package utils

import (
	"crypto/md5"
	"crypto/rand"
	"encoding/hex"
	"io"
	"math"
	"math/big"
	"os"
	"reflect"
	"strings"

	"golang.org/x/exp/constraints"
)

// Concat 字符串拼接
func Concat(strArr ...string) string {

	var builder strings.Builder
	for i := 0; i < len(strArr); i++ {
		builder.WriteString(strArr[i])
	}

	return builder.String()
}

// PageLimitOffset 根据分页页数和页大小得到Limit&Offset
func PageLimitOffset(page int64, pageSize int64) (limit int64, offset int64) {

	limit = pageSize
	offset = pageSize * (page - 1)

	// 分页大小默认值
	if limit == 0 {
		limit = 10
	}

	return
}

// Ternary 三元运算
func Ternary[T any](ifOp bool, trueV, falseV T) T {
	if ifOp {
		return trueV
	}

	return falseV
}

// InSlice 判断指定值是否在切片中
func InSlice[T constraints.Ordered | reflect.Kind](needle T, haystack []T) bool {

	if len(haystack) == 0 {
		return false
	}

	for i := 0; i < len(haystack); i++ {
		if haystack[i] == needle {
			return true
		}
	}

	return false
}

// RandomExpire redis过期时间添加一个随机值
func RandomExpire(timestamp int64, randSecond int64) int64 {
	return timestamp + Rand(0, randSecond)
}

// Rand 生成区间[-m, n]的安全随机数
func Rand(min, max int64) int64 {
	if min > max {
		min, max = max, min
	}

	if min < 0 {
		i64Min := int64(math.Abs(float64(min)))
		result, _ := rand.Int(rand.Reader, big.NewInt(max+i64Min+1))

		return result.Int64() - i64Min
	} else {
		result, _ := rand.Int(rand.Reader, big.NewInt(max-min+1))
		return min + result.Int64()
	}
}

// SliceSum 切片求和
func SliceSum[T constraints.Integer | constraints.Float](slice []T) (sum T) {

	for i := 0; i < len(slice); i++ {
		sum += slice[i]
	}

	return sum
}

// SliceColumn 结构体切片,数组切片,map切片中提取指定字段
func SliceColumn[T, V any](slice []T, column string) []V {

	values := make([]V, len(slice))
	switch reflect.TypeOf(slice).Elem().Kind() {
	case reflect.Slice, reflect.Array:
		for i, v := range slice {
			values[i] = reflect.ValueOf(v).Index(int(reflect.ValueOf(column).Int())).Interface().(V)
		}
	case reflect.Map:
		for i, v := range slice {
			values[i] = reflect.ValueOf(v).MapIndex(reflect.ValueOf(column)).Interface().(V)
		}
	case reflect.Struct:
		for i, v := range slice {
			values[i] = StructColumnByTag[V](v, column, "json")
		}
	}

	return values
}

// SliceColumns 结构体切片,数组切片,map切片中提取指定多个字段, 以指定符号分割
func SliceColumns[T any](slice []T, sep string, columns ...string) []string {

	values := make([]string, 0, len(slice))

	sCols := make([][]any, 0, len(columns))
	for _, column := range columns {
		sCols = append(sCols, SliceColumn[T, any](slice, column))
	}

	for i := range sCols[0] {
		elems := make([]any, 0, len(columns))
		for j := range columns {
			elems = append(elems, sCols[j][i])
		}
		values = append(values, Implode(elems, sep))
	}

	return values
}

func StructColumnByTag[V any](s any, column, tag string) (ret V) {

	val, typ := Indirect(s)
	if typ.Kind() != reflect.Struct {
		panic("expect struct")
	}

	for i := 0; i < typ.NumField(); i++ {
		typField := typ.Field(i)

		if typField.Anonymous && typField.Type.Kind() == reflect.Struct {
			return StructColumnByTag[V](val.Field(i).Interface(), column, tag)
		}

		tagName := typField.Tag.Get(tag)
		if tagName == column {
			return val.Field(i).Interface().(V)
		}
	}

	return ret
}

// SliceDelIdx 删除切片中指定索引
func SliceDelIdx[T any](slice []T, idx ...int) []T {
	ret := make([]T, 0, len(slice))
	for i := 0; i < len(slice); i++ {
		if !InSlice(i, idx) {
			ret = append(ret, slice[i])
		}
	}
	return ret
}

// SliceDelVal 删除切片中指定值
func SliceDelVal[T constraints.Ordered](slice []T, val ...T) []T {

	ret := make([]T, 0, len(slice))
	for i := 0; i < len(slice); i++ {
		if !InSlice(slice[i], val) {
			ret = append(ret, slice[i])
		}
	}
	return ret
}

// IsDir 判断路径是否存在且为文件夹
func IsDir(path string) bool {
	stat, err := os.Stat(path)
	if err != nil {
		return false
	}

	return stat.IsDir()
}

// IsFile 判断路径是否存在且为文件
func IsFile(path string) bool {
	stat, err := os.Stat(path)
	if err != nil {
		return false
	}

	return !stat.IsDir()
}

// FileMD5 计算文件的Md5
func FileMD5(filePath string) (string, error) {
	file, err := os.Open(filePath)
	defer func() { _ = file.Close() }()

	if err != nil {
		return "", err
	}
	hash := md5.New()
	_, _ = io.Copy(hash, file)

	return hex.EncodeToString(hash.Sum(nil)), nil
}

// EqualSlice 切片是否相等
func EqualSlice[T constraints.Ordered](s1, s2 []T) bool {
	if len(s1) != len(s2) {
		return false
	}

	if (s1 == nil) != (s2 == nil) {
		return false
	}

	for i := 0; i < len(s1); i++ {
		if s1[i] != s2[i] {
			return false
		}
	}
	return true
}

// IsComplexType 判断是否为复杂数据结构
func IsComplexType(typ reflect.Type) bool {
	kind := typ.Kind()
	if !InSlice(kind, ComplexType) {
		return false
	}

	// []byte 不作为复杂类型
	if (kind == reflect.Slice || kind == reflect.Array) && typ.Elem().Kind() == reflect.Uint8 {
		return false
	}

	return true
}

// b=++a
func IncrementAfter(inNum *int64, increStepOpt ...int64) int64 {
	var (
		outNum, increStep int64
	)
	increStep = int64(1)
	if len(increStepOpt) > 0 {
		increStep = increStepOpt[0]
	}
	*inNum += increStep
	outNum = *inNum
	return outNum
}

// b=a++
func IncrementBefore(inNum *int64, increStepOpt ...int64) int64 {
	var (
		outNum, increStep int64
	)
	increStep = int64(1)
	if len(increStepOpt) > 0 {
		increStep = increStepOpt[0]
	}
	outNum = *inNum
	*inNum += increStep
	return outNum
}