/*
 * Copyright (C) 2012 - Juan Ferrer Toribio
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program. If not, see <http://www.gnu.org/licenses/>.
 */

#include "db-request.h"

/**
 * SECTION: db-request
 * @Short_description: a request to the database sent by the model
 * @Title: DbRequest
 * @See_also: #DbConn, #DbModel
 * 
 * This class is used to send an SQL query to the database through a #DbConn,
 * and to retrieve any data or metadata obtained by it in the model.
 **/
G_DEFINE_TYPE (DbRequest, db_request, G_TYPE_OBJECT);

//+++++++++++++++++++++++++++++++++++++++++++++++++++ Private

static gboolean db_request_idle (DbRequest * obj)
{
	if (obj->callback)
		obj->callback (obj, obj->user_data);

	return G_SOURCE_REMOVE;
}

static void db_request_idle_notify (DbRequest * obj)
{
	if (obj->notify)
		obj->notify (obj->user_data);

	g_object_unref (obj);
}

//+++++++++++++++++++++++++++++++++++++++++++++++++++ Methods

/**
 * db_request_new:
 * @conn: a #DbConn
 * @sql: SQL statement to execute
 *
 * Creates a new request to execute the %sql query.
 *
 * Return value: a new #DbRequest
 **/
DbRequest * db_request_new (DbConn * conn, const gchar * sql)
{
	g_return_val_if_fail (DB_IS_CONN (conn), NULL);

	return g_object_new (DB_TYPE_REQUEST, "conn", conn, "sql", sql, NULL);
}

/**
 * db_request_new_with_stmt:
 * @conn: a #DbConn
 * @stmt: the #SqlStmt statement to execute.
 *
 * Creates a new request to execute the statement.
 *
 * Return value: a new #DbRequest
 **/
DbRequest * db_request_new_with_stmt (DbConn * conn, SqlStmt * stmt, SqlBatch * batch)
{
	DbRequest * obj;

	g_return_val_if_fail (DB_IS_CONN (conn), NULL);
	g_return_val_if_fail (SQL_IS_STMT (stmt), NULL);
	g_return_val_if_fail (SQL_IS_BATCH (batch) || !batch, NULL);

	obj = g_object_new (DB_TYPE_REQUEST, "conn", conn, NULL);
	obj->sql = db_conn_render (conn, stmt, batch, NULL);

	return obj;
}

/**
 * db_request_fetch_result:
 * @obj: a #DbRequest
 * @err: (out) (allow-none): return location for a #GError or %NULL
 *
 * Obtains the first result of the query. The request must have been made to
 * call this method.
 *
 * Return value: (transfer full) (allow-none): the #DbResult
 **/
DbResult * db_request_fetch_result (DbRequest * obj, GError ** err)
{
	DbResult * result = NULL;

	g_return_val_if_fail (DB_IS_REQUEST (obj), NULL);

	g_mutex_lock (&obj->mutex);
	
	if (obj->result_set)
	{
		result = db_result_set_take_next (obj->result_set);
	}
	else if (err)
	{
		g_propagate_error (err, obj->error);
		obj->error = NULL;
	}
	
	g_mutex_unlock (&obj->mutex);
	return result;
}

/**
 * db_request_fetch_non_select:
 * @obj: a #DbRequest
 * @err: (out) (allow-none): return location for a #GError or %NULL
 *
 * Fetchs the result of a non select statement.
 *
 * Return value: returns 0 or the number of affected rows on success, -1 on failure
 **/
gint db_request_fetch_non_select (DbRequest * obj, GError ** err)
{
	DbResult * result;
	
	g_return_val_if_fail (DB_IS_REQUEST (obj), -1);
	
	result = db_request_fetch_result (obj, err);

	if (result)
	{
		gint affected_rows = result->nrows;
		db_result_free (result);
		return affected_rows;
	}
	
	return -1;
}

/**
 * db_request_fetch_value:
 * @obj: a #DbRequest
 * @value: (out): return location for a #GValue
 * @err: (out) (allow-none): return location for a #GError or %NULL
 *
 * Obtains the first result of the query. The request must have been made to
 * call this method.
 *
 * Return value: %TRUE on success, %FALSE on failure
 **/
gboolean db_request_fetch_value (DbRequest * obj, GValue * value, GError ** err)
{
	DbResult * result;

