import Foundation
import Testing

@testable import Todos

@Suite("NewTaskView view model tests")
struct NewTaskViewModelTests {

    // MARK: Initialization tests

    @Test("View model initializes with default values")
    func initialization() {
        // GIVEN
        // WHEN
        let viewModel = NewTaskView.ViewModel()

        // THEN
        #expect(viewModel.title == "")
        #expect(viewModel.note == "")
        #expect(viewModel.due.timeIntervalSinceNow < 1.0)
    }

    // MARK: Properties tests

    @Test("due property can be modified")
    func dueModifications() {
        // GIVEN
        let dateInsert = Date(timeIntervalSince1970: 1000000000)
        let dateUpdate = Date(timeIntervalSince1970: 2000000000)

        // WHEN
        let viewModel = NewTaskView.ViewModel()

        // THEN
        viewModel.due = dateInsert
        #expect(viewModel.due == dateInsert)

        viewModel.due = dateUpdate
        #expect(viewModel.due == dateUpdate)
    }

    @Test("note property can be modified")
    func noteModifications() {
        // GIVEN
        let noteInsert = "Initial note"
        let noteUpdate = "Updated note"

        // WHEN
        let viewModel = NewTaskView.ViewModel()

        // THEN
        viewModel.note = noteInsert
        #expect(viewModel.note == noteInsert)

        viewModel.note = noteUpdate
        #expect(viewModel.note == noteUpdate)
    }

    @Test("title property can be modified")
    func titleModifications() {
        // GIVEN
        let titleInsert = "Initial title"
        let titleUpdate = "Updated title"

        // WHEN
        let viewModel = NewTaskView.ViewModel()

        // THEN
        viewModel.title = titleInsert
        #expect(viewModel.title == titleInsert)

        viewModel.title = titleUpdate
        #expect(viewModel.title == titleUpdate)
    }

    // MARK: Computed tests

    @Test(
        "canConfirm property validation",
        arguments: zip(
            ["", "Some title goes here...", "   "],
            [false, true, false]
        )
    )
    func canConfirm(
        with title: String,
        expects expectation: Bool
    ) {
        // GIVEN
        let viewModel = NewTaskView.ViewModel()

        // WHEN
        viewModel.title = title

        // THEN
        #expect(viewModel.canConfirm == expectation)
    }

    @Test("canConfirm updates when title changes")
    func canConfirmWithTitleChanges() {
        // GIVEN
        let titleEmpty = ""
        let titleFilled = "New task"
        let titleTrimmed = "  "

        // WHEN
        let viewModel = NewTaskView.ViewModel()

        // THEN
        viewModel.title = titleEmpty
        #expect(viewModel.canConfirm == false)

        viewModel.title = titleFilled
        #expect(viewModel.canConfirm == true)

        viewModel.title = titleTrimmed
        #expect(viewModel.canConfirm == false)
    }

    // MARK: Functions tests

    @Test("save creates todo with all properties")
    func saveWithAllProperties() throws {
        // GIVEN
        let repository = MockTodoRepository()
        let viewModel = NewTaskView.ViewModel()

        // WHEN
        viewModel.title = "Complete project"
        viewModel.note = "Finish by end of week"
        viewModel.due = Date(timeIntervalSince1970: 1000000000)

        viewModel.save(to: repository)

        // THEN
        let todo = try #require(repository.todos.first)

        #expect(todo.title == viewModel.title)
        #expect(todo.note == viewModel.note)
        #expect(todo.due == viewModel.due)
        #expect(todo.completed == nil)
    }

    @Test("save creates todo without note when note is empty")
    func saveWithEmptyNote() throws {
        // GIVEN
        let repository = MockTodoRepository()
        let viewModel = NewTaskView.ViewModel()

        // WHEN
        viewModel.title = "Task without note"
        viewModel.note = ""
        viewModel.due = Date()

        viewModel.save(to: repository)

        // THEN
        let todo = try #require(repository.todos.first)

        #expect(todo.title == viewModel.title)
        #expect(todo.note == nil)
        #expect(todo.due == viewModel.due)
        #expect(todo.completed == nil)
    }

    @Test("save creates todo with note containing only whitespace as nil")
    func saveWithWhitespaceNote() throws {
        // GIVEN
        let repository = MockTodoRepository()
        let viewModel = NewTaskView.ViewModel()

        // WHEN
        viewModel.title = "Task with whitespace note"
        viewModel.note = "   "
        viewModel.due = Date()

        viewModel.save(to: repository)

        // THEN
        let todo = try #require(repository.todos.first)

        #expect(todo.title == viewModel.title)
        #expect(todo.note == nil)
        #expect(todo.due == viewModel.due)
        #expect(todo.completed == nil)
    }

    @Test("save inserts multiple todos independently")
    func saveMultipleTodos() {
        // GIVEN
        let repository = MockTodoRepository()
        let viewModelFirst = NewTaskView.ViewModel()
        let viewModelSecond = NewTaskView.ViewModel()

        // WHEN
        viewModelFirst.title = "First task"
        viewModelFirst.save(to: repository)

        viewModelSecond.title = "Second task"
        viewModelSecond.note = "With a note"
        viewModelSecond.save(to: repository)

        // THEN
        #expect(repository.todos.count == 2)
        #expect(repository.todos.contains { $0.title == "First task" })
        #expect(repository.todos.contains { $0.title == "Second task" })
    }

}