using MongoDB.Bson;
using MongoDB.Bson.IO;

namespace FozFc.Api.Infrastructure.Mongo;

/// <summary>
/// Helpers to convert between the flexible JSON documents the frontend exchanges
/// and the BSON documents stored in MongoDB, and to map Mongo's <c>_id</c> to the
/// <c>id</c> the frontend expects.
/// </summary>
public static class BsonJson
{
    private static readonly JsonWriterSettings RelaxedJson = new()
    {
        OutputMode = JsonOutputMode.RelaxedExtendedJson,
    };

    /// <summary>Parse a raw JSON object string into a BSON document (or null if invalid).</summary>
    public static BsonDocument? TryParse(string? json)
    {
        if (string.IsNullOrWhiteSpace(json)) return null;
        try
        {
            return BsonDocument.Parse(json);
        }
        catch
        {
            return null;
        }
    }

    /// <summary>Serialize a BSON document to relaxed extended JSON (plain numbers/strings).</summary>
    public static string ToJson(BsonDocument document) => document.ToJson(RelaxedJson);

    /// <summary>Serialize a sequence of documents to a JSON array string.</summary>
    public static string ToJsonArray(IEnumerable<BsonDocument> documents) =>
        "[" + string.Join(",", documents.Select(ToJson)) + "]";

    /// <summary>Rename <c>_id</c> to <c>id</c> for output. Returns the same instance for chaining.</summary>
    public static BsonDocument NormalizeForOutput(BsonDocument document)
    {
        if (document.Contains("_id"))
        {
            var id = document["_id"];
            document.Remove("_id");
            document["id"] = id;
        }
        document.Remove("passwordHash");
        return document;
    }
}