	g_return_val_if_fail (DB_IS_REQUEST (obj), FALSE);
	
	result = db_request_fetch_result (obj, err);
	
	if (result)
	{
		DbRow * row = db_result_get_row (result, 0);

		if (row)
		{
			const GValue * row_value = db_row_get_value (row, 0);
		
			if (row_value)
			{
				g_value_init (value, G_VALUE_TYPE (row_value));
				g_value_copy (row_value, value);
				return TRUE;			
			}
		}
		
		db_result_free (result);
	}
	
	return FALSE;
}

/**
 * db_request_exec:
 * @obj: a #DbRequest
 * @err: (out) (allow-none): return location for a #GError or %NULL
 *
 * Sends the request to the database.
 **/
gboolean db_request_exec (DbRequest * obj, GError ** err)
{
	gboolean ret;
	
	g_return_val_if_fail (DB_IS_REQUEST (obj), FALSE);

	ret = TRUE;
	g_mutex_lock (&obj->mutex);

	switch ((gint) obj->status)
	{
		case DB_REQUEST_CLEAN:
		case DB_REQUEST_ERROR:
		{
			DbResultSet * set;
			GError * query_error = NULL;

			obj->status = DB_REQUEST_LOADING;
			g_mutex_unlock (&obj->mutex);

			set = db_conn_exec (obj->conn, obj->sql, &query_error);

			g_mutex_lock (&obj->mutex);

			if (obj->status != DB_REQUEST_CANCELED)
			{
				if (set)
				{
					obj->result_set = set;
					obj->status = DB_REQUEST_DONE;
				}
				else if (query_error)
				{
					g_clear_error (&obj->error);
					obj->error = g_error_copy (query_error);
					g_propagate_error (err, query_error);
					obj->status = DB_REQUEST_ERROR;
					ret = FALSE;
				}
			}
			else
			{
				if (set)
					db_result_set_free (set);
				else
					g_clear_error (&query_error);
			}
		}
	}

	g_mutex_unlock (&obj->mutex);

	return ret;
}

/**
 * db_request_set_callback:
 * @obj: a #DbRequest
 * @callback:
 * @user_data:
 * @notify:
 *
 * Sends the request to the database.
 **/
void db_request_set_callback (DbRequest * obj,
	DbRequestDoneCallback callback, gpointer user_data, GDestroyNotify notify)
{
	g_return_if_fail (DB_IS_REQUEST (obj));

	g_mutex_lock (&obj->mutex);

	obj->callback = callback;
	obj->user_data = user_data;
	obj->notify = notify;

	g_mutex_unlock (&obj->mutex);
}

/**
 * db_request_complete:
 * @obj: a #DbRequest
 *
 * Emits the ready or error signal of the object.
 **/
void db_request_complete (DbRequest * obj)
{
	g_return_if_fail (DB_IS_REQUEST (obj));
	
	g_idle_add_full (G_PRIORITY_HIGH_IDLE,
		(GSourceFunc) db_request_idle, g_object_ref (obj), (GDestroyNotify) db_request_idle_notify);
}

/**
 * db_request_cancel:
 * @obj: a #DbRequest
 *
 * Attempts to cancel the request.
 *
 * Return value: %TRUE if request was canceled %FALSE otherwise.
 **/
void db_request_cancel (DbRequest * obj)
{
	g_return_if_fail (DB_IS_REQUEST (obj));

	g_mutex_lock (&obj->mutex);
	
	if (obj->status != DB_REQUEST_CANCELED)
	{
		if (obj->result_set)
		{
			db_result_set_free (obj->result_set);
			obj->result_set = NULL;
		}
		else		
			g_clear_error (&obj->error);
	
		obj->status = DB_REQUEST_CANCELED;
		obj->error = g_error_new (
			 DB_REQUEST_LOG_DOMAIN
			,DB_REQUEST_ERROR_CANCELED
			,_("The request was canceled")
		);	
	}

	g_mutex_unlock (&obj->mutex);
}

/**
 * db_request_get_conn:
 * @obj: a #DbRequest
 *
 * Gets the connection used by request.
 *
 * Return value: (transfer full): the #DbConn
 **/
DbConn * db_request_get_conn (DbRequest * obj)
{
	g_return_val_if_fail (DB_IS_REQUEST (obj), NULL);

