// Copyright 2021 dudaodong@gmail.com. All rights reserved.
// Use of this source code is governed by MIT license.

// Package fileutil implements some basic functions for file operations
package fileutil

import (
	"archive/zip"
	"bufio"
	"bytes"
	"errors"
	"fmt"
	"io"
	"io/fs"
	"net/http"
	"os"
	"path"
	"path/filepath"
	"runtime"
	"strings"
)

// IsExist checks if a file or directory exists.
// Play: https://go.dev/play/p/nKKXt8ZQbmh
func IsExist(path string) bool {
	_, err := os.Stat(path)
	if err == nil {
		return true
	}
	if errors.Is(err, os.ErrNotExist) {
		return false
	}
	return false
}

// CreateFile create a file in path.
// Play: https://go.dev/play/p/lDt8PEsTNKI
func CreateFile(path string) bool {
	file, err := os.Create(path)
	if err != nil {
		return false
	}

	defer file.Close()
	return true
}

// CreateDir create directory in absolute path. param `absPath` like /a/, /a/b/.
// Play: https://go.dev/play/p/qUuCe1OGQnM
func CreateDir(absPath string) error {
	return os.MkdirAll(path.Dir(absPath), os.ModePerm)
}

// IsDir checks if the path is directory or not.
// Play: https://go.dev/play/p/WkVwEKqtOWk
func IsDir(path string) bool {
	file, err := os.Stat(path)
	if err != nil {
		return false
	}
	return file.IsDir()
}

// RemoveFile remove the path file.
// Play: https://go.dev/play/p/P2y0XW8a1SH
func RemoveFile(path string) error {
	return os.Remove(path)
}

// CopyFile copy src file to dest file.
// Play: https://go.dev/play/p/Jg9AMJMLrJi
func CopyFile(srcFilePath string, dstFilePath string) error {
	srcFile, err := os.Open(srcFilePath)
	if err != nil {
		return err
	}
	defer srcFile.Close()

	distFile, err := os.Create(dstFilePath)
	if err != nil {
		return err
	}
	defer distFile.Close()

	var tmp = make([]byte, 1024*4)
	for {
		n, err := srcFile.Read(tmp)
		if err != nil {
			if err == io.EOF {
				return nil
			}
			return err
		}
		_, err = distFile.Write(tmp[:n])
		if err != nil {
			return err
		}
	}
}

// ClearFile write empty string to path file.
// Play: https://go.dev/play/p/NRZ0ZT-G94H
func ClearFile(path string) error {
	f, err := os.OpenFile(path, os.O_WRONLY|os.O_TRUNC, 0777)
	if err != nil {
		return err
	}
	defer f.Close()

	_, err = f.WriteString("")
	return err
}

// ReadFileToString return string of file content.
// Play: https://go.dev/play/p/cmfwp_5SQTp
func ReadFileToString(path string) (string, error) {
	bytes, err := os.ReadFile(path)
	if err != nil {
		return "", err
	}
	return string(bytes), nil
}

// ReadFileByLine read file line by line.
// Play: https://go.dev/play/p/svJP_7ZrBrD
func ReadFileByLine(path string) ([]string, error) {
	f, err := os.Open(path)
	if err != nil {
		return nil, err
	}
	defer f.Close()

	result := make([]string, 0)
	buf := bufio.NewReader(f)

	for {
		line, _, err := buf.ReadLine()
		l := string(line)
		if err == io.EOF {
			break
		}
		if err != nil {
			continue
		}
		result = append(result, l)
	}

	return result, nil
}

// ListFileNames return all file names in the path.
// Play: https://go.dev/play/p/Tjd7Y07rejl
func ListFileNames(path string) ([]string, error) {
	if !IsExist(path) {
		return []string{}, nil
	}

	fs, err := os.ReadDir(path)
	if err != nil {
		return []string{}, err
	}

	sz := len(fs)
	if sz == 0 {
		return []string{}, nil
	}

	result := []string{}
	for i := 0; i < sz; i++ {
		if !fs[i].IsDir() {
			result = append(result, fs[i].Name())
		}
	}

	return result, nil
}

// IsZipFile checks if file is zip or not.
// Play: todo
func IsZipFile(filepath string) bool {
	f, err := os.Open(filepath)
	if err != nil {
		return false
	}
	defer f.Close()

	buf := make([]byte, 4)
	if n, err := f.Read(buf); err != nil || n < 4 {
		return false
	}

