using MongoDB.Bson;
using MongoDB.Bson.Serialization.Attributes;

namespace QuestionsApi.Models;

public sealed class UserNotepad
{
    [BsonId, BsonRepresentation(BsonType.ObjectId)] public string? Id { get; set; }
    public string UserId { get; set; } = "";
    public string Content { get; set; } = "";
    public long Revision { get; set; }
    public DateTime CreatedUtc { get; set; } = DateTime.UtcNow;
    public DateTime UpdatedUtc { get; set; } = DateTime.UtcNow;
}

public sealed class UpdateUserNotepadRequest
{
    public string Content { get; set; } = "";
    public long ExpectedRevision { get; set; }
}

public sealed class UserNotepadResponse
{
    public string Content { get; set; } = "";
    public long Revision { get; set; }
    public DateTime? UpdatedUtc { get; set; }

    public static UserNotepadResponse Empty() => new();

    public static UserNotepadResponse FromModel(UserNotepad note) => new()
    {
        Content = note.Content,
        Revision = note.Revision,
        UpdatedUtc = note.UpdatedUtc
    };
}

public static class UserNotepadValidator
{
    public const int MaxContentLength = 50_000;

    public static string? Validate(UpdateUserNotepadRequest request)
    {
        if (request.ExpectedRevision < 0) return "expectedRevision cannot be negative";
        if ((request.Content ?? "").Length > MaxContentLength)
            return $"content must be {MaxContentLength} characters or fewer";
        return null;
    }
}