Reorganize and consolidate HTTP routes.

HTTP routes are now defined in a single, unified module, pulling them out of the topical modules they were formerly part of.

This is intended to improve the navigability of the codebase. Previously, finding the handler corresponding to a specific endpoint required prior familiarity, though in practice you could usually guess from topic area. Now, all routes are defined in one place; if you know the path, you can read down the list to find the handler.

Handlers themselves live with the domain they are most appropriately "part of," generally (in this version, universally) in a `handlers` submodule. The handlers themselves have been flattened down; rather than representing a path and a method, they now represent a named operation (which is suspiciously similar to the path in most cases). This means that we no longer have constructs like `crate::ui::routes::ch::channel` - it's now `crate::ui::handlers::channel` instead.

## Disclaimer

I Solemnly Swear I Didn't Change Any Handlers.

## Prior art

I've inadvertently reinvented Django's `urls.py` convention, and I've opted to lean into that.

Merges flatter-routes-reorg into main.

2 files changed, 233 insertions, 0 deletions

diff --git a/src/channel/handlers/delete/mod.rs b/src/channel/handlers/delete/mod.rs
new file mode 100644
index 0000000..b986bec
--- /dev/null
+++ b/src/channel/handlers/delete/mod.rs
@@ -0,0 +1,59 @@
+use axum::{
+    extract::{Json, Path, State},
+    http::StatusCode,
+    response::{self, IntoResponse},
+};
+
+use crate::{
+    app::App,
+    channel::{self, app, handlers::PathInfo},
+    clock::RequestedAt,
+    error::{Internal, NotFound},
+    token::extract::Identity,
+};
+
+#[cfg(test)]
+mod test;
+
+pub async fn handler(
+    State(app): State<App>,
+    Path(channel): Path<PathInfo>,
+    RequestedAt(deleted_at): RequestedAt,
+    _: Identity,
+) -> Result<Response, Error> {
+    app.channels().delete(&channel, &deleted_at).await?;
+
+    Ok(Response { id: channel })
+}
+
+#[derive(Debug, serde::Serialize)]
+pub struct Response {
+    pub id: channel::Id,
+}
+
+impl IntoResponse for Response {
+    fn into_response(self) -> response::Response {
+        (StatusCode::ACCEPTED, Json(self)).into_response()
+    }
+}
+
+#[derive(Debug, thiserror::Error)]
+#[error(transparent)]
+pub struct Error(#[from] pub app::DeleteError);
+
+impl IntoResponse for Error {
+    fn into_response(self) -> response::Response {
+        let Self(error) = self;
+        match error {
+            app::DeleteError::NotFound(_) | app::DeleteError::Deleted(_) => {
+                NotFound(error).into_response()
+            }
+            app::DeleteError::NotEmpty(_) => {
+                (StatusCode::CONFLICT, error.to_string()).into_response()
+            }
+            app::DeleteError::Name(_) | app::DeleteError::Database(_) => {
+                Internal::from(error).into_response()
+            }
+        }
+    }
+}
diff --git a/src/channel/handlers/delete/test.rs b/src/channel/handlers/delete/test.rs
new file mode 100644
index 0000000..b1e42ea
--- /dev/null
+++ b/src/channel/handlers/delete/test.rs
@@ -0,0 +1,174 @@
+use axum::extract::{Path, State};
+
+use crate::{channel::app, test::fixtures};
+
+#[tokio::test]
+pub async fn valid_channel() {
+    // Set up the environment
+
+    let app = fixtures::scratch_app().await;
+    let channel = fixtures::channel::create(&app, &fixtures::now()).await;
+
+    // Send the request
+
+    let deleter = fixtures::identity::create(&app, &fixtures::now()).await;
+    let response = super::handler(
+        State(app.clone()),
+        Path(channel.id.clone()),
+        fixtures::now(),
+        deleter,
+    )
+    .await
+    .expect("deleting a valid channel succeeds");
+
+    // Verify the response
+
+    assert_eq!(channel.id, response.id);
+
+    // Verify the semantics
+
+    let snapshot = app.boot().snapshot().await.expect("boot always succeeds");
