using System.Globalization;
using System.Net;
using System.Text;
using System.Text.RegularExpressions;
using Microsoft.AspNetCore.Html;

namespace Finch.Extensions;

public static class StringExtensions
{
  const string SPACE = " ";

  static Regex replaceMultipleSpacesRegex { get; } = new Regex("[ ]{2,}", RegexOptions.None);

  static Regex newLineCharsRegex { get; } = new Regex("\t|\n|\r", RegexOptions.None);


  public static string FullTrim(this string value)
  {
    if (String.IsNullOrEmpty(value))
    {
      return value;
    }

    return replaceMultipleSpacesRegex.Replace(value, SPACE).Trim();
  }


  public static string EnsureStartsWith(this string input, string toStartWith)
  {
    if (input.StartsWith(toStartWith)) return input;
    return toStartWith + input.TrimStart(toStartWith);
  }


  public static string EnsureStartsWith(this string input, char value)
  {
    return input.StartsWith(value.ToString(CultureInfo.InvariantCulture)) ? input : value + input;
  }


  public static string EnsureEndsWith(this string input, char value)
  {
    return input.EndsWith(value.ToString(CultureInfo.InvariantCulture)) ? input : input + value;
  }


  public static string EnsureEndsWith(this string input, string toEndWith)
  {
    return input.EndsWith(toEndWith.ToString(CultureInfo.InvariantCulture)) ? input : input + toEndWith;
  }


  public static string EnsureSurroundedWith(this string input, char toSurroundWith)
  {
    return input.EnsureStartsWith(toSurroundWith).EnsureEndsWith(toSurroundWith);
  }


  public static string Or(this string value, string fallback)
  {
    return String.IsNullOrWhiteSpace(value) ? fallback : value;
  }


  public static string TrimEnd(this string value, string forRemoving)
  {
    if (String.IsNullOrEmpty(value)) return value;
    if (String.IsNullOrEmpty(forRemoving)) return value;

    while (value.EndsWith(forRemoving, StringComparison.InvariantCultureIgnoreCase))
    {
      value = value.Remove(value.LastIndexOf(forRemoving, StringComparison.InvariantCultureIgnoreCase));
    }
    return value;
  }


  public static string TrimStart(this string value, string forRemoving)
  {
    if (String.IsNullOrEmpty(value)) return value;
    if (String.IsNullOrEmpty(forRemoving)) return value;

    while (value.StartsWith(forRemoving, StringComparison.InvariantCultureIgnoreCase))
    {
      value = value.Substring(forRemoving.Length);
    }
    return value;
  }


  public static bool HasValue(this string input)
  {
    return !String.IsNullOrWhiteSpace(input);
  }


  public static bool IsNullOrEmpty(this string input)
  {
    return String.IsNullOrEmpty(input);
  }


  public static bool IsNullOrWhiteSpace(this string input)
  {
    return String.IsNullOrWhiteSpace(input);
  }

  public static string ToCamelCase(this string input)
  {
    if (!String.IsNullOrEmpty(input) && input.Length > 1)
    {
      return Char.ToLowerInvariant(input[0]) + input.Substring(1);
    }
    return input;
  }

  public static string ToPascalCase(this string input)
  {
    if (!String.IsNullOrEmpty(input) && input.Length > 1)
    {
      return Char.ToUpperInvariant(input[0]) + input.Substring(1);
    }
    return input;
  }

  public static string ToCamelCaseId(this string input)
  {
    if (String.IsNullOrEmpty(input))
    {
      return input;
    }

    if (input.Length < 2)
    {
      return input.ToLowerInvariant();
    }

    string[] parts = input.Split('.');

    return String.Join(".", parts.Select(x => x.ToCamelCase()));
  }


  public static string ToPascalCaseId(this string input)
  {
    if (String.IsNullOrEmpty(input))
    {
      return input;
    }

    if (input.Length < 2)
    {
      return input.ToUpperInvariant();
    }

    string[] parts = input.Split('.');

    return String.Join(".", parts.Select(x => x.ToPascalCase()));
  }


  public static string RemoveNewLines(this string input)
  {
    if (String.IsNullOrEmpty(input))
    {
      return input;
    }

    return newLineCharsRegex.Replace(input, String.Empty).Trim();
  }


  public static string Shorten(this string input, int maxLength)
  {
    if (maxLength < 4)
    {
      throw new ArgumentOutOfRangeException("maxLength", "Has to be at least 4 characters long");
    }

    if (String.IsNullOrEmpty(input) || input.Length <= maxLength)
    {
      return input;
    }

    return input.Substring(0, maxLength - 3) + "...";
  }


  public static string ReplaceFirst(this string text, string search, string replace)
  {
    int pos = text.IndexOf(search);
    if (pos < 0)
    {
      return text;
    }
    return text.Substring(0, pos) + replace + text.Substring(pos + search.Length);
  }
  
  
  public static string NewLinesToBr(this string source)
  {
    StringBuilder builder = new();
    string[] lines = source.Split('\n');
    for (int i = 0; i < lines.Length; i++)
    {
      if (i > 0)
      {
        builder.Append("<br/>");
      }
      builder.Append(WebUtility.HtmlEncode(lines[i]));
    }

    return builder.ToString();
  }


  public static string NewLinesToParagraphs(this string source, string classes = null)
  {
    StringBuilder builder = new();
    string classAttribute = classes.HasValue() ? $" class=\"{classes}\"" : string.Empty;
    builder.Append($"<p{classAttribute}>");
    string[] lines = source.Split('\n');
    for (int i = 0; i < lines.Length; i++)
    {
      if (i > 0)
      {
        builder.Append($"</p><p{classAttribute}>");
      }
      builder.Append(WebUtility.HtmlEncode(lines[i]));
    }

    builder.Append("</p>");
    return builder.ToString();
  }


  public static string FormatTwoFactorAuthenticationKey(this string unformattedKey)
  {
    var result = new StringBuilder();
    int currentPosition = 0;
    while (currentPosition + 4 < unformattedKey.Length)
    {
      result.Append(unformattedKey.AsSpan(currentPosition, 4)).Append(' ');
      currentPosition += 4;
    }
    if (currentPosition < unformattedKey.Length)
    {
      result.Append(unformattedKey.AsSpan(currentPosition));
    }

    return result.ToString().ToLowerInvariant();
  }


  public static IEnumerable<string> Chunks(this string text, int groupSize)
  {
    ArgumentException.ThrowIfNullOrEmpty(text);

    if (groupSize < 1)
    {
      throw new ArgumentException();
    }

    for (int i = 0; i < text.Length; i += groupSize)
    {
      if (groupSize + i > text.Length)
      {
        groupSize = text.Length - i;
      }

      yield return text.Substring(i, groupSize);
    }
  }


  public static IHtmlContent ToHtmlEntities(this string text)
  {
    StringBuilder sb = new();

    foreach (char ch in text)
    {
      sb.Append("&#");
      sb.Append((int)ch);
      sb.Append(';');
    }

    HtmlContentBuilder builder = new();
    builder.SetHtmlContent(sb.ToString());
    return builder;
  }
}