package utils

import (
	"crypto/md5"
	"crypto/rand"
	"encoding/hex"
	"fmt"
	"hash"
	rand2 "math/rand"
	"net/url"
	"reflect"
	"sort"
	"strconv"
	"strings"
	"time"
)

type UUID [16]byte

const letterBytes = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ"

func GetUUID() (uuidHex string) {
	uuid := NewUUID()
	uuidHex = hex.EncodeToString(uuid[:])
	return
}

func NewUUID() UUID {
	ns := UUID{}
	safeRandom(ns[:])
	u := newFromHash(md5.New(), ns, RandStringBytes(16))
	u[6] = (u[6] & 0x0f) | (byte(2) << 4)
	u[8] = (u[8]&(0xff>>2) | (0x02 << 6))

	return u
}

func RandStringBytes(n int) string {
	b := make([]byte, n)
	for i := range b {
		b[i] = letterBytes[rand2.Intn(len(letterBytes))]
	}
	return string(b)
}

func newFromHash(h hash.Hash, ns UUID, name string) UUID {
	u := UUID{}
	h.Write(ns[:])
	h.Write([]byte(name))
	copy(u[:], h.Sum(nil))

	return u
}

func safeRandom(dest []byte) {
	if _, err := rand.Read(dest); err != nil {
		panic(err)
	}
}

func GetUrlFormedMap(source map[string]string) (urlEncoded string) {
	urlEncoder := url.Values{}
	for key, value := range source {
		urlEncoder.Add(key, value)
	}
	urlEncoded = urlEncoder.Encode()
	return
}

func GetUrlByKeySort(source map[string]string) (url string) {
	keys := make([]string, 0, len(source))
	for k := range source {
		keys = append(keys, k)
	}
	sort.Strings(keys)
	for _, key := range keys {
		url += fmt.Sprintf("%s=%s&", key, source[key])
	}
	return strings.TrimRight(url, "&")
}

func InitStructWithDefaultTag(bean interface{}) {
	beantype := reflect.TypeOf(bean)
	for i := 0; i < beantype.Elem().NumField(); i++ {
		field := beantype.Elem().Field(i)
		defaultValue := strings.TrimSpace(field.Tag.Get("default"))
		if defaultValue == "" || defaultValue == "-" {
			continue
		}
		setter := reflect.ValueOf(bean).Elem().Field(i)
		fieldTypeName := field.Type.String()
		switch fieldTypeName {
		case "int", "int64", "int32", "int8", "int16":
			intval, _ := strconv.ParseInt(defaultValue, 10, 64)
			setter.SetInt(intval)
		case "uint", "uint8", "uint16", "uint32", "uint64", "uintptr":
			uintval, _ := strconv.ParseUint(defaultValue, 10, 64)
			setter.SetUint(uintval)
		case "string":
			setter.SetString(defaultValue)
		case "time.Duration":
			intval, _ := strconv.ParseInt(defaultValue, 10, 64)
			setter.SetInt(intval * int64(time.Second))
		case "bool":
			boolval, _ := strconv.ParseBool(defaultValue)
			setter.SetBool(boolval)
		default:
			fmt.Println(field.Type.String(), field.Name)
		}
	}
}