Re-wrote Provider::sync

Cargo.toml

@@ -6,6 +6,10 @@ edition = "2018"
 
 # See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
 
+[features]
+integration_tests = ["mock_version_tag"]
+mock_version_tag = []
+
 [dependencies]
 env_logger = "0.8"
 log = "0.4"

src/calendar/cached_calendar.rs

@@ -70,16 +70,38 @@ impl PartialCalendar for CachedCalendar {
         Ok(())
     }
 
+    #[cfg(not(feature = "mock_version_tag"))]
+    #[allow(unreachable_code)]
     async fn get_item_version_tags(&self) -> Result<HashMap<ItemId, VersionTag>, Box<dyn Error>> {
-        Ok(self.items.iter()
-            .map(|(id, item)| (id.clone(), item.version_tag().clone()))
-            .collect()
-        )
+        panic!("This function only makes sense in remote calendars and in mocked calendars");
+        Err("This function only makes sense in remote calendars and in mocked calendars".into())
+    }
+    #[cfg(feature = "mock_version_tag")]
+    async fn get_item_version_tags(&self) -> Result<HashMap<ItemId, VersionTag>, Box<dyn Error>> {
+        use crate::item::SyncStatus;
+
+        let mut result = HashMap::new();
+
+        for (id, item) in &self.items {
+            let vt = match item.sync_status() {
+                SyncStatus::Synced(vt) => vt.clone(),
+                _ => {
+                    panic!("Mock calendars must contain only SyncStatus::Synced. Got {:?}", item);
+                }
+            };
+            result.insert(id.clone(), vt);
+        }
+
+        Ok(result)
     }
 
     async fn get_item_by_id_mut<'a>(&'a mut self, id: &ItemId) -> Option<&'a mut Item> {
         self.items.get_mut(id)
     }
+
+    async fn get_item_by_id<'a>(&'a self, id: &ItemId) -> Option<&'a Item> {
+        self.items.get(id)
+    }
 }
 
 #[async_trait]

src/calendar/remote_calendar.rs

@@ -1,7 +1,6 @@
 use std::collections::{HashMap, HashSet};
 use std::error::Error;
 
-use chrono::{DateTime, Utc};
 use async_trait::async_trait;
 
 use crate::traits::PartialCalendar;
@@ -86,6 +85,12 @@ impl PartialCalendar for RemoteCalendar {
         None
     }
 
+    async fn get_item_by_id<'a>(&'a self, id: &ItemId) -> Option<&'a Item> {
+        log::error!("Not implemented");
+        None
+    }
+
+
     /// Add an item into this calendar
     async fn add_item(&mut self, _item: Item) {
         log::error!("Not implemented");

src/event.rs

@@ -4,7 +4,7 @@ use serde::{Deserialize, Serialize};
 use chrono::{Utc, DateTime};
 
 use crate::item::ItemId;
-use crate::item::VersionTag;
+use crate::item::SyncStatus;
 
 /// TODO: implement Event one day.
 /// This crate currently only supports tasks, not calendar events.
@@ -13,7 +13,7 @@ pub struct Event {
     id: ItemId,
     name: String,
     last_modified: DateTime<Utc>,
-    version_tag: VersionTag,
+    sync_status: SyncStatus,
 }
 
 impl Event {
@@ -29,7 +29,10 @@ impl Event {
         self.last_modified
     }
 
-    pub fn version_tag(&self) -> &VersionTag {
-        &self.version_tag
+    pub fn sync_status(&self) -> &SyncStatus {
+        &self.sync_status
+    }
+    pub fn set_sync_status(&mut self, new_status: SyncStatus) {
+        self.sync_status = new_status;
     }
 }

src/item.rs

@@ -37,10 +37,16 @@ impl Item {
         }
     }
 
-    pub fn version_tag(&self) -> &VersionTag {
+    pub fn sync_status(&self) -> &SyncStatus {
         match self {
-            Item::Event(e) => e.version_tag(),
-            Item::Task(t) => t.version_tag(),
+            Item::Event(e) => e.sync_status(),
+            Item::Task(t) => t.sync_status(),
+        }
+    }
+    pub fn set_sync_status(&mut self, new_status: SyncStatus) {
+        match self {
+            Item::Event(e) => e.set_sync_status(new_status),
+            Item::Task(t) => t.set_sync_status(new_status),
         }
     }
 
