using Omika.Core.Observability.External;
using Omika.Diagnostics.Import;

namespace Omika.Diagnostics.Tests.Fakes;

/// <summary>
/// Source JSONL en mémoire : modèle un flux de <see cref="RemoteDiagnosticRecord"/>
/// avec un checkpoint (LineIndex = index du dernier enregistrement lu). Permet de
/// tester l'importeur et son avancement de checkpoint sans PostgreSQL.
/// </summary>
public sealed class FakeDiagnosticJsonlSource : IDiagnosticJsonlSource
{
    private readonly List<RemoteDiagnosticRecord> _records;
    private DiagnosticImportCheckpoint? _checkpoint;

    public FakeDiagnosticJsonlSource(IReadOnlyList<RemoteDiagnosticRecord> records)
    {
        _records = records.ToList();
    }

    public int CommitCount { get; private set; }

    public DiagnosticImportCheckpoint? LastCommitted { get; private set; }

    public DiagnosticImportCheckpoint? LoadCheckpoint() => _checkpoint;

    public DiagnosticJsonlReadResult ReadNext(DiagnosticImportCheckpoint? after, int maxCount)
    {
        int start = after is null ? 0 : after.LineIndex + 1;
        if (start >= _records.Count)
        {
            return new DiagnosticJsonlReadResult { ReachedEnd = true };
        }

        int count = Math.Min(maxCount, _records.Count - start);
        List<RemoteDiagnosticRecord> records = _records.GetRange(start, count);

        var next = new DiagnosticImportCheckpoint
        {
            FileName = "fake.jsonl",
            LineIndex = start + count - 1
        };

        return new DiagnosticJsonlReadResult
        {
            Records = records,
            NextPosition = next,
            ReachedEnd = start + count >= _records.Count
        };
    }

    public void Commit(DiagnosticImportCheckpoint position)
    {
        _checkpoint = position;
        LastCommitted = position;
        CommitCount++;
    }
}