Add endpoints for deleting channels and messages.

It is deliberate that the expire() functions do not use them. To avoid races, the transactions must be committed before events get sent, in both cases, which makes them structurally pretty different.

15 files changed, 304 insertions, 113 deletions

diff --git a/.sqlx/query-46403b84bfc79a53aec36b4a808afb115f6e47d545dfbeb18f9c54e6eb15eb80.json b/.sqlx/query-46403b84bfc79a53aec36b4a808afb115f6e47d545dfbeb18f9c54e6eb15eb80.json
new file mode 100644
index 0000000..ee0f235
--- /dev/null
+++ b/.sqlx/query-46403b84bfc79a53aec36b4a808afb115f6e47d545dfbeb18f9c54e6eb15eb80.json
@@ -0,0 +1,20 @@
+{
+  "db_name": "SQLite",
+  "query": "\n                select\n                    message.id as \"id: Id\"\n                from message\n                    join channel on message.channel = channel.id\n                where channel.id = $1\n                order by message.sent_sequence\n            ",
+  "describe": {
+    "columns": [
+      {
+        "name": "id: Id",
+        "ordinal": 0,
+        "type_info": "Text"
+      }
+    ],
+    "parameters": {
+      "Right": 1
+    },
+    "nullable": [
+      false
+    ]
+  },
+  "hash": "46403b84bfc79a53aec36b4a808afb115f6e47d545dfbeb18f9c54e6eb15eb80"
+}
diff --git a/.sqlx/query-4d4dce1b034f4a540f49490b1a8433a8ca334f1d666b104823e3fb0c08efb2cc.json b/.sqlx/query-4d4dce1b034f4a540f49490b1a8433a8ca334f1d666b104823e3fb0c08efb2cc.json
deleted file mode 100644
index fb5f94b..0000000
--- a/.sqlx/query-4d4dce1b034f4a540f49490b1a8433a8ca334f1d666b104823e3fb0c08efb2cc.json
+++ /dev/null
@@ -1,32 +0,0 @@
-{
-  "db_name": "SQLite",
-  "query": "\n                select\n                    channel.id as \"channel_id: channel::Id\",\n                    channel.name as \"channel_name\",\n                    message.id as \"message: Id\"\n                from message\n                    join channel on message.channel = channel.id\n                where sent_at < $1\n            ",
-  "describe": {
-    "columns": [
-      {
-        "name": "channel_id: channel::Id",
-        "ordinal": 0,
-        "type_info": "Text"
-      },
-      {
-        "name": "channel_name",
-        "ordinal": 1,
-        "type_info": "Text"
-      },
-      {
-        "name": "message: Id",
-        "ordinal": 2,
-        "type_info": "Text"
-      }
-    ],
-    "parameters": {
-      "Right": 1
-    },
-    "nullable": [
-      false,
-      false,
-      false
-    ]
-  },
-  "hash": "4d4dce1b034f4a540f49490b1a8433a8ca334f1d666b104823e3fb0c08efb2cc"
-}
diff --git a/.sqlx/query-e93702ad922c7ce802499e99e837106c799e84015425286b79f42e4001d8a4c7.json b/.sqlx/query-6fc4be85527af518da17c49cedc6bee1750d28a6176980ed7040b8a3301fc7e5.json
index 288a657..257e1f6 100644
--- a/.sqlx/query-e93702ad922c7ce802499e99e837106c799e84015425286b79f42e4001d8a4c7.json
+++ b/.sqlx/query-6fc4be85527af518da17c49cedc6bee1750d28a6176980ed7040b8a3301fc7e5.json
@@ -1,6 +1,6 @@
 {
   "db_name": "SQLite",
-  "query": "\n                select\n                    channel.id as \"channel_id: channel::Id\",\n                    channel.name as \"channel_name\",\n                    sender.id as \"sender_id: login::Id\",\n                    sender.name as \"sender_name\",\n                    message.id as \"id: Id\",\n                    message.body,\n                    sent_at as \"sent_at: DateTime\",\n                    sent_sequence as \"sent_sequence: Sequence\"\n                from message\n                    join channel on message.channel = channel.id\n                    join login as sender on message.sender = sender.id\n                where message.id = $1\n                    and message.channel = $2\n            ",
+  "query": "\n                select\n                    channel.id as \"channel_id: channel::Id\",\n                    channel.name as \"channel_name\",\n                    sender.id as \"sender_id: login::Id\",\n                    sender.name as \"sender_name\",\n                    message.id as \"id: Id\",\n                    message.body,\n                    sent_at as \"sent_at: DateTime\",\n                    sent_sequence as \"sent_sequence: Sequence\"\n                from message\n                    join channel on message.channel = channel.id\n                    join login as sender on message.sender = sender.id\n                where message.id = $1\n            ",
   "describe": {
     "columns": [
       {
@@ -45,7 +45,7 @@
       }
     ],
     "parameters": {
-      "Right": 2
+      "Right": 1
     },
     "nullable": [
       false,
@@ -58,5 +58,5 @@
       false
     ]
   },
-  "hash": "e93702ad922c7ce802499e99e837106c799e84015425286b79f42e4001d8a4c7"
+  "hash": "6fc4be85527af518da17c49cedc6bee1750d28a6176980ed7040b8a3301fc7e5"
 }
diff --git a/.sqlx/query-f3a338b9e4a65856decd79ad2d2dec42949522f182a61bfb249f13ee78564179.json b/.sqlx/query-f3a338b9e4a65856decd79ad2d2dec42949522f182a61bfb249f13ee78564179.json
new file mode 100644
index 0000000..92a64a3
--- /dev/null
+++ b/.sqlx/query-f3a338b9e4a65856decd79ad2d2dec42949522f182a61bfb249f13ee78564179.json
@@ -0,0 +1,20 @@
+{
+  "db_name": "SQLite",
+  "query": "\n                select\n                    id as \"message: Id\"\n                from message\n                where sent_at < $1\n            ",
+  "describe": {
+    "columns": [
+      {
+        "name": "message: Id",
+        "ordinal": 0,
+        "type_info": "Text"
+      }
+    ],
+    "parameters": {
+      "Right": 1
+    },
+    "nullable": [
+      false
+    ]
+  },
+  "hash": "f3a338b9e4a65856decd79ad2d2dec42949522f182a61bfb249f13ee78564179"
+}
diff --git a/docs/api.md b/docs/api.md
index 5adf28d..ef211bc 100644
--- a/docs/api.md
+++ b/docs/api.md
@@ -151,6 +151,34 @@ Once the message is accepted, this will return a 202 Accepted response. The mess
 
