import Foundation
import Combine
#if canImport(WidgetKit)
import WidgetKit
#endif

final class TaskStore: ObservableObject {
    static let groupIdentifier = "group.com.example.utrello"
    private static let tasksKey = "tasks"

    @Published private(set) var tasks: [TaskItem] {
        didSet { save() }
    }

    init() {
        tasks = Self.loadTasks()
    }

    func add(title: String, to list: TaskList = .todo) {
        let title = title.trimmingCharacters(in: .whitespacesAndNewlines)
        guard !title.isEmpty else { return }
        tasks.insert(TaskItem(title: title, list: list), at: 0)
    }

    func move(_ task: TaskItem, to list: TaskList) {
        guard let index = tasks.firstIndex(of: task) else { return }
        tasks[index].list = list
    }

    func delete(_ task: TaskItem) {
        tasks.removeAll { $0.id == task.id }
    }

    private func save() {
        guard let data = try? JSONEncoder().encode(tasks) else { return }
        Self.defaults.set(data, forKey: Self.tasksKey)
#if canImport(WidgetKit)
        WidgetCenter.shared.reloadTimelines(ofKind: "UTrelloTasksWidget")
#endif
    }

    static func loadTasks() -> [TaskItem] {
        guard
            let data = defaults.data(forKey: tasksKey),
            let tasks = try? JSONDecoder().decode([TaskItem].self, from: data)
        else { return [] }
        return tasks
    }

    private static var defaults: UserDefaults {
        UserDefaults(suiteName: groupIdentifier) ?? .standard
    }
}