//! Multiple scenarios that are performed to test sync operations correctly work
//!
//! This module creates test data.
//! To do so, "scenarii" are defined. A scenario contains an inital state before sync, changes made either on the local or remote side, then the expected final state that should be present in both sources after sync.
//!
//! This module builds actual CalDAV sources (actually [`crate::cache::Cache`]s, that can also mock what would be [`crate::client::Client`]s in a real program) and [`crate::provider::Provider]`s that contain this data
//!
//! This module can also check the sources after a sync contain the actual data we expect
#![cfg(feature = "local_calendar_mocks_remote_calendars")]

use std::path::PathBuf;
use std::sync::{Arc, Mutex};
use std::error::Error;
use url::Url;

use chrono::Utc;

use kitchen_fridge::calendar::SupportedComponents;
use kitchen_fridge::traits::CalDavSource;
use kitchen_fridge::traits::BaseCalendar;
use kitchen_fridge::traits::CompleteCalendar;
use kitchen_fridge::traits::DavCalendar;
use kitchen_fridge::cache::Cache;
use kitchen_fridge::Item;
use kitchen_fridge::item::SyncStatus;
use kitchen_fridge::Task;
use kitchen_fridge::task::CompletionStatus;
use kitchen_fridge::calendar::cached_calendar::CachedCalendar;
use kitchen_fridge::provider::Provider;
use kitchen_fridge::mock_behaviour::MockBehaviour;
use kitchen_fridge::utils::random_url;

pub enum LocatedState {
    /// Item does not exist yet or does not exist anymore
    None,
    /// Item is only in the local source
    Local(ItemState),
    /// Item is only in the remote source
    Remote(ItemState),
    /// Item is synced at both locations,
    BothSynced(ItemState),
}

pub struct ItemState {
    // TODO: if/when this crate supports Events as well, we could add such events here
    /// The calendar it is in
    calendar: Url,
    /// Its name
    name: String,
    /// Its completion status
    completed: bool,
}

pub enum ChangeToApply {
    Rename(String),
    SetCompletion(bool),
    Create(Url, Item),
    /// "remove" means "mark for deletion" in the local calendar, or "immediately delete" on the remote calendar
    Remove,
    // ChangeCalendar(Url) is useless, as long as changing a calendar is implemented as "delete in one calendar and re-create it in another one"
}


pub struct ItemScenario {
    url: Url,
    initial_state: LocatedState,
    local_changes_to_apply:  Vec<ChangeToApply>,
    remote_changes_to_apply: Vec<ChangeToApply>,
    after_sync: LocatedState,
}

/// Generate the scenarii required for the following test:
/// * At the last sync: both sources had A, B, C, D, E, F, G, H, I, J, K, L, M✓, N✓, O✓, P✓ at last sync
///   A-F are in a calendar, G-M are in a second one, and in a third calendar from N on
///
/// * Before the newer sync, this will be the content of the sources:
///     * cache:  A, B,    D', E,  F'', G , H✓, I✓, J✓,        M,  N✓, O, P' ,    R
///     * server: A,    C, D,  E', F',  G✓, H , I',      K✓,    M✓, N , O, P✓,  Q
///
/// Hence, here is the expected result after the sync:
///     * both:   A,       D', E', F',  G✓, H✓, I',      K✓,   M, N, O, P', Q, R
///
/// Notes:
/// * X': name has been modified since the last sync
/// * X'/X'': name conflict
/// * X✓: task has been marked as completed
pub fn scenarii_basic() -> Vec<ItemScenario> {
    let mut tasks = Vec::new();

    let first_cal = Url::from("https://some.calend.ar/calendar-1/".parse().unwrap());
    let second_cal = Url::from("https://some.calend.ar/calendar-2/".parse().unwrap());
    let third_cal = Url::from("https://some.calend.ar/calendar-3/".parse().unwrap());

