=head1 NAME

GvaScript.Grid - ChoiceList based Grid with Pagination

=head1 SYNOPSIS

  var my_url  = "/app/path/to/data/list";
  var grid_id = "my_unique_grid_id";
  
  var my_grid = new GvaScript.Grid(grid_id, my_url, {
        css: 'grid-class-name',
        grid_container: 'grid_will_display_here',
        toolbar_container: 'grid_toolbar_will_display_here',
        dto: {VUE: 'JSON'},
        columns: [
            {label: 'Full Name', value: function(e) { 
                return e.lname.toUpperCase() + ' ' + e.name;
            }},
            {label: 'Gender', value: 'gender', css: 'tcenter', default_value: 'unknown'}
        ],
        actions: [
            {
                label: 'Add', 
                condition: function() {return this.rights.can_create},
                callback: function()  {alert('Add action has been called')}
            }
        ],
        grabfocus: true,
        onShow: function() {
        
        },
        onEmpty: function() {
            $('grid_will_display_here').update('empty list was retrieved');
        },        
        onPing: function(target) {
            alert('record:\n'+$H(target).inspect() + '\nin grid has been pinged!')}
        }, 
        onCancel: function() {alert('ESC pressed')}
    });

=head1 DEPENDENCIES

This class depends on the following GvaScript classes:

=over 12

=item GvaScript.ChoiceList

=item GvaScript.Paginator

=item GvaScript.CustomButtons

=back

=head1 DESTRUCTOR 

  my_grid.destroy();

This method will unregister the Grid in the GvaScript.Grids namespace and 
will iteratively call the destructor on all the grid's depedencies
this removing all handlers attached.
Call this method when the grid is removed
from the DOM.

=head1 DESCRIPTION

Displays a dataset in a grid format.  
Dataset is bound to a JSON datasource retrieved via an AJAX request.  

JSON object has a predefined format that the Grid class understands and renders.

A Grid is made up of two components:

=over

=item Grid Result

The grid (table) that would be the container to display the result dataset.
Result is displayed with the help of C<GvaScript.ChoiceList>.

=item Grid Toolbar

The grid's toolbar that would be the container to display grid's actions and pagination links.
Toolbar is displayed with the help of C<GvaScript.CustomButtons> and C<GvaScript.Paginator>

=back

=head2 GvaScript.Grids 

interface that provides one useful method:

=head3 GvaScript.Grids.get(id)

finds and returns the Grid instance where id is the unique id of the grid. 

=head1 BEHAVIOUR

Grid's display is based on a C<GvaScript.ChoiceList> object and thus has the behaviour of that of a choice list.

=head2 Grid Navigation Behaviour

=over 

=item C<DOWN> / C<UP> 

navigate by recordCustomButtons

=item C<HOME> / C<END> 

start/end of current page
CustomButtons
=item C<RETURN> 

fires onPing event handler

=item C<ESC> 

fires onCancel event handler

=item C<PAGEUP / LEFT> and C<PAGEDOWN / RIGHT> 

navigate by page

=item C<[Ctrl-HOME]> and C<[Ctrl-END]> 

navigate to first and last page correspondingly.

=back

=head1 JSON Datasource

As mentioned before, the Grid expects the JSON datasource object to be of a predefined format.

  json = {
    'liste'  : [
        {'fname': 'John',    'lname': 'Stiles', 'gender': 'm'},
        {'fname': 'Mary',    'lname': 'Major',  'gender': 'f'},
        {'fname': 'Richard', 'lname': 'Miles',  'gender': 'm'}
    ], 
    'total'  : 15,
    'rights' : {
        can_create : 0,
        can_update : 1,
        can_delete : 0
    }
  };

=over

=item liste I<(Array)>

array of records.

mandatory.

=item total I<(numeric)>

total number of records that are being paginated.

mandatory.

=item rights I<(JSON Object)>

object containing the access rights to the records in the list. Rights values should be boolean expressions.
this object will be stored and referenced later via C<grid.rights> for grid actions conditions.

=back

=head1 CONSTRUCTOR

  var grid = new GvaScript.Grid(id, url, options);

=head2 id

A unique id to identify a Grid.  Might be later used in C<GvaScript.Grids.get(id)> to retrieve the grid instance.

=head2 url

Url for AJAX request to retrieve current page dataset.

=head2 options

=over

=item css I<(String)>

A string value of space seperated list of class names to be applied to the table element.

optional - defaulted to ''

=item dto I<(JSON Object)>

Data transfer Object to the AJAX request. C<Ex: {param1: 'value1', param2: 'value2'}>

optional - defaulted to C<{VUE: 'JSON'}>

=item method I<(String)>

HTTP method to open in the AJAX request.

optional - defaulted to C<'post'>

=item columns I<(Array)>

Array of objects that defines the grid columns. 

