package db

import (
	"os"
	"path/filepath"
	"regexp"
	"strings"
)

var (
	appIdRE       = regexp.MustCompile(`^\d+$`)
	matchFirstCap = regexp.MustCompile("(.)([A-Z][a-z]+)")
	matchAllCap   = regexp.MustCompile("([a-z0-9])([A-Z])")
)

func ToSnakeCase(str string) string {
	snake := matchFirstCap.ReplaceAllString(str, "${1}_${2}")
	snake = matchAllCap.ReplaceAllString(snake, "${1}_${2}")
	return strings.ToLower(snake)
}

func IsAppID(s string) bool {
	return len(s) > 0 && appIdRE.MatchString(s)
}

// WriteFile will write the info on array of bytes b to filepath. It will set the file
// permission mode to 0660
// Returns an error in case there's any.
func WriteFile(filepath string, b []byte) error {
	return os.WriteFile(filepath, b, 0660)
}

// GetFile will open filepath.
// Returns a tuple with a file and an error in case there's any.
func GetFile(filepath string) (*os.File, error) {
	return os.OpenFile(filepath, os.O_CREATE|os.O_RDWR|os.O_APPEND, 0777)
}

// DeleteFile will delete filepath permanently.
// Returns an error in case there's any.
func DeleteFile(filepath string) error {
	_, err := os.Stat(filepath)
	if err != nil {
		if os.IsNotExist(err) {
			return nil
		}
		return err
	}
	return os.Remove(filepath)
}

func TempDir(appName string) (string, error) {
	homeDir, err := os.UserHomeDir()
	if err != nil {
		return "", err
	}
	tempDir, err := filepath.Abs(homeDir + "/.pmt/" + appName)
	if err != nil {
		return "", err
	}
	err = os.MkdirAll(tempDir, os.ModePerm)
	if err != nil {
		return "", err
	}
	return tempDir, nil
}