using MeterVault.Core.Domain;
using MeterVault.Infrastructure.Persistence;
using Microsoft.EntityFrameworkCore;
using Microsoft.Extensions.Logging;

namespace MeterVault.Infrastructure.Ingestion;

/// <summary>
/// Routes an incoming MQTT message to every enabled MQTT/Tasmota source that is bound to the
/// delivering broker <em>and</em> whose topic filter covers it, extracts the value (and payload
/// timestamp), and ingests it (SDD §6.1). Decoupled from the broker client so it can be exercised
/// directly against the database in tests.
/// </summary>
/// <remarks>
/// The endpoint predicate is load-bearing, not defensive: topic filters routinely overlap between
/// brokers (every Tasmota install publishes <c>tele/+/SENSOR</c>), so matching on topic alone would
/// let a message from one broker be ingested by a source bound to another.
/// </remarks>
public sealed class MqttMessageRouter(
    MeterVaultDbContext db, IngestionService ingestion, ILogger<MqttMessageRouter> logger)
{
    private readonly MeterVaultDbContext _db = db;
    private readonly IngestionService _ingestion = ingestion;
    private readonly ILogger<MqttMessageRouter> _logger = logger;

    public async Task<int> RouteAsync(
        int endpointId, string topic, string payload, CancellationToken cancellationToken = default)
    {
        var sources = await _db.MeterSources
            .Where(s => s.IsEnabled
                        && (s.SourceType == SourceType.Mqtt || s.SourceType == SourceType.Tasmota)
                        && s.EndpointId == endpointId)
            .ToListAsync(cancellationToken).ConfigureAwait(false);

        var routed = 0;
        foreach (var source in sources)
        {
            var config = SourceConfig.Parse(source.Config);
            if (!MqttTopicMatcher.Matches(config.Topic, topic))
            {
                continue;
            }

            if (!PayloadExtractor.TryExtractValue(payload, config.Path, out var value))
            {
                _logger.LogDebug("Source {SourceId}: no value at path '{Path}' in topic {Topic}",
                    source.Id, config.Path, topic);
                continue;
            }

            // Prefer the payload's own time; Tasmota SENSOR messages carry "Time"; else receive time.
            var timePath = config.TimePath ?? (source.SourceType == SourceType.Tasmota ? "Time" : null);
            var time = PayloadExtractor.TryExtractTime(payload, timePath, out var payloadTime)
                ? payloadTime
                : DateTimeOffset.UtcNow;

            await _ingestion.IngestAsync(source.Id, time, value, cancellationToken).ConfigureAwait(false);
            routed++;
        }

        return routed;
    }
}