 If the channel ID is not valid, this will return a 404 Not Found response.
 
+### `DELETE /api/channels/:channel`
+
+Deletes a channel (and all messages in it).
+
+The `:channel` placeholder must be a channel ID, as returned by `GET /api/channels` or `POST /api/channels`.
+
+#### On success
+
+This will return a 202 Accepted response on success, and delete the channel.
+
+#### Invalid channel ID
+
+If the channel ID is not valid, this will return a 404 Not Found response.
+
+### `DELETE /api/messages/:message`
+
+Deletes a message.
+
+The `:message` placeholder must be a message ID, as returned from the event stream or from a list of messages.
+
+#### On success
+
+This will return a 202 Accepted response on success, and delete the message.
+
+#### Invalid message ID
+
+If the message ID is not valid, this will return a 404 Not Found response.
+
 ### `GET /api/events`
 
 Subscribes to events. This endpoint returns an `application/event-stream` response, and is intended for use with the `EventSource` browser API. Events will be delivered on this stream as they occur, and the request will remain open to deliver events.
diff --git a/src/channel/app.rs b/src/channel/app.rs
index 6ce826b..24be2ff 100644
--- a/src/channel/app.rs
+++ b/src/channel/app.rs
@@ -2,10 +2,12 @@ use chrono::TimeDelta;
 use itertools::Itertools;
 use sqlx::sqlite::SqlitePool;
 
+use super::{repo::Provider as _, Channel, Id};
 use crate::{
-    channel::{repo::Provider as _, Channel},
     clock::DateTime,
-    event::{broadcaster::Broadcaster, repo::Provider as _, Sequence},
+    db::NotFound,
+    event::{broadcaster::Broadcaster, repo::Provider as _, Event, Sequence, Sequenced},
+    message::repo::Provider as _,
 };
 
 pub struct Channels<'a> {
@@ -28,9 +30,8 @@ impl<'a> Channels<'a> {
             .map_err(|err| CreateError::from_duplicate_name(err, name))?;
         tx.commit().await?;
 
-        for event in channel.events() {
-            self.events.broadcast(event);
-        }
+        self.events
+            .broadcast(channel.events().map(Event::from).collect::<Vec<_>>());
 
