/**
 * @author Ed Spencer
 *
 * Represents a single read or write operation performed by a {@link Ext.data.proxy.Proxy Proxy}. Operation objects are
 * used to enable communication between Stores and Proxies. Application developers should rarely need to interact with
 * Operation objects directly.
 *
 * Several Operations can be batched together in a {@link Ext.data.Batch batch}.
 */
Ext.define('Ext.data.Operation', {
    /**
     * @cfg {Boolean} synchronous
     * True if this Operation is to be executed synchronously. This property is inspected by a
     * {@link Ext.data.Batch Batch} to see if a series of Operations can be executed in parallel or not.
     */
    synchronous: true,

    /**
     * @cfg {String} action
     * The action being performed by this Operation. Should be one of 'create', 'read', 'update' or 'destroy'.
     */
    action: undefined,

    /**
     * @cfg {Ext.util.Filter[]} filters
     * Optional array of filter objects. Only applies to 'read' actions.
     */
    filters: undefined,

    /**
     * @cfg {Ext.util.Sorter[]} sorters
     * Optional array of sorter objects. Only applies to 'read' actions.
     */
    sorters: undefined,

    /**
     * @cfg {Ext.util.Grouper[]} groupers
     * Optional grouping configuration. Only applies to 'read' actions where grouping is desired.
     */
    groupers: undefined,

    /**
     * @cfg {Number} start
     * The start index (offset), used in paging when running a 'read' action.
     */
    start: undefined,

    /**
     * @cfg {Number} limit
     * The number of records to load. Used on 'read' actions when paging is being used.
     */
    limit: undefined,

    /**
     * @cfg {Ext.data.Batch} batch
     * The batch that this Operation is a part of.
     */
    batch: undefined,
    
    /**
     * @cfg {Object} params
     * Parameters to pass along with the request when performing the operation.
     */

    /**
     * @cfg {Function} callback
     * Function to execute when operation completed.
     * @cfg {Ext.data.Model[]} callback.records Array of records.
     * @cfg {Ext.data.Operation} callback.operation The Operation itself.
     * @cfg {Boolean} callback.success True when operation completed successfully.
     */
    callback: undefined,

    /**
     * @cfg {Object} scope
     * Scope for the {@link #callback} function.
     */
    scope: undefined,

    /**
     * @property {Boolean} started
     * The start status of this Operation. Use {@link #isStarted}.
     * @readonly
     * @private
     */
    started: false,

    /**
     * @property {Boolean} running
     * The run status of this Operation. Use {@link #isRunning}.
     * @readonly
     * @private
     */
    running: false,

    /**
     * @property {Boolean} complete
     * The completion status of this Operation. Use {@link #isComplete}.
     * @readonly
     * @private
     */
    complete: false,

    /**
     * @property {Boolean} success
     * Whether the Operation was successful or not. This starts as undefined and is set to true
     * or false by the Proxy that is executing the Operation. It is also set to false by {@link #setException}. Use
     * {@link #wasSuccessful} to query success status.
     * @readonly
     * @private
     */
    success: undefined,

    /**
     * @property {Boolean} exception
     * The exception status of this Operation. Use {@link #hasException} and see {@link #getError}.
     * @readonly
     * @private
     */
    exception: false,

    /**
     * @property {String/Object} error
     * The error object passed when {@link #setException} was called. This could be any object or primitive.
     * @private
     */
    error: undefined,

    /**
     * @property {RegExp} actionCommitRecordsRe
     * The RegExp used to categorize actions that require record commits.
     */
    actionCommitRecordsRe: /^(?:create|update)$/i,

    /**
     * @property {RegExp} actionSkipSyncRe
     * The RegExp used to categorize actions that skip local record synchronization. This defaults
     * to match 'destroy'.
     */
    actionSkipSyncRe: /^destroy$/i,

    /**
     * Creates new Operation object.
     * @param {Object} config (optional) Config object.
     */
    constructor: function(config) {
        Ext.apply(this, config || {});
    },

    /**
     * This method is called to commit data to this instance's records given the records in
     * the server response. This is followed by calling {@link Ext.data.Model#commit} on all
     * those records (for 'create' and 'update' actions).
     *
     * If this {@link #action} is 'destroy', any server records are ignored and the
     * {@link Ext.data.Model#commit} method is not called.
     *
     * @param {Ext.data.Model[]} serverRecords An array of {@link Ext.data.Model} objects returned by
     * the server.
     * @markdown
     */
    commitRecords: function (serverRecords) {
        var me = this,
            mc, index, clientRecords, serverRec, clientRec, i, len;

        if (!me.actionSkipSyncRe.test(me.action)) {
            clientRecords = me.records;

            if (clientRecords && clientRecords.length) {
                if (clientRecords.length > 1) {
                    // If this operation has multiple records, client records need to be matched up with server records
                    // so that any data returned from the server can be updated in the client records. If we don't have
                    // a clientIdProperty specified on the model and we've done a create, just assume the data is returned in order.
                    // If it's an update, the records should already have an id which should match what the server returns.
                    if (me.action == 'update' || clientRecords[0].clientIdProperty) {
                        mc = new Ext.util.MixedCollection();
                        mc.addAll(serverRecords);

