using EonaCat.FirstLight.SaveTransfer.VdfGenerator.KeyValue.Models;
using System.Text;

namespace EonaCat.FirstLight.SaveTransfer.VdfGenerator.KeyValue;

/// <summary>
/// Provides functionality to serialize key–value groups into a text-based format.
/// </summary>
public class KeyValueSerializer
{
    /// <summary>
    /// Serializes the given key–value group into a text format.
    /// </summary>
    /// <param name="group">The key–value group to serialize. Cannot be null.</param>
    /// <returns>A string representing the serialized form of the key–value group.</returns>
    public static string Serialize(KeyValueGroup group)
    {
        var sb = new StringBuilder();
        SerializeGroup(group, sb, 0);
        return sb.ToString();
    }

    /// <summary>
    /// Serializes the specified key-value group and its child elements into a formatted string representation, appending the result to the provided StringBuilder.
    /// </summary>
    /// <param name="group">The key-value group to serialize. Cannot be null.</param>
    /// <param name="sb">The StringBuilder to which the serialized output is appended. Cannot be null.</param>
    /// <param name="indent">The indentation level to apply to the serialized output.</param>
    private static void SerializeGroup(KeyValueGroup group, StringBuilder sb, int indent)
    {
        const char padChar = '\t';
        var pad = new string(padChar, indent);

        sb.Append($"{pad}\"{group.Key}\"\n");
        sb.Append($"{pad}{{\n");

        foreach (var node in group.Nodes)
        {
            switch (node)
            {
                case Models.KeyValuePair pair:
                    sb.Append($"{pad}{padChar}\"{pair.Key}\"{padChar}{padChar}\"{pair.Value}\"\n");
                    break;

                case KeyValueGroup childGroup:
                    SerializeGroup(childGroup, sb, indent + 1);
                    break;
            }
        }

        sb.Append($"{pad}}}\n");
    }
}