package files

import (
	"errors"
	"io"
	"lab.evlic.cn/go/pkg/md5"
	"mime/multipart"
	"os"

	"path/filepath"
	"strings"

	"go.uber.org/zap"
)

func FileSave(r io.Reader, dst string) (err error) {
	var (
		fp  string
		out io.WriteCloser
	)
	fp = filepath.Dir(dst)
	err = DirCheck(fp)

	out, err = os.Create(dst)
	if err != nil {
		return err
	}
	defer out.Close()

	_, err = io.Copy(out, r)
	return
}

// FileMD5 计算文件 md5 值
func FileMD5(file string) (string, error) {
	f, err := os.Open(file)

	if err != nil {
		return "", err
	}

	info, err := f.Stat()
	if err != nil {
		return "", err
	}

	size := info.Size()
	return md5.Sum(f, size, BlockSize, ChunkSize)
}

func MultipartMD5(fh *multipart.FileHeader) (string, error) {
	f, err := fh.Open()

	if err != nil {
		return "", err
	}

	size := fh.Size
	return md5.Sum(f, size, BlockSize, ChunkSize)
}

const (
	BlockSize = 1 << 10
	ChunkSize = BlockSize << 2
)

var (
	ErrorIsNotDir = errors.New("path is not dir. ")
)

func DirCheck(dir string) (err error) {
	var fi os.FileInfo
	if fi, err = os.Stat(dir); err != nil {
		if !os.IsExist(err) || os.IsNotExist(err) {
			return DirMk(dir)
		}
	}

	if !fi.IsDir() {
		err = ErrorIsNotDir
	}

	return
}

func DirMk(dir string) error {
	return os.MkdirAll(dir, 0755)
}

const MaxScanDeep = 20

var maxDeepError = errors.New("scanMaxDeep")

func IsScanMaxDeep(err error) bool {
	return errors.Is(err, maxDeepError)
}

// DirScan 扫描目录，on err skip
func DirScan(dir string, h func(dir string, info os.FileInfo)) error {
	return dirScan(dir, h, 0)
}

func dirScanIgnore(name string) bool {
	return strings.HasPrefix(name, ".") ||
		strings.Contains(strings.ToLower(name), "readme")
}

func dirScan(dir string, h func(dir string, info os.FileInfo), deep int) error {
	if deep > MaxScanDeep {
		return maxDeepError
	}
	dirs, err := os.ReadDir(dir)
	if err != nil {
		return err
	}

	var (
		info    os.FileInfo
		nextDir string
	)
	for _, entry := range dirs {
		info, err = entry.Info()
		if err != nil {
			zap.L().Warn("scan err", zap.String("name", entry.Name()), zap.Error(err))
			continue
		}

		if dirScanIgnore(info.Name()) {
			continue
		}

		h(dir, info)
		if entry.IsDir() {
			nextDir = filepath.Join(dir, info.Name())
			if err = dirScan(nextDir, h, deep+1); err != nil {
				zap.L().Warn("scan err", zap.String("dirname", nextDir), zap.Error(err))
			}
		}
	}
	return err
}

func PathAbs(path string) string {
	if filepath.IsAbs(path) {
		return path
	}

	abs, err := filepath.Abs(path)
	if err != nil {
		return path
	}
	return abs
}