    tasks.push(
        ItemScenario {
            url: random_url(&first_cal),
            initial_state: LocatedState::BothSynced( ItemState{
                calendar: first_cal.clone(),
                name: String::from("Task A"),
                completed: false,
            }),
            local_changes_to_apply: Vec::new(),
            remote_changes_to_apply: Vec::new(),
            after_sync: LocatedState::BothSynced( ItemState{
                calendar: first_cal.clone(),
                name: String::from("Task A"),
                completed: false,
            }),
        }
    );

    tasks.push(
        ItemScenario {
            url: random_url(&first_cal),
            initial_state: LocatedState::BothSynced( ItemState{
                calendar: first_cal.clone(),
                name: String::from("Task B"),
                completed: false,
            }),
            local_changes_to_apply: Vec::new(),
            remote_changes_to_apply: vec![ChangeToApply::Remove],
            after_sync: LocatedState::None,
        }
    );

    tasks.push(
        ItemScenario {
            url: random_url(&first_cal),
            initial_state: LocatedState::BothSynced( ItemState{
                calendar: first_cal.clone(),
                name: String::from("Task C"),
                completed: false,
            }),
            local_changes_to_apply: vec![ChangeToApply::Remove],
            remote_changes_to_apply: Vec::new(),
            after_sync: LocatedState::None,
        }
    );

    tasks.push(
        ItemScenario {
            url: random_url(&first_cal),
            initial_state: LocatedState::BothSynced( ItemState{
                calendar: first_cal.clone(),
                name: String::from("Task D"),
                completed: false,
            }),
            local_changes_to_apply: vec![ChangeToApply::Rename(String::from("Task D, locally renamed"))],
            remote_changes_to_apply: Vec::new(),
            after_sync: LocatedState::BothSynced( ItemState{
                calendar: first_cal.clone(),
                name: String::from("Task D, locally renamed"),
                completed: false,
            }),
        }
    );

    tasks.push(
        ItemScenario {
            url: random_url(&first_cal),
            initial_state: LocatedState::BothSynced( ItemState{
                calendar: first_cal.clone(),
                name: String::from("Task E"),
                completed: false,
            }),
            local_changes_to_apply: Vec::new(),
            remote_changes_to_apply: vec![ChangeToApply::Rename(String::from("Task E, remotely renamed"))],
            after_sync: LocatedState::BothSynced( ItemState{
                calendar: first_cal.clone(),
                name: String::from("Task E, remotely renamed"),
                completed: false,
            }),
        }
    );

    tasks.push(
        ItemScenario {
            url: random_url(&first_cal),
            initial_state: LocatedState::BothSynced( ItemState{
                calendar: first_cal.clone(),
                name: String::from("Task F"),
                completed: false,
            }),
            local_changes_to_apply: vec![ChangeToApply::Rename(String::from("Task F, locally renamed"))],
            remote_changes_to_apply: vec![ChangeToApply::Rename(String::from("Task F, remotely renamed"))],
            // Conflict: the server wins
            after_sync: LocatedState::BothSynced( ItemState{
                calendar: first_cal.clone(),
                name: String::from("Task F, remotely renamed"),
                completed: false,
            }),
        }
    );

    tasks.push(
        ItemScenario {
            url: random_url(&second_cal),
            initial_state: LocatedState::BothSynced( ItemState{
                calendar: second_cal.clone(),
                name: String::from("Task G"),
                completed: false,
            }),
            local_changes_to_apply: Vec::new(),
            remote_changes_to_apply: vec![ChangeToApply::SetCompletion(true)],
            after_sync: LocatedState::BothSynced( ItemState{
                calendar: second_cal.clone(),
                name: String::from("Task G"),
                completed: true,
            }),
        }
    );

