hrynco-notification-service/HrynCo.NotificationService.Worker.Services/Push/FcmPushSender.cs

using System.Security.Cryptography;
using System.Text.Json;
using HrynCo.NotificationService.Contracts.Messages;
using HrynCo.NotificationService.DAL.Abstract.Push;
using HrynCo.NotificationService.DAL.Abstract.PushChannels;
using HrynCo.NotificationService.DAL.Abstract.Repositories;
using HrynCo.NotificationService.DAL.Abstract.Templates;

namespace HrynCo.NotificationService.Worker.Services.Push;

public sealed class FcmPushSender(
    INotificationServiceRepository services, IPushChannelRepository channels, IFirebasePushClient client,
    IPushTemplateDefinitionRepository templates) : IPushSender
{
    public async Task<PushDeliveryOutcome> SendAsync(Guid messageId, SendPushMessageData data, CancellationToken cancellationToken)
    {
        if (!PushMessageValidator.IsSupportedVersion(data.Version))
            return new PushDeliveryOutcome("Unsupported push payload version. Supported versions are 1 and 2.");
        if (!PushMessageValidator.IsValidContent(data)) return new PushDeliveryOutcome("Invalid push content for the requested version.");
        if (data.ExpiresAt <= DateTimeOffset.UtcNow) return new PushDeliveryOutcome("Push expired.");
        var service = await services.GetByNameAsync(data.ServiceName, cancellationToken);
        if (service is null) return new PushDeliveryOutcome("Push service is not configured.");
        RenderedPushMessageData rendered;
        try { rendered = await RenderAsync(service.Id, data, cancellationToken); }
        catch (EmailTemplateWriteException) { return new PushDeliveryOutcome("Push template data or action configuration is invalid."); }
        var channel = await channels.GetActiveForServiceAsync(service.Id, cancellationToken);
        if (channel is null) return new PushDeliveryOutcome("No active push channel is configured for this service.");
        var credentials = await channels.GetCredentialsAsync(channel.Id, cancellationToken);
        return await SendWithCredentialsAsync(messageId, rendered, channel.FirebaseProjectId, credentials, cancellationToken);
    }

    private async Task<RenderedPushMessageData> RenderAsync(Guid serviceId, SendPushMessageData data, CancellationToken ct)
    {
        if (data.Version == 1) return new RenderedPushMessageData(data, data.Title!, data.Body!, null, []);
        var template = await templates.GetAsync(serviceId, data.TemplateKey!, ct)
            ?? throw new EmailTemplateWriteException("Push template is not configured.", false);
        return PushTemplateRenderer.Render(template, data);
    }

    private async Task<PushDeliveryOutcome> SendWithCredentialsAsync(Guid messageId, RenderedPushMessageData data,
        string projectId, string? json, CancellationToken ct)
    {
        try
        {
            var credentials = FirebaseServiceAccountCredentials.Parse(json ?? string.Empty, projectId);
            return await client.SendAsync(messageId, data, credentials, ct);
        }
        catch (Exception error) when (error is JsonException or FormatException or ArgumentException or CryptographicException)
        {
            // Never propagate credential parser details into broker retry logs or replies.
            return new PushDeliveryOutcome("The push channel Firebase configuration is invalid.");
        }
    }
}