using Npgsql;

namespace NpgsqlRest;

/// <summary>

/// Helper methods for creating and opening database connections.

/// </summary>

public static class ConnectionHelper

{

/// <summary>

/// Creates and opens a connection using the standard resolution order:

/// 1. Named DataSource (if connectionName provided)

/// 2. Named ConnectionString (if connectionName provided)

/// 3. Default DataSource

/// 4. Default ConnectionString

/// </summary>

/// <param name="options">NpgsqlRest options containing connection configuration</param>

/// <param name="connectionName">Optional connection name for named DataSource or ConnectionString lookup</param>

/// <param name="loggingMode">Mode for logging PostgreSQL NOTICE events</param>

/// <param name="cancellationToken">Cancellation token</param>

/// <param name="logger">Optional logger for retry logging</param>

/// <returns>An opened NpgsqlConnection</returns>

/// <exception cref="InvalidOperationException">

/// Thrown when connectionName is specified but not found, or when no default connection is configured

/// </exception>

public static async Task<NpgsqlConnection> OpenConnectionAsync(

NpgsqlRestOptions options,

string? connectionName,

PostgresConnectionNoticeLoggingMode loggingMode,

CancellationToken cancellationToken,

ILogger? logger = null)

{

NpgsqlConnection connection;

if (connectionName is not null)

{

// Named DataSource lookup

if (options.DataSources?.TryGetValue(connectionName, out var namedDataSource) is true)

{

connection = namedDataSource.CreateConnection();

}

// Named ConnectionString lookup

else if (options.ConnectionStrings?.TryGetValue(connectionName, out var connString) is true)

{

connection = new NpgsqlConnection(connString);

}

else

{

throw new InvalidOperationException(

$"Connection name '{connectionName}' not found in DataSources or ConnectionStrings");

}

}

else

{

// Default DataSource

if (options.DataSource is not null)

{

connection = options.DataSource.CreateConnection();

}

// Default ConnectionString

else if (!string.IsNullOrEmpty(options.ConnectionString))

{

connection = new NpgsqlConnection(options.ConnectionString);

}

else

{

throw new InvalidOperationException(

"No DataSource or ConnectionString configured");

}

}

// Setup notice logging

if (options.LogConnectionNoticeEvents)

{

connection.Notice += (sender, args) =>

{

NpgsqlRestLogger.LogConnectionNotice(args.Notice, loggingMode);

};

}

// Open with retry

await connection.OpenRetryAsync(options.ConnectionRetryOptions, cancellationToken, logger);

return connection;

}

}