From 36e659e971d091cfcbe370f5e45a0d01102d2e83 Mon Sep 17 00:00:00 2001
From: Owen Jacobson <owen@grimoire.ca>
Date: Wed, 30 Oct 2024 01:07:12 -0400
Subject: Prevent deletion of non-empty channels.

---
 src/channel/app.rs | 49 +++++++++++++++++++++++++++++++++++--------------
 1 file changed, 35 insertions(+), 14 deletions(-)

(limited to 'src/channel/app.rs')

diff --git a/src/channel/app.rs b/src/channel/app.rs
index 9a19b16..e32eb6c 100644
--- a/src/channel/app.rs
+++ b/src/channel/app.rs
@@ -10,7 +10,7 @@ use crate::{
     clock::DateTime,
     db::{Duplicate as _, NotFound as _},
     event::{repo::Provider as _, Broadcaster, Event, Sequence},
-    message::repo::Provider as _,
+    message::{self, repo::Provider as _},
     name::{self, Name},
 };
 
@@ -48,38 +48,36 @@ impl<'a> Channels<'a> {
     // it exists in the specific moment when you call it.
     pub async fn get(&self, channel: &Id) -> Result<Channel, Error> {
         let not_found = || Error::NotFound(channel.clone());
+        let deleted = || Error::Deleted(channel.clone());
 
         let mut tx = self.db.begin().await?;
         let channel = tx.channels().by_id(channel).await.not_found(not_found)?;
         tx.commit().await?;
 
-        channel.as_snapshot().ok_or_else(not_found)
+        channel.as_snapshot().ok_or_else(deleted)
     }
 
-    pub async fn delete(&self, channel: &Id, deleted_at: &DateTime) -> Result<(), Error> {
+    pub async fn delete(&self, channel: &Id, deleted_at: &DateTime) -> Result<(), DeleteError> {
         let mut tx = self.db.begin().await?;
 
         let channel = tx
             .channels()
             .by_id(channel)
             .await
-            .not_found(|| Error::NotFound(channel.clone()))?;
+            .not_found(|| DeleteError::NotFound(channel.clone()))?;
         channel
             .as_snapshot()
-            .ok_or_else(|| Error::Deleted(channel.id().clone()))?;
+            .ok_or_else(|| DeleteError::Deleted(channel.id().clone()))?;
 
         let mut events = Vec::new();
 
         let messages = tx.messages().live(&channel).await?;
-        for message in messages {
-            let deleted = tx.sequence().next(deleted_at).await?;
-            let message = tx.messages().delete(&message, &deleted).await?;
-            events.extend(
-                message
-                    .events()
-                    .filter(Sequence::start_from(deleted.sequence))
-                    .map(Event::from),
-            );
+        let has_messages = messages
+            .iter()
+            .map(message::History::as_snapshot)
+            .any(|message| message.is_some());
+        if has_messages {
+            return Err(DeleteError::NotEmpty(channel.id().clone()));
         }
 
         let deleted = tx.sequence().next(deleted_at).await?;
@@ -191,6 +189,29 @@ impl From<LoadError> for Error {
     }
 }
 
+#[derive(Debug, thiserror::Error)]
+pub enum DeleteError {
+    #[error("channel {0} not found")]
+    NotFound(Id),
+    #[error("channel {0} deleted")]
+    Deleted(Id),
+    #[error("channel {0} not empty")]
+    NotEmpty(Id),
+    #[error(transparent)]
+    Database(#[from] sqlx::Error),
+    #[error(transparent)]
+    Name(#[from] name::Error),
+}
+
+impl From<LoadError> for DeleteError {
+    fn from(error: LoadError) -> Self {
+        match error {
+            LoadError::Database(error) => error.into(),
+            LoadError::Name(error) => error.into(),
+        }
+    }
+}
+
 #[derive(Debug, thiserror::Error)]
 pub enum ExpireError {
     #[error(transparent)]
-- 
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