@@ -87,7 +93,7 @@ pub struct ItemId {
     content: Url,
 }
 impl ItemId{
-    /// Generate a random ItemId. This is only useful in tests
+    /// Generate a random ItemId. This should only be useful in tests
     pub fn random() -> Self {
         let random = uuid::Uuid::new_v4().to_hyphenated().to_string();
         let s = format!("https://server.com/{}", random);
@@ -133,9 +139,32 @@ impl From<String> for VersionTag {
 }
 
 impl VersionTag {
-    /// Generate a random VesionTag. This is only useful in tests
+    /// Generate a random VesionTag
+    #[cfg(feature = "mock_version_tag")]
     pub fn random() -> Self {
         let random = uuid::Uuid::new_v4().to_hyphenated().to_string();
         Self { tag: random }
     }
 }
+
+
+
+/// Desribes whether this item has been synced already, or modified since the last time it was synced
+#[derive(Clone, Debug, PartialEq, Serialize, Deserialize)]
+pub enum SyncStatus {
+    /// This item has ben locally created, and never synced yet
+    NotSynced,
+    /// At the time this item has ben synced, it has a given version tag, and has not been locally modified since then
+    Synced(VersionTag),
+    /// This item has been synced when it had a given version tag, and has been locally modified since then.
+    LocallyModified(VersionTag),
+    /// This item has been synced when it had a given version tag, and has been locally deleted since then.
+    LocallyDeleted(VersionTag),
+}
+impl SyncStatus {
+    /// Generate a random SyncStatus::Synced
+    #[cfg(feature = "mock_version_tag")]
+    pub fn random_synced() -> Self {
+        Self::Synced(VersionTag::random())
+    }
+}

src/lib.rs

@@ -16,6 +16,7 @@ mod item;
 pub use item::Item;
 pub use item::ItemId;
 pub use item::VersionTag;
+pub use item::SyncStatus;
 mod task;
 pub use task::Task;
 mod event;

src/provider.rs

@@ -4,18 +4,15 @@ use std::error::Error;
 use std::collections::HashSet;
 use std::marker::PhantomData;
 
-use chrono::{DateTime, Utc};
-
 use crate::traits::{CalDavSource, CompleteCalendar};
 use crate::traits::PartialCalendar;
-use crate::Item;
-use crate::item::ItemId;
+use crate::item::SyncStatus;
 
 /// A data source that combines two `CalDavSources` (usually a server and a local cache), which is able to sync both sources.
 pub struct Provider<L, T, R, U>
 where
     L: CalDavSource<T>,
-    T: CompleteCalendar,
+    T: CompleteCalendar + Sync + Send,
     R: CalDavSource<U>,
     U: PartialCalendar + Sync + Send,
 {
@@ -31,7 +28,7 @@ where
 impl<L, T, R, U> Provider<L, T, R, U>
 where
     L: CalDavSource<T>,
-    T: CompleteCalendar,
+    T: CompleteCalendar + Sync + Send,
     R: CalDavSource<U>,
     U: PartialCalendar + Sync + Send,
 {
@@ -45,15 +42,15 @@ where
         }
     }
 
-    /// Returns the data source described as the `server`
+    /// Returns the data source described as the `remote`
     pub fn remote(&self) -> &R { &self.remote }
     /// Returns the data source described as the `local`
     pub fn local(&self)  -> &L { &self.local }
 