         Ok(channel.snapshot())
     }
@@ -53,6 +54,46 @@ impl<'a> Channels<'a> {
         Ok(channels)
     }
 
+    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(|| DeleteError::NotFound(channel.clone()))?
+            .snapshot();
+
+        let mut events = Vec::new();
+
+        let messages = tx.messages().in_channel(&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 deleted = tx.sequence().next(deleted_at).await?;
+        let channel = tx.channels().delete(&channel.id, &deleted).await?;
+        events.extend(
+            channel
+                .events()
+                .filter(Sequence::start_from(deleted.sequence))
+                .map(Event::from),
+        );
+
+        tx.commit().await?;
+
+        self.events.broadcast(events);
+
+        Ok(())
+    }
+
     pub async fn expire(&self, relative_to: &DateTime) -> Result<(), sqlx::Error> {
         // Somewhat arbitrarily, expire after 90 days.
         let expire_at = relative_to.to_owned() - TimeDelta::days(90);
@@ -73,12 +114,13 @@ impl<'a> Channels<'a> {
 
         tx.commit().await?;
 
-        for event in events
-            .into_iter()
-            .kmerge_by(|a, b| a.instant.sequence < b.instant.sequence)
-        {
-            self.events.broadcast(event);
-        }
+        self.events.broadcast(
+            events
+                .into_iter()
+                .kmerge_by(|a, b| a.sequence() < b.sequence())
+                .map(Event::from)
+                .collect::<Vec<_>>(),
+        );
 
         Ok(())
     }
@@ -92,6 +134,14 @@ pub enum CreateError {
     DatabaseError(#[from] sqlx::Error),
 }
 
+#[derive(Debug, thiserror::Error)]
+pub enum DeleteError {
+    #[error("channel {0} not found")]
+    NotFound(Id),
+    #[error(transparent)]
+    DatabaseError(#[from] sqlx::Error),
+}
+
 impl CreateError {
     fn from_duplicate_name(error: sqlx::Error, name: &str) -> Self {
         if let Some(error) = error.as_database_error() {
diff --git a/src/channel/routes.rs b/src/channel/routes.rs
index 5bb1ee9..bce634e 100644
--- a/src/channel/routes.rs
+++ b/src/channel/routes.rs
@@ -2,20 +2,18 @@ use axum::{
     extract::{Json, Path, State},
     http::StatusCode,
     response::{IntoResponse, Response},
-    routing::{get, post},
+    routing::{delete, get, post},
     Router,
 };
 use axum_extra::extract::Query;
 
-use super::app;
+use super::{
+    app::{self, DeleteError},
+    Channel, Id,
+};
 use crate::{
-    app::App,
-    channel::{self, Channel},
-    clock::RequestedAt,
-    error::Internal,
-    event::Sequence,
-    login::Login,
-    message::app::Error as MessageError,
+    app::App, clock::RequestedAt, error::Internal, event::Sequence, login::Login,
+    message::app::SendError,
 };
 
 #[cfg(test)]
@@ -26,6 +24,7 @@ pub fn router() -> Router<App> {
         .route("/api/channels", get(list))
         .route("/api/channels", post(on_create))
         .route("/api/channels/:channel", post(on_send))
+        .route("/api/channels/:channel", delete(on_delete))
 }
 
 #[derive(Default, serde::Deserialize)]
@@ -95,28 +94,54 @@ struct SendRequest {
 
 async fn on_send(
     State(app): State<App>,
-    Path(channel): Path<channel::Id>,
+    Path(channel): Path<Id>,
     RequestedAt(sent_at): RequestedAt,
     login: Login,
     Json(request): Json<SendRequest>,
-) -> Result<StatusCode, ErrorResponse> {
+) -> Result<StatusCode, SendErrorResponse> {
     app.messages()
         .send(&channel, &login, &sent_at, &request.message)
-        .await
-        // Could impl `From` here, but it's more code and this is used once.
-        .map_err(ErrorResponse)?;
+        .await?;
 
