/**
 * @class Ext.data.DataWriter
 *

Ext.data.DataWriter facilitates create, update, and destroy actions between
 * an Ext.data.Store and a server-side framework. A Writer enabled Store will
 * automatically manage the Ajax requests to perform CRUD actions on a Store.


 *

Ext.data.DataWriter is an abstract base class which is intended to be extended
 * and should not be created directly. For existing implementations, see
 * {@link Ext.data.JsonWriter}.


 *

Creating a writer is simple:


 *

var writer = new Ext.data.JsonWriter();
 *

 *

The proxy for a writer enabled store can be configured with a simple url:


 *

// Create a standard HttpProxy instance.
var proxy = new Ext.data.HttpProxy({
    url: 'app.php/users'
});
 *

 *

For finer grained control, the proxy may also be configured with an api:


 *

// Use the api specification
var proxy = new Ext.data.HttpProxy({
    api: {
        read    : 'app.php/users/read',
        create  : 'app.php/users/create',
        update  : 'app.php/users/update',
        destroy : 'app.php/users/destroy'
    }
});
 *

 *

Creating a Writer enabled store:


 *

var store = new Ext.data.Store({
    proxy: proxy,
    reader: reader,
    writer: writer
});
 *

 * @constructor Create a new DataWriter
 * @param {Object} meta Metadata configuration options (implementation-specific)
 * @param {Object} recordType Either an Array of field definition objects as specified
 * in {@link Ext.data.Record#create}, or an {@link Ext.data.Record} object created
 * using {@link Ext.data.Record#create}.
 */

Ext.data.DataWriter = function(config){
   
/**
     * This DataWriter's configured metadata as passed to the constructor.
     * @type Mixed
     * @property meta
     */

   
Ext.apply(this, config);
};

Ext.data.DataWriter.prototype = {

   
/**
     * @cfg {Boolean} writeAllFields
     *
false by default.  Set true to have DataWriter return ALL fields of a modified
     * record -- not just those that changed.
     *
false to have DataWriter only request modified fields from a record.
     */

    writeAllFields
: false,
   
/**
     * @cfg {Boolean} listful
     *
false by default.  Set true to have the DataWriter always write HTTP params as a list,
     * even when acting upon a single record.
     */

    listful
: false,    // <-- listful is actually not used internally here in DataWriter.  @see Ext.data.Store#execute.

   
/**
     * Writes data in preparation for server-write action.  Simply proxies to DataWriter#update, DataWriter#create
     * DataWriter#destroy.
     * @param {String} action [CREATE|UPDATE|DESTROY]
     * @param {Object} params The params-hash to write-to
     * @param {Record/Record[]} rs The recordset write.
     */

    write
: function(action, params, rs) {
       
this.render(action, rs, params, this[action](rs));
   
},

   
/**
     * abstract method meant to be overridden by all DataWriter extensions.  It's the extension's job to apply the "data" to the "params".
     * The data-object provided to render is populated with data according to the meta-info defined in the user's DataReader config,
     * @param {String} action [Ext.data.Api.actions.create|read|update|destroy]
     * @param {Record[]} rs Store recordset
     * @param {Object} params Http params to be sent to server.
     * @param {Object} data object populated according to DataReader meta-data.
     */

    render
: Ext.emptyFn,

   
/**
     * update
     * @param {Object} p Params-hash to apply result to.
     * @param {Record/Record[]} rs Record(s) to write
     * @private
     */

    update
: function(rs) {
       
var params = {};
       
if (Ext.isArray(rs)) {
           
var data = [],
                ids
= [];
           
Ext.each(rs, function(val){
                ids
.push(val.id);
                data
.push(this.updateRecord(val));
           
}, this);
            params
[this.meta.idProperty] = ids;
            params
[this.meta.root] = data;
       
}
       
else if (rs instanceof Ext.data.Record) {
           
//params[this.meta.idProperty] = rs.id; // <-- removed, un-neccessary.
            params
[this.meta.root] = this.updateRecord(rs);
       
}
       
return params;
   
},

   
/**
     * @cfg {Function} saveRecord Abstract method that should be implemented in all subclasses
     * (e.g.: {@link Ext.data.JsonWriter#saveRecord JsonWriter.saveRecord}
     */

    updateRecord
: Ext.emptyFn,

   
/**
     * create
     * @param {Object} p Params-hash to apply result to.
     * @param {Record/Record[]} rs Record(s) to write
     * @private
     */

    create
: function(rs) {
       
var params = {};
       
if (Ext.isArray(rs)) {
           
var data = [];
           
Ext.each(rs, function(val){
                data
.push(this.createRecord(val));
           
}, this);
            params
[this.meta.root] = data;
       
}
       
else if (rs instanceof Ext.data.Record) {
            params
[this.meta.root] = this.createRecord(rs);
       
}
       
return params;
   
},

   
/**
     * @cfg {Function} createRecord Abstract method that should be implemented in all subclasses
     * (e.g.: {@link Ext.data.JsonWriter#createRecord JsonWriter.createRecord})
     */

    createRecord
: Ext.emptyFn,

   
/**
     * destroy
     * @param {Object} p Params-hash to apply result to.
     * @param {Record/Record[]} rs Record(s) to write
     * @private
     */

    destroy
: function(rs) {
       
var params = {};
       
if (Ext.isArray(rs)) {
           
var data = [],
                ids
= [];
           
Ext.each(rs, function(val){
                data
.push(this.destroyRecord(val));
           
}, this);
            params
[this.meta.root] = data;
       
} else if (rs instanceof Ext.data.Record) {
            params
[this.meta.root] = this.destroyRecord(rs);
       
}
       
return params;
   
},

   
/**
     * @cfg {Function} destroyRecord Abstract method that should be implemented in all subclasses
     * (e.g.: {@link Ext.data.JsonWriter#destroyRecord JsonWriter.destroyRecord})
     */

    destroyRecord
: Ext.emptyFn,

   
/**
     * Converts a Record to a hash
     * @param {Record}
     * @private
     */

    toHash
: function(rec) {
       
var map = rec.fields.map,
            data
= {},
            raw
= (this.writeAllFields === false && rec.phantom === false) ? rec.getChanges() : rec.data,
            m
;
       
Ext.iterate(raw, function(prop, value){
           
if((m = map[prop])){
                data
[m.mapping ? m.mapping : m.name] = value;
           
}
       
});
        data
[this.meta.idProperty] = rec.id;
       
return data;
   
}
};