-    /// Performs a synchronisation between `local` and `server`.
+    /// Performs a synchronisation between `local` and `remote`.
     ///
     /// This bidirectional sync applies additions/deletions made on a source to the other source.
-    /// In case of conflicts (the same item has been modified on both ends since the last sync, `server` always wins)
+    /// In case of conflicts (the same item has been modified on both ends since the last sync, `remote` always wins)
     pub async fn sync(&mut self) -> Result<(), Box<dyn Error>> {
         log::info!("Starting a sync.");
 
@@ -71,33 +68,151 @@ where
             let mut cal_local = cal_local.lock().unwrap();
 
             // Step 1 - find the differences
-            // let mut local_del = HashSet::new();
-            // let mut remote_del = HashSet::new();
-            // let mut local_changes = HashSet::new();
-            // let mut remote_change = HashSet::new();
-            // let mut local_additions = HashSet::new();
-            // let mut remote_additions = HashSet::new();
+            let mut local_del = HashSet::new();
+            let mut remote_del = HashSet::new();
+            let mut local_changes = HashSet::new();
+            let mut remote_changes = HashSet::new();
+            let mut local_additions = HashSet::new();
+            let mut remote_additions = HashSet::new();
+
+            let remote_items = cal_remote.get_item_version_tags().await?;
+            let mut local_items_to_handle = cal_local.get_item_ids().await?;
+            for (id, remote_tag) in remote_items {
+                match cal_local.get_item_by_id(&id).await {
+                    None => {
+                        // This was created on the remote
+                        remote_additions.insert(id);
+                    },
+                    Some(local_item) => {
+                        if local_items_to_handle.remove(&id) == true {
+                            log::error!("Inconsistent state: missing task {} from the local tasks", id);
+                        }
+
+                        match local_item.sync_status() {
+                            SyncStatus::NotSynced => {
+                                log::error!("ID reuse between remote and local sources ({}). Ignoring this item in the sync", id);
+                                continue;
+                            },
+                            SyncStatus::Synced(local_tag) => {
+                                if &remote_tag != local_tag {
+                                    // This has been modified on the remote
+                                    remote_changes.insert(id);
+                                }
+                            },
+                            SyncStatus::LocallyModified(local_tag) => {
+                                if &remote_tag == local_tag {
+                                    // This has been changed locally
+                                    local_changes.insert(id);
+                                } else {
+                                    log::info!("Conflict: task {} has been modified in both sources. Using the remote version.", id);
+                                    remote_changes.insert(id);
+                                }
+                            },
+                            SyncStatus::LocallyDeleted(local_tag) => {
+                                if &remote_tag == local_tag {
+                                    // This has been locally deleted
+                                    local_del.insert(id);
+                                } else {
+                                    log::info!("Conflict: task {} has been locally deleted and remotely modified. Reverting to the remote version.", id);
+                                    remote_changes.insert(id);
+                                }
+                            },
+                        }
+                    }
+                }
+            }
+
+            // Also iterate on the local tasks that are not on the remote
+            for id in local_items_to_handle {
+                let local_item = match cal_local.get_item_by_id(&id).await {
+                    None => {
+                        log::error!("Inconsistent state: missing task {} from the local tasks", id);
+                        continue;
+                    },
+                    Some(item) => item,
+                };
+                match local_item.sync_status() {
+                    SyncStatus::Synced(_) => {
+                        // This item has been removed from the remote
+                        remote_del.insert(id);
+                    },
+                    SyncStatus::NotSynced => {
+                        // This item has just been locally created
+                        local_additions.insert(id);
+                    },
+                    variant @ _=> {
+                        log::error!("Inconsistent state: unexpected variant {:?}", variant);
+                    }
+                }
+            }
+
+
+            // Step 2 - commit changes
+            for id_del in local_del {
+                if let Err(err) = cal_remote.delete_item(&id_del).await {
+                    log::warn!("Unable to delete remote item {}: {}", id_del, err);
+                }
+            }
+
+            for id_del in remote_del {
+                if let Err(err) = cal_local.delete_item(&id_del).await {
+                    log::warn!("Unable to delete local item {}: {}", id_del, err);
+                }
+            }
+
+            for id_add in remote_additions {
+                match cal_remote.get_item_by_id(&id_add).await {
+                    None => {
+                        log::error!("Inconsistency: new item {} has vanished from the remote end", id_add);
+                        continue;
+                    },
+                    Some(new_item) => cal_local.add_item(new_item.clone()).await,
+                }
+            }
+
+            for id_change in remote_changes {
+                match cal_remote.get_item_by_id(&id_change).await {
+                    None => {
+                        log::error!("Inconsistency: modified item {} has vanished from the remote end", id_change);
+                        continue;
+                    },
+                    Some(item) => {
+                        if let Err(err) = cal_local.delete_item(&id_change).await {
+                            log::error!("Unable to delete item {} from local calendar: {}", id_change, err);
+                        }
+                        cal_local.add_item(item.clone());
+                    },
+                }
+            }
+
+
+            for id_add in local_additions {
+                match cal_local.get_item_by_id(&id_add).await {
+                    None => {
+                        log::error!("Inconsistency: created item {} has been marked for upload but is locally missing", id_add);
+                        continue;
+                    },
+                    Some(item) => cal_remote.add_item(item.clone()),
+                };
+            }
+
+            for id_change in local_changes {
+                match cal_local.get_item_by_id(&id_change).await {
+                    None => {
+                        log::error!("Inconsistency: modified item {} has been marked for upload but is locally missing", id_change);
+                        continue;
+                    },
+                    Some(item) => {
+                        if let Err(err) = cal_remote.delete_item(&id_change).await {
+                            log::error!("Unable to delete item {} from remote calendar: {}", id_change, err);
+                        }
+                        cal_remote.add_item(item.clone());
+                    }
+                };
+            }
 
