namespace Core.Printing;

/// <summary>
/// Builds a case-insensitive token map. Fill order is imported, then entity, then chapter
/// so built-in names win over an imported column with the same name.
/// </summary>
public static class PrintTokenMap
{
    public static Dictionary<string, string> Create() =>
        new(StringComparer.OrdinalIgnoreCase);

    public static Dictionary<string, string> Build(
        IReadOnlyDictionary<string, string?>? imported,
        IReadOnlyDictionary<string, string?>? entity,
        IReadOnlyDictionary<string, string?>? chapter)
    {
        var map = Create();
        Apply(map, imported);
        Apply(map, entity);
        Apply(map, chapter);
        return map;
    }

    public static void Apply(IDictionary<string, string> map, IReadOnlyDictionary<string, string?>? values)
    {
        if (values is null)
            return;

        foreach (var (key, value) in values)
        {
            if (string.IsNullOrWhiteSpace(key))
                continue;
            map[key] = Escape(value);
        }
    }

    /// <summary>
    /// Treats substituted values as plain text so they cannot change markdown or inject HTML.
    /// Line breaks are flattened so a value cannot end a markdown table row.
    /// </summary>
    public static string Escape(string? value)
    {
        if (string.IsNullOrEmpty(value))
            return string.Empty;

        return FlattenLines(value)
            .Replace("\\", "\\\\", StringComparison.Ordinal)
            .Replace("|", "\\|", StringComparison.Ordinal)
            .Replace("*", "\\*", StringComparison.Ordinal)
            .Replace("_", "\\_", StringComparison.Ordinal)
            .Replace("`", "\\`", StringComparison.Ordinal)
            .Replace("[", "\\[", StringComparison.Ordinal)
            .Replace("]", "\\]", StringComparison.Ordinal)
            .Replace("<", "&lt;", StringComparison.Ordinal)
            .Replace(">", "&gt;", StringComparison.Ordinal);
    }

    /// <summary>
    /// Escapes a value for insertion into generated print HTML (badge labels).
    /// </summary>
    public static string EscapeHtml(string? value)
    {
        if (string.IsNullOrEmpty(value))
            return string.Empty;

        return FlattenLines(value)
            .Replace("&", "&amp;", StringComparison.Ordinal)
            .Replace("<", "&lt;", StringComparison.Ordinal)
            .Replace(">", "&gt;", StringComparison.Ordinal)
            .Replace("\"", "&quot;", StringComparison.Ordinal);
    }

    private static string FlattenLines(string value) =>
        string.Join(' ',
            value.Split(['\r', '\n', '\u2028', '\u2029'], StringSplitOptions.RemoveEmptyEntries | StringSplitOptions.TrimEntries));
}