RuntimeConfigurationLoader.cs

// Copyright © Datalust Pty Ltd
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//     http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;

namespace SeqCli.Config;

static class RuntimeConfigurationLoader
{
    public static readonly string DefaultConfigFilename =
        Path.Combine(Environment.GetFolderPath(Environment.SpecialFolder.UserProfile), "SeqCli.json");

    const string DefaultEnvironmentVariablePrefix = "SEQCLI_";

    /// <summary>
    /// This is the method to use when loading configuration for runtime use. It will read the configuration
    /// file, if any, and apply overrides from the environment.
    /// </summary>
    public static SeqCliConfig Load()
    {
        var config = SeqCliConfig.ReadFromFile(SeqCliConfigFilename());

        EnvironmentOverrides.Apply(DefaultEnvironmentVariablePrefix, config);

        return config;
    }

    /// <summary>
    /// Resolves location of the configuration file for runtime use, returning either the defaullt location
    /// or user-specified using `SEQCLI_CONFIG_FILE` environment variable.
    /// </summary>
    public static string SeqCliConfigFilename()
    {
        var environment = Environment.GetEnvironmentVariables();
        return SeqCliConfigFilename(environment.Keys.Cast<string>().ToDictionary(k => k, k => (string?)environment[k]));
    }

    internal static string SeqCliConfigFilename(Dictionary<string, string?> environment)
    {
        if (environment.TryGetValue("SEQCLI_CONFIG_FILE", out var customConfigFilename) && !string.IsNullOrEmpty(customConfigFilename))
        {
            return customConfigFilename;
        }

        return DefaultConfigFilename;
    }
}