using System;
using System.Collections.Generic;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Controls;

namespace WGneu
{
    static class Validator
    {
        private static readonly string[] MOBILE_NRS = {
            "650", "651", "652", "653", "655", "657", "659", "660", "661",
            "663", "664", "665", "666", "667", "668", "669", "67", "68", "69"
        };

        public static ValidationResult CheckNumericInput(TextBox input)
        {
            return CheckNumericInput(input, -1);
        }

        private static ValidationResult CheckNumericInput(TextBox input, int maxLen)
        {
            string text = "";
            int pos = input.CaretIndex;
            for (int i = 0; i < input.Text.Length; i++)
            {
                char ch = input.Text[i];
                if (Char.IsDigit(ch))
                    text += ch;
                if (i == input.CaretIndex - 1)
                    pos = text.Length;
            }
            input.Text = text;
            input.CaretIndex = pos;

            if (maxLen >= 0 && input.Text.Length > maxLen)
            {
                input.Text = input.Text.Substring(0, maxLen);
                input.CaretIndex = Math.Min(pos, maxLen);
            }

            return new(true, null);
        }

        public static ValidationResult CheckPhoneNumber(TextBox input)
        {
            string text = "";
            int pos = input.CaretIndex;
            for (int i = 0, v = 0; i < input.Text.Length; i++)
            {
                char ch = input.Text[i];
                if (v == 0 && ch == '0')
                {
                    v += 3;
                    text += "+43";
                }
                else if (v == 0 && ch == '+')
                {
                    v++;
                    text += ch;
                }
                else if (v > 0 && char.IsDigit(ch))
                {
                    if (text == "+43")
                        text += " ";
                    else if (v == 6 && MOBILE_NRS.Any(nr => text.StartsWith("+43 " + nr)))
                        text += " ";
                    else if (v == 4 && text.StartsWith("+43 1"))
                        text += " ";
                    else if (v == 7 && text.Length == 8 && text.StartsWith("+43 "))
                        text += " ";
                    v++;
                    text += ch;
                }
                if (i == input.CaretIndex - 1)
                    pos = text.Length;
            }
            input.Text = text;
            input.CaretIndex = pos;

            if (text.Length == 0)
                return new(true, null);
            if (text.Length < 10)
                return new(false, "Telefonnummer zu kurz");

            return new(true, null);
        }

        public static ValidationResult CheckEmailAddress(TextBox input)
        {
            string text = "";
            int pos = input.CaretIndex;
            bool domain = false;
            for (int i = 0; i < input.Text.Length; i++)
            {
                char ch = input.Text[i];
                if (domain)
                {
                    if ((char.IsAscii(ch) && char.IsLetterOrDigit(ch)) || ".-_öäüßÖÄÜẞ".Any(c => c == ch))
                    {
                        if (!(text.Last() == '.' && ch == '.'))
                            text += char.ToLower(ch);
                    }
                }
                else
                {
                    if (ch == '@') domain = true;
                    if (!char.IsControl(ch) && !char.IsWhiteSpace(ch))
                        text += ch;
                }

                if (i == input.CaretIndex - 1)
                    pos = text.Length;
            }
            input.Text = text;
            input.CaretIndex = pos;

            if (text.Length == 0)
                return new(true, null);
            else if (text[0] == '@' || !domain)
                return new(false, "E-Mail-Adresse ungültig");
            var last = text.Split(".").Last();
            if (last.Length < 2 || !last.All(ch => char.IsAscii(ch) && char.IsLower(ch)))
                return new(false, "E-Mail-Adresse ungültig");

            return new(true, null);
        }

        public static ValidationResult CheckLfbisNr(TextBox input)
        {
            var res = CheckNumericInput(input, 7);
            if (!res.IsValid)
                return res;
            if (input.Text.Length == 0)
                return new(true, null);
            if (input.Text.Length != 7)
                return new(false, "Betriebsnummer zu kurz");

            // TODO

            return new(true, "Not implemented yet");
        }

        public static ValidationResult CheckUstIdInput(TextBox input)
        {
            return new(false, "Not implemented yet");
        }

        public static void SetInputInvalid(TextBox input)
        {
            input.BorderBrush = System.Windows.Media.Brushes.Red;
        }

        public static void SetInputValid(TextBox input)
        {
            input.ClearValue(TextBox.BorderBrushProperty);
        }
    }
}