//
//  TodosViewModel.swift
//  iris
//
//  Created by Codex.
//

import Foundation

@MainActor
final class TodosViewModel: ObservableObject {
    @Published private(set) var todos: [TodoItem] = []
    @Published var newTitle: String = ""

    private let store: TodoStore

    init(store: TodoStore = TodoStore()) {
        self.store = store
        refresh()
    }

    func refresh() {
        todos = sortedItems(store.snapshot())
    }

    func addTodo() {
        let trimmed = normalizedTitle(newTitle)
        guard !trimmed.isEmpty else { return }
        store.add(title: trimmed)
        newTitle = ""
        refresh()
    }

    func deleteTodo(id: UUID) {
        store.delete(id: id)
        refresh()
    }

    func toggleCompleted(id: UUID) {
        guard let current = todos.first(where: { $0.id == id }) else { return }
        store.setCompleted(id: id, completed: !current.isCompleted)
        refresh()
    }

    func updateTitle(id: UUID, title: String) {
        let trimmed = normalizedTitle(title)
        guard !trimmed.isEmpty else { return }
        store.updateTitle(id: id, title: trimmed)
        refresh()
    }

    private func normalizedTitle(_ raw: String) -> String {
        raw.trimmingCharacters(in: .whitespacesAndNewlines)
    }

    private func sortedItems(_ items: [TodoItem]) -> [TodoItem] {
        items.sorted { lhs, rhs in
            if lhs.isCompleted != rhs.isCompleted {
                return !lhs.isCompleted
            }
            if lhs.isCompleted {
                let lhsDate = lhs.completedAt ?? lhs.updatedAt
                let rhsDate = rhs.completedAt ?? rhs.updatedAt
                if lhsDate != rhsDate {
                    return lhsDate > rhsDate
                }
            } else if lhs.createdAt != rhs.createdAt {
                return lhs.createdAt > rhs.createdAt
            }
            return lhs.id.uuidString < rhs.id.uuidString
        }
    }
}