package utils

import (
	"encoding/binary"
	"math/rand"
	"net"
	"os"
	"reflect"
	"strconv"
	"strings"
	"time"
)

//LowerFirst Make a string's first character lowercase
func LowerFirst(s string) string {
	isFirst := true
	return strings.Map(func(r rune) rune {
		if isFirst && r >= 'A' && r <= 'Z' {
			r = r + 32
		}
		isFirst = false
		return r
	}, s)
}

//UpperFirst Make a string's first character uppercase
func UpperFirst(s string) string {
	isFirst := true
	return strings.Map(func(r rune) rune {
		if isFirst && r >= 'a' && r <= 'z' {
			r = r - 32
		}
		isFirst = false
		return r
	}, s)
}

//InArray  Checks if a value exists in an array
func InArray(needle interface{}, haystack interface{}) bool {
	val := reflect.ValueOf(haystack)
	switch val.Kind() {
	case reflect.Slice, reflect.Array:
		for i := 0; i < val.Len(); i++ {
			if reflect.DeepEqual(needle, val.Index(i).Interface()) {
				return true
			}
		}
	case reflect.Map:
		for _, k := range val.MapKeys() {
			if reflect.DeepEqual(needle, val.MapIndex(k).Interface()) {
				return true
			}
		}
	default:
		panic("haystack: haystack type must be slice, array or map")
	}

	return false
}

//IsEmpty Determine whether a variable is empty
func IsEmpty(val interface{}) bool {
	if val == nil {
		return true
	}
	v := reflect.ValueOf(val)
	switch v.Kind() {
	case reflect.String, reflect.Array:
		return v.Len() == 0
	case reflect.Map, reflect.Slice:
		return v.Len() == 0 || v.IsNil()
	case reflect.Bool:
		return !v.Bool()
	case reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64:
		return v.Int() == 0
	case reflect.Uint, reflect.Uint8, reflect.Uint16, reflect.Uint32, reflect.Uint64, reflect.Uintptr:
		return v.Uint() == 0
	case reflect.Float32, reflect.Float64:
		return v.Float() == 0
	case reflect.Interface, reflect.Ptr:
		return v.IsNil()
	}
	return reflect.DeepEqual(val, reflect.Zero(v.Type()).Interface())
}

//IsNumeric Finds whether a variable is a number or a numeric string
func IsNumeric(val interface{}) bool {
	switch val.(type) {
	case int, int8, int16, int32, int64, uint, uint8, uint16, uint32, uint64:
		return true
	case float32, float64, complex64, complex128:
		return true
	case string:
		str := val.(string)
		if str == "" {
			return false
		}
		// Trim any whitespace
		str = strings.TrimSpace(str)
		if str[0] == '-' || str[0] == '+' {
			if len(str) == 1 {
				return false
			}
			str = str[1:]
		}
		// hex
		if len(str) > 2 && str[0] == '0' && (str[1] == 'x' || str[1] == 'X') {
			for _, h := range str[2:] {
				if !((h >= '0' && h <= '9') || (h >= 'a' && h <= 'f') || (h >= 'A' && h <= 'F')) {
					return false
				}
			}
			return true
		}
		// 0-9, Point, Scientific
		p, s, l := 0, 0, len(str)
		for i, v := range str {
			if v == '.' { // Point
				if p > 0 || s > 0 || i+1 == l {
					return false
				}
				p = i
			} else if v == 'e' || v == 'E' { // Scientific
				if i == 0 || s > 0 || i+1 == l {
					return false
				}
				s = i
			} else if v < '0' || v > '9' {
				return false
			}
		}
		return true
	}
	return false
}

//BreakUp break strings
func BreakUp(s string) []string {
	length := len(s)
	b := make([]byte, length)
	ss := make([]string, 0)
	var p int
	for i := 0; i < length; i++ {
		if s[i] >= 'A' && s[i] <= 'Z' {
			if p > 0 {
				ss = append(ss, string(b[:p]))
			}
			p = 0
			b[p] = s[i] + 32
		} else {
			b[p] = s[i]
		}
		p++
	}
	if p > 0 {
		ss = append(ss, string(b[:p]))
	}
	return ss
}

//Camel2id eg SendMail into send-mail
func Camel2id(s string) string {
	return strings.Join(BreakUp(s), "-")
}

//Rand Generate a random integer
func Rand(min, max int) int {
	if min > max {
		panic("min: min cannot be greater than max")
	}
	if int31 := 1<<31 - 1; max > int31 {
		panic("max: max can not be greater than " + strconv.Itoa(int31))
	}
	if min == max {
		return min
	}
	r := rand.New(rand.NewSource(time.Now().UnixNano()))
	return r.Intn(max+1-min) + min
}

//FileExists Checks whether a file or directory exists
func FileExists(filename string) bool {
	if _, err := os.Stat(filename); err != nil && os.IsNotExist(err) {
		return false
	}
	return true
}

//IsDir Tells whether the filename is a directory
func IsDir(filename string) (bool, error) {
	fd, err := os.Stat(filename)
	if err != nil {
		return false, err
	}
	fm := fd.Mode()
	return fm.IsDir(), nil
}

//SimilarText Calculate the similarity between two strings
func SimilarText(first, second string, percent *float64) int {
	var similarText func(string, string, int, int) int
	similarText = func(str1, str2 string, len1, len2 int) int {
		var sum, max int
		pos1, pos2 := 0, 0

		// Find the longest segment of the same section in two strings
		for i := 0; i < len1; i++ {
			for j := 0; j < len2; j++ {
				for l := 0; (i+l < len1) && (j+l < len2) && (str1[i+l] == str2[j+l]); l++ {
					if l+1 > max {
						max = l + 1
						pos1 = i
						pos2 = j
					}
				}
			}
		}

		if sum = max; sum > 0 {
			if pos1 > 0 && pos2 > 0 {
				sum += similarText(str1, str2, pos1, pos2)
			}
			if (pos1+max < len1) && (pos2+max < len2) {
				s1 := []byte(str1)
				s2 := []byte(str2)
				sum += similarText(string(s1[pos1+max:]), string(s2[pos2+max:]), len1-pos1-max, len2-pos2-max)
			}
		}
		return sum
	}
	l1, l2 := len(first), len(second)
	if l1+l2 == 0 {
		return 0
	}
	sim := similarText(first, second, l1, l2)
	if percent != nil {
		*percent = float64(sim*200) / float64(l1+l2)
	}
	return sim
}

//IP2long Converts a string containing an (IPv4) Internet Protocol dotted address into a long integer
func IP2long(ipAddress string) uint32 {
	ip := net.ParseIP(ipAddress)
	if ip == nil {
		return 0
	}
	return binary.BigEndian.Uint32(ip.To4())
}

//Long2IP Converts an long integer address into a string in (IPv4) Internet standard dotted format
func Long2IP(properAddress uint32) string {
	ipByte := make([]byte, 4)
	binary.BigEndian.PutUint32(ipByte, properAddress)
	ip := net.IP(ipByte)
	return ip.String()
}