package otto

import (
	"fmt"
	"math"
	"regexp"
	"strconv"
	"strings"
)

var stringToNumberParseInteger = regexp.MustCompile(`^(?:0[xX])`)

func stringToFloat(value string) float64 {
	value = strings.TrimSpace(value)

	if value == "" {
		return 0
	}

	parseFloat := false
	if strings.IndexRune(value, '.') != -1 {
		parseFloat = true
	} else if stringToNumberParseInteger.MatchString(value) {
		parseFloat = false
	} else {
		parseFloat = true
	}

	if parseFloat {
		number, err := strconv.ParseFloat(value, 64)
		if err != nil && err.(*strconv.NumError).Err != strconv.ErrRange {
			return math.NaN()
		}
		return number
	}

	number, err := strconv.ParseInt(value, 0, 64)
	if err != nil {
		return math.NaN()
	}
	return float64(number)
}

func toNumber(value Value) Value {
	if value._valueType == valueNumber {
		return value
	}
	return Value{valueNumber, toFloat(value)}
}

func toFloat(value Value) float64 {
	switch value._valueType {
	case valueUndefined:
		return math.NaN()
	case valueNull:
		return 0
	}
	switch value := value.value.(type) {
	case bool:
		if value {
			return 1
		}
		return 0
	case int:
		return float64(value)
	case int8:
		return float64(value)
	case int16:
		return float64(value)
	case int32:
		return float64(value)
	case int64:
		return float64(value)
	case uint:
		return float64(value)
	case uint8:
		return float64(value)
	case uint16:
		return float64(value)
	case uint32:
		return float64(value)
	case uint64:
		return float64(value)
	case float64:
		return value
	case string:
		return stringToFloat(value)
	case *_object:
		return toFloat(value.DefaultValue(defaultValueHintNumber))
	}
	panic(fmt.Errorf("toFloat(%T)", value.value))
}

const (
	float_2_32   float64 = 4294967296.0
	float_2_31   float64 = 2147483648.0
	float_2_16   float64 = 65536.0
	integer_2_32 int64   = 4294967296
	integer_2_31 int64   = 2146483648
	sqrt1_2      float64 = math.Sqrt2 / 2
)

const (
	_MaxInt8   = math.MaxInt8
	_MinInt8   = math.MinInt8
	_MaxInt16  = math.MaxInt16
	_MinInt16  = math.MinInt16
	_MaxInt32  = math.MaxInt32
	_MinInt32  = math.MinInt32
	_MaxInt64  = math.MaxInt64
	_MinInt64  = math.MinInt64
	_MaxUint8  = math.MaxUint8
	_MaxUint16 = math.MaxUint16
	_MaxUint32 = math.MaxUint32
	_MaxUint64 = math.MaxUint64
	_MaxUint   = ^uint(0)
	_MinUint   = 0
	_MaxInt    = int(^uint(0) >> 1)
	_MinInt    = -_MaxInt - 1

	// int64
	_MaxInt8_   int64 = math.MaxInt8
	_MinInt8_   int64 = math.MinInt8
	_MaxInt16_  int64 = math.MaxInt16
	_MinInt16_  int64 = math.MinInt16
	_MaxInt32_  int64 = math.MaxInt32
	_MinInt32_  int64 = math.MinInt32
	_MaxUint8_  int64 = math.MaxUint8
	_MaxUint16_ int64 = math.MaxUint16
	_MaxUint32_ int64 = math.MaxUint32

	// float64
	_MaxInt_    float64 = float64(int(^uint(0) >> 1))
	_MinInt_    float64 = float64(int(-_MaxInt - 1))
	_MinUint_   float64 = float64(0)
	_MaxUint_   float64 = float64(uint(^uint(0)))
	_MinUint64_ float64 = float64(0)
	_MaxUint64_ float64 = math.MaxUint64
	_MaxInt64_  float64 = math.MaxInt64
	_MinInt64_  float64 = math.MinInt64
)

func toIntegerFloat(value Value) float64 {
	floatValue := value.toFloat()
	if math.IsNaN(floatValue) {
		return 0
	} else if math.IsInf(floatValue, 0) {
		return floatValue
	}
	if floatValue > 0 {
		return math.Floor(floatValue)
	}
	return math.Ceil(floatValue)
}

func toInteger(value Value) int64 {
	{
		switch value := value.value.(type) {
		case int8:
			return int64(value)
		case int16:
			return int64(value)
		case int32:
			return int64(value)
		}
	}
	switch value._valueType {
	case valueUndefined, valueNull:
		return 0
	}
	floatValue := value.toFloat()
	if math.IsNaN(floatValue) {
		return 0
	} else if math.IsInf(floatValue, 0) {
		// FIXME
		dbgf("%/panic//%@: %f %v to int64", floatValue, value)
	}
	if floatValue > 0 {
		return int64(math.Floor(floatValue))
	}
	return int64(math.Ceil(floatValue))
}

// ECMA 262: 9.5
func toI32(value Value) int32 {
	{
		switch value := value.value.(type) {
		case int8:
			return int32(value)
		case int16:
			return int32(value)
		case int32:
			return value
		}
	}
	floatValue := value.toFloat()
	if math.IsNaN(floatValue) || math.IsInf(floatValue, 0) {
		return 0
	}
	if floatValue == 0 { // This will work for +0 & -0
		return 0
	}
	remainder := math.Mod(floatValue, float_2_32)
	if remainder > 0 {
		remainder = math.Floor(remainder)
	} else {
		remainder = math.Ceil(remainder) + float_2_32
	}
	if remainder > float_2_31 {
		return int32(remainder - float_2_32)
	}
	return int32(remainder)
}

func toUI32(value Value) uint32 {
	{
		switch value := value.value.(type) {
		case int8:
			return uint32(value)
		case int16:
			return uint32(value)
		case uint8:
			return uint32(value)
		case uint16:
			return uint32(value)
		case uint32:
			return value
		}
	}
	floatValue := value.toFloat()
	if math.IsNaN(floatValue) || math.IsInf(floatValue, 0) {
		return 0
	}
	if floatValue == 0 {
		return 0
	}
	remainder := math.Mod(floatValue, float_2_32)
	if remainder > 0 {
		remainder = math.Floor(remainder)
	} else {
		remainder = math.Ceil(remainder) + float_2_32
	}
	return uint32(remainder)
}

func toUI16(value Value) uint16 {
	{
		switch value := value.value.(type) {
		case int8:
			return uint16(value)
		case uint8:
			return uint16(value)
		case uint16:
			return value
		}
	}
	floatValue := value.toFloat()
	if math.IsNaN(floatValue) || math.IsInf(floatValue, 0) {
		return 0
	}
	if floatValue == 0 {
		return 0
	}
	remainder := math.Mod(floatValue, float_2_16)
	if remainder > 0 {
		remainder = math.Floor(remainder)
	} else {
		remainder = math.Ceil(remainder) + float_2_16
	}
	return uint16(remainder)
}