using MongoDB.Driver;
using MongoDB.Entities;

namespace PrivaPub.Models
{
	// The server's first-time setup (owner decision 2026-10-16): while no administrator exists, the client's setup page makes
	// the first login, which becomes the administrator; this document then closes setup for good, whoever is demoted or
	// deleted later (the CLI stays the way back). The first request to insert it wins, so two setups at once make one
	// administrator. A backup never holds it and a restore never drops it (ServerBackup.Excluded): a restore tombstones an
	// administrator made after the backup, and setup would otherwise be open to whoever came first.
	public class ServerSetup : Entity
	{
		public const string Name = "setup";

		public string AdminId { get; set; }//null while the claiming request is still making its login
		public DateTime SealedAt { get; set; }

		public static async Task<bool> IsPending(CancellationToken token) =>
			!await DB.Default.Find<ServerSetup>().Match(s => s.ID == Name).ExecuteAnyAsync(token);

		/// <summary>Takes the setup for one request: false when it is done, or another request took it first.</summary>
		public static async Task<bool> Claim(CancellationToken token)
		{
			try
			{
				await DB.Default.InsertAsync(new ServerSetup { ID = Name, SealedAt = DateTime.UtcNow }, token);
				return true;
			}
			catch (MongoWriteException ex) when (ex.WriteError?.Category == ServerErrorCategory.DuplicateKey)
			{
				return false;
			}
		}

		/// <summary>Names the administrator the claiming request made.</summary>
		public static Task Claimed(string adminId, CancellationToken token) =>
			DB.Default.Update<ServerSetup>().Match(s => s.ID == Name && s.AdminId == null).Modify(s => s.AdminId, adminId).ExecuteAsync(token);

		/// <summary>Gives a claim back when its login couldn't be made; a named administrator is never given back.</summary>
		public static Task Release() =>
			DB.Default.DeleteAsync<ServerSetup>(s => s.ID == Name && s.AdminId == null);//a delete takes no token outside a transaction

		/// <summary>Closes setup for an administrator made elsewhere (the CLI, a server that had one already).</summary>
		public static async Task Seal(string adminId, CancellationToken token)
		{
			try
			{
				await DB.Default.Update<ServerSetup>().Match(s => s.ID == Name)
					.Modify(b => b.SetOnInsert(s => s.AdminId, adminId))
					.Modify(b => b.SetOnInsert(s => s.SealedAt, DateTime.UtcNow))
					.Option(o => o.IsUpsert = true)
					.ExecuteAsync(token);
			}
			catch (MongoCommandException ex) when (ex.Code == 11000)
			{
				//sealed meanwhile
			}
			catch (MongoWriteException ex) when (ex.WriteError?.Category == ServerErrorCategory.DuplicateKey)
			{
				//sealed meanwhile
			}
		}
	}
}