// Licensed to StellaOps under the BUSL-1.1 license.
using Microsoft.Extensions.Logging;
using StackExchange.Redis;
using System.Collections.Generic;

namespace StellaOps.ReachGraph.Cache;

public sealed partial class ReachGraphValkeyCache
{
    private const int DefaultScanPageSize = 200;

    /// <inheritdoc />
    public async Task InvalidateAsync(
        string digest,
        CancellationToken cancellationToken = default)
    {
        ArgumentException.ThrowIfNullOrEmpty(digest);
        cancellationToken.ThrowIfCancellationRequested();

        var db = _redis.GetDatabase(_options.Database);
        var graphKey = BuildGraphKey(digest);

        try
        {
            await db.KeyDeleteAsync(graphKey).ConfigureAwait(false);
            cancellationToken.ThrowIfCancellationRequested();

            var endpoints = _redis.GetEndPoints();
            if (endpoints.Length == 0)
            {
                _logger.LogWarning("No Redis endpoints available for key enumeration");
                return;
            }

            var slicePattern = BuildSlicePattern(digest);
            var sliceKeys = new List<RedisKey>();

            foreach (var endpoint in endpoints)
            {
                cancellationToken.ThrowIfCancellationRequested();
                var server = _redis.GetServer(endpoint);
                if (server is null || !server.IsConnected)
                {
                    continue;
                }

                sliceKeys.AddRange(server.Keys(
                    _options.Database,
                    slicePattern,
                    pageSize: DefaultScanPageSize));
            }

            if (sliceKeys.Count > 0)
            {
                await db.KeyDeleteAsync(sliceKeys.ToArray()).ConfigureAwait(false);
                _logger.LogDebug("Invalidated {Count} slice keys for graph {Digest}", sliceKeys.Count, digest);
            }

            _logger.LogInformation("Invalidated cache for graph {Digest}", digest);
        }
        catch (OperationCanceledException)
        {
            throw;
        }
        catch (Exception ex)
        {
            _logger.LogWarning(ex, "Failed to invalidate cache for graph {Digest}", digest);
        }
    }
}