    tasks.push(
        ItemScenario {
            url: random_url(&second_cal),
            initial_state: LocatedState::BothSynced( ItemState{
                calendar: second_cal.clone(),
                name: String::from("Task H"),
                completed: false,
            }),
            local_changes_to_apply: vec![ChangeToApply::SetCompletion(true)],
            remote_changes_to_apply: Vec::new(),
            after_sync: LocatedState::BothSynced( ItemState{
                calendar: second_cal.clone(),
                name: String::from("Task H"),
                completed: true,
            }),
        }
    );

    tasks.push(
        ItemScenario {
            url: random_url(&second_cal),
            initial_state: LocatedState::BothSynced( ItemState{
                calendar: second_cal.clone(),
                name: String::from("Task I"),
                completed: false,
            }),
            local_changes_to_apply: vec![ChangeToApply::SetCompletion(true)],
            remote_changes_to_apply: vec![ChangeToApply::Rename(String::from("Task I, remotely renamed"))],
            // Conflict, the server wins
            after_sync: LocatedState::BothSynced( ItemState{
                calendar: second_cal.clone(),
                name: String::from("Task I, remotely renamed"),
                completed: false,
            }),
        }
    );

    tasks.push(
        ItemScenario {
            url: random_url(&second_cal),
            initial_state: LocatedState::BothSynced( ItemState{
                calendar: second_cal.clone(),
                name: String::from("Task J"),
                completed: false,
            }),
            local_changes_to_apply: vec![ChangeToApply::SetCompletion(true)],
            remote_changes_to_apply: vec![ChangeToApply::Remove],
            after_sync: LocatedState::None,
        }
    );

    tasks.push(
        ItemScenario {
            url: random_url(&second_cal),
            initial_state: LocatedState::BothSynced( ItemState{
                calendar: second_cal.clone(),
                name: String::from("Task K"),
                completed: false,
            }),
            local_changes_to_apply: vec![ChangeToApply::Remove],
            remote_changes_to_apply: vec![ChangeToApply::SetCompletion(true)],
            after_sync: LocatedState::BothSynced( ItemState{
                calendar: second_cal.clone(),
                name: String::from("Task K"),
                completed: true,
            }),
        }
    );

    tasks.push(
        ItemScenario {
            url: random_url(&second_cal),
            initial_state: LocatedState::BothSynced( ItemState{
                calendar: second_cal.clone(),
                name: String::from("Task L"),
                completed: false,
            }),
            local_changes_to_apply: vec![ChangeToApply::Remove],
            remote_changes_to_apply: vec![ChangeToApply::Remove],
            after_sync: LocatedState::None,
        }
    );

    tasks.push(
        ItemScenario {
            url: random_url(&second_cal),
            initial_state: LocatedState::BothSynced( ItemState{
                calendar: second_cal.clone(),
                name: String::from("Task M"),
                completed: true,
            }),
            local_changes_to_apply: vec![ChangeToApply::SetCompletion(false)],
            remote_changes_to_apply: Vec::new(),
            after_sync: LocatedState::BothSynced( ItemState{
                calendar: second_cal.clone(),
                name: String::from("Task M"),
                completed: false,
            }),
        }
    );

    tasks.push(
        ItemScenario {
            url: random_url(&third_cal),
            initial_state: LocatedState::BothSynced( ItemState{
                calendar: third_cal.clone(),
                name: String::from("Task N"),
                completed: true,
            }),
            local_changes_to_apply: Vec::new(),
            remote_changes_to_apply: vec![ChangeToApply::SetCompletion(false)],
            after_sync: LocatedState::BothSynced( ItemState{
                calendar: third_cal.clone(),
                name: String::from("Task N"),
                completed: false,
            }),
        }
    );

    tasks.push(
        ItemScenario {
            url: random_url(&third_cal),
            initial_state: LocatedState::BothSynced( ItemState{
                calendar: third_cal.clone(),
                name: String::from("Task O"),
                completed: true,
            }),
            local_changes_to_apply:  vec![ChangeToApply::SetCompletion(false)],
            remote_changes_to_apply: vec![ChangeToApply::SetCompletion(false)],
            after_sync: LocatedState::BothSynced( ItemState{
                calendar: third_cal.clone(),
                name: String::from("Task O"),
                completed: false,
            }),
        }
    );

