFOLDER_INDENT = 20;

// enableExpandDir adds the capability to folder rows to be expanded and folded
// It also teach the rows about their ancestors. It expects:
//  - `parent_tr`, the logical parent row (`null` if there's no ancestor)
//  - a `rows` jQuery object matching the newly created entry rows
//  - `qargs`, additional parameters to send to the server when expanding

function enableExpandDir(parent_tr, rows, qargs) {
  // the ancestors folder ids are present in the parent_tr class attribute
  var ancestor_folderids = [];
  if (parent_tr)
    ancestor_folderids = $.grep(parent_tr.attr("class").split(" "), 
                                function(c) { return c.match(/^f\d+$/)});
  rows.each(function () {
    var a = $(this).find("a.dir");

    if (a.length) { // then the entry is a folder
      // create new folder id
      var folderid = "f" + FOLDERID_COUNTER++;
      this.id = folderid;
      $(this).addClass(folderid);

      // add the expander icon
      a.wrap('<div></div>');
      var expander = a.before('<span class="expander">&#x200b;</span>').prev();
      expander.attr("title", "Expand sub-directory in place")
        .click(function() { toggleDir($(this), qargs); });
    }

    // tie that row to ancestor folders
    if (parent_tr)
      $(this).addClass(ancestor_folderids.join(" "));
  });
}

// handler for click event on the expander icons
function toggleDir(expander, qargs) {
  var tr = expander.parents("tr");
  var folderid = tr.get(0).id;

  if ( tr.filter(".expanded").length ) { // then *fold*
    tr.removeClass("expanded").addClass("collapsed");
    tr.siblings("tr."+folderid).hide();
    expander.attr("title", "Re-expand directory");
    return;
  }

  if ( tr.filter(".collapsed").length ) { // then *expand*
    tr.removeClass("collapsed").addClass("expanded");
    tr.siblings("tr."+folderid).show();
    // Note that the above will show all the already fetched subtree,
    // so we have to fold again the folders which were already collapsed.
    tr.siblings("tr.collapsed").each(function() {
      tr.siblings("tr."+this.id).not(this).hide();
    });
  } else {                                // then *fetch*
    var td = expander.parents("td");
    var td_class = td.attr("class");
    var a = expander.next("a");
    var depth = 
      parseFloat(td.css("padding-left").replace(/^(\d*\.\d*).*$/, "$1")) + 
      SUBFOLDER_INDENT;

    tr.addClass("expanded");
    // insert "Loading ..." row
    tr.after('<tr><td><span class="loading"></span></td></tr>');
    var loading_row = tr.next();
    loading_row.children("td").addClass(td_class)
      .attr("colspan", tr.children("td").length)
      .css("padding-left", depth);
    loading_row.find("span.loading").text("Loading " + a.text() + "...");

    // XHR for getting the rows corresponding to the folder entries
    $.ajax({
      type: "GET",
      url: a.attr("href"),
      data: qargs,
      dataType: "html",
      success: function(data) {
        var rows = $(data.replace(/^<!DOCTYPE[^>]+>/, "")).filter("tr");
        if (rows.length) {
          // insert entry rows 
          rows.children("td."+td_class).css("padding-left", depth);
          // make all entry rows collapsible but only subdir rows expandable
          enableExpandDir(tr, rows, qargs); 
          tr.after(rows);
          // remove "Loading ..." row
          loading_row.remove();
        } else {
          loading_row.find("span.loading").text("").append("<i>(empty)</i>")
            .removeClass("loading");
          // make the (empty) row collapsible
          enableExpandDir(tr, loading_row, qargs); 
        }
      },
      error: function(req, err, exc) {
        loading_row.find("span.loading").text("").append("<i>(error)</i>")
          .removeClass("loading");
        enableExpandDir(tr, loading_row, qargs);
      }
    });
  }
  expander.attr("title", "Fold directory");
}