package mysubaru

import (
	"fmt"
	"math"
	"net/mail"
	"reflect"
	"regexp"
	"strconv"
	"strings"
	"time"
)

// timestamp is a function
func timestamp() string {
	return strconv.FormatInt(time.Now().UnixNano()/1000000, 10)
}

// urlToGen .
func urlToGen(url string, gen string) string {
	var re = regexp.MustCompile(`api_gen`)
	// dirty trick for current G3
	if gen == "g3" {
		gen = "g2"
	}
	url = re.ReplaceAllString(url, gen)

	return url
}

// VinCheck - Vehicle Identification Number check digit validation
// Parameter: string - 17 digit VIN
// Return:
//
//	1- boolean - Validity flag. Set to true if VIN check digit is correct, false otherwise.
//	2- string - Valid VIN. Same VIN passed as parameter but with the correct check digit on it.
func vinCheck(vin string) (bool, string) {
	var valid = false
	vin = strings.ToUpper(vin)
	var retVin = vin

	if len(vin) == 17 {
		traSum := transcodeDigits(vin)
		checkNum := math.Mod(float64(traSum), 11)
		var checkDigit byte
		if checkNum == 10 {
			checkDigit = byte('X')
		} else {
			checkDigitTemp := strconv.Itoa(int(checkNum))
			checkDigit = checkDigitTemp[len(checkDigitTemp)-1]
		}
		if retVin[8] == checkDigit {
			valid = true
		}
		retVin = retVin[:8] + string(checkDigit) + retVin[9:]
	} else {
		valid = false
		retVin = ""
	}

	return valid, retVin
}

// transcodeDigits transcodes VIN digits to a numeric value
func transcodeDigits(vin string) int {
	var digitSum = 0
	var code int
	for i, chr := range vin {
		code = 0

		switch chr {
		case 'A', 'J', '1':
			code = 1
		case 'B', 'K', 'S', '2':
			code = 2
		case 'C', 'L', 'T', '3':
			code = 3
		case 'D', 'M', 'U', '4':
			code = 4
		case 'E', 'N', 'V', '5':
			code = 5
		case 'F', 'W', '6':
			code = 6
		case 'G', 'P', 'X', '7':
			code = 7
		case 'H', 'Y', '8':
			code = 8
		case 'R', 'Z', '9':
			code = 9
		case 'I', 'O', 'Q':
			code = 0
		}
		switch i + 1 {
		case 1, 11:
			digitSum += code * 8
		case 2, 12:
			digitSum += code * 7
		case 3, 13:
			digitSum += code * 6
		case 4, 14:
			digitSum += code * 5
		case 5, 15:
			digitSum += code * 4
		case 6, 16:
			digitSum += code * 3
		case 7, 17:
			digitSum += code * 2
		case 8:
			digitSum += code * 10
		case 9:
			digitSum += code * 0
		case 10:
			digitSum += code * 9
		}
	}

	return digitSum
}

// emailMasking takes an email address as input and returns a version of the email
// with the username part partially hidden for privacy. Only the first and last
// characters of the username are visible, with the middle characters replaced by asterisks.
// The function validates the email format before processing.
// Returns the obfuscated email or an error if the input is not a valid email address.
func emailMasking(email string) (string, error) {
	_, err := mail.ParseAddress(email)
	if err != nil {
		return "", fmt.Errorf("invalid email address: %s", email)
	}

	re1 := regexp.MustCompile(`^(.*?)@(.*)$`)
	matches := re1.FindStringSubmatch(email)

	var username, domain string
	if len(matches) == 3 { // Expecting the full match, username, and domain
		username = matches[1]
		domain = matches[2]
	} else {
		return "", fmt.Errorf("invalid email format: %s", email)
	}

	re2 := regexp.MustCompile(`(.)(.*)(.)`)

	replacedString := re2.ReplaceAllStringFunc(username, func(s string) string {
		firstChar := string(s[0])
		lastChar := string(s[len(s)-1])
		middleCharsCount := len(s) - 2

		if middleCharsCount < 0 { // Should not happen with the length check above, but for robustness
			return s
		}
		return firstChar + strings.Repeat("*", middleCharsCount) + lastChar
	})

	return replacedString + "@" + domain, nil
}

// containsValueInStruct checks if any string field in the given struct 's' contains the specified 'search' substring (case-insensitive).
// It returns true if at least one string field contains the substring, and false otherwise.
// If 's' is not a struct, it returns false.
func containsValueInStruct(s any, search string) bool {
	val := reflect.ValueOf(s)
	if val.Kind() != reflect.Struct {
		return false // Not a struct
	}

	for i := 0; i < val.NumField(); i++ {
		field := val.Field(i)
		if field.Kind() == reflect.String {
			if strings.Contains(strings.ToLower(field.String()), strings.ToLower(search)) {
				return true
			}
		}
	}

	return false
}

// timeTrack .
// func timeTrack(name string) {
// 	start := time.Now()
// 	fmt.Printf("%s took %v\n", name, time.Since(start))
// }