using MxGateway.Server.Galaxy;

namespace MxGateway.Server.Dashboard;

/// <summary>
///     Projects a <see cref="GalaxyHierarchyCacheEntry"/> into a
///     <see cref="DashboardGalaxySummary"/> for the Blazor pages. Top-templates and
///     per-category breakdowns are computed here rather than stored on the cache so the
///     Galaxy namespace stays free of dashboard-presentation concepts.
/// </summary>
internal static class DashboardGalaxyProjector
{
    private const int TopTemplatesLimit = 10;

    private static readonly IReadOnlyDictionary<int, string> CategoryNamesById = new Dictionary<int, string>
    {
        [1] = "WinPlatform",
        [3] = "AppEngine",
        [4] = "InTouchViewApp",
        [10] = "UserDefined",
        [11] = "FieldReference",
        [13] = "Area",
        [17] = "DIObject",
        [24] = "DDESuiteLinkClient",
        [26] = "OPCClient",
    };

    public static DashboardGalaxySummary Project(GalaxyHierarchyCacheEntry entry)
    {
        DashboardGalaxyStatus status = entry.Status switch
        {
            GalaxyCacheStatus.Healthy => DashboardGalaxyStatus.Healthy,
            GalaxyCacheStatus.Stale => DashboardGalaxyStatus.Stale,
            GalaxyCacheStatus.Unavailable => DashboardGalaxyStatus.Unavailable,
            _ => DashboardGalaxyStatus.Unknown,
        };

        IReadOnlyList<DashboardGalaxyTemplateUsage> topTemplates;
        IReadOnlyList<DashboardGalaxyCategoryCount> objectCategories;

        if (entry.Hierarchy.Count == 0)
        {
            topTemplates = Array.Empty<DashboardGalaxyTemplateUsage>();
            objectCategories = Array.Empty<DashboardGalaxyCategoryCount>();
        }
        else
        {
            Dictionary<int, int> objectsByCategory = new();
            Dictionary<string, int> templateUsage = new(StringComparer.OrdinalIgnoreCase);

            foreach (GalaxyHierarchyRow row in entry.Hierarchy)
            {
                objectsByCategory.TryGetValue(row.CategoryId, out int categoryCount);
                objectsByCategory[row.CategoryId] = categoryCount + 1;

                if (row.TemplateChain.Count > 0)
                {
                    string immediate = row.TemplateChain[0];
                    if (!string.IsNullOrWhiteSpace(immediate))
                    {
                        templateUsage.TryGetValue(immediate, out int templateCount);
                        templateUsage[immediate] = templateCount + 1;
                    }
                }
            }

            topTemplates = templateUsage
                .OrderByDescending(entry => entry.Value)
                .ThenBy(entry => entry.Key, StringComparer.OrdinalIgnoreCase)
                .Take(TopTemplatesLimit)
                .Select(entry => new DashboardGalaxyTemplateUsage(entry.Key, entry.Value))
                .ToArray();

            objectCategories = objectsByCategory
                .OrderByDescending(entry => entry.Value)
                .ThenBy(entry => entry.Key)
                .Select(entry => new DashboardGalaxyCategoryCount(
                    entry.Key,
                    CategoryNamesById.TryGetValue(entry.Key, out string? name) ? name : $"Category {entry.Key}",
                    entry.Value))
                .ToArray();
        }

        return new DashboardGalaxySummary(
            Status: status,
            LastQueriedAt: entry.LastQueriedAt,
            LastSuccessAt: entry.LastSuccessAt,
            LastDeployTime: entry.LastDeployTime,
            LastError: entry.LastError,
            ObjectCount: entry.ObjectCount,
            AreaCount: entry.AreaCount,
            AttributeCount: entry.AttributeCount,
            HistorizedAttributeCount: entry.HistorizedAttributeCount,
            AlarmAttributeCount: entry.AlarmAttributeCount,
            TopTemplates: topTemplates,
            ObjectCategories: objectCategories);
    }
}