RegexBot/InstanceConfig.cs

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3.5 KiB
C#
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using CommandLine;
using Newtonsoft.Json;
using System.Diagnostics.CodeAnalysis;
using System.Reflection;
namespace RegexBot;
/// <summary>
/// Contains essential instance configuration for this bot including Discord connection settings, service configuration,
/// and command-line options.
/// </summary>
class InstanceConfig {
/// <summary>
/// Token used for Discord authentication.
/// </summary>
internal string BotToken { get; }
/// <summary>
/// List of assemblies to load, by file. Paths are always relative to the bot directory.
/// </summary>
internal IReadOnlyList<string> Assemblies { get; }
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public string? SqlHost { get; }
public string? SqlDatabase { get; }
public string SqlUsername { get; }
public string SqlPassword { get; }
/// <summary>
/// Sets up instance configuration object from file and command line parameters.
/// </summary>
internal InstanceConfig() {
var args = CommandLineParameters.Parse(Environment.GetCommandLineArgs());
var path = args?.ConfigFile ?? Path.GetDirectoryName(Assembly.GetEntryAssembly()!.Location)
+ Path.DirectorySeparatorChar + "." + Path.DirectorySeparatorChar + "instance.json";
JObject conf;
try {
var conftxt = File.ReadAllText(path);
conf = JObject.Parse(conftxt);
} catch (Exception ex) {
string pfx;
if (ex is JsonException) pfx = "Unable to parse configuration: ";
else pfx = "Unable to access configuration: ";
throw new Exception(pfx + ex.Message, ex);
}
BotToken = ReadConfKey<string>(conf, nameof(BotToken), true);
try {
Assemblies = Common.Utilities.LoadStringOrStringArray(conf[nameof(Assemblies)]).AsReadOnly();
} catch (ArgumentNullException) {
Assemblies = Array.Empty<string>();
} catch (ArgumentException) {
throw new Exception($"'{nameof(Assemblies)}' is not properly specified in configuration.");
}
SqlHost = ReadConfKey<string>(conf, nameof(SqlHost), false);
SqlDatabase = ReadConfKey<string?>(conf, nameof(SqlDatabase), false);
SqlUsername = ReadConfKey<string>(conf, nameof(SqlUsername), true);
SqlPassword = ReadConfKey<string>(conf, nameof(SqlPassword), true);
}
private static T? ReadConfKey<T>(JObject jc, string key, [DoesNotReturnIf(true)] bool failOnEmpty) {
if (jc.ContainsKey(key)) return jc[key]!.Value<T>();
if (failOnEmpty) throw new Exception($"'{key}' must be specified in the instance configuration.");
return default;
}
/// <summary>
/// Command line options
/// </summary>
class CommandLineParameters {
[Option('c', "config", Default = null,
HelpText = "Custom path to instance configuration. Defaults to instance.json in bot directory.")]
public string ConfigFile { get; set; } = null!;
/// <summary>
/// Command line arguments parsed here. Depending on inputs, the program can exit here.
/// </summary>
public static CommandLineParameters? Parse(string[] args) {
CommandLineParameters? result = null;
new Parser(settings => {
settings.IgnoreUnknownArguments = true;
settings.AutoHelp = false;
settings.AutoVersion = false;
}).ParseArguments<CommandLineParameters>(args)
.WithParsed(p => result = p)
.WithNotParsed(e => { /* ignore */ });
return result;
}
}
}