dpot-backend/Application/Features/Api/Studio/DisconnectYouTube/Handler.cs

using Application.Abstractions.Data;
using Application.Abstractions.Messaging;
using Application.Abstractions.YouTube;
using Microsoft.EntityFrameworkCore;
using Microsoft.Extensions.Logging;

namespace Application.Features.Api.Studio.DisconnectYouTube;

internal sealed class Handler(
    IAppDbContext db,
    IYouTubeChannelCache channelCache,
    IGoogleOAuthService oauthService,
    ILogger<Handler> logger
) : ICommandHandler<Command>
{
    public async Task Handle(Command request, CancellationToken ct)
    {
        var channel = await db.Channel.FirstOrDefaultAsync(c => c.MemberID == request.MemberID && c.IsActive, ct);

        if (channel is null)
        {
            throw new InvalidOperationException("연동된 채널이 없습니다.");
        }

        // OAuth 토큰 조회 → revoke → 삭제
        var oauthToken = await db.MemberOAuthToken.FirstOrDefaultAsync(t => t.MemberID == request.MemberID && t.Provider == "YouTube", ct);

        if (oauthToken is not null)
        {
            // Google OAuth revoke (실패해도 무시)
            await oauthService.RevokeTokenAsync(oauthToken.AccessTokenEnc, ct);
            db.MemberOAuthToken.Remove(oauthToken);
        }

        // 채널 비활성화
        channel.Deactivate();

        // Redis 캐시 삭제
        var cacheKey = channel.YouTubeChannelID ?? channel.SID;
        await channelCache.RemoveAsync(cacheKey);

        await db.SaveChangesAsync(ct);

        logger.LogInformation("YouTube 연동 해지: MemberID={MemberID}, ChannelID={ChannelID}", request.MemberID, channel.ID);
    }
}