Sesame-Server/Sources/App/Config.swift

import Foundation

struct Config {

    /// The port where the server runs
    let port: Int

    /** 
     The path to the file containing the containing the device authentication token.
     
     If the path is relative, then it is relative to the `Resources` folder.
     */
    let keyFileName: String

    /// The seconds to wait for a response from the device
    let deviceTimeout: Int64

    /// The authentication tokens to use for monitoring of the service
    let authenticationTokens: Set<String>
    
    /**
     The path to the folder where the metric logs are stored
     
     If no path is provided, then a folder `logs` in the resources directory is created.
     If the path is relative, then it is assumed relative to the resources directory.
     */
    let logPath: String?
    
    func logURL(possiblyRelativeTo resourcesDirectory: URL) -> URL {
        guard let logPath else {
            return resourcesDirectory.appendingPathComponent("logs")
        }
        return Config.url(logPath, possiblyRelativeTo: resourcesDirectory)
    }
    
    func keyURL(possiblyRelativeTo resourcesDirectory: URL) -> URL {
        Config.url(keyFileName, possiblyRelativeTo: resourcesDirectory)
    }
    
    private static func url(_ name: String, possiblyRelativeTo resourcesDirectory: URL) -> URL {
        guard !name.hasPrefix("/") else {
            return .init(fileURLWithPath: name)
        }
        return resourcesDirectory.appendingPathComponent(name)
    }
}

extension Config: Codable {

}

extension Config {

    init(loadFrom url: URL) throws {
        guard FileManager.default.fileExists(atPath: url.path) else {
            printAndFlush("No configuration file found at \(url.path)")
            fatalError("No configuration file found")
        }
        let data: Data
        do {
            data = try Data(contentsOf: url)
        } catch {
            printAndFlush("Failed to read config data: \(error)")
            throw error
        }
        do {
            self = try JSONDecoder().decode(Config.self, from: data)
        } catch {
            printAndFlush("Failed to decode config data: \(error)")
            throw error
        }
    }
}