import Foundation

struct Config: Codable {

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

    /// The maximum size of the request body
    let maxBodySize: 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?

    /// Serve files in the Public directory using Vapor
    let serveFiles: Bool

    /// Authentication tokens for remotes allowed to write
    let writers: [String]
    
    let dataDirectory: String?
    
    func customDataDirectory(or publicDirectory: String) -> URL {
        guard let dataDirectory else {
            return URL(fileURLWithPath: publicDirectory)
        }
        return URL(fileURLWithPath: dataDirectory)
    }
    
    func logURL(possiblyRelativeTo resourcesDirectory: URL) -> URL {
        guard let logPath else {
            return resourcesDirectory.appendingPathComponent("logs")
        }
        guard !logPath.hasPrefix("/") else {
            return .init(fileURLWithPath: logPath)
        }
        return resourcesDirectory.appendingPathComponent(logPath)
    }
}

extension Config {

    private static func file(in directory: URL) -> URL {
        directory.appendingPathComponent("config.json")
    }

    init(loadFrom directory: URL) {
        let configFileUrl = Config.file(in: directory)

        guard FileManager.default.fileExists(atPath: configFileUrl.path) else {
            print("No configuration found at \(configFileUrl.path)")
            exit(-1)
        }
        self.init(loadAt: configFileUrl)
    }

    private init(loadAt url: URL) {
        do {
            let configData = try Data(contentsOf: url)
            self = try JSONDecoder().decode(Config.self, from: configData)
        } catch {
            print("Failed to load configuration from \(url.path): \(error)")
            exit(-1)
        }
    }
}