import Foundation
import Observation

/// One row of `web sessions list`: a browser signed in to the web.
nonisolated struct WebSession: Decodable, Sendable, Hashable, Identifiable {
    /// The first characters of the session's hash, which `revoke` takes.
    let id: String
    let createdAt: Date
    let expiresAt: Date
    let lastUsedAt: Date

    enum CodingKeys: String, CodingKey {
        case id
        case createdAt = "created_at"
        case expiresAt = "expires_at"
        case lastUsedAt = "last_used_at"
    }
}

/// `web sessions list` and `revoke`. The app signs in with an API token,
/// so ending a browser session never signs the app out.
@Observable
@MainActor
final class WebSessionsViewModel {

    private(set) var state: LoadState<[WebSession]> = .loading
    private(set) var actionError: String?
    private(set) var working = false

    private let client: GitbayClient

    init(client: GitbayClient) {
        self.client = client
    }

    func load() async {
        do {
            let sessions = try await client.readList(["web", "sessions", "list"], of: WebSession.self)
            state = sessions.isEmpty ? .empty("No browser is signed in.") : .loaded(sessions)
        } catch {
            state = .from(error)
        }
    }

    func revoke(id: String) async {
        await perform(["web", "sessions", "revoke", id])
    }

    func revokeAll() async {
        await perform(["web", "sessions", "revoke", "--all"])
    }

    private func perform(_ argv: [String]) async {
        working = true
        actionError = nil
        defer { working = false }
        do {
            try await client.run(argv)
            await load()
        } catch let error as GitbayError {
            actionError = error.userFacingMessage
        } catch {
            actionError = GitbayError.transport(error).userFacingMessage
        }
    }
}