+    assert!(!snapshot.channels.contains(&channel));
+}
+
+#[tokio::test]
+pub async fn invalid_channel_id() {
+    // Set up the environment
+
+    let app = fixtures::scratch_app().await;
+
+    // Send the request
+
+    let deleter = fixtures::identity::create(&app, &fixtures::now()).await;
+    let channel = fixtures::channel::fictitious();
+    let super::Error(error) = super::handler(
+        State(app.clone()),
+        Path(channel.clone()),
+        fixtures::now(),
+        deleter,
+    )
+    .await
+    .expect_err("deleting a nonexistent channel fails");
+
+    // Verify the response
+
+    assert!(matches!(error, app::DeleteError::NotFound(id) if id == channel));
+}
+
+#[tokio::test]
+pub async fn channel_deleted() {
+    // Set up the environment
+
+    let app = fixtures::scratch_app().await;
+    let channel = fixtures::channel::create(&app, &fixtures::now()).await;
+
+    app.channels()
+        .delete(&channel.id, &fixtures::now())
+        .await
+        .expect("deleting a recently-sent channel succeeds");
+
+    // Send the request
+
+    let deleter = fixtures::identity::create(&app, &fixtures::now()).await;
+    let super::Error(error) = super::handler(
+        State(app.clone()),
+        Path(channel.id.clone()),
+        fixtures::now(),
+        deleter,
+    )
+    .await
+    .expect_err("deleting a deleted channel fails");
+
+    // Verify the response
+
+    assert!(matches!(error, app::DeleteError::Deleted(id) if id == channel.id));
+}
+
+#[tokio::test]
+pub async fn channel_expired() {
+    // Set up the environment
+
+    let app = fixtures::scratch_app().await;
+    let channel = fixtures::channel::create(&app, &fixtures::ancient()).await;
+
+    app.channels()
+        .expire(&fixtures::now())
+        .await
+        .expect("expiring channels always succeeds");
+
+    // Send the request
+
+    let deleter = fixtures::identity::create(&app, &fixtures::now()).await;
+    let super::Error(error) = super::handler(
+        State(app.clone()),
+        Path(channel.id.clone()),
+        fixtures::now(),
+        deleter,
+    )
+    .await
+    .expect_err("deleting an expired channel fails");
+
+    // Verify the response
+
+    assert!(matches!(error, app::DeleteError::Deleted(id) if id == channel.id));
+}
+
+#[tokio::test]
+pub async fn channel_purged() {
+    // Set up the environment
+
+    let app = fixtures::scratch_app().await;
+    let channel = fixtures::channel::create(&app, &fixtures::ancient()).await;
+
+    app.channels()
+        .expire(&fixtures::old())
+        .await
+        .expect("expiring channels always succeeds");
+
+    app.channels()
+        .purge(&fixtures::now())
+        .await
+        .expect("purging channels always succeeds");
+
+    // Send the request
+
+    let deleter = fixtures::identity::create(&app, &fixtures::now()).await;
+    let super::Error(error) = super::handler(
+        State(app.clone()),
+        Path(channel.id.clone()),
+        fixtures::now(),
+        deleter,
+    )
+    .await
+    .expect_err("deleting a purged channel fails");
+
+    // Verify the response
+
+    assert!(matches!(error, app::DeleteError::NotFound(id) if id == channel.id));
+}
+
+#[tokio::test]
+pub async fn channel_not_empty() {
+    // Set up the environment
+
+    let app = fixtures::scratch_app().await;
+    let channel = fixtures::channel::create(&app, &fixtures::now()).await;
+    let sender = fixtures::user::create(&app, &fixtures::now()).await;
+    fixtures::message::send(&app, &channel, &sender, &fixtures::now()).await;
+
+    // Send the request
+
+    let deleter = fixtures::identity::create(&app, &fixtures::now()).await;
+    let super::Error(error) = super::handler(
+        State(app.clone()),
+        Path(channel.id.clone()),
+        fixtures::now(),
+        deleter,
+    )
+    .await
+    .expect_err("deleting a channel with messages fails");
+
+    // Verify the response
+
+    assert!(matches!(error, app::DeleteError::NotEmpty(id) if id == channel.id));
+}