/*
 * 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-calc.h"
#include "db-row.h"

/**
 * SECTION: db-calc
 * @short_description: the result of an operation made over a column or between
 * columns
 * @title: DbCalc
 *
 * A #GvnParam that holds the result of the user-given operation applied over
 * a given column of a #DbModel. When any of these values is modified, #DbCalc
 * updates its value according to the changes. 
 * 
 * #DbCalc has as built-in operations the sumatory and average that can be
 * selected passing #DB_CALC_TYPE_SUM OR #DB_CALC_TYPE_AVG, respectively.
 * 
 * While creating a #DbCalc it's possible to specify either a single column
 * number, to calculate using only this column and no additional operations, or
 * a #DbCalcFunc function, to use more than one column or do any operation
 * needed with the #DbModel fields, in the latter case, custom data can also be
 * passed.
 **/

G_DEFINE_TYPE (DbCalc, db_calc, GVN_TYPE_PARAM);

/**
 * db_calc_new:
 * @model: the #DbModel in which the operations will apply
 * @type: the #DbCalcOperationType
 * @col: the number of a column (starting with 0)
 * 
 * Creates a new #DbCalc using @col to select the only column to be processed
 * in each row of @model.
 * 
 * Return value: a new #DbCalc
 **/
DbCalc * db_calc_new (DbModel * model, DbCalcType type, gint col)
{
	g_return_val_if_fail (DB_IS_MODEL (model), NULL);
	g_return_val_if_fail (0 <= col || col < db_model_get_ncols (model), NULL);

	return g_object_new
		(DB_TYPE_CALC, "model", model, "type", type, "col", col, NULL);
}

/**
 * db_calc_new_with_func:
 * @model: the #DbModel in which the operations will apply
 * @type: the #DbCalcOperationType
 * @func: (scope call): a #DbCalcFunc
 * @data: additional data that will be passed to @func
 * 
 * Creates a new #DbCalc using @func as the operation that will apply to each
 * row of @model.
 * 
 * Return value: a new #DbCalc
 **/
DbCalc * db_calc_new_with_func (DbModel * model, DbCalcType type, DbCalcFunc func, gpointer data)
{
	g_return_val_if_fail (DB_IS_MODEL (model), NULL);
	g_return_val_if_fail (func, NULL);

	return g_object_new
		(DB_TYPE_CALC, "model", model, "type", type, "function", func, "data", data, NULL);
}

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

static gdouble db_calc_value_to_double (const GValue * v)
{
	switch (G_VALUE_TYPE (v))
	{
		case G_TYPE_UINT:
			return (gdouble) g_value_get_uint (v);
		case G_TYPE_UINT64:
			return (gdouble) g_value_get_uint64 (v);
		case G_TYPE_ULONG:
			return (gdouble) g_value_get_ulong (v);
		case G_TYPE_INT:
			return (gdouble) g_value_get_int (v);
		case G_TYPE_INT64:
			return (gdouble) g_value_get_int64 (v);
		case G_TYPE_LONG:
			return (gdouble) g_value_get_long (v);
		case G_TYPE_FLOAT:
			return (gdouble) g_value_get_float (v);
		case G_TYPE_DOUBLE:
			return g_value_get_double (v);
		case G_TYPE_STRING:
			return g_strtod (g_value_get_string (v), NULL);
		default:
			return 0;
	}
}

static void db_calc_internal_func
	(DbCalc * obj, DbIter * iter, GValue * out, gpointer data)
{
	const GValue * value = db_model_get_value (obj->model, iter, obj->col, NULL);
	g_value_copy (value, g_value_init (out, G_VALUE_TYPE (value)));
}

static void db_calc_before_unset (DbModel * model, DbIter * iter, DbCalc * obj)
{
	GValue value = G_VALUE_INIT;

	obj->func (obj, iter, &value, obj->data);

	if (!gvn_value_is_null (&value))
	{
		gdouble current, old;

		current = db_calc_value_to_double (gvn_param_get_value (GVN_PARAM (obj)));
		old = db_calc_value_to_double (&value);

