using System.Text.Json;
using System.Text.Json.Serialization;

namespace StellaOps.Bench.ScannerAnalyzers;

internal sealed record BenchmarkConfig
{
    [JsonPropertyName("iterations")]
    public int? Iterations { get; init; }

    [JsonPropertyName("thresholdMs")]
    public double? ThresholdMs { get; init; }

    [JsonPropertyName("scenarios")]
    public List<BenchmarkScenarioConfig> Scenarios { get; init; } = new();

    public static async Task<BenchmarkConfig> LoadAsync(string path)
    {
        if (string.IsNullOrWhiteSpace(path))
        {
            throw new ArgumentException("Config path is required.", nameof(path));
        }

        await using var stream = File.OpenRead(path);
        var config = await JsonSerializer.DeserializeAsync<BenchmarkConfig>(stream, SerializerOptions).ConfigureAwait(false);
        if (config is null)
        {
            throw new InvalidOperationException($"Failed to parse benchmark config '{path}'.");
        }

        if (config.Scenarios.Count == 0)
        {
            throw new InvalidOperationException("config.scenarios must declare at least one scenario.");
        }

        foreach (var scenario in config.Scenarios)
        {
            scenario.Validate();
        }

        return config;
    }

    private static JsonSerializerOptions SerializerOptions => new()
    {
        PropertyNameCaseInsensitive = true,
        ReadCommentHandling = JsonCommentHandling.Skip,
        AllowTrailingCommas = true,
    };
}

internal sealed record BenchmarkScenarioConfig
{
    [JsonPropertyName("id")]
    public string? Id { get; init; }

    [JsonPropertyName("label")]
    public string? Label { get; init; }

    [JsonPropertyName("root")]
    public string? Root { get; init; }

    [JsonPropertyName("analyzers")]
    public List<string>? Analyzers { get; init; }

    [JsonPropertyName("matcher")]
    public string? Matcher { get; init; }

    [JsonPropertyName("parser")]
    public string? Parser { get; init; }

    [JsonPropertyName("thresholdMs")]
    public double? ThresholdMs { get; init; }

    public bool HasAnalyzers => Analyzers is { Count: > 0 };

    public void Validate()
    {
        if (string.IsNullOrWhiteSpace(Id))
        {
            throw new InvalidOperationException("scenario.id is required.");
        }

        if (string.IsNullOrWhiteSpace(Root))
        {
            throw new InvalidOperationException($"Scenario '{Id}' must specify a root path.");
        }

        if (HasAnalyzers)
        {
            return;
        }

        if (string.IsNullOrWhiteSpace(Parser))
        {
            throw new InvalidOperationException($"Scenario '{Id}' must specify parser or analyzers.");
        }

        if (string.IsNullOrWhiteSpace(Matcher))
        {
            throw new InvalidOperationException($"Scenario '{Id}' must specify matcher when parser is used.");
        }
    }
}