     Ok(StatusCode::ACCEPTED)
 }
 
-#[derive(Debug)]
-struct ErrorResponse(MessageError);
+#[derive(Debug, thiserror::Error)]
+#[error(transparent)]
+struct SendErrorResponse(#[from] SendError);
+
+impl IntoResponse for SendErrorResponse {
+    fn into_response(self) -> Response {
+        let Self(error) = self;
+        match error {
+            not_found @ SendError::ChannelNotFound(_) => {
+                (StatusCode::NOT_FOUND, not_found.to_string()).into_response()
+            }
+            other => Internal::from(other).into_response(),
+        }
+    }
+}
+
+async fn on_delete(
+    State(app): State<App>,
+    Path(channel): Path<Id>,
+    RequestedAt(deleted_at): RequestedAt,
+    _: Login,
+) -> Result<StatusCode, DeleteErrorResponse> {
+    app.channels().delete(&channel, &deleted_at).await?;
+
+    Ok(StatusCode::ACCEPTED)
+}
+
+#[derive(Debug, thiserror::Error)]
+#[error(transparent)]
+struct DeleteErrorResponse(#[from] DeleteError);
 
-impl IntoResponse for ErrorResponse {
+impl IntoResponse for DeleteErrorResponse {
     fn into_response(self) -> Response {
         let Self(error) = self;
         match error {
-            not_found @ MessageError::ChannelNotFound(_) => {
+            not_found @ DeleteError::NotFound(_) => {
                 (StatusCode::NOT_FOUND, not_found.to_string()).into_response()
             }
             other => Internal::from(other).into_response(),
diff --git a/src/channel/routes/test/on_send.rs b/src/channel/routes/test/on_send.rs
index 1027b29..3297093 100644
--- a/src/channel/routes/test/on_send.rs
+++ b/src/channel/routes/test/on_send.rs
@@ -5,7 +5,7 @@ use crate::{
     channel,
     channel::routes,
     event,
-    message::app,
+    message::app::SendError,
     test::fixtures::{self, future::Immediately as _},
 };
 
@@ -77,7 +77,7 @@ async fn nonexistent_channel() {
     let request = routes::SendRequest {
         message: fixtures::message::propose(),
     };
-    let routes::ErrorResponse(error) = routes::on_send(
+    let routes::SendErrorResponse(error) = routes::on_send(
         State(app),
         Path(channel.clone()),
         sent_at,
@@ -91,6 +91,6 @@ async fn nonexistent_channel() {
 
     assert!(matches!(
         error,
-        app::Error::ChannelNotFound(error_channel) if channel == error_channel
+        SendError::ChannelNotFound(error_channel) if channel == error_channel
     ));
 }
diff --git a/src/cli.rs b/src/cli.rs
index 893fae2..2d9f512 100644
--- a/src/cli.rs
+++ b/src/cli.rs
@@ -10,7 +10,7 @@ use clap::Parser;
 use sqlx::sqlite::SqlitePool;
 use tokio::net;
 
-use crate::{app::App, channel, clock, db, event, expire, login};
+use crate::{app::App, channel, clock, db, event, expire, login, message};
 
 /// Command-line entry point for running the `hi` server.
 ///
@@ -105,9 +105,14 @@ impl Args {
 }
 
 fn routers() -> Router<App> {
-    [channel::router(), event::router(), login::router()]
-        .into_iter()
-        .fold(Router::default(), Router::merge)
+    [
+        channel::router(),
+        event::router(),
+        login::router(),
+        message::router(),
+    ]
+    .into_iter()
+    .fold(Router::default(), Router::merge)
 }
 
 fn started_msg(listener: &net::TcpListener) -> io::Result<String> {
diff --git a/src/event/app.rs b/src/event/app.rs
index e58bea9..32f0a97 100644
--- a/src/event/app.rs
+++ b/src/event/app.rs
@@ -61,6 +61,7 @@ impl<'a> Events<'a> {
             // Filtering on the broadcast resume point filters out messages
             // before resume_at, and filters out messages duplicated from
             // `replay_events`.
+            .flat_map(stream::iter)
             .filter(Self::resume(resume_live_at));
 
         Ok(replay.chain(live_messages))
diff --git a/src/event/broadcaster.rs b/src/event/broadcaster.rs
index de2513a..3c4efac 100644
--- a/src/event/broadcaster.rs
+++ b/src/event/broadcaster.rs
@@ -1,3 +1,3 @@
 use crate::broadcast;
 
-pub type Broadcaster = broadcast::Broadcaster<super::Event>;
+pub type Broadcaster = broadcast::Broadcaster<Vec<super::Event>>;
diff --git a/src/message/app.rs b/src/message/app.rs
index 51f772e..1d34c14 100644
--- a/src/message/app.rs
+++ b/src/message/app.rs
@@ -2,12 +2,12 @@ use chrono::TimeDelta;
 use itertools::Itertools;
 use sqlx::sqlite::SqlitePool;
 