		if (obj->type == DB_CALC_TYPE_AVG)
		{
			if (obj->count != 1)
				current = (current * (gdouble) obj->count - old) / (gdouble) (obj->count - 1);
			else
				current = 0;
		}
		else if (obj->type == DB_CALC_TYPE_SUM)
			current -= old;

		obj->count--;
		g_value_unset (&value);
		g_value_set_double (g_value_init (&value, G_TYPE_DOUBLE), current);
		GVN_PARAM_GET_CLASS (obj)->put_value (GVN_PARAM (obj), &value);
	}

	g_value_unset (&value);
}

static void db_calc_before_delete (DbModel * model, gint path, DbCalc * obj)
{
	DbIter iter;
	db_model_get_iter (model, &iter, path);
	db_calc_before_unset (model, &iter, obj);
}

static void db_calc_after_set (DbModel * model, DbIter * iter, DbCalc * obj)
{
	GValue value = G_VALUE_INIT;

	obj->func (obj, iter, &value, obj->data);

	if (!gvn_value_is_null (&value))
	{
		gdouble current, new;

		current = db_calc_value_to_double (gvn_param_get_value (GVN_PARAM (obj)));
		new = db_calc_value_to_double (&value);

		if (obj->type == DB_CALC_TYPE_AVG)
			current = (current * (gdouble) obj->count + new) / (gdouble) (obj->count + 1);
		else if (obj->type == DB_CALC_TYPE_SUM)
			current += new;

		obj->count++;
		g_value_unset (&value);
		g_value_set_double (g_value_init (&value, G_TYPE_DOUBLE), current);
		GVN_PARAM_GET_CLASS (obj)->put_value (GVN_PARAM (obj), &value);
	}

	g_value_unset (&value);
}

static void db_calc_refresh (DbModel * model, DbModelStatus status, DbCalc * obj)
{
	DbIter iter;
	gdouble current = 0;
	GValue val = G_VALUE_INIT;

	if (status != DB_MODEL_STATUS_READY) return;
	if (!db_model_get_iter_first (model, &iter)) return;

	obj->count = 0;

	do {
		obj->func (obj, &iter, &val, obj->data);

		if (!gvn_value_is_null (&val))
		{
			current += db_calc_value_to_double (&val);
			obj->count++;
		}

		g_value_unset (&val);
	}
	while (db_model_iter_next (model, &iter));

	if (obj->type == DB_CALC_TYPE_AVG)
		current = (obj->count > 0) ? current / (gdouble) obj->count : 0;

	g_value_set_double (g_value_init (&val, G_TYPE_DOUBLE), current);
	GVN_PARAM_GET_CLASS (obj)->put_value (GVN_PARAM (obj), &val);
	g_value_unset (&val);
}

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

enum
{
	 PROP_MODEL = 1
	,PROP_TYPE
	,PROP_FUNC
	,PROP_DATA
	,PROP_COL
};

static void db_calc_set_property (DbCalc * obj, guint id,
	const GValue * value, GParamSpec * pspec)
{
	switch (id)
	{
		case PROP_MODEL:
			obj->model = g_value_dup_object (value);
			if (obj->model)
				g_object_connect (obj->model
					,"signal::line-updated", db_calc_before_unset, obj
					,"signal-after::line-updated", db_calc_after_set, obj
					,"signal::line-deleted", db_calc_before_delete, obj
					,"signal::status-changed", db_calc_refresh, obj
					, NULL);
			break;
		case PROP_TYPE:
			obj->type = g_value_get_int (value);
			break;
		case PROP_FUNC:
			if (g_value_get_pointer (value))
				obj->func = g_value_get_pointer (value);
			break;
		case PROP_DATA:
			obj->data = g_value_get_pointer (value);
			break;
		case PROP_COL:
			obj->col = g_value_get_int (value);

			if (!obj->func)
				obj->func = db_calc_internal_func;
			break;
		default:
			G_OBJECT_WARN_INVALID_PROPERTY_ID (obj, id, pspec);
	}
}