    let url_p = random_url(&third_cal);
    tasks.push(
        ItemScenario {
            url: url_p.clone(),
            initial_state: LocatedState::BothSynced( ItemState{
                calendar: third_cal.clone(),
                name: String::from("Task P"),
                completed: true,
            }),
            local_changes_to_apply: vec![
                ChangeToApply::Rename(String::from("Task P, locally renamed and un-completed")),
                ChangeToApply::SetCompletion(false),
            ],
            remote_changes_to_apply: Vec::new(),
            after_sync: LocatedState::BothSynced( ItemState{
                calendar: third_cal.clone(),
                name: String::from("Task P, locally renamed and un-completed"),
                completed: false,
            }),
        }
    );

    let url_q = random_url(&third_cal);
    tasks.push(
        ItemScenario {
            url: url_q.clone(),
            initial_state: LocatedState::None,
            local_changes_to_apply: Vec::new(),
            remote_changes_to_apply: vec![ChangeToApply::Create(third_cal.clone(), Item::Task(
                Task::new_with_parameters(
                    String::from("Task Q, created on the server"),
                    url_q.to_string(), url_q,
                    CompletionStatus::Uncompleted,
                    SyncStatus::random_synced(), Some(Utc::now()), Utc::now(), "prod_id".to_string(), Vec::new() )
            ))],
            after_sync: LocatedState::BothSynced( ItemState{
                calendar: third_cal.clone(),
                name: String::from("Task Q, created on the server"),
                completed: false,
            }),
        }
    );

    let url_r = random_url(&third_cal);
    tasks.push(
        ItemScenario {
            url: url_r.clone(),
            initial_state: LocatedState::None,
            local_changes_to_apply: vec![ChangeToApply::Create(third_cal.clone(), Item::Task(
                Task::new_with_parameters(
                    String::from("Task R, created locally"),
                    url_r.to_string(), url_r,
                    CompletionStatus::Uncompleted,
                    SyncStatus::NotSynced, Some(Utc::now()), Utc::now(), "prod_id".to_string(), Vec::new() )
            ))],
            remote_changes_to_apply: Vec::new(),
            after_sync: LocatedState::BothSynced( ItemState{
                calendar: third_cal.clone(),
                name: String::from("Task R, created locally"),
                completed: false,
            }),
        }
    );

    tasks
}

/// This scenario basically checks a first sync to an empty local cache
pub fn scenarii_first_sync_to_local() -> Vec<ItemScenario> {
    let mut tasks = Vec::new();

    let cal1 = Url::from("https://some.calend.ar/first/".parse().unwrap());
    let cal2 = Url::from("https://some.calend.ar/second/".parse().unwrap());

    tasks.push(
        ItemScenario {
            url: random_url(&cal1),
            initial_state: LocatedState::Remote( ItemState{
                calendar: cal1.clone(),
                name: String::from("Task A1"),
                completed: false,
            }),
            local_changes_to_apply: Vec::new(),
            remote_changes_to_apply: Vec::new(),
            after_sync: LocatedState::BothSynced( ItemState{
                calendar: cal1.clone(),
                name: String::from("Task A1"),
                completed: false,
            }),
        }
    );

    tasks.push(
        ItemScenario {
            url: random_url(&cal2),
            initial_state: LocatedState::Remote( ItemState{
                calendar: cal2.clone(),
                name: String::from("Task A2"),
                completed: false,
            }),
            local_changes_to_apply: Vec::new(),
            remote_changes_to_apply: Vec::new(),
            after_sync: LocatedState::BothSynced( ItemState{
                calendar: cal2.clone(),
                name: String::from("Task A2"),
                completed: false,
            }),
        }
    );