	return bytes.Equal(buf, []byte("PK\x03\x04"))
}

// Zip create zip file, fpath could be a single file or a directory.
// Play: https://go.dev/play/p/j-3sWBp8ik_P
func Zip(fpath string, destPath string) error {
	zipFile, err := os.Create(destPath)
	if err != nil {
		return err
	}
	defer zipFile.Close()

	archive := zip.NewWriter(zipFile)
	defer archive.Close()

	err = filepath.Walk(fpath, func(path string, info os.FileInfo, err error) error {
		if err != nil {
			return err
		}

		header, err := zip.FileInfoHeader(info)
		if err != nil {
			return err
		}

		header.Name = strings.TrimPrefix(path, filepath.Dir(fpath)+"/")

		if info.IsDir() {
			header.Name += "/"
		} else {
			header.Method = zip.Deflate
		}

		writer, err := archive.CreateHeader(header)
		if err != nil {
			return err
		}

		if !info.IsDir() {
			file, err := os.Open(path)
			if err != nil {
				return err
			}
			defer file.Close()
			_, err = io.Copy(writer, file)
			if err != nil {
				return err
			}
		}
		return nil
	})

	if err != nil {
		return err
	}

	return nil
}

// UnZip unzip the file and save it to destPath.
// Play: https://go.dev/play/p/g0w34kS7B8m
func UnZip(zipFile string, destPath string) error {

	zipReader, err := zip.OpenReader(zipFile)
	if err != nil {
		return err
	}
	defer zipReader.Close()

	for _, f := range zipReader.File {
		//issue#62: fix ZipSlip bug
		path, err := safeFilepathJoin(destPath, f.Name)
		if err != nil {
			return err
		}

		if f.FileInfo().IsDir() {
			err = os.MkdirAll(path, os.ModePerm)
			if err != nil {
				return err
			}
		} else {
			err = os.MkdirAll(filepath.Dir(path), os.ModePerm)
			if err != nil {
				return err
			}

			inFile, err := f.Open()
			if err != nil {
				return err
			}
			defer inFile.Close()

			outFile, err := os.OpenFile(path, os.O_WRONLY|os.O_CREATE|os.O_TRUNC, f.Mode())
			if err != nil {
				return err
			}
			defer outFile.Close()

			_, err = io.Copy(outFile, inFile)
			if err != nil {
				return err
			}
		}
	}

	return nil
}

func safeFilepathJoin(path1, path2 string) (string, error) {
	relPath, err := filepath.Rel(".", path2)
	if err != nil || strings.HasPrefix(relPath, "..") {
		return "", fmt.Errorf("(zipslip) filepath is unsafe %q: %v", path2, err)
	}
	if path1 == "" {
		path1 = "."
	}
	return filepath.Join(path1, filepath.Join("/", relPath)), nil
}

// IsLink checks if a file is symbol link or not.
// Play: https://go.dev/play/p/TL-b-Kzvf44
func IsLink(path string) bool {
	fi, err := os.Lstat(path)
	if err != nil {
		return false
	}
	return fi.Mode()&os.ModeSymlink != 0
}

// FileMode return file's mode and permission.
// Play: https://go.dev/play/p/2l2hI42fA3p
func FileMode(path string) (fs.FileMode, error) {
	fi, err := os.Lstat(path)
	if err != nil {
		return 0, err
	}
	return fi.Mode(), nil
}

// MiMeType return file mime type
// param `file` should be string(file path) or *os.File.
// Play: https://go.dev/play/p/bd5sevSUZNu
func MiMeType(file any) string {
	var mediatype string

	readBuffer := func(f *os.File) ([]byte, error) {
		buffer := make([]byte, 512)
		_, err := f.Read(buffer)
		if err != nil {
			return nil, err
		}
		return buffer, nil
	}

	if filePath, ok := file.(string); ok {
		f, err := os.Open(filePath)
		if err != nil {
			return mediatype
		}
		buffer, err := readBuffer(f)
		if err != nil {
			return mediatype
		}
		return http.DetectContentType(buffer)
	}

	if f, ok := file.(*os.File); ok {
		buffer, err := readBuffer(f)
		if err != nil {
			return mediatype
		}
		return http.DetectContentType(buffer)
	}
	return mediatype
}

// CurrentPath return current absolute path.
// Play: https://go.dev/play/p/s74a9iBGcSw
func CurrentPath() string {
	var absPath string
	_, filename, _, ok := runtime.Caller(1)
	if ok {
		absPath = path.Dir(filename)
	}

	return absPath
}