         }
 
         Ok(())
     }
 }
-
-
-async fn move_to_calendar<C: PartialCalendar>(items: &mut Vec<Item>, calendar: &mut C) {
-    while items.len() > 0 {
-        let item = items.remove(0);
-        log::warn!("Moving {} to calendar", item.name());
-        calendar.add_item(item).await;
-    }
-}
-
-async fn remove_from_calendar<C: PartialCalendar>(ids: &Vec<ItemId>, calendar: &mut C) {
-    for id in ids {
-        log::info!("  Removing {:?} from calendar", id);
-        if let Err(err) = calendar.delete_item(id).await {
-            log::warn!("Unable to delete item {:?} from calendar: {}", id, err);
-        }
-    }
-}

src/task.rs

@@ -2,7 +2,7 @@ use chrono::{Utc, DateTime};
 use serde::{Deserialize, Serialize};
 
 use crate::item::ItemId;
-use crate::item::VersionTag;
+use crate::item::SyncStatus;
 
 /// A to-do task
 #[derive(Clone, Debug, PartialEq, Serialize, Deserialize)]
@@ -12,8 +12,8 @@ pub struct Task {
 
     /// The last modification date of this task
     last_modified: DateTime<Utc>,
-    /// The version tag of this item
-    version_tag: VersionTag,
+    /// The sync status of this item
+    sync_status: SyncStatus,
 
     /// The display name of the task
     name: String,
@@ -23,12 +23,12 @@ pub struct Task {
 
 impl Task {
     /// Create a new Task
-    pub fn new(name: String, id: ItemId, last_modified: DateTime<Utc>, version_tag: VersionTag) -> Self {
+    pub fn new(name: String, id: ItemId, last_modified: DateTime<Utc>, sync_status: SyncStatus) -> Self {
         Self {
             id,
             name,
             last_modified,
-            version_tag,
+            sync_status,
             completed: false,
         }
     }
@@ -37,7 +37,10 @@ impl Task {
     pub fn name(&self) -> &str      { &self.name        }
     pub fn completed(&self) -> bool { self.completed    }
     pub fn last_modified(&self) -> DateTime<Utc> { self.last_modified }
-    pub fn version_tag(&self) -> &VersionTag     { &self.version_tag  }
+    pub fn sync_status(&self) -> &SyncStatus     { &self.sync_status  }
+    pub fn set_sync_status(&mut self, new_status: SyncStatus) {
+        self.sync_status = new_status;
+    }
 