    tasks.push(
        ItemScenario {
            url: random_url(&cal1),
            initial_state: LocatedState::Remote( ItemState{
                calendar: cal1.clone(),
                name: String::from("Task B1"),
                completed: false,
            }),
            local_changes_to_apply: Vec::new(),
            remote_changes_to_apply: Vec::new(),
            after_sync: LocatedState::BothSynced( ItemState{
                calendar: cal1.clone(),
                name: String::from("Task B1"),
                completed: false,
            }),
        }
    );

    tasks
}

/// This scenario basically checks a first sync to an empty server
pub fn scenarii_first_sync_to_server() -> Vec<ItemScenario> {
    let mut tasks = Vec::new();

    let cal3 = Url::from("https://some.calend.ar/third/".parse().unwrap());
    let cal4 = Url::from("https://some.calend.ar/fourth/".parse().unwrap());

    tasks.push(
        ItemScenario {
            url: random_url(&cal3),
            initial_state: LocatedState::Local( ItemState{
                calendar: cal3.clone(),
                name: String::from("Task A3"),
                completed: false,
            }),
            local_changes_to_apply: Vec::new(),
            remote_changes_to_apply: Vec::new(),
            after_sync: LocatedState::BothSynced( ItemState{
                calendar: cal3.clone(),
                name: String::from("Task A3"),
                completed: false,
            }),
        }
    );

    tasks.push(
        ItemScenario {
            url: random_url(&cal4),
            initial_state: LocatedState::Local( ItemState{
                calendar: cal4.clone(),
                name: String::from("Task A4"),
                completed: false,
            }),
            local_changes_to_apply: Vec::new(),
            remote_changes_to_apply: Vec::new(),
            after_sync: LocatedState::BothSynced( ItemState{
                calendar: cal4.clone(),
                name: String::from("Task A4"),
                completed: false,
            }),
        }
    );

    tasks.push(
        ItemScenario {
            url: random_url(&cal3),
            initial_state: LocatedState::Local( ItemState{
                calendar: cal3.clone(),
                name: String::from("Task B3"),
                completed: false,
            }),
            local_changes_to_apply: Vec::new(),
            remote_changes_to_apply: Vec::new(),
            after_sync: LocatedState::BothSynced( ItemState{
                calendar: cal3.clone(),
                name: String::from("Task B3"),
                completed: false,
            }),
        }
    );

    tasks
}


/// This scenario tests a task added and deleted before a sync happens
pub fn scenarii_transient_task() -> Vec<ItemScenario> {
    let mut tasks = Vec::new();

    let cal = Url::from("https://some.calend.ar/transient/".parse().unwrap());

    tasks.push(
        ItemScenario {
            url: random_url(&cal),
            initial_state: LocatedState::Local( ItemState{
                calendar: cal.clone(),
                name: String::from("A task, so that the calendar actually exists"),
                completed: false,
            }),
            local_changes_to_apply: Vec::new(),
            remote_changes_to_apply: Vec::new(),
            after_sync: LocatedState::BothSynced( ItemState{
                calendar: cal.clone(),
                name: String::from("A task, so that the calendar actually exists"),
                completed: false,
            }),
        }
    );

    let url_transient = random_url(&cal);
    tasks.push(
        ItemScenario {
            url: url_transient.clone(),
            initial_state: LocatedState::None,
            local_changes_to_apply: vec![
                ChangeToApply::Create(cal, Item::Task(
                    Task::new_with_parameters(
                        String::from("A transient task that will be deleted before the sync"),
                        url_transient.to_string(), url_transient,
                        CompletionStatus::Uncompleted,
                        SyncStatus::NotSynced, Some(Utc::now()), Utc::now(),
                        "prod_id".to_string(), Vec::new() )
                )),

