import Foundation
import Observation

/// `label list <repo>`, plus the two commands that change the set:
/// `label set` creates one or recolours it, `label remove` takes it off
/// the repository and off every issue that carried it.
@Observable
@MainActor
final class LabelListViewModel {

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

    private let client: GitbayClient
    let repoPath: String

    init(client: GitbayClient, repoPath: String) {
        self.client = client
        self.repoPath = repoPath
    }

    func load() async {
        state = .loading
        do {
            let labels = try await client.readList(
                ["label", "list", repoPath], of: IssueLabel.self
            )
            state = labels.isEmpty ? .empty("No labels yet.") : .loaded(labels)
        } catch {
            state = .from(error)
        }
    }

    /// Create a label or set its colour. A nil colour omits `--color`
    /// entirely, which the server reads as "make sure it exists" and
    /// leaves any colour it already had; an empty string clears it.
    func setLabel(_ name: String, color: String?) async {
        var argv = ["label", "set", repoPath, name]
        if let color { argv.append(contentsOf: ["--color", color]) }
        await perform(argv)
    }

    func remove(_ name: String) async {
        await perform(["label", "remove", repoPath, name])
    }

    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
        }
    }
}