Ex column object: 

    {
        label: 'Gender',  
        value: 'gender', 
        css: 'tcenter', 
        default_value: 'unknown'
    }


=over 

=item label I<(string)>

column label. can be an empty string

mandatory.

=item value I<(string|Function)>

string representing the key of the json element that the column is bound to.

Function that takes the records as an argument and returns string value of the column.
Ex: C<value: function(e) {return e.fname + ' ' + e.lname}>

mandatory.

=item default_value I<(string)>

string value representing the column's default value if no value was found in the JSON datasource.

optional.

=item css I<(string|Array)>

a single css class or and array of css classes to be given to the column header/cells.

optional.

=back 

=item actions I<(Array)>

Array that defines the grids list of actions (to be rendered in the grid's tool bar).

Action object here is identical to GvaScript.CustomButtons.Button.options

=item grabfocus I<(boolean)>

boolean indicating whether the grid container is to grab focus right after the grid has been initialized.

optional - defaulted to C<true>

=item pagesize I<(numeric|'auto')>

a numeric specifying number of records to show on a page. To keep this number variable and dependant on grid's container available space, set it to 'auto'.

optional - defaulted to C<'auto'>

=item gridheight I<(numeric|'auto')>

height to set to the grid. To keep this number variable and dependant on the grid's container available space, set it to 'auto'.

optional - defaulted to C<'auto'>

=item recordheight I<(numeric)>

height to set to the grid record.

optional - defaulted to C<21>

=item requestTimeout I<(numeric)>

time in seconds to wait before aborting the AJAX request.

optional - defaulted to 15

=item errorMsg I<(string)>

message to display in the grid container area when the request times out.

optional - defaulted to "Problème de connexion. Réessayer et si le problème persiste, contacter un administrateur.".

=back

=head1 PROPERTIES

Here's a list of useful properties of the Grid Object.

=head2 grid_container

  grid.grid_container

C<HTMLElement> container of the grid list 

=head2 toolbar_container

  grid.toolbar_container

C<HTMLElement> container of the toolbar (pagination links + action buttons)

=head2 paginatorbar_container

  grid.paginatorbar_container 

C<HTMLElement> container of the pagination links

=head2 actionsbar_container

 grid.actionsbar_container 

C<HTMLElement> container of the action buttons

=head1 METHODS

=head2 clearResult

  grid.clearResult(msg)

This method clears the grid result container and displays C<msg> instead.

=head2 clearToolbar

  grid.clearToolbar()

This methods clears the grid toolbar container.

=head2 clearActionButtons

  grid.clearActionButtons()

This method clears the action buttons container and thus removes the buttons

=head2 clear

  grid.clear(msg)

This method is equivalent to C<grid.clearResult(msg)> and C<grid.clearToolbar()>

=head2 addActionButtons

  grid.addActionButtons()

This method renders the action buttons based on the grids actions. 
NOTE that the actions conditions will be re-evaluated.

=head1 EVENTS

=head2 onShow

This event is triggered of the table is rendered and displayed.
Useful for attaching custom events on table records/cells.

=head2 onHighlight

This event is triggered when a choice in the list is highlighted.
The event handler may use C<event.index> to know the index of the
highlighted choice.

=head2 onPing

This event is triggered when a choice in the list is "ping-ed", i.e.
either by dblclicking, clicking on selected row or by pressing the C<RETURN> key.
The event handler will recieve 1 arguement C<target> which is the record object that has been "Pinged".

Ex: C<{'fname': 'Mary', 'lname': 'Major', 'gender': 'f'}>

=head2 onCancel

This event is triggered when the user presses the C<ESCAPE> key.

=head2 onEmpty 

This event is triggered when the list is empty.

=head1 EXAMPLE

=head2 JAVASCRIPT

  var my_url  = "/app/path/to/data/list";
  var my_grid = new GvaScript.Grid("ex_grid", my_url, {
    grid_container: 'ex_grid_list',
    toolbar_container: 'ex_grid_toolbar',
    dto: {VUE: 'JSON'},
    pagesize: 3,
    columns: [
        {label: 'Full Name', value: function(e) { 
            return e.fname + ' ' + e.lname;
        }},
        {label: 'Gender', value: 'gender', css: 'tcenter', default_value: 'unknown'}
    ],
    actions: [
        {
            label: 'Add', 
            condition: function() {return this.rights.can_create},
            callback: function()  {alert('Add action has been called')}
        }
    ]
  });

  // my_url response : Content-type "application/json"
  {
    'liste'  : [
        {'fname': 'John',    'lname': 'Stiles', 'gender': 'm'},
        {'fname': 'Mary',    'lname': 'Major',  'gender': 'f'},
        {'fname': 'Richard', 'lname': 'Miles',  'gender': 'm'}
    ], 
    'total'  : 15,
    'rights' : {
        can_create : 0,
        can_update : 1,
        can_delete : 0
    }
  }

