using System;
using System.Collections.Generic;
using System.Threading;
using System.Threading.Tasks;
using MarcusLaw.OutlookAddin.Core.Models;
using Serilog;

namespace MarcusLaw.OutlookAddin.Core.Services
{
    public sealed class AttachmentSaveService : IAttachmentSaveService
    {
        private readonly IEspoCrmClient _client;
        private readonly ILogger _logger;

        public AttachmentSaveService(IEspoCrmClient client, ILogger logger)
        {
            _client = client ?? throw new ArgumentNullException(nameof(client));
            _logger = logger ?? throw new ArgumentNullException(nameof(logger));
        }

        public async Task<AttachmentSaveSummary> SaveAsync(
            IReadOnlyList<EspoAttachment> attachments,
            FilingTarget target,
            string? folderId,
            CancellationToken cancellationToken = default)
        {
            if (attachments == null) throw new ArgumentNullException(nameof(attachments));
            if (target == null) throw new ArgumentNullException(nameof(target));

            var summary = new AttachmentSaveSummary();
            if (attachments.Count == 0) return summary;

            foreach (var att in attachments)
            {
                cancellationToken.ThrowIfCancellationRequested();

                if (summary.AuthRequired)
                {
                    summary.Items.Add(new AttachmentSaveItemResult
                    {
                        FileName = att.Name,
                        Outcome = AttachmentSaveOutcome.AuthRequired,
                        ErrorMessage = "Skipped — earlier upload rejected by EspoCRM"
                    });
                    continue;
                }

                try
                {
                    var uploaded = await _client.UploadAttachmentAsync(
                        att.Name, att.ContentType, att.ContentBase64, cancellationToken).ConfigureAwait(false);

                    var doc = await _client.CreateDocumentAsync(
                        att.Name, uploaded.Id, target.ParentType, target.ParentId, folderId, cancellationToken).ConfigureAwait(false);

                    _logger.Information(
                        "Saved attachment {Name} → Document/{DocId} (parent={ParentType}/{ParentId}, folder={FolderId})",
                        att.Name, doc.Id, target.ParentType, target.ParentId, folderId ?? "(none)");

                    summary.Items.Add(new AttachmentSaveItemResult
                    {
                        FileName = att.Name,
                        Outcome = AttachmentSaveOutcome.Saved,
                        DocumentId = doc.Id
                    });
                }
                catch (EspoCrmAuthorizationException ex)
                {
                    _logger.Warning(ex, "Attachment save aborted: EspoCRM rejected credentials");
                    summary.AuthRequired = true;
                    summary.Items.Add(new AttachmentSaveItemResult
                    {
                        FileName = att.Name,
                        Outcome = AttachmentSaveOutcome.AuthRequired,
                        ErrorMessage = ex.Message
                    });
                }
                catch (OperationCanceledException)
                {
                    throw;
                }
                catch (Exception ex)
                {
                    _logger.Warning(ex, "Attachment save failed for {Name}", att.Name);
                    summary.Items.Add(new AttachmentSaveItemResult
                    {
                        FileName = att.Name,
                        Outcome = AttachmentSaveOutcome.Failed,
                        ErrorMessage = ex.Message
                    });
                }
            }

            return summary;
        }
    }
}