package niri

import (
	"encoding/json"
	"fmt"
	"regexp"
	"strconv"
)

type SizeChange struct {
	SetFixed         *int     `json:"SetFixed,omitempty"`
	SetProportion    *float64 `json:"SetProportion,omitempty"`
	AdjustFixed      *int     `json:"AdjustFixed,omitempty"`
	AdjustProportion *float64 `json:"AdjustProportion,omitempty"`
}

func (m SizeChange) String() string {
	data, _ := json.MarshalIndent(m, "", "\t")
	return string(data)
}

func SizeSetFixed(size int) SizeChange {
	return SizeChange{SetFixed: &size}
}

func SizeSetProportion(size float64) SizeChange {
	return SizeChange{SetProportion: &size}
}

func SizeAdjustFixed(size int) SizeChange {
	return SizeChange{AdjustFixed: &size}
}

func SizeAdjustProportion(size float64) SizeChange {
	return SizeChange{AdjustProportion: &size}
}

const sizePatternString = `^(\+|-)?((\d+?)(?:\.\d+)?)(%)?$`
const sizePatternGroupAdjust = 1
const sizePatternGroupFloatValue = 2
const sizePatternGroupIntValue = 3
const sizePatternGroupPercentage = 4

var sizePattern = regexp.MustCompile(sizePatternString)

func ParseSize(str string) (SizeChange, error) {
	matches := sizePattern.FindStringSubmatch(str)
	if matches == nil {
		return SizeChange{}, fmt.Errorf("invalid size spec '%s'. Expected pattern: %s", str, sizePatternString)
	}

	adjust := matches[sizePatternGroupAdjust] != ""
	proportion := matches[sizePatternGroupPercentage] == "%"
	negative := matches[sizePatternGroupAdjust] == "-"

	factor := 1
	if negative {
		factor = -1
	}

	floatValue, err := strconv.ParseFloat(matches[sizePatternGroupFloatValue], 64)
	if err != nil {
		return SizeChange{}, fmt.Errorf("invalid size spec '%s'. Expected pattern: %s", str, sizePatternString)
	}

	intValue, err := strconv.ParseInt(matches[sizePatternGroupIntValue], 10, 64)
	if err != nil {
		return SizeChange{}, fmt.Errorf("invalid size spec '%s'. Expected pattern: %s", str, sizePatternString)
	}

	switch true {
	case adjust && proportion:
		return SizeAdjustProportion(floatValue * float64(factor)), nil
	case adjust && !proportion:
		return SizeAdjustFixed(int(intValue) * factor), nil
	case !adjust && proportion:
		return SizeSetProportion(floatValue * float64(factor)), nil
	case !adjust && !proportion:
		return SizeSetFixed(int(intValue) * factor), nil
	default:
		return SizeChange{}, fmt.Errorf("invalid size spec '%s'. Expected pattern: %s", str, sizePatternString)
	}
}