-use super::{repo::Provider as _, Message};
+use super::{repo::Provider as _, Id, Message};
 use crate::{
     channel::{self, repo::Provider as _},
     clock::DateTime,
     db::NotFound as _,
-    event::{broadcaster::Broadcaster, repo::Provider as _, Sequence},
+    event::{broadcaster::Broadcaster, repo::Provider as _, Event, Sequence},
     login::Login,
 };
 
@@ -27,13 +27,13 @@ impl<'a> Messages<'a> {
         sender: &Login,
         sent_at: &DateTime,
         body: &str,
-    ) -> Result<Message, Error> {
+    ) -> Result<Message, SendError> {
         let mut tx = self.db.begin().await?;
         let channel = tx
             .channels()
             .by_id(channel)
             .await
-            .not_found(|| Error::ChannelNotFound(channel.clone()))?;
+            .not_found(|| SendError::ChannelNotFound(channel.clone()))?;
         let sent = tx.sequence().next(sent_at).await?;
         let message = tx
             .messages()
@@ -41,24 +41,40 @@ impl<'a> Messages<'a> {
             .await?;
         tx.commit().await?;
 
-        for event in message.events() {
-            self.events.broadcast(event);
-        }
+        self.events
+            .broadcast(message.events().map(Event::from).collect::<Vec<_>>());
 
         Ok(message.snapshot())
     }
 
+    pub async fn delete(&self, message: &Id, deleted_at: &DateTime) -> Result<(), DeleteError> {
+        let mut tx = self.db.begin().await?;
+        let deleted = tx.sequence().next(deleted_at).await?;
+        let message = tx.messages().delete(message, &deleted).await?;
+        tx.commit().await?;
+
+        self.events.broadcast(
+            message
+                .events()
+                .filter(Sequence::start_from(deleted.sequence))
+                .map(Event::from)
+                .collect::<Vec<_>>(),
+        );
+
+        Ok(())
+    }
+
     pub async fn expire(&self, relative_to: &DateTime) -> Result<(), sqlx::Error> {
         // Somewhat arbitrarily, expire after 90 days.
         let expire_at = relative_to.to_owned() - TimeDelta::days(90);
 
         let mut tx = self.db.begin().await?;
-        let expired = tx.messages().expired(&expire_at).await?;
 
+        let expired = tx.messages().expired(&expire_at).await?;
         let mut events = Vec::with_capacity(expired.len());
-        for (channel, message) in expired {
+        for message in expired {
             let deleted = tx.sequence().next(relative_to).await?;
-            let message = tx.messages().delete(&channel, &message, &deleted).await?;
+            let message = tx.messages().delete(&message, &deleted).await?;
             events.push(
                 message
                     .events()
@@ -68,21 +84,32 @@ impl<'a> Messages<'a> {
 
         tx.commit().await?;
 
-        for event in events
-            .into_iter()
-            .kmerge_by(|a, b| a.instant.sequence < b.instant.sequence)
-        {
-            self.events.broadcast(event);
-        }
+        self.events.broadcast(
+            events
+                .into_iter()
+                .kmerge_by(|a, b| a.instant.sequence < b.instant.sequence)
+                .map(Event::from)
+                .collect::<Vec<_>>(),
+        );
 
         Ok(())
     }
 }
 
 #[derive(Debug, thiserror::Error)]
-pub enum Error {
+pub enum SendError {
+    #[error("channel {0} not found")]
+    ChannelNotFound(channel::Id),
+    #[error(transparent)]
+    DatabaseError(#[from] sqlx::Error),
+}
+
+#[derive(Debug, thiserror::Error)]
+pub enum DeleteError {
     #[error("channel {0} not found")]
     ChannelNotFound(channel::Id),
+    #[error("message {0} not found")]
+    NotFound(Id),
     #[error(transparent)]
     DatabaseError(#[from] sqlx::Error),
 }
diff --git a/src/message/mod.rs b/src/message/mod.rs
index 52d56c1..a8f51ab 100644
--- a/src/message/mod.rs
+++ b/src/message/mod.rs
@@ -3,6 +3,7 @@ pub mod event;
 mod history;
 mod id;
 pub mod repo;
+mod routes;
 mod snapshot;
 
