using Newtonsoft.Json;
using System.Collections.Generic;

namespace CurrencyConvert
{
    public partial class Form1 : Form
    {
        
        private readonly HashSet<string> supportedCurrencies = new HashSet<string>
        {
            "AUD", "BGN", "BRL", "CAD", "CHF", "CNY", "CZK", "DKK", 
            "EUR", "GBP", "HKD", "HUF", "IDR", "ILS", "INR", "ISK", 
            "JPY", "KRW", "MXN", "MYR", "NOK", "NZD", "PHP", "PLN", 
            "RON", "SEK", "SGD", "THB", "TRY", "USD", "ZAR"
        };

        public Form1()
        {
            InitializeComponent();

            
            comboBox1.Items.Clear();
            comboBox2.Items.Clear();
            foreach (string currency in supportedCurrencies)
            {
                comboBox1.Items.Add(currency);
                comboBox2.Items.Add(currency);
            }

            comboBox1.SelectedIndex = comboBox1.Items.IndexOf("EUR");
            comboBox2.SelectedIndex = comboBox2.Items.IndexOf("USD");
            
            
            label4.AutoSize = true;
            label4.Font = new Font(label4.Font.FontFamily, 12, FontStyle.Bold);
        }

        private void comboBox1_SelectedIndexChanged(object sender, EventArgs e)
        {

        }

        private void textBox1_KeyPress(object sender, KeyPressEventArgs e)
        {
            if (!char.IsDigit(e.KeyChar) && e.KeyChar != ',' && e.KeyChar != '.' && e.KeyChar != (char)Keys.Back)
            {
                e.Handled = true;
            }
        }

        private async void button1_Click(object sender, EventArgs e)
        {
            try
            {
                
                label4.Text = "Berechne...";
                button1.Enabled = false;

                if (string.IsNullOrWhiteSpace(textBox1.Text))
                {
                    MessageBox.Show("Bitte geben Sie einen Betrag ein.");
                    return;
                }

                
                string amount = textBox1.Text.Replace(',', '.');
                if (!double.TryParse(amount, System.Globalization.NumberStyles.Any, System.Globalization.CultureInfo.InvariantCulture, out double menge))
                {
                    MessageBox.Show("Bitte geben Sie einen gültigen Betrag ein.");
                    return;
                }

                if (comboBox1.SelectedItem == null || comboBox2.SelectedItem == null)
                {
                    MessageBox.Show("Bitte wählen Sie beide Währungen aus.");
                    return;
                }

                string von = comboBox1.SelectedItem.ToString().Trim().ToUpper();
                string zu = comboBox2.SelectedItem.ToString().Trim().ToUpper();

                if (!supportedCurrencies.Contains(von) || !supportedCurrencies.Contains(zu))
                {
                    MessageBox.Show($"Eine oder beide Währungen werden nicht unterstützt.\nUnterstützte Währungen: {string.Join(", ", supportedCurrencies)}");
                    return;
                }
                
                
                string url = $"https://api.frankfurter.app/latest?amount={amount}&from={von}&to={zu}";
                
                using (HttpClient client = new HttpClient())
                {
                    var response = await client.GetAsync(url);
                    string json = await response.Content.ReadAsStringAsync();

                    if (!response.IsSuccessStatusCode)
                    {
                        MessageBox.Show("Fehler beim Abrufen der Wechselkurse.");
                        return;
                    }

                    var data = JsonConvert.DeserializeObject<FrankfurterResponse>(json);

                    if (data?.rates == null || !data.rates.ContainsKey(zu))
                    {
                        MessageBox.Show("Fehler beim Abrufen der Wechselkurse.");
                        return;
                    }

                    double ergebnis = data.rates[zu];
                    label4.Text = $"{menge} {von} = {ergebnis:0.00} {zu}";
                }
            }
            catch (Exception)
            {
                MessageBox.Show("Ein Fehler ist aufgetreten. Bitte versuchen Sie es später erneut.");
            }
            finally
            {
                button1.Enabled = true;
            }
        }
    }

    public class FrankfurterResponse
    {
        public double amount { get; set; }
        public string base_currency { get; set; }
        public string date { get; set; }
        public Dictionary<string, double> rates { get; set; }
    }
}