	return obj->conn;
}

/**
 * db_request_get_sql:
 * @obj: a #DbRequest
 *
 * Gets the SQL statement used by #DbRequest.
 *
 * Return value: the sql string, must be freed with g_free()
 **/
gchar * db_request_get_sql (DbRequest * obj)
{
	g_return_val_if_fail (DB_IS_REQUEST (obj), NULL);

	return g_strdup (obj->sql);
}

//+++++++++++++++++++++++++++++++++++++++++++++++++++ Properties

typedef enum
{
	 PROP_CONN = 1
	,PROP_SQL
	,PROP_RESULT_SET
	,PROP_ERROR
}
DbRequestProp;

static void db_request_set_property (DbRequest * obj, guint property_id,
	const GValue * value, GParamSpec * pspec)
{
	g_mutex_lock (&obj->mutex);
	
	switch (property_id)
	{
		case PROP_CONN:
			obj->conn = g_value_dup_object (value);
			break;
		case PROP_SQL:
			obj->sql = g_value_dup_string (value);
			break;
		default:		
			G_OBJECT_WARN_INVALID_PROPERTY_ID (obj, property_id, pspec);
	}

	g_mutex_unlock (&obj->mutex);
}

static void db_request_get_property (DbRequest * obj, guint property_id,
	GValue * value, GParamSpec * pspec)
{	
	switch (property_id)
	{
		case PROP_CONN:
			g_value_set_object (value, obj->conn);
			break;
		case PROP_SQL:
			g_value_set_string (value, obj->sql);
			break;
		case PROP_RESULT_SET:
			g_value_set_boxed (value, obj->result_set);
			break;
		case PROP_ERROR:
			g_value_set_boxed (value, obj->error);
			break;
		default:		
			G_OBJECT_WARN_INVALID_PROPERTY_ID (obj, property_id, pspec);
	}
}

//+++++++++++++++++++++++++++++++++++++++++++++++++++ Class

static void db_request_init (DbRequest * obj)
{
	obj->sql = NULL;
	obj->error = NULL;
	obj->result_set = NULL;
	obj->conn = NULL;
	obj->callback = NULL;
	obj->notify = NULL;
	obj->status = DB_REQUEST_CLEAN;
	g_mutex_init (&obj->mutex);
}

static void db_request_finalize (DbRequest * obj)
{
	if (obj->result_set)
		db_result_set_free (obj->result_set);

	g_clear_error (&obj->error);
	g_clear_object (&obj->conn);
	g_free (obj->sql);
	g_mutex_clear (&obj->mutex);
	G_OBJECT_CLASS (db_request_parent_class)->finalize (G_OBJECT (obj));
}

static void db_request_class_init (DbRequestClass * k)
{
	GObjectClass * klass = G_OBJECT_CLASS (k);
	klass->finalize = (GObjectFinalizeFunc) db_request_finalize;
	klass->set_property = (GObjectSetPropertyFunc) db_request_set_property;
	klass->get_property = (GObjectGetPropertyFunc) db_request_get_property;

	g_object_class_install_property (klass, PROP_CONN,
		g_param_spec_object ("conn"
			,_("Connection")
			,_("The connection used to render and execute the query")
			,DB_TYPE_CONN
			,G_PARAM_CONSTRUCT_ONLY | G_PARAM_READWRITE
	));
	g_object_class_install_property (klass, PROP_SQL,
		g_param_spec_string ("sql"
			,_("SQL")
			,_("The SQL query to execute")
			,NULL
			,G_PARAM_CONSTRUCT_ONLY | G_PARAM_READWRITE
	));
	g_object_class_install_property (klass, PROP_RESULT_SET,
		g_param_spec_boxed ("result-set"
			,_("Result")
			,_("The result data of the query")
			,DB_TYPE_RESULT_SET
			,G_PARAM_READABLE
	));
	g_object_class_install_property (klass, PROP_ERROR,
		g_param_spec_boxed ("error"
			,_("Error")
			,_("The GError, if an error ocurred")
			,G_TYPE_ERROR
			,G_PARAM_READABLE
	));
}