using Application.Abstractions.Data;
using Application.Abstractions.Messaging;
using Application.Abstractions.YouTube;
using Domain.Entities.Members;
using Microsoft.EntityFrameworkCore;
using Microsoft.Extensions.Logging;
using SharedKernel.Results;

namespace Application.Features.Api.MyPage.Sns.Connect;

internal sealed class Handler(
    IAppDbContext db,
    IGoogleOAuthService oauthService,
    ILogger<Handler> logger
) : ICommandHandler<Command, Result<Response>>
{
    private const string Provider = "Google";

    public async Task<Result<Response>> Handle(Command request, CancellationToken ct)
    {
        if (string.IsNullOrWhiteSpace(request.Code))
        {
            return Result.Failure<Response>(Error.Problem("Sns.CodeRequired", "Authorization code 가 필요합니다."));
        }

        if (string.IsNullOrWhiteSpace(request.RedirectUri))
        {
            return Result.Failure<Response>(Error.Problem("Sns.RedirectUriRequired", "Redirect URI 가 필요합니다."));
        }

        var config = await db.Config.AsNoTracking().OrderByDescending(x => x.ID).FirstOrDefaultAsync(ct);

        if (config is null
            || string.IsNullOrEmpty(config.External.GoogleClientId)
            || string.IsNullOrEmpty(config.External.GoogleClientSecretEnc)
        ) {
            return Result.Failure<Response>(Error.Problem("Sns.OAuthConfigMissing", "Google OAuth 설정이 없습니다."));
        }

        var tokens = await oauthService.ExchangeCodeAsync(
            request.Code,
            request.RedirectUri,
            config.External.GoogleClientId,
            config.External.GoogleClientSecretEnc,
            ct
        );

        if (tokens is null)
        {
            return Result.Failure<Response>(Error.Problem("Sns.OAuthExchangeFailed", "Google 인증 코드 교환에 실패했습니다."));
        }

        var existing = await db.MemberOAuthToken.FirstOrDefaultAsync(t => t.MemberID == request.MemberID && t.Provider == Provider, ct);
        var scopesStr = string.Join(" ", tokens.Scopes);

        if (existing is null)
        {
            var token = MemberOAuthToken.Create(
                request.MemberID,
                Provider,
                tokens.AccessToken,
                tokens.RefreshToken,
                tokens.ExpiresAt,
                scopesStr
            );
            db.MemberOAuthToken.Add(token);
        }
        else
        {
            existing.UpdateTokens(tokens.AccessToken, tokens.RefreshToken, tokens.ExpiresAt, scopesStr);
        }

        await db.SaveChangesAsync(ct);

        logger.LogInformation("[Sns.Connect] Google 연동 완료: memberID={MemberID}", request.MemberID);

        return Result.Success(new Response(Provider, DateTime.UtcNow, tokens.ExpiresAt));
    }
}