import SwiftUI
import Testing

@testable import Todos

@MainActor
@Suite("TaskList view model tests")
struct TaskListViewModelTests {

    // MARK: Initializers tests

    @Test(
        "properties are set correctly during initialization",
        arguments: [TodoGroup.today, .upcoming, .overdue, .completed]
    )
    func initialization(for group: TodoGroup) {
        // GIVEN
        // WHEN
        let viewModel = TaskListView.ViewModel(group: group)

        // THEN
        #expect(viewModel.group == group)
        #expect(viewModel.showCompleted == false)
    }

    // MARK: Computed property tests

    @Test(
        "buttonCompleted returns correct values when showCompleted is true",
        arguments: [TodoGroup.today, .upcoming, .overdue, .completed], [true, false]
    )
    func buttonCompleted(
        for group: TodoGroup,
        showCompleted: Bool
    ) {
        // GIVEN
        let viewModel = TaskListView.ViewModel(group: group)

        viewModel.showCompleted = showCompleted

        // WHEN
        let (title, icon) = viewModel.buttonCompleted

        // THEN
        if showCompleted {
            #expect(title == "view.task-list.label.hide-completed")
            #expect(icon == "eye.slash")
        }
        else {
            #expect(title == "view.task-list.label.show-completed")
            #expect(icon == "eye")
        }
    }

    @Test(
        "canShowCompleted returns correct value for each group",
        arguments: zip(
            [TodoGroup.today, .upcoming, .overdue, .completed],
            [true, true, true, false]
        )
    )
    func canShowCompleted(
        for group: TodoGroup,
        expects expectation: Bool
    ) {
        // GIVEN
        let viewModel = TaskListView.ViewModel(group: group)

        // WHEN
        let canShowCompleted = viewModel.canShowCompleted

        // THEN
        #expect(canShowCompleted == expectation)
    }

    @Test(
        "navigationTitle returns correct view title for each group",
        arguments: [TodoGroup.today, .upcoming, .overdue, .completed]
    )
    func navigationTitle(for group: TodoGroup) {
        // GIVEN
        let viewModel = TaskListView.ViewModel(group: group)

        // WHEN
        let title = viewModel.navigationTitle

        // THEN
        #expect(title == group.title)
    }

    // MARK: Method tests

    @Test("delete removes a single todo task from repository")
    func deleteSingleTodo() {
        // GIVEN
        let todos: [Todo] = [
            .init(title: "Task 1", due: .now, order: 0),
            .init(title: "Task 2", due: .now, order: 1),
            .init(title: "Task 3", due: .now, order: 2),
        ]
        let repository = MockTodoRepository(todos: todos)
        let viewModel = TaskListView.ViewModel(group: .today)

        // WHEN
        viewModel.delete(
            todos,
            at: IndexSet(integer: 1),
            from: repository
        )

        // THEN
        #expect(repository.todos.count == 2)
        #expect(repository.todos.contains { $0.title == "Task 1" })
        #expect(repository.todos.contains { $0.title == "Task 3" })
        #expect(!repository.todos.contains { $0.title == "Task 2" })
    }

    @Test("delete removes multiple todo tasks from repository")
    func deleteMultipleTodos() {
        // GIVEN
        let todos: [Todo] = [
            .init(title: "Task 1", due: .now, order: 0),
            .init(title: "Task 2", due: .now, order: 1),
            .init(title: "Task 3", due: .now, order: 2),
            .init(title: "Task 4", due: .now, order: 3),
            .init(title: "Task 5", due: .now, order: 4),
        ]
        
        let repository = MockTodoRepository(todos: todos)
        let viewModel = TaskListView.ViewModel(group: .today)

        // WHEN
        viewModel.delete(
            todos,
            at: IndexSet([1, 3]),
            from: repository
        )

        // THEN
        #expect(repository.todos.count == 3)
        #expect(repository.todos.contains { $0.title == "Task 1" })
        #expect(repository.todos.contains { $0.title == "Task 3" })
        #expect(repository.todos.contains { $0.title == "Task 5" })
        #expect(!repository.todos.contains { $0.title == "Task 2" })
        #expect(!repository.todos.contains { $0.title == "Task 4" })
    }

    @Test("reorderTasks updates order property when moving task forward")
    func reorderTasksMovingForward() {
        // GIVEN
        let viewModel = TaskListView.ViewModel(group: .today)
        let tasks: [Todo] = [
            .init(title: "Task 1", due: .now, order: 0),
            .init(title: "Task 2", due: .now, order: 1),
            .init(title: "Task 3", due: .now, order: 2),
            .init(title: "Task 4", due: .now, order: 3),
        ]

        // WHEN
        viewModel.reorderTasks(
            tasks,
            from: IndexSet(integer: 0),
            to: 3
        )

        // THEN
        #expect(tasks[0].order == 2)
        #expect(tasks[1].order == 0)
        #expect(tasks[2].order == 1)
        #expect(tasks[3].order == 3)
    }

    @Test("reorderTasks updates order property when moving task backward")
    func reorderTasksMovingBackward() {
        // GIVEN
        let viewModel = TaskListView.ViewModel(group: .today)
        let tasks: [Todo] = [
            .init(title: "Task 1", due: .now, order: 0),
            .init(title: "Task 2", due: .now, order: 1),
            .init(title: "Task 3", due: .now, order: 2),
            .init(title: "Task 4", due: .now, order: 3),
        ]

        // WHEN
        viewModel.reorderTasks(
            tasks,
            from: IndexSet(integer: 3),
            to: 1
        )

        // THEN
        #expect(tasks[0].order == 0)
        #expect(tasks[1].order == 2)
        #expect(tasks[2].order == 3)
        #expect(tasks[3].order == 1)
    }

    @Test("toggleCompletedVisibility toggles the showCompleted property")
    func toggleCompletedVisibility() {
        // GIVEN
        let viewModel = TaskListView.ViewModel(group: .today)
        let initialValue = viewModel.showCompleted

        // WHEN
        viewModel.toggleCompletedVisibility()
        let afterFirstToggle = viewModel.showCompleted

        viewModel.toggleCompletedVisibility()
        let afterSecondToggle = viewModel.showCompleted

        // THEN
        #expect(initialValue == false)
        #expect(afterFirstToggle == true)
        #expect(afterSecondToggle == false)
    }

}