using Microsoft.Extensions.DependencyInjection;
using StellaOps.DependencyInjection;
using StellaOps.Notify.Engine;
using StellaOps.Notify.Models;
using System;
using System.Collections.Generic;
using System.Threading;
using System.Threading.Tasks;

namespace StellaOps.Notify.Connectors.Email;

[ServiceBinding(typeof(INotifyChannelTestProvider), ServiceLifetime.Singleton)]
public sealed class EmailChannelTestProvider : INotifyChannelTestProvider
{
    public NotifyChannelType ChannelType => NotifyChannelType.Email;

    public Task<ChannelTestPreviewResult> BuildPreviewAsync(ChannelTestPreviewContext context, CancellationToken cancellationToken)
    {
        cancellationToken.ThrowIfCancellationRequested();

        var subject = context.Request.Title ?? "Stella Ops Notify Preview";
        var summary = context.Request.Summary ?? $"Preview generated at {context.Timestamp:O}.";
        var htmlBody = !string.IsNullOrWhiteSpace(context.Request.Body)
            ? context.Request.Body!
            : $"<p>{summary}</p><p><small>Trace: {context.TraceId}</small></p>";
        var textBody = context.Request.TextBody ?? $"{summary}{Environment.NewLine}Trace: {context.TraceId}";

        var preview = NotifyDeliveryRendered.Create(
            NotifyChannelType.Email,
            NotifyDeliveryFormat.Email,
            context.Target,
            subject,
            htmlBody,
            summary,
            textBody,
            context.Request.Locale,
            ChannelTestPreviewUtilities.ComputeBodyHash(htmlBody),
            context.Request.Attachments);

        var metadata = EmailMetadataBuilder.Build(context);

        return Task.FromResult(new ChannelTestPreviewResult(preview, metadata));
    }
}