using System.Text.Json;
using System.Text.Json.Nodes;
using System.Text.Json.Serialization;

namespace HSchool.Content;

/// <summary>JSON with comments and trailing commas — the format of every def, patch, locale and map file.</summary>
public static class Jsonc
{
    public static JsonSerializerOptions SerializerOptions { get; } = new()
    {
        PropertyNamingPolicy = JsonNamingPolicy.CamelCase,
        PropertyNameCaseInsensitive = true,
        AllowTrailingCommas = true,
        WriteIndented = true,
        Converters = { new JsonStringEnumConverter(JsonNamingPolicy.CamelCase) },
    };

    public static JsonDocumentOptions DocumentOptions { get; } = new()
    {
        // Skip, not Allow: JsonDocument will not store comments. The files may still contain them.
        CommentHandling = JsonCommentHandling.Skip,
        AllowTrailingCommas = true,
    };

    public static JsonNode Parse(string text, string? source = null)
    {
        try
        {
            var node = JsonNode.Parse(text, documentOptions: DocumentOptions);
            if (node is null)
            {
                throw new ContentLoadException(source is null ? "JSONC was empty." : $"JSONC {source} was empty.");
            }

            return node;
        }
        catch (JsonException ex)
        {
            var where = source is null ? "JSONC" : $"JSONC {source}";
            throw new ContentLoadException($"{where} is not valid: {ex.Message}", ex);
        }
    }

    public static T Deserialize<T>(JsonNode node)
    {
        var value = node.Deserialize<T>(SerializerOptions);
        if (value is null)
        {
            throw new ContentLoadException($"Could not read a {typeof(T).Name} from JSONC.");
        }

        return value;
    }
}