     fn update_last_modified(&mut self) {
         self.last_modified = Utc::now();

src/traits.rs

@@ -39,6 +39,9 @@ pub trait PartialCalendar {
     /// Returns a particular item
     async fn get_item_by_id_mut<'a>(&'a mut self, id: &ItemId) -> Option<&'a mut Item>;
 
+    /// Returns a particular item
+    async fn get_item_by_id<'a>(&'a self, id: &ItemId) -> Option<&'a Item>;
+
     /// Add an item into this calendar
     async fn add_item(&mut self, item: Item);
 

tests/sync.rs

@@ -1,3 +1,5 @@
+#![cfg(feature = "integration_tests")]
+
 use std::path::PathBuf;
 use std::sync::{Arc, Mutex};
 
@@ -9,7 +11,7 @@ use my_tasks::traits::PartialCalendar;
 use my_tasks::cache::Cache;
 use my_tasks::Item;
 use my_tasks::ItemId;
-use my_tasks::VersionTag;
+use my_tasks::SyncStatus;
 use my_tasks::Task;
 use my_tasks::calendar::cached_calendar::CachedCalendar;
 use my_tasks::Provider;
@@ -54,19 +56,19 @@ async fn populate_test_provider() -> Provider<Cache, CachedCalendar, Cache, Cach
 
     let cal_id = Url::parse("http://todo.list/cal").unwrap();
 
