package file

import (
	"errors"
	"fmt"
	"io"
	"mime/multipart"
	"os"
	"path"
	"time"

	"github.com/h2non/filetype"
	gonanoid "github.com/matoous/go-nanoid/v2"
)

const (
	MaxImageSize = 10 << 20 // 10 MB
	MaxFileSize  = 50 << 20 // 50 MB
)

var ErrUnsupported = errors.New("文件格式不支持")

type FileType int

const (
	ALL FileType = 0
	IMG FileType = 1
)

func UploadFilename(filepath string, t FileType) (string, error) {
	fileOpen, err := os.Open(filepath)
	if err != nil {
		return "", err
	}
	defer fileOpen.Close()

	fileBytes, err := io.ReadAll(fileOpen)
	if err != nil {
		return "", errors.New("failed to read file")
	}

	if t == IMG {
		// 判断是不是图片
		if !filetype.IsImage(fileBytes) {
			return "", ErrUnsupported
		}
	}

	kind, err := filetype.Match(fileBytes)
	if err != nil {
		return "", err
	}

	if kind == filetype.Unknown {
		return "", ErrUnsupported
	}

	// 使用 filetype 判断类型后已经去读了一些bytes了
	// 要恢复文件读取位置
	_, err = fileOpen.Seek(0, io.SeekStart)
	if err != nil {
		return "", err
	}

	dir := GetPath()
	exist, _ := Exists(dir)
	if !exist {
		if err := Mkdir(dir); err != nil {
			return "", err
		}
	}

	filename := GenFilename(kind.Extension)
	path := path.Join(dir, filename)
	f, err := os.Create(path)
	if err != nil {
		return "", err
	}
	defer f.Close()

	_, err = io.Copy(f, fileOpen)
	if err != nil {
		return "", err
	}

	return "/" + path, nil
}

func UploadFile(file *multipart.FileHeader, t FileType) (string, error) {
	if file.Size > MaxFileSize {
		return "", errors.New("failed to receive file too large")
	}

	fileOpen, err := file.Open()
	if err != nil {
		return "", errors.New("fialed to open file")
	}
	defer fileOpen.Close()

	fileBytes, err := io.ReadAll(fileOpen)
	if err != nil {
		return "", errors.New("failed to read file")
	}

	if t == IMG {
		// 判断是不是图片
		if !filetype.IsImage(fileBytes) {
			return "", ErrUnsupported
		}
	}

	kind, err := filetype.Match(fileBytes)
	if err != nil {
		return "", err
	}

	if kind == filetype.Unknown {
		return "", ErrUnsupported
	}

	// 使用 filetype 判断类型后已经去读了一些bytes了
	// 要恢复文件读取位置
	_, err = fileOpen.Seek(0, io.SeekStart)
	if err != nil {
		return "", err
	}

	dir := GetPath()
	exist, _ := Exists(dir)
	if !exist {
		if err := Mkdir(dir); err != nil {
			return "", err
		}
	}

	filename := GenFilename(kind.Extension)
	path := path.Join(dir, filename)
	f, err := os.Create(path)
	if err != nil {
		return "", err
	}
	defer f.Close()

	_, err = io.Copy(f, fileOpen)
	if err != nil {
		return "", err
	}

	return "/" + path, nil
}

func GetPath() string {
	return fmt.Sprintf("public/%s/%s/%s/", time.Now().Format("2006"), time.Now().Format("01"), time.Now().Format("02"))
}

func GenFilename(ext string) string {
	id, _ := gonanoid.New()
	return fmt.Sprintf("%s.%s", id, ext)
}