=head2 HTML

  <div id="ex_container">
     
   <div tabindex="0" id="ex_grid_list">
     <table class="dmweb-grid">
       <thead>
         <tr>
           <th class="grid-marker"> </th>
           <th class="grid-header">Full Name</th>
           <th class="grid-header">Gender</th>
        </tr>
       </thead>
       <tbody>
        <tr id="ex_grid_list.CL_choice.0" class="CL_choiceItem liste_highlight">
           <td class="grid-marker"> </td>
           <td valign="top" class="grid-cell index_0">John Stiles</td>
           <td valign="top" class="grid-cell index_0 tcenter">m</td>
        </tr>
        <tr id="ex_grid_list.CL_choice.1" class="CL_choiceItem">
           <td class="grid-marker"> </td>
           <td valign="top" class="grid-cell index_1">Mary Major</td>
           <td valign="top" class="grid-cell index_1 tcenter">f</td>
        </tr>
         <tr id="ex_grid_list.CL_choice.3" class="CL_choiceItem">
           <td class="grid-marker"> </td>
           <td valign="top" class="grid-cell index_0">Richard Miles</td>
           <td valign="top" class="grid-cell index_0 tcenter">m</td>
        </tr>
      </tbody>
    </table>
   </div>
  
   <div id="ex_grid_toolbar" class="dmweb-grid-toolbar">
    <div class="dmweb-paginatorbar">
      <div title="Dernière page" class="last"></div>
      <div title="Page suivante" class="forward"></div>
      <div class="text">1 à 3 de 15</div>
      <div title="Page précédente" class="back inactive"></div>
      <div title="Première page" class="first inactive"></div>
    </div>
    <div class="dmweb-grid-actionsbar">
      <span id="grid_id_btn_0" class="dmweb-btn-container">
        <span class="left"/>
        <span class="center">
          <button class="btn" style="width: auto;" type="button">Add</button>
        </span>
        <span class="right"/>
      </span>
    </div>
   </div>
 
  </div>

=head2 CSS

  /* class given to grid list container when an AJAX request is being affected */
  .dmweb-loading {
    background:url(ajax_loading.gif) no-repeat center center;
    position:absolute;
    width:30px;height:30px;
    top:50%;left:50%;
  }

  /* grid toolbar */
  .dmweb-grid-toolbar {
    background:#C5CCE8 url(glass-bg-n.gif) repeat-x scroll left top;
    border:1px solid #A3BAD9;
    height:28px;
  }
  .dmweb-grid-actionsbar {float:left;}
  .dmweb-paginatorbar {float:right;width:250px;}
  .dmweb-paginatorbar div {width:16px;height:16px;cursor:pointer;float:right;}
  .dmweb-paginatorbar div.first {background:url(page-first.gif) no-repeat top center;}
  .dmweb-paginatorbar div.last {background:url(page-last.gif) no-repeat top center;}
  .dmweb-paginatorbar div.back {background:url(page-prev.gif) no-repeat top center;}
  .dmweb-paginatorbar div.forward {background:url(page-next.gif) no-repeat top center;}
  .dmweb-paginatorbar div.inactive {cursor:default;opacity:0.25;filter:alpha(opacity=25);}
  .dmweb-paginatorbar div.text {text-align:center;width:140px;color:#4b34c5;font-size:10pt;}
  .dmweb-paginatorbar span.dmweb-btn-container {display:block;margin-right:4px;}
  
  /* grid table */
  .dmweb-grid {width:100%;}
  .dmweb-grid th.grid-header {
    text-align:center;
    padding:2px;
    font-size:75%;
    color: #183E6C;
    background-color: #D0D6ED;
    border:1px solid #6F82A5;
  }
  .dmweb-grid td {font-size:75%;color:#183E6C;}
  .dmweb-grid .grid-marker {width:15px;background-color: #D0D6ED;border:1px solid #6F82A5;}
  .dmweb-grid tr.liste_highlight td.grid-marker {
    background: #D0D6ED url(selector.gif) no-repeat center center;
  }
  .dmweb-grid tr.liste_highlight td.grid-cell {background-color: #6F82A5 !important;color:#f5f5f5 !important;}
  .dmweb-grid td.grid-cell {padding:2px !important;border:1px solid #e8e8e8;}
  .dmweb-grid td.grid-cell.index_1 {background-color:#EFEFEF;}
  .dmweb-grid td.grid-cell.center {text-align:center;float:none;}
  .dmweb-grid td.grid-cell.right {text-align:right;float:none;}
  .dmweb-grid td.grid-cell.red {color:red;}
