using StellaOps.PacksRegistry.Core.Contracts;
using StellaOps.PacksRegistry.Core.Models;
using System.Text.Json;

namespace StellaOps.PacksRegistry.Infrastructure.FileSystem;

public sealed class FileAuditRepository : IAuditRepository
{
    private readonly string _path;
    private readonly JsonSerializerOptions _jsonOptions;
    private readonly SemaphoreSlim _mutex = new(1, 1);

    public FileAuditRepository(string rootPath)
    {
        var root = string.IsNullOrWhiteSpace(rootPath) ? Path.GetFullPath("data/packs") : Path.GetFullPath(rootPath);
        Directory.CreateDirectory(root);
        _path = Path.Combine(root, "audit.ndjson");
        _jsonOptions = new JsonSerializerOptions { PropertyNamingPolicy = JsonNamingPolicy.CamelCase };
    }

    public async Task AppendAsync(AuditRecord record, CancellationToken cancellationToken = default)
    {
        ArgumentNullException.ThrowIfNull(record);
        await _mutex.WaitAsync(cancellationToken).ConfigureAwait(false);
        try
        {
            await using var stream = new FileStream(_path, FileMode.Append, FileAccess.Write, FileShare.Read);
            await using var writer = new StreamWriter(stream);
            var json = JsonSerializer.Serialize(record, _jsonOptions);
            await writer.WriteLineAsync(json.AsMemory(), cancellationToken).ConfigureAwait(false);
        }
        finally
        {
            _mutex.Release();
        }
    }

    public async Task<IReadOnlyList<AuditRecord>> ListAsync(string? tenantId = null, CancellationToken cancellationToken = default)
    {
        if (!File.Exists(_path))
        {
            return Array.Empty<AuditRecord>();
        }

        await _mutex.WaitAsync(cancellationToken).ConfigureAwait(false);
        try
        {
            var lines = await File.ReadAllLinesAsync(_path, cancellationToken).ConfigureAwait(false);
            IEnumerable<AuditRecord> records = lines
                .Where(l => !string.IsNullOrWhiteSpace(l))
                .Select(l => JsonSerializer.Deserialize<AuditRecord>(l, _jsonOptions))
                .Where(r => r is not null)!
                .Cast<AuditRecord>();

            if (!string.IsNullOrWhiteSpace(tenantId))
            {
                records = records.Where(r => string.Equals(r.TenantId, tenantId, StringComparison.OrdinalIgnoreCase));
            }

            return records
                .OrderBy(r => r.OccurredAtUtc)
                .ThenBy(r => r.PackId, StringComparer.OrdinalIgnoreCase)
                .ToList();
        }
        finally
        {
            _mutex.Release();
        }
    }
}