/*
 * 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, const gchar * column_name)
{
	g_return_val_if_fail (DB_IS_MODEL (model), NULL);

	return g_object_new (DB_TYPE_CALC
		,"model", model
		,"type", type
		,"column-name", column_name
		,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 * self, DbIter * iter, GValue * out, gpointer data)
{
	const GValue * value;

	if (self->column_index != -1)
	{
		value = db_model_get_value (self->model, iter, self->column_index, NULL);
		g_value_copy (value, g_value_init (out, G_VALUE_TYPE (value)));
	}
	else
		g_value_init (out, GVN_TYPE_NULL);
}

static void db_calc_reset (DbCalc * self)
{
	g_free (self->column_name);
	self->column_name = NULL;
	self->column_index = -1;
	self->func = db_calc_internal_func;
}

static void db_calc_refresh (DbCalc * self)
{
	DbIter iter;
	gdouble current = 0;
	GValue val = G_VALUE_INIT;
	DbModel * model = self->model;
	
	self->count = 0;
	
	if (model)
	{
		DbModelStatus status = db_model_get_status (model);

		if (status == DB_MODEL_STATUS_READY && self->column_name)
			self->column_index = db_model_get_column_index (model, self->column_name);
	
		if (status == DB_MODEL_STATUS_READY
		&& self->column_index != -1
		&& db_model_get_iter_first (model, &iter))
		{
			do {
				self->func (self, &iter, &val, self->data);

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

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

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

	if (self->count > 0)
		g_value_set_double (g_value_init (&val, G_TYPE_DOUBLE), current);
	else
		g_value_init (&val, GVN_TYPE_NULL);

	GVN_PARAM_GET_CLASS (self)->put_value (GVN_PARAM (self), &val);
	g_value_unset (&val);
}

static void db_calc_on_model_refresh (DbModel * model, DbModelStatus status, DbCalc * self)
{
	db_calc_refresh (self);
}

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

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

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

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

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

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

	g_value_unset (&value);
}

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

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

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

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

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

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

	g_value_unset (&value);
}

static void db_calc_on_delete (DbModel * model, gint path, DbCalc * self)
{
	DbIter iter;
	db_model_get_iter (model, &iter, path);
	db_calc_on_update (model, &iter, self);
}

//+++++++++++++++++++++++++++++++++++++++++++++++++++ Public

void db_calc_set_column_name (DbCalc * self, const gchar * name)
{
	g_return_if_fail (DB_IS_CALC (self));

	db_calc_reset (self);
	self->column_name = g_strdup (name);
	db_calc_refresh (self);
}

void db_calc_set_column_index (DbCalc * self, gint index)
{
	g_return_if_fail (DB_IS_CALC (self));

	db_calc_reset (self);
	self->column_index = index;
	db_calc_refresh (self);
}

void db_calc_set_model (DbCalc * self, DbModel * model)
{
	g_return_if_fail (DB_IS_CALC (self));
	g_return_if_fail (DB_IS_MODEL (model) || !model);

	if (self->model)
	{
		g_object_disconnect (self->model
			,"any_signal::line-updated", db_calc_on_update, self
			,"any_signal::line-updated", db_calc_on_update_after, self
			,"any_signal::line-deleted", db_calc_on_delete, self
			,"any_signal::status-changed", db_calc_on_model_refresh, self
		    ,NULL
		);
		g_clear_object (&self->model);
	}
	if (model)
	{
		self->model = g_object_ref (model);
		g_object_connect (self->model
			,"signal::line-updated", db_calc_on_update, self
			,"signal-after::line-updated", db_calc_on_update_after, self
			,"signal::line-deleted", db_calc_on_delete, self
			,"signal::status-changed", db_calc_on_model_refresh, self
			,NULL
		);
	}
	
	db_calc_refresh (self);
}

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

enum
{
	 PROP_MODEL = 1
	,PROP_TYPE
	,PROP_FUNC
	,PROP_DATA
	,PROP_COLUMN_INDEX
	,PROP_COLUMN_NAME
};

static void db_calc_set_property (DbCalc * self, guint id,
	const GValue * value, GParamSpec * pspec)
{
	switch (id)
	{
		case PROP_MODEL:
			db_calc_set_model (self, g_value_get_object (value));
			break;
		case PROP_TYPE:
			self->type = g_value_get_enum (value);
			db_calc_refresh (self);
			break;
		case PROP_FUNC:
			db_calc_reset (self);
			if (g_value_get_pointer (value))
				self->func = g_value_get_pointer (value);
			db_calc_refresh (self);
			break;
		case PROP_DATA:
			self->data = g_value_get_pointer (value);
			break;
		case PROP_COLUMN_INDEX:
			db_calc_set_column_index (self, g_value_get_int (value));
			break;
		case PROP_COLUMN_NAME:
			db_calc_set_column_name (self, g_value_get_string (value));
			break;
		default:
			G_OBJECT_WARN_INVALID_PROPERTY_ID (self, id, pspec);
	}
}

static void db_calc_get_property (DbCalc * self, guint id,
	GValue * value, GParamSpec * pspec)
{
	switch (id)
	{
		case PROP_MODEL:
			g_value_set_object (value, self->model);
			break;
		case PROP_TYPE:
			g_value_set_enum (value, self->type);
			break;
		case PROP_FUNC:
			g_value_set_pointer (value, self->func);
			break;
		case PROP_DATA:
			g_value_set_pointer (value, self->data);
			break;
		case PROP_COLUMN_INDEX:
			g_value_set_int (value, self->column_index);
			break;
		case PROP_COLUMN_NAME:
			g_value_set_string (value, self->column_name);
			break;
		default:
			G_OBJECT_WARN_INVALID_PROPERTY_ID (self, id, pspec);
	}
}

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

	self->model = NULL;
	self->type = 0;
	self->func = NULL;
	self->data = NULL;
	self->column_index = -1;
	self->column_name = NULL;
	self->count = 0;

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

static void db_calc_finalize (DbCalc * self)
{
	db_calc_set_model (self, NULL);
	g_free (self->column_name);
	G_OBJECT_CLASS (db_calc_parent_class)->finalize (G_OBJECT (self));
}

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_COLUMN_INDEX
		,g_param_spec_int ("column-index"
			,_("Column index")
			,_("A column to apply the operations over it")
			,-1
			,G_MAXINT
			,-1
			,G_PARAM_CONSTRUCT_ONLY | G_PARAM_READWRITE)
	);

	g_object_class_install_property (klass, PROP_COLUMN_NAME
		,g_param_spec_string ("column-name"
			,_("Column name")
			,_("A column name to apply the operations over it")
			,NULL
			,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;
}