using System.Reflection;
using System.Security.Cryptography;
using System.Text;
using Microsoft.Data.Sqlite;
using OpenNest.Data;
using static OpenNest.Server.Tests.DrawingLibraryFixtures;

namespace OpenNest.Server.Tests;

public sealed class DrawingLibraryDatabaseTests
{
    [Fact]
    public void V3Upgrade_KeepsNestRowsByteIdenticalAndIsIdempotent()
    {
        using var factory = new ServerFactory();
        CreateVersion3Database(factory.DatabasePath);
        var before = NestDigest(factory.DatabasePath);

        for (var open = 0; open < 2; open++)
        {
            using (var database = new NestDatabase(factory.DatabasePath, pooling: false))
                Assert.Empty(database.QueryDrawings(new DrawingLibraryQuery { IncludeArchived = true }).Items);
            Assert.Equal(before, NestDigest(factory.DatabasePath));
            Assert.Equal(4L, Scalar(factory.DatabasePath, "PRAGMA user_version"));
        }

        using var upgraded = new NestDatabase(factory.DatabasePath, pooling: false);
        var record = Record();
        upgraded.InsertDrawing(record.Id, record, Package());
        Assert.Equal(1, upgraded.GetDrawing(record.Id)!.Revision);
        Assert.Equal(2, upgraded.List().Count);
    }

    [Fact]
    public void NewerSchema_IsRefused()
    {
        using var factory = new ServerFactory();
        using (new NestDatabase(factory.DatabasePath, pooling: false)) { }
        Execute(factory.DatabasePath, "PRAGMA user_version=5");

        Assert.Throws<InvalidOperationException>(() => new NestDatabase(factory.DatabasePath, pooling: false));
    }

    [Fact]
    public void FailedV4Migration_RollsBackAndCanRestart()
    {
        using var factory = new ServerFactory();
        CreateVersion3Database(factory.DatabasePath);
        var before = NestDigest(factory.DatabasePath);
        Execute(factory.DatabasePath, "CREATE TABLE drawing_revisions (fixture TEXT)");

        Assert.Throws<SqliteException>(() => new NestDatabase(factory.DatabasePath, pooling: false));

        Assert.Equal(3L, Scalar(factory.DatabasePath, "PRAGMA user_version"));
        Assert.Equal(0L, Scalar(factory.DatabasePath, "SELECT COUNT(*) FROM sqlite_master WHERE name='drawings'"));
        Assert.Equal(before, NestDigest(factory.DatabasePath));
        Execute(factory.DatabasePath, "DROP TABLE drawing_revisions");
        using var database = new NestDatabase(factory.DatabasePath, pooling: false);
        Assert.Equal(2, database.List().Count);
    }

    [Fact]
    public void DirectWrites_EnforceTheSharedRules()
    {
        using var factory = new ServerFactory();
        using var database = new NestDatabase(factory.DatabasePath, pooling: false);
        var record = Record();

        Assert.Throws<ArgumentException>(() => database.InsertDrawing(Guid.Empty, record, Package()));
        Assert.Throws<ArgumentException>(() => database.InsertDrawing(record.Id, record, new byte[] { 1, 2, 3, 4 }));
        record.CutType = (CutType)7;
        Assert.Throws<ArgumentException>(() => database.InsertDrawing(record.Id, record, Package()));
        Assert.Throws<ArgumentException>(() => database.QueryDrawings(new DrawingLibraryQuery { Limit = 501 }));
        Assert.Throws<ArgumentOutOfRangeException>(() => database.DrawingHistory(record.Id, 0, 201));
        Assert.Empty(database.QueryDrawings(new DrawingLibraryQuery { IncludeArchived = true }).Items);
    }

    // Code-level ownership gate, as for the nest operations: hold the database's monitor
    // and observe a dedicated synchronous caller waiting on it.
    [Theory]
    [InlineData("GetDrawing")]
    [InlineData("GetDrawingPackage")]
    [InlineData("QueryDrawings")]
    [InlineData("InsertDrawing")]
    [InlineData("UpdateDrawing")]
    [InlineData("UpdateDrawingMetadata")]
    [InlineData("SetDrawingArchived")]
    [InlineData("DrawingHistory")]
    [InlineData("GetDrawingRevisionPackage")]
    public async Task Concurrency_EveryDrawingOperationWaitsForTheSameMonitor(string operation)
    {
        using var factory = new ServerFactory();
        using var database = new NestDatabase(factory.DatabasePath, pooling: false);
        var record = Record();
        database.InsertDrawing(record.Id, record, Package());
        var sync = typeof(NestDatabase).GetField("_sync", BindingFlags.Instance | BindingFlags.NonPublic)!.GetValue(database)!;
        var completed = new TaskCompletionSource<Exception?>(TaskCreationOptions.RunContinuationsAsynchronously);
        var worker = new Thread(() => completed.SetResult(Xunit.Record.Exception(() =>
        {
            switch (operation)
            {
                case "GetDrawing": database.GetDrawing(record.Id); break;
                case "GetDrawingPackage": database.GetDrawingPackage(record.Id); break;
                case "QueryDrawings": database.QueryDrawings(new DrawingLibraryQuery { Search = "bracket" }); break;
                case "InsertDrawing": database.InsertDrawing(Guid.NewGuid(), record, Package("other")); break;
                case "UpdateDrawing": database.UpdateDrawing(record.Id, record, Package("changed"), 1); break;
                case "UpdateDrawingMetadata": database.UpdateDrawing(record.Id, Record("Renamed", record.Id), null, 1); break;
                case "SetDrawingArchived": database.SetDrawingArchived(record.Id, true, 1); break;
                case "DrawingHistory": database.DrawingHistory(record.Id, 0, 100); break;
                case "GetDrawingRevisionPackage": database.GetDrawingRevisionPackage(record.Id, 1); break;
                default: throw new InvalidOperationException($"Unknown test operation: {operation}");
            }
        })))
        { IsBackground = true };

        bool observedWaiting;
        bool completedWhileHeld;
        lock (sync)
        {
            worker.Start();
            observedWaiting = SpinWait.SpinUntil(() => completed.Task.IsCompleted ||
                (worker.ThreadState & ThreadState.WaitSleepJoin) != 0, TimeSpan.FromSeconds(10));
            completedWhileHeld = completed.Task.IsCompleted;
        }

