From 22348bfa35f009e62abe2f30863e0434079a1fe2 Mon Sep 17 00:00:00 2001
From: Owen Jacobson <owen@grimoire.ca>
Date: Wed, 18 Sep 2024 22:49:38 -0400
Subject: Remove the HTML client, and expose a JSON API.

This API structure fell out of a conversation with Kit. Described loosely:

	kit: ok
	kit: Here's what I'm picturing in a client
	kit: list channels, make-new-channel, zero to one active channels, post-to-active.
	kit: login/sign-up, logout

	owen: you will likely also want "am I logged in" here

	kit: sure, whoami
---
 src/channel/app.rs    | 32 +++++++++++++++++++++---
 src/channel/routes.rs | 68 +++++++++++++++++++++++++++++++++++++++------------
 2 files changed, 81 insertions(+), 19 deletions(-)

(limited to 'src/channel')

diff --git a/src/channel/app.rs b/src/channel/app.rs
index 2f37878..8ae0c3c 100644
--- a/src/channel/app.rs
+++ b/src/channel/app.rs
@@ -31,13 +31,17 @@ impl<'a> Channels<'a> {
         Self { db, broadcaster }
     }
 
-    pub async fn create(&self, name: &str) -> Result<(), InternalError> {
+    pub async fn create(&self, name: &str) -> Result<Channel, CreateError> {
         let mut tx = self.db.begin().await?;
-        let channel = tx.channels().create(name).await?;
-        self.broadcaster.register_channel(&channel);
+        let channel = tx
+            .channels()
+            .create(name)
+            .await
+            .map_err(|err| CreateError::from_duplicate_name(err, name))?;
+        self.broadcaster.register_channel(&channel.id);
         tx.commit().await?;
 
-        Ok(())
+        Ok(channel)
     }
 
     pub async fn all(&self) -> Result<Vec<Channel>, InternalError> {
@@ -121,6 +125,26 @@ impl<'a> Channels<'a> {
     }
 }
 
+#[derive(Debug, thiserror::Error)]
+pub enum CreateError {
+    #[error("channel named {0} already exists")]
+    DuplicateName(String),
+    #[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() {
+            if error.is_unique_violation() {
+                return Self::DuplicateName(name.into());
+            }
+        }
+
+        Self::from(error)
+    }
+}
+
 #[derive(Debug, thiserror::Error)]
 pub enum InternalError {
     #[error(transparent)]
diff --git a/src/channel/routes.rs b/src/channel/routes.rs
index 847e0b4..383ec58 100644
--- a/src/channel/routes.rs
+++ b/src/channel/routes.rs
@@ -1,23 +1,43 @@
 use axum::{
-    extract::{Form, Path, State},
+    extract::{Json, Path, State},
     http::StatusCode,
-    response::{IntoResponse, Redirect, Response},
-    routing::post,
+    response::{IntoResponse, Response},
+    routing::{get, post},
     Router,
 };
 
-use super::app::EventsError;
+use super::app::{self, EventsError};
 use crate::{
     app::App,
     clock::RequestedAt,
     error::InternalError,
-    repo::{channel, login::Login},
+    repo::{
+        channel::{self, Channel},
+        login::Login,
+    },
 };
 
 pub fn router() -> Router<App> {
     Router::new()
-        .route("/create", post(on_create))
-        .route("/:channel/send", post(on_send))
+        .route("/api/channels", get(list_channels))
+        .route("/api/channels", post(on_create))
+        .route("/api/channels/:channel", post(on_send))
+}
+
+async fn list_channels(State(app): State<App>, _: Login) -> Result<Channels, InternalError> {
+    let channels = app.channels().all().await?;
+    let response = Channels(channels);
+
+    Ok(response)
+}
+
+struct Channels(Vec<Channel>);
+
+impl IntoResponse for Channels {
+    fn into_response(self) -> Response {
+        let Self(channels) = self;
+        Json(channels).into_response()
+    }
 }
 
 #[derive(serde::Deserialize)]
@@ -28,11 +48,29 @@ struct CreateRequest {
 async fn on_create(
     State(app): State<App>,
     _: Login, // requires auth, but doesn't actually care who you are
-    Form(form): Form<CreateRequest>,
-) -> Result<impl IntoResponse, InternalError> {
-    app.channels().create(&form.name).await?;
+    Json(form): Json<CreateRequest>,
+) -> Result<Json<Channel>, CreateError> {
+    let channel = app
+        .channels()
+        .create(&form.name)
+        .await
+        .map_err(CreateError)?;
 
-    Ok(Redirect::to("/"))
+    Ok(Json(channel))
+}
+
+struct CreateError(app::CreateError);
+
+impl IntoResponse for CreateError {
+    fn into_response(self) -> Response {
+        let Self(error) = self;
+        match error {
+            duplicate @ app::CreateError::DuplicateName(_) => {
+                (StatusCode::BAD_REQUEST, duplicate.to_string()).into_response()
+            }
+            other => InternalError::from(other).into_response(),
+        }
+    }
 }
 
 #[derive(serde::Deserialize)]
@@ -45,15 +83,15 @@ async fn on_send(
     RequestedAt(sent_at): RequestedAt,
     State(app): State<App>,
     login: Login,
-    Form(form): Form<SendRequest>,
-) -> Result<impl IntoResponse, ErrorResponse> {
+    Json(form): Json<SendRequest>,
+) -> Result<StatusCode, ErrorResponse> {
     app.channels()
         .send(&login, &channel, &form.message, &sent_at)
         .await
         // Could impl `From` here, but it's more code and this is used once.
         .map_err(ErrorResponse)?;
 
-    Ok(Redirect::to(&format!("/{}", channel)))
+    Ok(StatusCode::ACCEPTED)
 }
 
 struct ErrorResponse(EventsError);
@@ -65,7 +103,7 @@ impl IntoResponse for ErrorResponse {
             not_found @ EventsError::ChannelNotFound(_) => {
                 (StatusCode::NOT_FOUND, not_found.to_string()).into_response()
             }
-            EventsError::DatabaseError(error) => InternalError::from(error).into_response(),
+            other => InternalError::from(other).into_response(),
         }
     }
 }
-- 
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