                ChangeToApply::Rename(String::from("A new name")),
                ChangeToApply::SetCompletion(true),
                ChangeToApply::Remove,
            ],
            remote_changes_to_apply: Vec::new(),
            after_sync: LocatedState::None,
        }
    );

    tasks
}


/// Build a `Provider` that contains the data (defined in the given scenarii) before sync
pub async fn populate_test_provider_before_sync(scenarii: &[ItemScenario], mock_behaviour: Arc<Mutex<MockBehaviour>>) -> Provider<Cache, CachedCalendar, Cache, CachedCalendar> {
    let mut provider = populate_test_provider(scenarii, mock_behaviour, false).await;
    apply_changes_on_provider(&mut provider, scenarii).await;
    provider
}

/// Build a `Provider` that contains the data (defined in the given scenarii) after sync
pub async fn populate_test_provider_after_sync(scenarii: &[ItemScenario], mock_behaviour: Arc<Mutex<MockBehaviour>>) -> Provider<Cache, CachedCalendar, Cache, CachedCalendar> {
    populate_test_provider(scenarii, mock_behaviour, true).await
}

async fn populate_test_provider(scenarii: &[ItemScenario], mock_behaviour: Arc<Mutex<MockBehaviour>>, populate_for_final_state: bool) -> Provider<Cache, CachedCalendar, Cache, CachedCalendar> {
    let mut local = Cache::new(&PathBuf::from(String::from("test_cache/local/")));
    let mut remote = Cache::new(&PathBuf::from(String::from("test_cache/remote/")));
    remote.set_mock_behaviour(Some(mock_behaviour));

    // Create the initial state, as if we synced both sources in a given state
    for item in scenarii {
        let required_state = if populate_for_final_state { &item.after_sync } else { &item.initial_state };
        let (state, sync_status) = match required_state {
            LocatedState::None => continue,
            LocatedState::Local(s) => {
                assert!(populate_for_final_state == false, "You are not supposed to expect an item in this state after sync");
                (s, SyncStatus::NotSynced)
            },
            LocatedState::Remote(s) => {
                assert!(populate_for_final_state == false, "You are not supposed to expect an item in this state after sync");
                (s, SyncStatus::random_synced())
            }
            LocatedState::BothSynced(s) => (s, SyncStatus::random_synced()),
        };

        let now = Utc::now();
        let completion_status = match state.completed {
            false => CompletionStatus::Uncompleted,
            true => CompletionStatus::Completed(Some(now)),
        };

        let new_item = Item::Task(
            Task::new_with_parameters(
                state.name.clone(),
                item.url.to_string(),
                item.url.clone(),
                completion_status,
                sync_status,
                Some(now),
                now,
                "prod_id".to_string(), Vec::new(),
            ));

        match required_state {
            LocatedState::None => panic!("Should not happen, we've continued already"),
            LocatedState::Local(s) => {
                get_or_insert_calendar(&mut local,  &s.calendar).await.unwrap().lock().unwrap().add_item(new_item).await.unwrap();
            },
            LocatedState::Remote(s) => {
                get_or_insert_calendar(&mut remote, &s.calendar).await.unwrap().lock().unwrap().add_item(new_item).await.unwrap();
            },
            LocatedState::BothSynced(s) => {
                get_or_insert_calendar(&mut local,  &s.calendar).await.unwrap().lock().unwrap().add_item(new_item.clone()).await.unwrap();
                get_or_insert_calendar(&mut remote, &s.calendar).await.unwrap().lock().unwrap().add_item(new_item).await.unwrap();
            },
        }
    }
    Provider::new(remote, local)
}

