// Screens the app can open, and the `wristcode://` URLs the complication uses to open them.

import Foundation

enum Route: Hashable, Sendable {
    case thread(hostId: String, threadId: String)
    case newThread
    /// The status overview, and from it one host or the notifications page.
    case status
    case host(id: String)
    case notifications

    static let scheme = "wristcode"

    /// `wristcode://thread/<hostId>/<threadId>`, `wristcode://new`, `wristcode://status`,
    /// `wristcode://host/<hostId>` or `wristcode://notifications`.
    var url: URL {
        var components = URLComponents()
        components.scheme = Self.scheme
        switch self {
        case let .thread(hostId, threadId):
            components.host = "thread"
            components.percentEncodedPath = "/" + [hostId, threadId]
                .map { $0.addingPercentEncoding(withAllowedCharacters: .alphanumerics) ?? $0 }
                .joined(separator: "/")
        case .newThread:
            components.host = "new"
        case .status:
            components.host = "status"
        case let .host(id):
            components.host = "host"
            components.percentEncodedPath = "/" + (id.addingPercentEncoding(withAllowedCharacters: .alphanumerics) ?? id)
        case .notifications:
            components.host = "notifications"
        }
        return components.url!
    }

    /// The route a `wristcode://` URL names, or nil when it names none.
    init?(url: URL) {
        guard url.scheme == Self.scheme,
              let components = URLComponents(url: url, resolvingAgainstBaseURL: false)
        else { return nil }
        let parts = components.percentEncodedPath.split(separator: "/").map { $0.removingPercentEncoding ?? String($0) }
        switch components.host {
        case "thread" where parts.count == 2 && parts.allSatisfy { !$0.isEmpty }:
            self = .thread(hostId: parts[0], threadId: parts[1])
        case "new":
            self = .newThread
        case "status":
            self = .status
        case "host" where parts.count == 1 && !parts[0].isEmpty:
            self = .host(id: parts[0])
        case "notifications":
            self = .notifications
        default:
            return nil
        }
    }
}