Foxchat.NET/Foxchat.Core/Database/IDatabaseContext.cs

using System.Security.Cryptography;
using Microsoft.EntityFrameworkCore;

namespace Foxchat.Core.Database;

public abstract class IDatabaseContext : DbContext
{
    public virtual DbSet<Instance> Instance { get; set; }

    public async ValueTask<bool> InitializeInstanceAsync(CancellationToken ct = default)
    {
        var instance = await Instance.Where(i => i.Id == 1).FirstOrDefaultAsync(ct);
        if (instance != null) return false;

        var rsa = RSA.Create();
        var publicKey = rsa.ExportRSAPublicKeyPem();
        var privateKey = rsa.ExportRSAPrivateKeyPem();

        await Instance.AddAsync(new Instance
        {
            PublicKey = publicKey!,
            PrivateKey = privateKey!,
        }, ct);

        await SaveChangesAsync(ct);
        return true;
    }

    public async Task<Instance> GetInstanceAsync(CancellationToken ct = default)
    {
        var instance = await Instance.FirstOrDefaultAsync(ct)
            ?? throw new Exception("GetInstanceAsync called without Instance being initialized"); // TODO: replace this with specific exception type
        return instance;
    }

    public async Task<RSA> GetInstanceKeysAsync(CancellationToken ct = default)
    {
        var instance = await GetInstanceAsync(ct);

        var rsa = RSA.Create();
        rsa.ImportFromPem(instance.PrivateKey);
        return rsa;
    }
}