-    let task_a = Item::Task(Task::new("task A".into(), ItemId::random(), Utc.ymd(2000, 1, 1).and_hms(0, 0, 0), VersionTag::random()));
-    let task_b = Item::Task(Task::new("task B".into(), ItemId::random(), Utc.ymd(2000, 1, 2).and_hms(0, 0, 0), VersionTag::random()));
-    let task_c = Item::Task(Task::new("task C".into(), ItemId::random(), Utc.ymd(2000, 1, 3).and_hms(0, 0, 0), VersionTag::random()));
-    let task_d = Item::Task(Task::new("task D".into(), ItemId::random(), Utc.ymd(2000, 1, 4).and_hms(0, 0, 0), VersionTag::random()));
-    let task_e = Item::Task(Task::new("task E".into(), ItemId::random(), Utc.ymd(2000, 1, 5).and_hms(0, 0, 0), VersionTag::random()));
-    let task_f = Item::Task(Task::new("task F".into(), ItemId::random(), Utc.ymd(2000, 1, 6).and_hms(0, 0, 0), VersionTag::random()));
-    let task_g = Item::Task(Task::new("task G".into(), ItemId::random(), Utc.ymd(2000, 1, 7).and_hms(0, 0, 0), VersionTag::random()));
-    let task_h = Item::Task(Task::new("task H".into(), ItemId::random(), Utc.ymd(2000, 1, 8).and_hms(0, 0, 0), VersionTag::random()));
-    let task_i = Item::Task(Task::new("task I".into(), ItemId::random(), Utc.ymd(2000, 1, 9).and_hms(0, 0, 0), VersionTag::random()));
-    let task_j = Item::Task(Task::new("task J".into(), ItemId::random(), Utc.ymd(2000, 1, 10).and_hms(0, 0, 0), VersionTag::random()));
-    let task_k = Item::Task(Task::new("task K".into(), ItemId::random(), Utc.ymd(2000, 1, 11).and_hms(0, 0, 0), VersionTag::random()));
-    let task_l = Item::Task(Task::new("task L".into(), ItemId::random(), Utc.ymd(2000, 1, 12).and_hms(0, 0, 0), VersionTag::random()));
-    let task_m = Item::Task(Task::new("task M".into(), ItemId::random(), Utc.ymd(2000, 1, 12).and_hms(0, 0, 0), VersionTag::random()));
+    let task_a = Item::Task(Task::new("task A".into(), ItemId::random(), Utc.ymd(2000, 1, 1).and_hms(0, 0, 0), SyncStatus::random_synced()));
+    let task_b = Item::Task(Task::new("task B".into(), ItemId::random(), Utc.ymd(2000, 1, 2).and_hms(0, 0, 0), SyncStatus::random_synced()));
+    let task_c = Item::Task(Task::new("task C".into(), ItemId::random(), Utc.ymd(2000, 1, 3).and_hms(0, 0, 0), SyncStatus::random_synced()));
+    let task_d = Item::Task(Task::new("task D".into(), ItemId::random(), Utc.ymd(2000, 1, 4).and_hms(0, 0, 0), SyncStatus::random_synced()));
+    let task_e = Item::Task(Task::new("task E".into(), ItemId::random(), Utc.ymd(2000, 1, 5).and_hms(0, 0, 0), SyncStatus::random_synced()));
+    let task_f = Item::Task(Task::new("task F".into(), ItemId::random(), Utc.ymd(2000, 1, 6).and_hms(0, 0, 0), SyncStatus::random_synced()));
+    let task_g = Item::Task(Task::new("task G".into(), ItemId::random(), Utc.ymd(2000, 1, 7).and_hms(0, 0, 0), SyncStatus::random_synced()));
+    let task_h = Item::Task(Task::new("task H".into(), ItemId::random(), Utc.ymd(2000, 1, 8).and_hms(0, 0, 0), SyncStatus::random_synced()));
+    let task_i = Item::Task(Task::new("task I".into(), ItemId::random(), Utc.ymd(2000, 1, 9).and_hms(0, 0, 0), SyncStatus::random_synced()));
+    let task_j = Item::Task(Task::new("task J".into(), ItemId::random(), Utc.ymd(2000, 1, 10).and_hms(0, 0, 0), SyncStatus::random_synced()));
+    let task_k = Item::Task(Task::new("task K".into(), ItemId::random(), Utc.ymd(2000, 1, 11).and_hms(0, 0, 0), SyncStatus::random_synced()));
+    let task_l = Item::Task(Task::new("task L".into(), ItemId::random(), Utc.ymd(2000, 1, 12).and_hms(0, 0, 0), SyncStatus::random_synced()));
+    let task_m = Item::Task(Task::new("task M".into(), ItemId::random(), Utc.ymd(2000, 1, 12).and_hms(0, 0, 0), SyncStatus::random_synced()));
 
     // let last_sync = task_m.last_modified();
     // local.update_last_sync(Some(last_sync));
@@ -130,7 +132,7 @@ async fn populate_test_provider() -> Provider<Cache, CachedCalendar, Cache, Cach
 
     cal_server.delete_item(&task_l_id).await.unwrap();
 
-    let task_n = Item::Task(Task::new("task N (new from server)".into(), ItemId::random(), Utc::now(), VersionTag::random()));
+    let task_n = Item::Task(Task::new("task N (new from server)".into(), ItemId::random(), Utc::now(), SyncStatus::random_synced()));
     cal_server.add_item(task_n).await;
 
 
@@ -159,7 +161,7 @@ async fn populate_test_provider() -> Provider<Cache, CachedCalendar, Cache, Cach
     cal_local.delete_item(&task_k_id).await.unwrap();
     cal_local.delete_item(&task_l_id).await.unwrap();
 
-    let task_o = Item::Task(Task::new("task O (new from local)".into(), ItemId::random(), Utc::now(), VersionTag::random()));
+    let task_o = Item::Task(Task::new("task O (new from local)".into(), ItemId::random(), Utc::now(), SyncStatus::NotSynced));
     cal_local.add_item(task_o).await;
 
     Provider::new(server, local)