-pub use self::{event::Event, history::History, id::Id, snapshot::Message};
+pub use self::{event::Event, history::History, id::Id, routes::router, snapshot::Message};
diff --git a/src/message/repo.rs b/src/message/repo.rs
index 3b2b8f7..ae41736 100644
--- a/src/message/repo.rs
+++ b/src/message/repo.rs
@@ -62,7 +62,25 @@ impl<'c> Messages<'c> {
         Ok(message)
     }
 
-    async fn by_id(&mut self, channel: &Channel, message: &Id) -> Result<History, sqlx::Error> {
+    pub async fn in_channel(&mut self, channel: &Channel) -> Result<Vec<Id>, sqlx::Error> {
+        let messages = sqlx::query_scalar!(
+            r#"
+                select
+                    message.id as "id: Id"
+                from message
+                    join channel on message.channel = channel.id
+                where channel.id = $1
+                order by message.sent_sequence
+            "#,
+            channel.id,
+        )
+        .fetch_all(&mut *self.0)
+        .await?;
+
+        Ok(messages)
+    }
+
+    async fn by_id(&mut self, message: &Id) -> Result<History, sqlx::Error> {
         let message = sqlx::query!(
             r#"
                 select
@@ -78,10 +96,8 @@ impl<'c> Messages<'c> {
                     join channel on message.channel = channel.id
                     join login as sender on message.sender = sender.id
                 where message.id = $1
-                    and message.channel = $2
             "#,
             message,
-            channel.id,
         )
         .map(|row| History {
             message: Message {
@@ -110,11 +126,10 @@ impl<'c> Messages<'c> {
 
     pub async fn delete(
         &mut self,
-        channel: &Channel,
         message: &Id,
         deleted: &Instant,
     ) -> Result<History, sqlx::Error> {
-        let history = self.by_id(channel, message).await?;
+        let history = self.by_id(message).await?;
 
         sqlx::query_scalar!(
             r#"
@@ -134,31 +149,16 @@ impl<'c> Messages<'c> {
         })
     }
 
-    pub async fn expired(
-        &mut self,
-        expire_at: &DateTime,
-    ) -> Result<Vec<(Channel, Id)>, sqlx::Error> {
-        let messages = sqlx::query!(
+    pub async fn expired(&mut self, expire_at: &DateTime) -> Result<Vec<Id>, sqlx::Error> {
+        let messages = sqlx::query_scalar!(
             r#"
                 select
-                    channel.id as "channel_id: channel::Id",
-                    channel.name as "channel_name",
-                    message.id as "message: Id"
+                    id as "message: Id"
                 from message
-                    join channel on message.channel = channel.id
                 where sent_at < $1
             "#,
             expire_at,
         )
-        .map(|row| {
-            (
-                Channel {
-                    id: row.channel_id,
-                    name: row.channel_name,
-                },
-                row.message,
-            )
-        })
         .fetch_all(&mut *self.0)
         .await?;
 
diff --git a/src/message/routes.rs b/src/message/routes.rs
new file mode 100644
index 0000000..29fe3d7
--- /dev/null
+++ b/src/message/routes.rs
@@ -0,0 +1,46 @@
+use axum::{
+    extract::{Path, State},
+    http::StatusCode,
+    response::{IntoResponse, Response},
+    routing::delete,
+    Router,
+};
+
+use crate::{
+    app::App,
+    clock::RequestedAt,
+    error::Internal,
+    login::Login,
+    message::{self, app::DeleteError},
+};
+
+pub fn router() -> Router<App> {
+    Router::new().route("/api/messages/:message", delete(on_delete))
+}
+
+async fn on_delete(
+    State(app): State<App>,
+    Path(message): Path<message::Id>,
+    RequestedAt(deleted_at): RequestedAt,
+    _: Login,
+) -> Result<StatusCode, ErrorResponse> {
+    app.messages().delete(&message, &deleted_at).await?;
+
+    Ok(StatusCode::ACCEPTED)
+}
+
+#[derive(Debug, thiserror::Error)]
+#[error(transparent)]
+struct ErrorResponse(#[from] DeleteError);
+
+impl IntoResponse for ErrorResponse {
+    fn into_response(self) -> Response {
+        let Self(error) = self;
+        match error {
+            not_found @ (DeleteError::ChannelNotFound(_) | DeleteError::NotFound(_)) => {
+                (StatusCode::NOT_FOUND, not_found.to_string()).into_response()
+            }
+            other => Internal::from(other).into_response(),
+        }
+    }
+}