feat: dynamic png-based clock favicon

src/main.rs

@@ -1,7 +1,8 @@
 use std::net::SocketAddr;
 
 use crate::routes::{
-    absolute_handler, fallback_handler, implicit_handler, index_handler, relative_handler,
+    absolute_handler, fallback_handler, favicon_handler, implicit_handler, index_handler,
+    relative_handler,
 };
 use axum::{routing::get, Router};
 use config::Configuration;
@@ -34,6 +35,7 @@ async fn main() {
 
     let app = Router::new()
         .route("/", get(index_handler))
+        .route("/favicon.ico", get(favicon_handler))
         .route("/{path}", get(implicit_handler))
         .route("/rel/{path}", get(relative_handler))
         .route("/relative/{path}", get(relative_handler))

src/routes.rs

@@ -3,8 +3,10 @@ use crate::error::{get_error_response, TimeBannerError};
 use crate::render::render_time_response;
 use crate::template::OutputForm;
 use crate::utils::parse_path;
+use axum::extract::ConnectInfo;
 use axum::extract::Path;
 use axum::response::IntoResponse;
+use std::net::SocketAddr;
 
 /// Root handler - redirects to current time in relative format.
 pub async fn index_handler() -> impl IntoResponse {
@@ -49,6 +51,19 @@ pub async fn implicit_handler(Path(path): Path<String>) -> impl IntoResponse {
     render_time_response(time, OutputForm::Absolute, extension).into_response()
 }
 
+/// Handles `/favicon.ico` - generates a dynamic clock favicon showing the current time.
+///
+/// Logs the client IP address and returns a PNG image of an analog clock.
+pub async fn favicon_handler(ConnectInfo(addr): ConnectInfo<SocketAddr>) -> impl IntoResponse {
+    let now = chrono::Utc::now();
+
+    // Log the IP address for the favicon request
+    tracing::info!("Favicon request from IP: {}", addr.ip());
+
+    // Generate clock favicon showing current time
+    render_time_response(now, OutputForm::Clock, "png").into_response()
+}
+
 /// Fallback handler for unmatched routes.
 pub async fn fallback_handler() -> impl IntoResponse {
     get_error_response(TimeBannerError::NotFound).into_response()

src/template.rs

@@ -1,4 +1,4 @@
-use chrono::{DateTime, Utc};
+use chrono::{DateTime, Timelike, Utc};
 use lazy_static::lazy_static;
 use tera::{Context, Tera};
 use timeago::Formatter;
@@ -36,9 +36,11 @@ pub enum OutputForm {
     Relative,
     /// Absolute display: "2025-01-17 14:30:00 UTC"  
     Absolute,
+    /// Clock display: analog clock with hands showing the time
+    Clock,
 }
 
-/// Timezone specification formats.
+/// Timezone specification formats (currently unused but reserved for future features).
 pub enum TzForm {
     Abbreviation(String), // e.g. "CST"
     Iso(String),          // e.g. "America/Chicago"
@@ -58,19 +60,70 @@ pub struct RenderContext {
     pub now: Option<i64>,
 }
 
+/// Calculates clock hand positions for a given time.
+///
+/// Returns (hour_x, hour_y, minute_x, minute_y) coordinates for SVG rendering.
+/// Clock center is at (16, 16) with appropriate hand lengths for a 32x32 favicon.
+fn calculate_clock_hands(time: DateTime<Utc>) -> (f64, f64, f64, f64) {
+    let hour = time.hour() as f64;
+    let minute = time.minute() as f64;
+
+    // Calculate angles (12 o'clock = 0°, clockwise)
+    let hour_angle = ((hour % 12.0) + minute / 60.0) * 30.0; // 30° per hour
+    let minute_angle = minute * 6.0; // 6° per minute
+
+    // Convert to radians and adjust for SVG coordinate system (0° at top)
+    let hour_rad = (hour_angle - 90.0).to_radians();
+    let minute_rad = (minute_angle - 90.0).to_radians();
+
+    // Clock center and hand lengths
+    let center_x = 16.0;
+    let center_y = 16.0;
+    let hour_length = 7.0; // Shorter hour hand
+    let minute_length = 11.0; // Longer minute hand
+
+    // Calculate end positions
+    let hour_x = center_x + hour_length * hour_rad.cos();
+    let hour_y = center_y + hour_length * hour_rad.sin();
+    let minute_x = center_x + minute_length * minute_rad.cos();
+    let minute_y = center_y + minute_length * minute_rad.sin();
+
+    (hour_x, hour_y, minute_x, minute_y)
+}
+
 /// Renders a time value using the appropriate template.
+///
+/// Uses different templates based on output form:
+/// - Relative/Absolute: "basic.svg" with text content
+/// - Clock: "clock.svg" with calculated hand positions
 pub fn render_template(context: RenderContext) -> Result<String, tera::Error> {
     let mut template_context = Context::new();
-    let formatter = Formatter::new();
 
