namespace SeaHaven.Services.Helpers
{
    /// <summary>
    /// Fixed board flag palette (must match FE FLAG_COLORS). Values stored as canonical #RRGGBB.
    /// </summary>
    public static class WorkOrderFlagColors
    {
        public static readonly HashSet<string> Allowed = new(StringComparer.OrdinalIgnoreCase)
        {
            "#EF4444",
            "#F97316",
            "#F59E0B",
            "#EAB308",
            "#22C55E",
            "#14B8A6",
            "#3B82F6",
            "#8B5CF6"
        };

        /// <summary>
        /// Normalizes to # + 6 uppercase hex digits, or null if empty.
        /// Returns false if the value is non-empty but not a valid hex color.
        /// </summary>
        public static bool TryNormalize(string? value, out string? canonical)
        {
            canonical = null;
            if (string.IsNullOrWhiteSpace(value))
                return true;

            var trimmed = value.Trim();
            if (trimmed.Length == 6 && trimmed[0] != '#')
                trimmed = "#" + trimmed;

            if (trimmed.Length != 7 || trimmed[0] != '#')
                return false;

            for (var i = 1; i < 7; i++)
            {
                if (!Char.IsAsciiHexDigit(trimmed[i]))
                    return false;
            }

            canonical = "#" + trimmed[1..].ToUpperInvariant();
            return true;
        }

        public static bool IsAllowed(string? canonical)
            => canonical != null && Allowed.Contains(canonical);
    }
}