package utils

import (
	"api/globals"
	"api/models"
	"crypto/rand"
	"encoding/json"
	"errors"
	"fmt"
	"io/ioutil"
	"log"
	"math/big"
	"net/http"
	"strconv"
	"strings"

	"gopkg.in/gomail.v2"

	"golang.org/x/crypto/bcrypt"
)

type Charset string

const (
	Alphanumeric      = Charset("abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789")
	Lowercase         = Charset("abcdefghijklmnopqrstuvwxyz")
	Uppercase         = Charset("ABCDEFGHIJKLMNOPQRSTUVWXYZ")
	Numeric           = Charset("0123456789")
	SpecialCharacters = Charset("!@#$%^&*()-_=+[]{}|;:'<>,.?/~")
)

var (
	GenerateString = generateString
)

type GenerationOptions struct {
	Length                 int
	DisableNumeric         bool
	DisableLowercase       bool
	DisableUppercase       bool
	EnableSpecialCharacter bool
	CustomCharset          Charset
}

// generateStringFromCharset generates a random string from a given charset
func generateStringFromCharset(charset Charset, length int) (string, error) {
	if len(charset) == 0 || length <= 0 {
		return "", errors.New("invalid charset or length")
	}

	result := make([]byte, length)
	charsetLen := big.NewInt(int64(len(charset)))
	for i := 0; i < length; i++ {
		randomIndex, err := rand.Int(rand.Reader, charsetLen)
		if err != nil {
			return "", err
		}
		result[i] = charset[randomIndex.Int64()]
	}

	return string(result), nil
}

// modifyCharset modifies the charset based on the options
func modifyCharset(opts GenerationOptions, charsetMappings map[string]Charset, charset Charset) Charset {
	if opts.DisableNumeric {
		charset = Charset(strings.ReplaceAll(string(charset), string(charsetMappings["numeric"]), ""))
	}
	if opts.DisableLowercase {
		charset = Charset(strings.ReplaceAll(string(charset), string(charsetMappings["lowercase"]), ""))
	}
	if opts.DisableUppercase {
		charset = Charset(strings.ReplaceAll(string(charset), string(charsetMappings["uppercase"]), ""))
	}
	if opts.EnableSpecialCharacter {
		charset += charsetMappings["specialCharater"]
	}
	return charset
}

// generateString generates a random string based on the options
func generateString(opts GenerationOptions) (string, error) {
	charsetMappings := map[string]Charset{
		"numeric":         Numeric,
		"lowercase":       Lowercase,
		"uppercase":       Uppercase,
		"specialCharater": SpecialCharacters,
	}

	charset := Alphanumeric
	if opts.CustomCharset != "" {
		charset = opts.CustomCharset
	} else {
		charset = modifyCharset(opts, charsetMappings, charset)
	}

	if len(charset) == 0 {
		return "", errors.New("resulting charset is empty. adjust your options")
	}

	return generateStringFromCharset(charset, opts.Length)
}

func HashPassword(password string) ([]byte, error) {
	return bcrypt.GenerateFromPassword([]byte(password), bcrypt.DefaultCost)
}

func PrettyPrintJson(data interface{}) {
	b, err := json.MarshalIndent(data, "", "  ")
	if err != nil {
		fmt.Println("error:", err)
	}
	log.Println(string(b))
}

// IsValid checks if a CNPJ is valid
func IsValid(cnpj string) bool {
	// Remove non-numeric characters
	cnpj = removeNonDigits(cnpj)

	if len(cnpj) != 14 || allDigitsEqual(cnpj) {
		return false
	}

	// Validate check digits
	return checkCNPJCheckDigits(cnpj)
}

// removeNonDigits removes all non-numeric characters from a string
func removeNonDigits(input string) string {
	var result strings.Builder
	for _, r := range input {
		if r >= '0' && r <= '9' {
			result.WriteRune(r)
		}
	}
	return result.String()
}

// allDigitsEqual checks if all characters in a string are the same
func allDigitsEqual(cnpj string) bool {
	for i := 1; i < len(cnpj); i++ {
		if cnpj[i] != cnpj[0] {
			return false
		}
	}
	return true
}

// checkCNPJCheckDigits validates the two check digits of a CNPJ
func checkCNPJCheckDigits(cnpj string) bool {
	weights1 := []int{5, 4, 3, 2, 9, 8, 7, 6, 5, 4, 3, 2}
	weights2 := []int{6, 5, 4, 3, 2, 9, 8, 7, 6, 5, 4, 3, 2}

	// Calculate first check digit
	digit1 := calculateCheckDigit(cnpj[:12], weights1)

	// Calculate second check digit
	digit2 := calculateCheckDigit(cnpj[:13], weights2)

	// Check if the calculated digits match the actual ones
	return cnpj[12] == digit1 && cnpj[13] == digit2
}

// calculateCheckDigit calculates a single check digit for a given CNPJ slice and weight array
func calculateCheckDigit(numbers string, weights []int) byte {
	sum := 0
	for i, weight := range weights {
		num, _ := strconv.Atoi(string(numbers[i]))
		sum += num * weight
	}

	remainder := sum % 11
	if remainder < 2 {
		return '0'
	}
	return byte('0' + (11 - remainder))
}

func GetEmpresa(cnpj string) models.Empresa {
	url := "https://receitaws.com.br/v1/cnpj/" + cnpj

	// Call the external URL
	resp, err := http.Get(url)
	if err != nil {
		fmt.Println("Error fetching data:", err)
		return models.Empresa{}
	}
	defer resp.Body.Close()

	// Read the response body
	body, err := ioutil.ReadAll(resp.Body)
	if err != nil {
		fmt.Println("Error reading response:", err)
		return models.Empresa{}
	}

	// Parse the JSON response into the struct
	var response models.Empresa
	err = json.Unmarshal(body, &response)
	if err != nil {
		fmt.Println("Error parsing JSON:", err)
		return models.Empresa{}
	}

	// Print the parsed response
	return response
}

func SendTestEmail(email, name, message string) {

	var emaildb models.Email

	globals.DB.First(&emaildb, "name = ?", "TESTE-ERRO")

	errText := emaildb.EmailText

	errText = strings.Replace(errText, "[[ERRO]]", message, -1)
	errText = strings.Replace(errText, "[[NOME]]", name, -1)

	m := gomail.NewMessage()
	m.SetHeader("From", "suporte@pcastlive.com")
	m.SetHeader("To", email)
	m.SetHeader("Subject", "Solicitação de teste da plataforma PCastLive")
	m.SetBody("text/html", errText)

	d := gomail.NewDialer("smtp.kinghost.net", 465, "suporte@pcastlive.com", "@407Smc837")

	if err := d.DialAndSend(m); err != nil {
		panic(err)
	}
}

func SendTestEmailApproval(email, name, transmkey, url string) {

	var emaildb models.Email

	globals.DB.First(&emaildb, "name = ?", "TESTE-APROVADO")

	errText := emaildb.EmailText

	errText = strings.Replace(errText, "[[NOME]]", name, -1)
	errText = strings.Replace(errText, "[[TRANSMKEY]]", transmkey, -1)
	errText = strings.Replace(errText, "[[URL]]", url, -1)

	m := gomail.NewMessage()
	m.SetHeader("From", "suporte@pcastlive.com")
	m.SetHeader("To", email)
	m.SetHeader("Subject", "Solicitação de teste da plataforma PCastLive")
	m.SetBody("text/html", errText)

	d := gomail.NewDialer("smtp.kinghost.net", 465, "suporte@pcastlive.com", "@407Smc837")

	if err := d.DialAndSend(m); err != nil {
		panic(err)
	}
}