                        for (index = clientRecords.length; index--; ) {
                            clientRec = clientRecords[index];
                            serverRec = mc.findBy(me.matchClientRec, clientRec);

                            // Replace client record data with server record data
                            clientRec.copyFrom(serverRec);
                        }
                    } else {
                        for (i = 0, len = clientRecords.length; i < len; ++i) {
                            clientRec = clientRecords[i];
                            serverRec = serverRecords[i];
                            if (clientRec && serverRec) {
                                me.updateRecord(clientRec, serverRec);
                            }
                        }
                    }
                } else {
                    // operation only has one record, so just match the first client record up with the first server record
                    this.updateRecord(clientRecords[0], serverRecords[0]);   
                }

                if (me.actionCommitRecordsRe.test(me.action)) {
                    for (index = clientRecords.length; index--; ) {
                        clientRecords[index].commit();
                    }
                }
            }
        }
    },
    
    updateRecord: function(clientRec, serverRec) {
        // if the client record is not a phantom, make sure the ids match before replacing the client data with server data.
        if(serverRec && (clientRec.phantom || clientRec.getId() === serverRec.getId())) {
            clientRec.copyFrom(serverRec);
        }
    },

    // Private.
    // Record matching function used by commitRecords
    // IMPORTANT: This is called in the scope of the clientRec being matched
    matchClientRec: function(record) {
        var clientRec = this,
            clientRecordId = clientRec.getId();

        if(clientRecordId && record.getId() === clientRecordId) {
            return true;
        }
        // if the server record cannot be found by id, find by internalId.
        // this allows client records that did not previously exist on the server
        // to be updated with the correct server id and data.
        return record.internalId === clientRec.internalId;
    },

    /**
     * Marks the Operation as started.
     */
    setStarted: function() {
        this.started = true;
        this.running = true;
    },

    /**
     * Marks the Operation as completed.
     */
    setCompleted: function() {
        this.complete = true;
        this.running  = false;
    },

    /**
     * Marks the Operation as successful.
     */
    setSuccessful: function() {
        this.success = true;
    },

    /**
     * Marks the Operation as having experienced an exception. Can be supplied with an option error message/object.
     * @param {String/Object} error (optional) error string/object
     */
    setException: function(error) {
        this.exception = true;
        this.success = false;
        this.running = false;
        this.error = error;
    },

    /**
     * Returns true if this Operation encountered an exception (see also {@link #getError})
     * @return {Boolean} True if there was an exception
     */
    hasException: function() {
        return this.exception === true;
    },

    /**
     * Returns the error string or object that was set using {@link #setException}
     * @return {String/Object} The error object
     */
    getError: function() {
        return this.error;
    },

    /**
     * Returns the {@link Ext.data.Model record}s associated with this operation.  For read operations the records as set by the {@link Ext.data.proxy.Proxy Proxy} will be returned (returns `null` if the proxy has not yet set the records).
     * For create, update, and destroy operations the operation's initially configured records will be returned, although the proxy may modify these records' data at some point after the operation is initialized.
     * @return {Ext.data.Model[]}
     */
    getRecords: function() {
        var resultSet = this.getResultSet();
        return this.records || (resultSet ? resultSet.records : null);
    },

    /**
     * Returns the ResultSet object (if set by the Proxy). This object will contain the {@link Ext.data.Model model}
     * instances as well as meta data such as number of instances fetched, number available etc
     * @return {Ext.data.ResultSet} The ResultSet object
     */
    getResultSet: function() {
        return this.resultSet;
    },

    /**
     * Returns true if the Operation has been started. Note that the Operation may have started AND completed, see
     * {@link #isRunning} to test if the Operation is currently running.
     * @return {Boolean} True if the Operation has started
     */
    isStarted: function() {
        return this.started === true;
    },

    /**
     * Returns true if the Operation has been started but has not yet completed.
     * @return {Boolean} True if the Operation is currently running
     */
    isRunning: function() {
        return this.running === true;
    },

    /**
     * Returns true if the Operation has been completed
     * @return {Boolean} True if the Operation is complete
     */
    isComplete: function() {
        return this.complete === true;
    },

    /**
     * Returns true if the Operation has completed and was successful
     * @return {Boolean} True if successful
     */
    wasSuccessful: function() {
        return this.isComplete() && this.success === true;
    },

    /**
     * @private
     * Associates this Operation with a Batch
     * @param {Ext.data.Batch} batch The batch
     */
    setBatch: function(batch) {
        this.batch = batch;
    },

    /**
     * Checks whether this operation should cause writing to occur.
     * @return {Boolean} Whether the operation should cause a write to occur.
     */
    allowWrite: function() {
        return this.action != 'read';
    }
});