static void db_calc_get_property (DbCalc * obj, guint id,
	GValue * value, GParamSpec * pspec)
{
	switch (id)
	{
		case PROP_MODEL:
			g_value_set_object (value, obj->model);
			break;
		case PROP_TYPE:
			g_value_set_int (value, obj->type);
			break;
		case PROP_FUNC:
			g_value_set_pointer (value, obj->func);
			break;
		case PROP_DATA:
			g_value_set_pointer (value, obj->data);
			break;
		case PROP_COL:
			g_value_set_int (value, obj->col);
			break;
		default:
			G_OBJECT_WARN_INVALID_PROPERTY_ID (obj, id, pspec);
	}
}

static void db_calc_init (DbCalc * obj)
{
	GvnParamSpec * spec;

	obj->model = NULL;
	obj->type = 0;
	obj->func = NULL;
	obj->data = NULL;
	obj->col = 0;
	obj->count = 0;

	spec = gvn_param_spec_new_with_attrs (G_TYPE_DOUBLE, FALSE, TRUE, NULL);
	GVN_PARAM_GET_CLASS (obj)->set_spec (GVN_PARAM (obj), spec);
}

static void db_calc_finalize (DbCalc * obj)
{
	if (obj->model)
	{
		g_object_disconnect (obj->model
			,"any_signal::line-updated", db_calc_before_unset, obj
			,"any_signal::line-updated", db_calc_after_set, obj
			,"any_signal::line-deleted", db_calc_before_delete, obj
			,"any_signal::status-changed", db_calc_refresh, obj
		    ,NULL
		);
		g_clear_object (&obj->model);
	}
}

static void db_calc_class_init (DbCalcClass * k)
{
	GObjectClass * klass = G_OBJECT_CLASS (k);
	klass->finalize = (GObjectFinalizeFunc) db_calc_finalize;
	klass->set_property = (GObjectSetPropertyFunc) db_calc_set_property;
	klass->get_property = (GObjectGetPropertyFunc) db_calc_get_property;

	g_object_class_install_property (klass, PROP_MODEL
		,g_param_spec_object ("model"
			,_("Model")
			,_("The model where the operations will be applied")
			,DB_TYPE_MODEL
			,G_PARAM_CONSTRUCT_ONLY | G_PARAM_READWRITE)
	);

	g_object_class_install_property (klass, PROP_TYPE
		,g_param_spec_enum	("type"
			,_("Operation type")
			,_("The type of the operation applied over the function")
			,DB_TYPE_CALC_TYPE
			,DB_CALC_TYPE_SUM
			,G_PARAM_CONSTRUCT_ONLY | G_PARAM_READWRITE)
	);

	g_object_class_install_property (klass, PROP_FUNC
		,g_param_spec_pointer ("function"
			,_("Function")
			,_("The function to execute")
			,G_PARAM_CONSTRUCT_ONLY | G_PARAM_READWRITE)
	);

	g_object_class_install_property (klass, PROP_DATA
		,g_param_spec_pointer ("data"
			,_("Data")
			,_("The user provided data for the function")
			,G_PARAM_CONSTRUCT_ONLY | G_PARAM_READWRITE)
	);

	g_object_class_install_property (klass, PROP_COL
		,g_param_spec_int ("col"
			,_("Column")
			,_("A column to apply the operations over it")
			,0
			,G_MAXINT32
			,0
			,G_PARAM_CONSTRUCT_ONLY | G_PARAM_READWRITE)
	);
}

GType db_calc_type_get_type ()
{
	static GType type = 0;

	if (type == 0)
	{
		static const GEnumValue values[] =
		{
			 {DB_CALC_TYPE_SUM, "DB_CALC_TYPE_SUM", "sum"}
			,{DB_CALC_TYPE_AVG, "DB_CALC_TYPE_AVG", "avg"}
			,{0, NULL, NULL}
		};

		type = g_enum_register_static
			(g_intern_static_string ("DbCalcType"), values);
	}

	return type;
}