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(5L, 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 V4Upgrade_ReplacesTheDrawingTablesAndKeepsNests()
    {
        using var factory = new ServerFactory();
        CreateVersion3Database(factory.DatabasePath);
        // The v4 layout: one column set with the package blob copied into every revision.
        Execute(factory.DatabasePath, """
            CREATE TABLE drawings (id TEXT NOT NULL, revision INTEGER NOT NULL, name TEXT NOT NULL, package BLOB NOT NULL, PRIMARY KEY (id));
            CREATE TABLE drawing_revisions (id TEXT NOT NULL, revision INTEGER NOT NULL, name TEXT NOT NULL, package BLOB NOT NULL);
            INSERT INTO drawings VALUES ('00000000-0000-0000-0000-000000000001', 1, 'Old', x'504B');
            INSERT INTO drawing_revisions SELECT * FROM drawings;
            PRAGMA user_version=4;
            """);
        var before = NestDigest(factory.DatabasePath);

        using var database = new NestDatabase(factory.DatabasePath, pooling: false);

        Assert.Equal(5L, Scalar(factory.DatabasePath, "PRAGMA user_version"));
        Assert.Equal(before, NestDigest(factory.DatabasePath));
        Assert.Empty(database.QueryDrawings(new DrawingLibraryQuery { IncludeArchived = true }).Items);
        var record = Record();
        database.InsertDrawing(record.Id, record, Package());
        Assert.Equal(1L, Scalar(factory.DatabasePath, "SELECT COUNT(*) FROM drawing_packages"));
    }

    [Fact]
    public void NewerSchema_IsRefused()
    {
        using var factory = new ServerFactory();
        using (new NestDatabase(factory.DatabasePath, pooling: false)) { }
        Execute(factory.DatabasePath, "PRAGMA user_version=6");

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

    [Fact]
    public void FailedDrawingMigration_RollsBackAndCanRestart()
    {
        using var factory = new ServerFactory();
        CreateVersion3Database(factory.DatabasePath);
        var before = NestDigest(factory.DatabasePath);
        // A table holding an index's name makes the drawing schema fail part-way through.
        Execute(factory.DatabasePath, "CREATE TABLE ix_drawings_savedAt (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 ix_drawings_savedAt");
        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: the drawing tables are additive, so dropping them 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; DROP TABLE drawing_packages; 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();
    }
}