using System;
using System.IO;
using System.Runtime.InteropServices;
using System.Threading;
using SQLitePCL;

namespace Mrleo1nid.SwarmAssistent;

/// <summary>
/// SwarmUI loads extensions in an isolated AssemblyLoadContext — Microsoft.Data.Sqlite
/// does not auto-init native SQLite there. Native libs ship under the extension dir
/// (runtimes/linux-x64/native/libe_sqlite3.so), but the loader searches the host
/// base dir unless we preload from the extension assembly location.
/// </summary>
internal static class AssistentSqliteBootstrap
{
    static int _ready;

    internal static void EnsureInitialized()
    {
        if (Interlocked.CompareExchange(ref _ready, 1, 0) != 0)
        {
            return;
        }
        PreloadNativeLibrary();
        Batteries_V2.Init();
    }

    static void PreloadNativeLibrary()
    {
        string extDir = Path.GetDirectoryName(typeof(AssistentSqliteBootstrap).Assembly.Location)
            ?? AppContext.BaseDirectory
            ?? "";
        if (string.IsNullOrWhiteSpace(extDir))
        {
            return;
        }
        foreach (string rel in CandidatePaths())
        {
            string path = Path.Combine(extDir, rel);
            if (!File.Exists(path))
            {
                continue;
            }
            try
            {
                IntPtr handle = NativeLibrary.Load(path);
                RegisterResolver(handle);
                return;
            }
            catch (Exception ex)
            {
                SwarmUI.Utils.Logs.Debug($"AssistentSqliteBootstrap: NativeLibrary.Load({path}): {ex.Message}");
            }
        }
    }

    /// <summary>Native e_sqlite3 locations for the current OS / arch, most specific first.</summary>
    static string[] CandidatePaths()
    {
        string arch = RuntimeInformation.ProcessArchitecture switch
        {
            Architecture.Arm64 => "arm64",
            Architecture.X86 => "x86",
            Architecture.Arm => "arm",
            _ => "x64",
        };
        if (OperatingSystem.IsWindows())
        {
            return [Path.Combine("runtimes", $"win-{arch}", "native", "e_sqlite3.dll"), "e_sqlite3.dll"];
        }
        if (OperatingSystem.IsMacOS())
        {
            return [Path.Combine("runtimes", $"osx-{arch}", "native", "libe_sqlite3.dylib"), "libe_sqlite3.dylib"];
        }
        return
        [
            Path.Combine("runtimes", $"linux-{arch}", "native", "libe_sqlite3.so"),
            Path.Combine("runtimes", $"linux-{arch}", "native", "e_sqlite3.so"),
            "libe_sqlite3.so",
            "e_sqlite3.so",
        ];
    }

    /// <summary>The provider's [DllImport("e_sqlite3")] would otherwise probe the host dir, not the extension dir.</summary>
    static void RegisterResolver(IntPtr handle)
    {
        try
        {
            NativeLibrary.SetDllImportResolver(typeof(SQLite3Provider_e_sqlite3).Assembly,
                (name, _, _) => name.Contains("e_sqlite3", StringComparison.OrdinalIgnoreCase) ? handle : IntPtr.Zero);
        }
        catch (InvalidOperationException)
        {
            // A resolver is already set for this assembly — the preloaded handle still helps on Windows.
        }
    }
}