/// Apply `local_changes_to_apply` and `remote_changes_to_apply` to a provider that contains data before sync
async fn apply_changes_on_provider(provider: &mut Provider<Cache, CachedCalendar, Cache, CachedCalendar>, scenarii: &[ItemScenario]) {
    // Apply changes to each item
    for item in scenarii {
        let initial_calendar_url = match &item.initial_state {
            LocatedState::None => None,
            LocatedState::Local(state) => Some(state.calendar.clone()),
            LocatedState::Remote(state) => Some(state.calendar.clone()),
            LocatedState::BothSynced(state) => Some(state.calendar.clone()),
        };

        let mut calendar_url = initial_calendar_url.clone();
        for local_change in &item.local_changes_to_apply {
            calendar_url = Some(apply_change(provider.local(), calendar_url, &item.url, local_change, false).await);
        }

        let mut calendar_url = initial_calendar_url;
        for remote_change in &item.remote_changes_to_apply {
            calendar_url = Some(apply_change(provider.remote(), calendar_url, &item.url, remote_change, true).await);
        }
    }
}

async fn get_or_insert_calendar(source: &mut Cache, url: &Url)
    -> Result<Arc<Mutex<CachedCalendar>>, Box<dyn Error>>
{
    match source.get_calendar(url).await {
        Some(cal) => Ok(cal),
        None => {
            let new_name = format!("Test calendar for URL {}", url);
            let supported_components = SupportedComponents::TODO;
            let color = csscolorparser::parse("#ff8000").unwrap(); // TODO: we should rather have specific colors, depending on the calendars

            source.create_calendar(
                url.clone(),
                new_name.to_string(),
                supported_components,
                Some(color),
            ).await
        }
    }
}

/// Apply a single change on a given source, and returns the calendar URL that was modified
async fn apply_change<S, C>(source: &S, calendar_url: Option<Url>, item_url: &Url, change: &ChangeToApply, is_remote: bool) -> Url
where
    S: CalDavSource<C>,
    C: CompleteCalendar + DavCalendar, // in this test, we're using a calendar that mocks both kinds
{
    match calendar_url {
        Some(cal) => {
            apply_changes_on_an_existing_item(source, &cal, item_url, change, is_remote).await;
            cal
        },
        None => {
            create_test_item(source, change).await
        },
    }
}

async fn apply_changes_on_an_existing_item<S, C>(source: &S, calendar_url: &Url, item_url: &Url, change: &ChangeToApply, is_remote: bool)
where
    S: CalDavSource<C>,
    C: CompleteCalendar + DavCalendar, // in this test, we're using a calendar that mocks both kinds
{
    let cal = source.get_calendar(calendar_url).await.unwrap();
    let mut cal = cal.lock().unwrap();
    let task = cal.get_item_by_url_mut(item_url).await.unwrap().unwrap_task_mut();

    match change {
        ChangeToApply::Rename(new_name) => {
            if is_remote {
                task.mock_remote_calendar_set_name(new_name.clone());
            } else {
                task.set_name(new_name.clone());
            }
        },
        ChangeToApply::SetCompletion(new_status) => {
            let completion_status = match new_status {
                false => CompletionStatus::Uncompleted,
                true => CompletionStatus::Completed(Some(Utc::now())),
            };
            if is_remote {
                task.mock_remote_calendar_set_completion_status(completion_status);
            } else {
                task.set_completion_status(completion_status);
            }
        },
        ChangeToApply::Remove => {
            match is_remote {
                false => cal.mark_for_deletion(item_url).await.unwrap(),
                true => cal.delete_item(item_url).await.unwrap(),
            };
        },
        ChangeToApply::Create(_calendar_url, _item) => {
            panic!("This function only handles already existing items");
        },
    }
}

/// Create an item, and returns the URL of the calendar it was inserted in
async fn create_test_item<S, C>(source: &S, change: &ChangeToApply) -> Url
where
    S: CalDavSource<C>,
    C: CompleteCalendar + DavCalendar, // in this test, we're using a calendar that mocks both kinds
{
    match change {
        ChangeToApply::Rename(_) |
        ChangeToApply::SetCompletion(_) |
        ChangeToApply::Remove => {
            panic!("This function only creates items that do not exist yet");
        }
        ChangeToApply::Create(calendar_url, item) => {
            let cal = source.get_calendar(calendar_url).await.unwrap();
            cal.lock().unwrap().add_item(item.clone()).await.unwrap();
            calendar_url.clone()
        },
    }
}