using System.Text.Json;
using System.Text.Json.Serialization;
using SQLInsight.Core.Instances;

namespace SQLInsight.Rules.Lifecycle;

public sealed record SupportLifecycle(SqlServerRelease Release, DateOnly? MainstreamEnd, DateOnly? ExtendedEnd);

/// <summary>
/// Microsoft's support dates per SQL Server release. Shipped as data so it can be updated with the rule pack.
/// </summary>
public sealed class SupportLifecycleCatalog
{
    private const string ResourceName = "SQLInsight.Rules.support-lifecycle.json";

    private static readonly JsonSerializerOptions JsonOptions = new()
    {
        PropertyNameCaseInsensitive = true,
        Converters = { new JsonStringEnumConverter() },
    };

    private readonly Dictionary<SqlServerRelease, SupportLifecycle> _entries;

    public SupportLifecycleCatalog(IEnumerable<SupportLifecycle> entries)
    {
        ArgumentNullException.ThrowIfNull(entries);
        _entries = entries.ToDictionary(e => e.Release);
    }

    public static SupportLifecycleCatalog LoadEmbedded()
    {
        using var stream = typeof(SupportLifecycleCatalog).Assembly.GetManifestResourceStream(ResourceName)
            ?? throw new InvalidOperationException($"Embedded resource '{ResourceName}' is missing.");
        return From(JsonSerializer.Deserialize<CatalogDocument>(stream, JsonOptions));
    }

    /// <summary>Reads the lifecycle section of a rule pack. Throws <see cref="InvalidDataException"/> if it is malformed.</summary>
    public static SupportLifecycleCatalog FromJson(JsonElement element) => From(element.Deserialize<CatalogDocument>(JsonOptions));

    private static SupportLifecycleCatalog From(CatalogDocument? document)
    {
        if (document?.Releases is not { Count: > 0 } releases)
        {
            throw new InvalidDataException("The support lifecycle catalog is empty.");
        }

        try
        {
            return new SupportLifecycleCatalog(releases);
        }
        catch (ArgumentException ex)
        {
            throw new InvalidDataException("The support lifecycle catalog is invalid: " + ex.Message, ex);
        }
    }

    public SupportLifecycle? Find(SqlServerRelease release) => _entries.GetValueOrDefault(release);

    private sealed record CatalogDocument(IReadOnlyList<SupportLifecycle> Releases);
}