using Microsoft.EntityFrameworkCore;
using Npgsql;
using Xunit;

namespace BuildFlow.Workflow.Tests.Reliability;

/// <summary>
/// 为工作流可靠性测试创建并销毁独立 PostgreSQL 数据库。
/// </summary>
public sealed class PostgresWorkflowFixture : IAsyncLifetime
{
    private const string DefaultConnection =
        "Host=127.0.0.1;Port=55432;Username=buildflow;Password=buildflow;Database=postgres";

    private string _databaseName = default!;
    private string _adminConnectionString = default!;

    /// <summary>当前测试数据库连接串。</summary>
    public string ConnectionString { get; private set; } = default!;

    public async Task InitializeAsync()
    {
        var configured = Environment.GetEnvironmentVariable("BUILDFLOW_WORKFLOW_TEST_CONNECTION")
                         ?? DefaultConnection;
        var adminBuilder = new NpgsqlConnectionStringBuilder(configured)
        {
            Database = "postgres",
            Pooling = false,
        };
        _adminConnectionString = adminBuilder.ConnectionString;
        _databaseName = $"workflow_reliability_{Guid.NewGuid():N}";

        await using (var connection = new NpgsqlConnection(_adminConnectionString))
        {
            await connection.OpenAsync();
            await using var command = connection.CreateCommand();
            command.CommandText = $"CREATE DATABASE \"{_databaseName}\"";
            await command.ExecuteNonQueryAsync();
        }

        var databaseBuilder = new NpgsqlConnectionStringBuilder(configured)
        {
            Database = _databaseName,
            Pooling = true,
        };
        ConnectionString = databaseBuilder.ConnectionString;

        await using var db = CreateDbContext();
        await db.Database.EnsureCreatedAsync();
    }

    /// <summary>创建指向独立测试数据库的 WorkflowDbContext。</summary>
    public WorkflowDbContext CreateDbContext()
    {
        var options = new DbContextOptionsBuilder<WorkflowDbContext>()
            .UseNpgsql(ConnectionString)
            .UseSnakeCaseNamingConvention()
            .Options;
        var db = new WorkflowDbContext(options);
        db.SavingChanges += AuditStub.OnSave;
        return db;
    }

    public async Task DisposeAsync()
    {
        NpgsqlConnection.ClearAllPools();
        await using var connection = new NpgsqlConnection(_adminConnectionString);
        await connection.OpenAsync();

        await using (var terminate = connection.CreateCommand())
        {
            terminate.CommandText =
                "SELECT pg_terminate_backend(pid) FROM pg_stat_activity WHERE datname = @database AND pid <> pg_backend_pid()";
            terminate.Parameters.AddWithValue("database", _databaseName);
            await terminate.ExecuteNonQueryAsync();
        }

        await using var drop = connection.CreateCommand();
        drop.CommandText = $"DROP DATABASE IF EXISTS \"{_databaseName}\"";
        await drop.ExecuteNonQueryAsync();
    }
}