using System;
using System.Text;

namespace DCIT.Core.Utilities
{
    public static class DisplayWidthUtility
    {
        public static int Measure(string value)
        {
            if (string.IsNullOrEmpty(value))
            {
                return 0;
            }

            var width = 0;
            foreach (var character in value)
            {
                width += GetCharacterWidth(character);
            }

            return width;
        }

        public static string TruncateToWidth(string value, int maxWidth, out bool truncated)
        {
            if (string.IsNullOrEmpty(value) || maxWidth <= 0)
            {
                truncated = !string.IsNullOrEmpty(value);
                return string.Empty;
            }

            var builder = new StringBuilder();
            var width = 0;
            truncated = false;

            foreach (var character in value)
            {
                var charWidth = GetCharacterWidth(character);
                if (width + charWidth > maxWidth)
                {
                    truncated = true;
                    break;
                }

                builder.Append(character);
                width += charWidth;
            }

            if (!truncated && builder.Length < value.Length)
            {
                truncated = true;
            }

            return builder.ToString();
        }

        public static string PadToWidth(string value, int targetWidth, out bool padded)
        {
            var builder = new StringBuilder(value ?? string.Empty);
            var currentWidth = Measure(builder.ToString());
            padded = currentWidth < targetWidth;

            while (currentWidth + 2 <= targetWidth)
            {
                builder.Append('\u3000');
                currentWidth += 2;
            }

            while (currentWidth < targetWidth)
            {
                builder.Append(' ');
                currentWidth += 1;
            }

            return builder.ToString();
        }

        private static int GetCharacterWidth(char character)
        {
            if (character == '\u3000')
            {
                return 2;
            }

            if (character >= 0x1100 &&
                (character <= 0x115F ||
                 character == 0x2329 ||
                 character == 0x232A ||
                 (character >= 0x2E80 && character <= 0xA4CF && character != 0x303F) ||
                 (character >= 0xAC00 && character <= 0xD7A3) ||
                 (character >= 0xF900 && character <= 0xFAFF) ||
                 (character >= 0xFE10 && character <= 0xFE19) ||
                 (character >= 0xFE30 && character <= 0xFE6F) ||
                 (character >= 0xFF00 && character <= 0xFF60) ||
                 (character >= 0xFFE0 && character <= 0xFFE6)))
            {
                return 2;
            }

            return 1;
        }
    }
}