using Microsoft.Data.Sqlite;
using ZB.MOM.WW.Auth.ApiKeys.Sqlite;

namespace ZB.MOM.WW.Auth.ApiKeys.Tests;

public sealed class SqliteMigratorTests : IDisposable
{
    private readonly string _dbPath =
        Path.Combine(Path.GetTempPath(), Path.GetRandomFileName() + ".db");

    private AuthSqliteConnectionFactory Factory => new(_dbPath);

    [Fact]
    public async Task MigrateAsync_CreatesAllThreeTables()
    {
        var migrator = new SqliteAuthStoreMigrator(Factory);

        await migrator.MigrateAsync(CancellationToken.None);

        Assert.True(await TableExistsAsync(SqliteAuthSchema.ApiKeysTable));
        Assert.True(await TableExistsAsync(SqliteAuthSchema.ApiKeyAuditTable));
        Assert.True(await TableExistsAsync(SqliteAuthSchema.SchemaVersionTable));
    }

    [Fact]
    public async Task MigrateAsync_RunTwice_IsIdempotentAndRecordsCurrentVersion()
    {
        var migrator = new SqliteAuthStoreMigrator(Factory);

        await migrator.MigrateAsync(CancellationToken.None);
        await migrator.MigrateAsync(CancellationToken.None);

        Assert.Equal(SqliteAuthSchema.CurrentVersion, await ReadVersionAsync());
        Assert.Equal(1, await CountSchemaVersionRowsAsync());
    }

    [Fact]
    public void CurrentVersion_Is2_ToMatchDonorGatewayDeployedSchema() =>
        // The store was extracted from MxAccessGateway, whose deployed gateway-auth.db is
        // stamped version 2. The library must stamp 2 (not reset to 1) so it does not refuse
        // those existing databases on first boot. Locking this invariant.
        Assert.Equal(2, SqliteAuthSchema.CurrentVersion);

    [Fact]
    public async Task MigrateAsync_AgainstExistingVersion2Db_DoesNotThrow_AndStaysAt2()
    {
        // The deployed-gateway scenario: a database already provisioned at version 2.
        var migrator = new SqliteAuthStoreMigrator(Factory);
        await migrator.MigrateAsync(CancellationToken.None);
        await SetVersionAsync(2);

        await migrator.MigrateAsync(CancellationToken.None); // must not throw

        Assert.Equal(2, await ReadVersionAsync());
        Assert.True(await TableExistsAsync(SqliteAuthSchema.ApiKeysTable));
    }

    [Fact]
    public async Task MigrateAsync_FutureSchemaVersion_Throws()
    {
        var migrator = new SqliteAuthStoreMigrator(Factory);
        await migrator.MigrateAsync(CancellationToken.None);

        await SetVersionAsync(99);

        await Assert.ThrowsAsync<AuthStoreMigrationException>(
            () => migrator.MigrateAsync(CancellationToken.None));
    }

    private async Task<bool> TableExistsAsync(string tableName)
    {
        await using SqliteConnection connection =
            await Factory.OpenConnectionAsync(CancellationToken.None);
        await using SqliteCommand command = connection.CreateCommand();
        command.CommandText =
            "SELECT COUNT(*) FROM sqlite_master WHERE type = 'table' AND name = $name;";
        command.Parameters.AddWithValue("$name", tableName);
        long count = (long)(await command.ExecuteScalarAsync(CancellationToken.None) ?? 0L);
        return count == 1;
    }

    private async Task<int> ReadVersionAsync()
    {
        await using SqliteConnection connection =
            await Factory.OpenConnectionAsync(CancellationToken.None);
        await using SqliteCommand command = connection.CreateCommand();
        command.CommandText = "SELECT version FROM schema_version WHERE id = 1;";
        object? value = await command.ExecuteScalarAsync(CancellationToken.None);
        return Convert.ToInt32(value, System.Globalization.CultureInfo.InvariantCulture);
    }

    private async Task<int> CountSchemaVersionRowsAsync()
    {
        await using SqliteConnection connection =
            await Factory.OpenConnectionAsync(CancellationToken.None);
        await using SqliteCommand command = connection.CreateCommand();
        command.CommandText = "SELECT COUNT(*) FROM schema_version;";
        long count = (long)(await command.ExecuteScalarAsync(CancellationToken.None) ?? 0L);
        return (int)count;
    }

    private async Task SetVersionAsync(int version)
    {
        await using SqliteConnection connection =
            await Factory.OpenConnectionAsync(CancellationToken.None);
        await using SqliteCommand command = connection.CreateCommand();
        command.CommandText = "UPDATE schema_version SET version = $version WHERE id = 1;";
        command.Parameters.AddWithValue("$version", version);
        await command.ExecuteNonQueryAsync(CancellationToken.None);
    }

    public void Dispose()
    {
        SqliteConnection.ClearAllPools();
        TryDelete(_dbPath);
        TryDelete(_dbPath + "-wal");
        TryDelete(_dbPath + "-shm");
    }

    private static void TryDelete(string path)
    {
        try
        {
            if (File.Exists(path))
            {
                File.Delete(path);
            }
        }
        catch (IOException)
        {
            // Best-effort cleanup of the per-test temp database.
        }
    }
}