using DigitalData.MessagingService.Application.Common.Interfaces;
using DigitalData.MessagingService.Application.EmailAccount.Queries;
using DigitalData.MessagingService.Abstraction;
using DigitalData.MessagingService.Domain.Exceptions;
using MediatR;

namespace DigitalData.MessagingService.Application.EmailReceiving.Queries;

/// <summary>
/// Query to fetch emails from an IMAP mailbox.
/// </summary>
public record FetchEmailsQuery : IRequest<IEnumerable<ReceivedEmailContext>>
{
    /// <summary>
    /// Identifies the email account to use.
    /// </summary>
    public required GetSenderQuery Account { get; init; }

    /// <summary>
    /// Mailbox folder to read from (default: "INBOX").
    /// </summary>
    public string Folder { get; init; } = "INBOX";

    /// <summary>
    /// When <see langword="true"/> returns only unread messages.
    /// </summary>
    public bool UnseenOnly { get; init; } = false;

    /// <summary>
    /// Maximum number of messages to retrieve (most-recent first). 0 = unlimited.
    /// </summary>
    public int MaxCount { get; init; } = 50;
}

public class FetchEmailsQueryHandler(
    ISender Sender,
    IImapEmailService ImapService) : IRequestHandler<FetchEmailsQuery, IEnumerable<ReceivedEmailContext>>
{
    public async Task<IEnumerable<ReceivedEmailContext>> Handle(FetchEmailsQuery request, CancellationToken cancellationToken)
    {
        var account = await Sender.Send(request.Account, cancellationToken)
            ?? throw new NotFoundException(
                $"No email account found for the given criteria (Id: {request.Account.Id}, Username: {request.Account.Username}).");

        if (string.IsNullOrWhiteSpace(account.ImapServer))
            throw new InvalidOperationException(
                $"IMAP is not configured for account '{account.Username}' (Id: {account.Id}). Set ImapServer in EmailAccounts configuration.");

        return await ImapService.FetchEmailsAsync(
            account,
            request.Folder,
            request.UnseenOnly,
            request.MaxCount,
            cancellationToken);
    }
}