using System.Globalization;

namespace Azaion.Missions.E2E.Helpers;

/// <summary>
/// Appends one row per NFT-PERF / NFT-RES-LIM scenario to a side-channel
/// CSV referenced by an environment variable. The Reporting.Cli converter
/// only knows about compile-time <c>[Trait]</c> data — runtime measurements
/// (P50/P95, MAX_FD, P95_RSS_MiB, etc.) need this separate file so
/// deployment planning + trend dashboards can read them.
/// </summary>
/// <remarks>
/// File schema (idempotent header written on first append):
/// <code>Timestamp,Category,Scenario,Result,Traces,ErrorMessage</code>
/// The Traces column carries the dynamic key=value pairs the spec requires
/// (e.g., <c>"AC-3.6; P50_MS=23.4; P95_MS=41.8"</c>); the recorder just
/// joins them with semicolons — callers compose the right shape.
/// </remarks>
public sealed class MetricCsvRecorder
{
    private readonly string? _path;
    private static readonly object Lock = new();

    /// <param name="envVar">name of the env var that carries the target CSV path
    /// (e.g., <c>PERF_RESULTS_FILE</c> for NFT-PERF, <c>RESLIM_RESULTS_FILE</c>
    /// for NFT-RES-LIM). When the env var is missing or whitespace, every
    /// <see cref="Record"/> call is a no-op — the recorder is intentionally
    /// silent inside the standard CI run.</param>
    public MetricCsvRecorder(string envVar)
    {
        var v = Environment.GetEnvironmentVariable(envVar);
        _path = string.IsNullOrWhiteSpace(v) ? null : v;
    }

    public bool IsEnabled => _path is not null;

    public void Record(string category, string scenario, string result, string traces, string? errorMessage = null)
    {
        if (_path is null) return;
        lock (Lock)
        {
            var dir = Path.GetDirectoryName(_path);
            if (!string.IsNullOrEmpty(dir)) Directory.CreateDirectory(dir);
            var newFile = !File.Exists(_path);
            using var sw = new StreamWriter(_path, append: true);
            if (newFile)
                sw.WriteLine("Timestamp,Category,Scenario,Result,Traces,ErrorMessage");
            sw.WriteLine(
                $"{DateTime.UtcNow.ToString("O", CultureInfo.InvariantCulture)},"
                + $"{Csv(category)},{Csv(scenario)},{Csv(result)},{Csv(traces)},{Csv(errorMessage ?? "")}");
        }
    }

    private static string Csv(string value) =>
        value.Contains(',') || value.Contains('"') || value.Contains('\n')
            ? "\"" + value.Replace("\"", "\"\"", StringComparison.Ordinal) + "\""
            : value;
}