package password

import (
	"fmt"
	"regexp"
	"strings"
	"unicode"
)

// Check checks if password is valid, and returns message, and if its a strong password
func Check(input string, wordList, passwordList []string) (string, error) {
	// Variables to check state of password
	hasCapitalLetter := false
	hasSpecialCharacter := false
	isTwelveCharacters := false
	hasNumber := false

	// Check if password is shorter than 8 characters
	if len(input) < 2 {
		return "Weak password", fmt.Errorf("password cannot be shorter than 12 characters")
	} else {
		isTwelveCharacters = true
	}

	// Check if password contains a number and a special character and a capital letter
	for _, letter := range input {
		// Check if letter is a symbol
		if !(unicode.IsLetter(letter) || unicode.IsDigit(letter) || unicode.IsSpace(letter)) {
			hasSpecialCharacter = true
		}

		// Check if letter is a number
		if unicode.IsDigit(letter) {
			hasNumber = true
		}

		// Check if letter is a capital letter
		if unicode.IsUpper(letter) {
			hasCapitalLetter = true
		}

		// Check for spaces
		if unicode.IsSpace(letter) {
			return "Invalid password", fmt.Errorf("password cannot contain spaces")
		}
	}

	// Check if password is in common passwords
	for _, entry := range passwordList {
		if strings.Contains(strings.ToLower(entry), strings.ToLower(input)) {
			return "Weak password", fmt.Errorf("password found inside common passwords")
		}
	}

	// Check if password contains any common words
	re, _ := regexp.Compile(`[^a-zA-Z]+`) // Use regex to match anything thats not a letter
	// Replace all nonletter characters with blank space
	strippedPassword := re.ReplaceAllString(input, "")
	// Iterate through common words and see if input contains any
	for _, word := range wordList {
		if strings.Contains(strings.ToLower(word), strings.ToLower(strippedPassword)) {
			return "Weak password", fmt.Errorf("password contains common word from wordlist")
		}
	}

	if !(hasNumber && hasSpecialCharacter && isTwelveCharacters && hasCapitalLetter) {
		return "Weak password", fmt.Errorf("Has number: %v, Has special character: %v, Has 12+ characters: %v, Has capital letter: %v", hasNumber, hasSpecialCharacter, isTwelveCharacters, hasCapitalLetter)
	}

	return "Strong password", nil
}