From 11fa975fb2508be7c0cece679f8f9f7c4daf5a2a Mon Sep 17 00:00:00 2001
From: Astro <astro@spaceboyz.net>
Date: Mon, 20 Mar 2023 01:14:01 +0100
Subject: [PATCH] ticker-serve/export: implement ics export

---
 ticker-serve/askama.toml          |  3 ++
 ticker-serve/src/export.rs        | 62 +++++++++++++++++++++++++++++++
 ticker-serve/src/main.rs          |  2 +
 ticker-serve/templates/export.ics | 24 ++++++++++++
 ticker-serve/templates/index.html |  5 +++
 5 files changed, 96 insertions(+)
 create mode 100644 ticker-serve/askama.toml
 create mode 100644 ticker-serve/src/export.rs
 create mode 100644 ticker-serve/templates/export.ics

diff --git a/ticker-serve/askama.toml b/ticker-serve/askama.toml
new file mode 100644
index 0000000..09b52de
--- /dev/null
+++ b/ticker-serve/askama.toml
@@ -0,0 +1,3 @@
+[[escaper]]
+path = "Text"
+extensions = ["ics"]
diff --git a/ticker-serve/src/export.rs b/ticker-serve/src/export.rs
new file mode 100644
index 0000000..b392c06
--- /dev/null
+++ b/ticker-serve/src/export.rs
@@ -0,0 +1,62 @@
+use askama::{Template, Text};
+use axum::{
+    response::{IntoResponse, Response},
+    http::{StatusCode, HeaderMap, HeaderName, HeaderValue},
+    Extension,
+};
+
+use diesel::prelude::*;
+use chrono::{offset::Local, Duration};
+
+use libticker::{
+    schema::{self, events::dsl::events},
+    model::Event,
+};
+use crate::AppState;
+
+#[derive(Template)]
+#[template(path = "export.ics")]
+struct IcsTemplate {
+    events: Vec<Event>,
+}
+
+pub async fn ics(Extension(app_state): Extension<AppState>) -> Response {
+    export(app_state, |es| (
+        IcsTemplate { events: es },
+        "text/calendar"
+    )).await
+}
+
+async fn export<F, T>(app_state: AppState, f: F) -> Response
+where
+    F: FnOnce(Vec<Event>) -> (T, &'static str),
+    T: Template,
+{
+    let db = app_state.db.lock().unwrap();
+    let today = Local::now().date_naive().and_hms_opt(0, 0, 0).unwrap();
+    let limit = Local::now().date_naive().and_hms_opt(0, 0, 0).unwrap() +
+        Duration::days(app_state.config.upcoming_days.into());
+    let es: Vec<Event> = events
+        .filter(schema::events::dtend.ge(&today))
+        .or_filter(schema::events::dtstart.ge(&today))
+        .filter(schema::events::dtstart.lt(&limit))
+        .order_by(schema::events::dtstart.asc())
+        .then_order_by(schema::events::dtend.desc())
+        .load::<Event>(&*db)
+        .unwrap();
+        // .into_iter().collect::<Vec<Event>>();
+    let (template, content_type) = f(es);
+    match template.render() {
+        Ok(rendered) =>
+            (
+                [(HeaderName::from_static("content-type"), HeaderValue::from_static(content_type))]
+                    .iter().cloned()
+                    .collect::<HeaderMap>(),
+                rendered
+            ).into_response(),
+        Err(e) => (
+            StatusCode::INTERNAL_SERVER_ERROR,
+            format!("Failed to render template. Error: {}", e),
+        ).into_response(),
+    }
+}
diff --git a/ticker-serve/src/main.rs b/ticker-serve/src/main.rs
index 4180a35..2b318e0 100644
--- a/ticker-serve/src/main.rs
+++ b/ticker-serve/src/main.rs
@@ -12,6 +12,7 @@ use diesel::{Connection, pg::PgConnection};
 
 use libticker::config::Config;
 mod index;
+mod export;
 
 #[derive(Clone)]
 pub struct AppState {
@@ -33,6 +34,7 @@ async fn main() {
     };
     let app = Router::new()
         .route("/", get(index::index))
+        .route("/export.ics", get(export::ics))
         .layer(Extension(state))
         .nest_service("/static", ServeDir::new("static"));
     axum::Server::bind(&http_bind)
diff --git a/ticker-serve/templates/export.ics b/ticker-serve/templates/export.ics
new file mode 100644
index 0000000..1d31137
--- /dev/null
+++ b/ticker-serve/templates/export.ics
@@ -0,0 +1,24 @@
+BEGIN:VCALENDAR
+VERSION:2.0
+METHOD:PUBLISH
+X-WR-TIMEZONE;VALUE=TEXT:Europe/Berlin
+
+{% for e in events -%}
+BEGIN:VEVENT
+SUMMARY:{{ e.summary }}
+DTSTART:{{ e.dtstart.format("%Y%m%dT%H%M%S").to_string() }}
+{% if let Some(dtend) = e.dtend -%}
+DTEND:{{ dtend.format("%Y%m%dT%H%M%S") }}
+{% endif -%}
+UID:{{ e.id.replace(char::is_whitespace, "_") }}
+{% if let Some(url) = e.url -%}
+URL:{{ url }}
+{% endif -%}
+{% if let Some(location) = e.location -%}
+LOCATION:{{ location }}
+{% endif -%}
+END:VEVENT
+
+{% endfor -%}
+END:VCALENDAR
+
diff --git a/ticker-serve/templates/index.html b/ticker-serve/templates/index.html
index eca822f..660095c 100644
--- a/ticker-serve/templates/index.html
+++ b/ticker-serve/templates/index.html
@@ -6,6 +6,7 @@
     <meta name="viewport" content="width=device-width"/>
     <link rel="stylesheet" title="Style" type="text/css" href="static/style.css"/>
     <link rel="icon" type="image/png" href="static/favicon.png"/>
+    <link rel="alternate" type="text/calendar" title="ICS" href="export.ics"/>
   </head>
   <body>
     <h1>Dresden Ticker</h1>
@@ -62,6 +63,10 @@
       </div>
     {% endfor %}
     <footer>
+      <p>
+        Maschinenlesbarer Export:
+        <a href="export.rss">ICS</a>
+      </p>
       <p>
         Ein Projekt des
         <a href="https://www.c3d2.de/">C3D2</a>