using Microsoft.Extensions.DependencyInjection;
using ZB.MOM.WW.OtOpcUa.Configuration.LocalCache;

namespace ZB.MOM.WW.OtOpcUa.Server;

/// <summary>
///     DI registration helpers consumed by <c>Program.cs</c>. Extracted so tests can assert
///     the production wire-up actually composes without spinning up the full <c>Host</c>.
/// </summary>
public static class ServerWiring
{
    /// <summary>
    ///     Server-014 — registers the Phase 6.1 Stream D generation-sealed bootstrap chain:
    ///     <see cref="GenerationSealedCache"/>, <see cref="StaleConfigFlag"/>,
    ///     <see cref="ResilientConfigReader"/>, and <see cref="SealedBootstrap"/>. Without these
    ///     registrations <c>OpcUaServerService</c> cannot consume the sealed bootstrap and the
    ///     <see cref="StaleConfigFlag"/> stays inert — <c>/healthz</c>'s <c>usingStaleConfig</c>
    ///     never flips on a DB outage with a warm cache.
    /// </summary>
    /// <remarks>
    ///     The cache root is sourced from <see cref="NodeOptions.LocalCachePath"/> — same path
    ///     the legacy <see cref="NodeBootstrap"/> uses for its LiteDB cache, so both bootstrap
    ///     paths persist alongside each other while the migration completes.
    /// </remarks>
    public static IServiceCollection AddSealedBootstrap(this IServiceCollection services, NodeOptions options)
    {
        // Use a sibling directory off LocalCachePath so the LiteDB file and the
        // GenerationSealedCache snapshots don't clash. The cache root is a directory;
        // LocalCachePath is canonically the LiteDB file path.
        var cacheRoot = ResolveCacheRoot(options.LocalCachePath);
        // Register NodeOptions only if the caller hasn't already done so — Program.cs
        // registers it earlier in its DI chain, but the wiring helper supports standalone
        // unit tests that want to compose just the SealedBootstrap chain.
        if (!services.Any(d => d.ServiceType == typeof(NodeOptions)))
            services.AddSingleton(options);
        services.AddSingleton(new GenerationSealedCache(cacheRoot));
        services.AddSingleton<StaleConfigFlag>();
        services.AddSingleton<ResilientConfigReader>();
        services.AddSingleton<SealedBootstrap>();
        return services;
    }

    private static string ResolveCacheRoot(string localCachePath)
    {
        // LocalCachePath is the LiteDB file (e.g. "config_cache.db"); the sealed cache is a
        // directory. Pick a sibling folder so the two don't share a path.
        if (string.IsNullOrWhiteSpace(localCachePath))
            return Path.Combine(Path.GetTempPath(), "otopcua-sealed-cache");

        var dir = Path.GetDirectoryName(localCachePath);
        var name = Path.GetFileNameWithoutExtension(localCachePath);
        var root = string.IsNullOrEmpty(dir)
            ? $"{name}.sealed"
            : Path.Combine(dir, $"{name}.sealed");
        return root;
    }
}