using Microsoft.Data.SqlClient;

namespace SQLInsight.IntegrationTests;

/// <summary>
/// Runs db/permissions/grant-least-privilege.sql and proves that the agent login can read everything it needs,
/// and nothing else.
/// </summary>
[Collection(SqlServerTestGroup.Name)]
[Trait("Category", "Integration")]
public class LeastPrivilegeTests(SqlServerFixture sql) : IAsyncLifetime
{
    private const string Login = "sqlinsight_agent";
    private const string Password = "Agent-Pa55word!";
    private const string Database = "SQLInsightQsTest";

    public async Task InitializeAsync()
    {
        await sql.ExecuteAsSaAsync($"""
            IF SUSER_ID(N'{Login}') IS NULL CREATE LOGIN [{Login}] WITH PASSWORD = N'{Password}', CHECK_POLICY = OFF;
            IF DB_ID(N'{Database}') IS NULL CREATE DATABASE [{Database}];
            """);
        await sql.ExecuteAsSaAsync($"""
            USE [{Database}];
            ALTER DATABASE [{Database}] SET QUERY_STORE = ON;
            IF OBJECT_ID(N'dbo.CustomerData') IS NULL
            BEGIN
                CREATE TABLE dbo.CustomerData (Id int NOT NULL PRIMARY KEY, Secret nvarchar(50) NOT NULL);
                INSERT dbo.CustomerData VALUES (1, N'fortroligt');
            END;
            """);

        var script = await File.ReadAllTextAsync(Path.Combine(AppContext.BaseDirectory, "Scripts", "grant-least-privilege.sql"));
        script = script.Replace(@"N'DOMÆNE\svc-sqlinsight$'", $"N'{Login}'", StringComparison.Ordinal);
        await sql.ExecuteAsSaAsync(script);
    }

    public Task DisposeAsync() => Task.CompletedTask;

    [Fact]
    public async Task Agent_login_is_not_sysadmin()
    {
        Assert.Equal(0, await ScalarAsync<int>("SELECT IS_SRVROLEMEMBER('sysadmin')"));
    }

    [Theory]
    [InlineData("SELECT COUNT(*) FROM sys.dm_os_wait_stats")]
    [InlineData("SELECT COUNT(*) FROM sys.dm_exec_requests r CROSS APPLY sys.dm_exec_sql_text(r.sql_handle) t")]
    [InlineData("SELECT COUNT(*) FROM sys.dm_exec_query_stats qs CROSS APPLY sys.dm_exec_query_plan(qs.plan_handle) p")]
    [InlineData("SELECT COUNT(*) FROM sys.dm_io_virtual_file_stats(NULL, NULL)")]
    [InlineData("SELECT COUNT(*) FROM sys.dm_os_ring_buffers")]
    [InlineData("SELECT COUNT(*) FROM sys.dm_xe_sessions WHERE name = 'system_health'")]
    [InlineData("SELECT COUNT(*) FROM sys.configurations")]
    [InlineData("SELECT COUNT(*) FROM msdb.dbo.backupset")]
    [InlineData("SELECT COUNT(*) FROM msdb.dbo.sysjobs")]
    [InlineData("SELECT COUNT(*) FROM msdb.dbo.sysjobhistory")]
    [InlineData("SELECT COUNT(*) FROM msdb.dbo.suspect_pages")]
    [InlineData($"SELECT COUNT(*) FROM [{Database}].sys.database_query_store_options")]
    [InlineData($"SELECT COUNT(*) FROM [{Database}].sys.query_store_runtime_stats")]
    [InlineData($"SELECT COUNT(*) FROM [{Database}].sys.indexes WHERE object_id = OBJECT_ID(N'[{Database}].dbo.CustomerData')")]
    [InlineData($"SELECT COUNT(*) FROM [{Database}].sys.dm_db_index_usage_stats")]
    [InlineData($"SELECT COUNT(*) WHERE DATABASEPROPERTYEX(N'{Database}', 'LastGoodCheckDbTime') IS NOT NULL")]
    public async Task Agent_can_read_monitoring_sources(string query)
    {
        Assert.True(await ScalarAsync<int>(query) >= 0);
    }

    [Fact]
    public async Task Agent_cannot_read_customer_data()
    {
        var ex = await Assert.ThrowsAsync<SqlException>(
            () => ScalarAsync<int>($"SELECT COUNT(*) FROM [{Database}].dbo.CustomerData"));
        Assert.Equal(229, ex.Number); // The SELECT permission was denied.
    }

    [Fact]
    public async Task Agent_cannot_change_anything()
    {
        var ex = await Assert.ThrowsAsync<SqlException>(
            () => ScalarAsync<int>($"USE [{Database}]; CREATE TABLE dbo.ShouldNotExist (Id int); SELECT 1"));
        Assert.Equal(262, ex.Number); // CREATE TABLE permission denied.
    }

    [Fact]
    public async Task Script_is_idempotent()
    {
        var script = await File.ReadAllTextAsync(Path.Combine(AppContext.BaseDirectory, "Scripts", "grant-least-privilege.sql"));
        script = script.Replace(@"N'DOMÆNE\svc-sqlinsight$'", $"N'{Login}'", StringComparison.Ordinal);

        await sql.ExecuteAsSaAsync(script);
    }

    private async Task<T> ScalarAsync<T>(string query)
    {
        var builder = new SqlConnectionStringBuilder(sql.SaConnectionString)
        {
            UserID = Login,
            Password = Password,
            InitialCatalog = "master",
        };
        await using var connection = new SqlConnection(builder.ConnectionString);
        await connection.OpenAsync();
        await using var command = connection.CreateCommand();
        command.CommandText = query;
        return (T)Convert.ChangeType((await command.ExecuteScalarAsync())!, typeof(T), System.Globalization.CultureInfo.InvariantCulture);
    }
}