-    template_context.insert(
-        "text",
     match context.output_form {
-            OutputForm::Relative => formatter.convert_chrono(context.value, Utc::now()),
-            OutputForm::Absolute => context.value.to_rfc3339(),
-        }
-        .as_str(),
-    );
-
+        OutputForm::Relative => {
+            let formatter = Formatter::new();
+            template_context.insert("text", &formatter.convert_chrono(context.value, Utc::now()));
             TEMPLATES.render("basic.svg", &template_context)
         }
+        OutputForm::Absolute => {
+            template_context.insert("text", &context.value.to_rfc3339());
+            TEMPLATES.render("basic.svg", &template_context)
+        }
+        OutputForm::Clock => {
+            let (hour_x, hour_y, minute_x, minute_y) = calculate_clock_hands(context.value);
+
+            // Format to 2 decimal places to avoid precision issues
+            let hour_x_str = format!("{:.2}", hour_x);
+            let hour_y_str = format!("{:.2}", hour_y);
+            let minute_x_str = format!("{:.2}", minute_x);
+            let minute_y_str = format!("{:.2}", minute_y);
+
+            template_context.insert("hour_x", &hour_x_str);
+            template_context.insert("hour_y", &hour_y_str);
+            template_context.insert("minute_x", &minute_x_str);
+            template_context.insert("minute_y", &minute_y_str);
+
+            TEMPLATES.render("clock.svg", &template_context)
+        }
+    }
+}

src/templates/clock.svg

@@ -0,0 +1,37 @@
+<svg width="32" height="32" viewBox="0 0 32 32" xmlns="http://www.w3.org/2000/svg">
+    <!-- Clock face -->
+    <circle cx="16" cy="16" r="15" fill="#ffffff" stroke="#000000" stroke-width="1" />
+
+    <!-- Hour markers -->
+    <g stroke="#000000" stroke-width="1">
+        <!-- 12 o'clock -->
+        <line x1="16" y1="2" x2="16" y2="5" />
+        <!-- 3 o'clock -->
+        <line x1="30" y1="16" x2="27" y2="16" />
+        <!-- 6 o'clock -->
+        <line x1="16" y1="30" x2="16" y2="27" />
+        <!-- 9 o'clock -->
+        <line x1="2" y1="16" x2="5" y2="16" />
+
+        <!-- Minor markers -->
+        <line x1="24.5" y1="4.5" x2="23.5" y2="5.5" />
+        <line x1="27.5" y1="7.5" x2="26.5" y2="8.5" />
+        <line x1="27.5" y1="24.5" x2="26.5" y2="23.5" />
+        <line x1="24.5" y1="27.5" x2="23.5" y2="26.5" />
+        <line x1="7.5" y1="27.5" x2="8.5" y2="26.5" />
+        <line x1="4.5" y1="24.5" x2="5.5" y2="23.5" />
+        <line x1="4.5" y1="7.5" x2="5.5" y2="8.5" />
+        <line x1="7.5" y1="4.5" x2="8.5" y2="5.5" />
+    </g>
+
+    <!-- Hour hand -->
+    <line x1="16" y1="16" x2="{{ hour_x }}" y2="{{ hour_y }}" stroke="#000000" stroke-width="2"
+        stroke-linecap="round" />
+
+    <!-- Minute hand -->
+    <line x1="16" y1="16" x2="{{ minute_x }}" y2="{{ minute_y }}" stroke="#000000"
+        stroke-width="1.5" stroke-linecap="round" />
+
+    <!-- Center dot -->
+    <circle cx="16" cy="16" r="1.5" fill="#000000" />
+</svg>