1 files changed, 57 insertions, 13 deletions

diff --git a/src/message/history.rs b/src/message/history.rs
index 2abdf2c..92cecc9 100644
--- a/src/message/history.rs
+++ b/src/message/history.rs
@@ -1,18 +1,67 @@
 use itertools::Itertools as _;
 
 use super::{
-    Message,
+    Body, Id, Message,
     event::{Deleted, Event, Sent},
 };
-use crate::event::Sequence;
+use crate::{
+    conversation::Conversation,
+    event::{Instant, Sequence},
+    user::{self, User},
+};
 
 #[derive(Clone, Debug, Eq, PartialEq)]
 pub struct History {
     pub message: Message,
 }
 
+// Lifecycle interface
+impl History {
+    pub fn begin(conversation: &Conversation, sender: &User, body: &Body, sent: Instant) -> Self {
+        Self {
+            message: Message {
+                id: Id::generate(),
+                conversation: conversation.id.clone(),
+                sender: sender.id.clone(),
+                body: body.clone(),
+                sent,
+                deleted: None,
+            },
+        }
+    }
+
+    pub fn delete(self, deleted: Instant) -> Result<Self, DeleteError> {
+        if self.message.deleted.is_none() {
+            Ok(Self {
+                message: Message {
+                    deleted: Some(deleted),
+                    ..self.message
+                },
+            })
+        } else {
+            Err(DeleteError::Deleted(self.into()))
+        }
+    }
+}
+
+#[derive(Debug, thiserror::Error)]
+pub enum DeleteError {
+    #[error("message {} already deleted", .0.message.id)]
+    // Payload is boxed here to avoid copying an entire `History` around in any errors this error
+    // gets chained into. See <https://rust-lang.github.io/rust-clippy/master/index.html#result_large_err>.
+    Deleted(Box<History>),
+}
+
 // State interface
 impl History {
+    pub fn id(&self) -> &Id {
+        &self.message.id
+    }
+
+    pub fn sender(&self) -> &user::Id {
+        &self.message.sender
+    }
+
     // Snapshot of this message as it was when sent. (Note to the future: it's okay
     // if this returns a redacted or modified version of the message. If we
     // implement message editing by redacting the original body, then this should
@@ -30,15 +79,16 @@ impl History {
             .filter(Sequence::up_to(sequence.into()))
             .collect()
     }
-
-    // Snapshot of this message as of all events recorded in this history.
-    pub fn as_snapshot(&self) -> Option<Message> {
-        self.events().collect()
-    }
 }
 
 // Events interface
 impl History {
+    pub fn events(&self) -> impl Iterator<Item = Event> + Clone + use<> {
+        [self.sent()]
+            .into_iter()
+            .merge_by(self.deleted(), Sequence::merge)
+    }
+
     fn sent(&self) -> Event {
         Sent {
             message: self.message.clone(),
@@ -55,10 +105,4 @@ impl History {
             .into()
         })
     }
-
-    pub fn events(&self) -> impl Iterator<Item = Event> + use<> {
-        [self.sent()]
-            .into_iter()
-            .merge_by(self.deleted(), Sequence::merge)
-    }
 }