package util

import (
	"io"
	"log"
	"math/rand"
	"os"
	"path/filepath"
	"time"
)

type ReadWriteSeekCloser interface {
	io.Reader
	io.Writer
	io.Seeker
	io.Closer
}

func Conditoinal[T any](cond bool, t, f T) T {
	if cond {
		return t
	} else {
		return f
	}
}

// Bit1 检查字节中的某一位是否为1 |0|1|2|3|4|5|6|7|
func Bit1(b byte, index int) bool {
	return b&(1<<(7-index)) != 0
}

const charset = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789"

func RandomString(length int) string {
	seededRand := rand.New(rand.NewSource(time.Now().UnixNano()))
	b := make([]byte, length)
	for i := range b {
		b[i] = charset[seededRand.Intn(len(charset))]
	}
	return string(b)
}

func RandomNumString(length int) string {
	seededRand := rand.New(rand.NewSource(time.Now().UnixNano()))
	b := make([]byte, length)
	for i := range b {
		b[i] = "0123456789"[seededRand.Intn(10)]
	}
	return string(b)
}

func initFatalLog() *os.File {
	fatal_log_dir := "./fatal"
	if _fatal_log := os.Getenv("M7S_FATAL_LOG"); _fatal_log != "" {
		fatal_log_dir = _fatal_log
	}
	os.MkdirAll(fatal_log_dir, 0766)
	fatal_log := filepath.Join(fatal_log_dir, "latest.log")
	info, err := os.Stat(fatal_log)
	if err == nil && info.Size() != 0 {
		os.Rename(fatal_log, filepath.Join(fatal_log_dir, info.ModTime().Format("2006-01-02 15:04:05")+".log"))
	}
	logFile, err := os.OpenFile(fatal_log, os.O_CREATE|os.O_APPEND|os.O_RDWR, 0666)
	if err != nil {
		log.Println("服务启动出错", "打开异常日志文件失败", err)
		return nil
	}
	return logFile
}

func Exist(filename string) bool {
	_, err := os.Stat(filename)
	return err == nil || os.IsExist(err)
}