        Assert.True(worker.Join(TimeSpan.FromSeconds(10)), "Operation did not finish after releasing the monitor.");
        Assert.True(observedWaiting, "Caller never reached the operation within the watchdog.");
        Assert.False(completedWhileHeld, operation + " bypassed the shared monitor.");
        Assert.Null(await completed.Task);
    }

    [Fact]
    public void Concurrency_AllDrawingSqlStepsOwnTheMonitor()
    {
        using var factory = new ServerFactory();
        using var database = new NestDatabase(factory.DatabasePath, pooling: false);
        var sync = typeof(NestDatabase).GetField("_sync", BindingFlags.Instance | BindingFlags.NonPublic)!.GetValue(database)!;
        var connection = (SqliteConnection)typeof(NestDatabase)
            .GetField("_connection", BindingFlags.Instance | BindingFlags.NonPublic)!.GetValue(database)!;
        var steps = 0;
        var unownedSteps = 0;
        SQLitePCL.raw.sqlite3_progress_handler(connection.Handle, 1, _ =>
        {
            steps++;
            if (!Monitor.IsEntered(sync))
                unownedSteps++;
            return 0;
        }, null);
        try
        {
            var record = Record();
            Action[] operations =
            [
                () => database.InsertDrawing(record.Id, record, Package()),
                () => database.GetDrawing(record.Id),
                () => database.GetDrawingPackage(record.Id),
                () => database.QueryDrawings(new DrawingLibraryQuery { Search = "Synthetic", CutType = CutType.Laser, Thickness = 0.25 }),
                () => database.UpdateDrawing(record.Id, record, Package("changed"), 1),
                () => database.UpdateDrawing(record.Id, Record("Renamed", record.Id), null, 2),
                () => database.SetDrawingArchived(record.Id, true, 3),
                () => database.SetDrawingArchived(record.Id, false, 4),
                () => database.DrawingHistory(record.Id, 0, 100),
                () => database.GetDrawingRevisionPackage(record.Id, 1),
            ];
            foreach (var operation in operations)
            {
                var before = steps;
                operation();
                Assert.True(steps > before, "Operation did not execute the observed SQLite VM.");
                Assert.Equal(0, unownedSteps);
            }
        }
        finally
        {
            SQLitePCL.raw.sqlite3_progress_handler(connection.Handle, 0, null, null);
        }
    }

    /// <summary>A real schema-v3 file: v4 is additive, so dropping its tables restores v3 exactly.</summary>
    private static void CreateVersion3Database(string path)
    {
        using (var database = new NestDatabase(path, pooling: false))
        {
            var first = new NestRecord { Name = "Synthetic nest A", Customer = "Synthetic", Material = "Alloy", Thickness = 0.25 };
            var second = new NestRecord { Name = "Synthetic nest B", Comments = "Notes" };
            var a = database.Insert(Guid.NewGuid(), first, new byte[] { 0, 1, 255 });
            database.Insert(Guid.NewGuid(), second, new byte[] { 7, 8, 9 });
            first.Comments = "Edited";
            database.Update(a.Id, first, new byte[] { 2, 3 }, 1);
            database.SetDeleted(a.Id, true, 2);
            database.SetDeleted(a.Id, false, 3);
        }

        Execute(path, "DROP TABLE drawing_revisions; DROP TABLE drawings; PRAGMA user_version=3;");
    }

    private static string NestDigest(string path)
    {
        using var connection = new SqliteConnection($"Data Source={path};Pooling=False");
        connection.Open();
        var text = new StringBuilder();
        foreach (var sql in new[] { "SELECT * FROM nests ORDER BY id", "SELECT * FROM nest_revisions ORDER BY id, revision" })
        {
            using var command = connection.CreateCommand();
            command.CommandText = sql;
            using var reader = command.ExecuteReader();
            while (reader.Read())
            {
                for (var i = 0; i < reader.FieldCount; i++)
                {
                    var value = reader.GetValue(i);
                    text.Append(reader.GetName(i)).Append('=')
                        .Append(value is byte[] bytes ? Convert.ToHexString(SHA256.HashData(bytes)) : Convert.ToString(value, System.Globalization.CultureInfo.InvariantCulture))
                        .Append(';');
                }
                text.Append('\n');
            }
        }
        return text.ToString();
    }

    private static void Execute(string path, string sql)
    {
        using var connection = new SqliteConnection($"Data Source={path};Pooling=False");
        connection.Open();
        using var command = connection.CreateCommand();
        command.CommandText = sql;
        command.ExecuteNonQuery();
    }

    private static object? Scalar(string path, string sql)
    {
        using var connection = new SqliteConnection($"Data Source={path};Pooling=False");
        connection.Open();
        using var command = connection.CreateCommand();
        command.CommandText = sql;
        return command.ExecuteScalar();
    }
}