using System.Diagnostics;
using Catalogger.Backend.Cache;
using Catalogger.Backend.Database;
using Catalogger.Backend.Database.Models;
using Catalogger.Backend.Extensions;
using Remora.Discord.API.Abstractions.Gateway.Events;
using Remora.Discord.Gateway.Responders;
using Remora.Results;

namespace Catalogger.Backend.Bot.Responders;

public class GuildCreateResponder(ILogger logger, DatabaseContext db, ChannelCacheService channelCache)
    : IResponder<IGuildCreate>
{
    private readonly ILogger _logger = logger.ForContext<GuildCreateResponder>();

    public async Task<Result> RespondAsync(IGuildCreate evt, CancellationToken ct = default)
    {
        ulong guildId;
        string? guildName = null;
        if (evt.Guild.TryPickT0(out var guild, out _))
        {
            _logger.Verbose("Received guild create for available guild {GuildId} ({Name})", guild.ID, guild.Name);
            guildId = guild.ID.ToUlong();
            guildName = guild.Name;

            foreach (var c in guild.Channels) channelCache.AddChannel(c, guild.ID);
        }
        else if (evt.Guild.TryPickT1(out var unavailableGuild, out _))
        {
            _logger.Verbose("Received guild create for unavailable guild {GuildId}", unavailableGuild.ID);
            guildId = unavailableGuild.ID.ToUlong();
        }
        else throw new UnreachableException();

        var tx = await db.Database.BeginTransactionAsync(ct);
        if (await db.Guilds.FindAsync([guildId], ct) != null) return Result.Success;

        db.Add(new Guild
        {
            Id = guildId
        });
        await db.SaveChangesAsync(ct);
        await tx.CommitAsync(ct);

        _logger.Information("Joined new guild {GuildId} ({Name})", guildId, guildName);
        return Result.Success;
    }
}