// Copyright 2017 Baliance. All rights reserved.
//
// Use of this source code is governed by the terms of the Affero GNU General
// Public License version 3.0 as published by the Free Software Foundation and
// appearing in the file LICENSE included in the packaging of this file. A
// commercial license can be purchased by contacting sales@baliance.com.

package spreadsheet

import (
	"strconv"
)

// SortOrder is a column sort order.
//go:generate stringer -type=SortOrder
type SortOrder byte

// SortOrder constants
const (
	SortOrderAscending SortOrder = iota
	SortOrderDescending
)

// Comparer is used to compare rows based off a column and cells based off of
// their value.
type Comparer struct {
	Order SortOrder
}

// LessRows compares two rows based off of a column. If the column doesn't exist
// in one row, that row is 'less'.
func (c Comparer) LessRows(column string, lhs, rhs Row) bool {
	var lhsCell, rhsCell Cell
	for _, c := range lhs.Cells() {
		cellCol, _, _ := ParseCellReference(c.Reference())
		if cellCol == column {
			lhsCell = c
			break
		}
	}

	for _, c := range rhs.Cells() {
		cellCol, _, _ := ParseCellReference(c.Reference())
		if cellCol == column {
			rhsCell = c
			break
		}
	}

	return c.LessCells(lhsCell, rhsCell)
}

// LessCells returns true if the lhs value is less than the rhs value. If the
// cells contain numeric values, their value interpreted as a floating point is
// compared. Otherwise their string contents are compared.
func (c Comparer) LessCells(lhs, rhs Cell) bool {
	if c.Order == SortOrderDescending {
		lhs, rhs = rhs, lhs
	}

	// handle zero-value cells first as we can get those based off of LessRows
	// above
	if lhs.X() == nil {
		if rhs.X() == nil {
			return false
		}
		return true
	}
	if rhs.X() == nil {
		return false
	}

	lhsValue, lhsIsNum := lhs.getRawSortValue()
	rhsValue, rhsIsNum := rhs.getRawSortValue()

	switch {
	// both numbers
	case lhsIsNum && rhsIsNum:
		lf, _ := strconv.ParseFloat(lhsValue, 64)
		rf, _ := strconv.ParseFloat(rhsValue, 64)
		return lf < rf
	// numbers sort before non-numbers
	case lhsIsNum:
		return true
	case rhsIsNum:
		return false
	}

	lhsValue = lhs.GetFormattedValue()
	rhsValue = lhs.GetFormattedValue()
	return lhsValue < rhsValue
}