feat: fix emscripten browser logging, streamline console initialization and logging

src/platform/emscripten.rs

@@ -1,18 +1,21 @@
 //! Emscripten platform implementation.
 
-use std::borrow::Cow;
-use std::time::Duration;
-
 use crate::asset::Asset;
 use crate::error::{AssetError, PlatformError};
 use rand::{rngs::SmallRng, SeedableRng};
+use sdl2::rwops::RWops;
+use std::borrow::Cow;
+use std::ffi::CString;
+use std::io::{self, Read, Write};
+use std::time::Duration;
 
 // Emscripten FFI functions
 #[allow(dead_code)]
 extern "C" {
-    fn emscripten_get_now() -> f64;
     fn emscripten_sleep(ms: u32);
     fn emscripten_get_element_css_size(target: *const u8, width: *mut f64, height: *mut f64) -> i32;
+    // Standard C functions that Emscripten redirects to console
+    fn printf(format: *const u8, ...) -> i32;
 }
 
 pub fn sleep(duration: Duration, _focused: bool) {
@@ -22,11 +25,44 @@ pub fn sleep(duration: Duration, _focused: bool) {
 }
 
 pub fn init_console() -> Result<(), PlatformError> {
-    Ok(()) // No-op for Emscripten
+    use tracing_subscriber::{fmt, layer::SubscriberExt, EnvFilter};
+
+    // Set up a custom tracing subscriber that writes directly to emscripten console
+    let subscriber = tracing_subscriber::registry()
+        .with(
+            fmt::layer()
+                .with_writer(|| EmscriptenConsoleWriter)
+                .with_ansi(false)
+                .without_time()
+                .with_target(false),
+        )
+        .with(EnvFilter::try_from_default_env().unwrap_or_else(|_| EnvFilter::new("debug")));
+
+    tracing::subscriber::set_global_default(subscriber)
+        .map_err(|e| PlatformError::ConsoleInit(format!("Failed to set tracing subscriber: {}", e)))?;
+
+    Ok(())
 }
 
-pub fn requires_console() -> bool {
-    false
+/// A writer that outputs to the browser console via printf (redirected by emscripten)
+struct EmscriptenConsoleWriter;
+
+impl Write for EmscriptenConsoleWriter {
+    fn write(&mut self, buf: &[u8]) -> io::Result<usize> {
+        if let Ok(s) = std::str::from_utf8(buf) {
+            if let Ok(cstr) = CString::new(s.trim_end_matches('\n')) {
+                let format_str = CString::new("%s\n").unwrap();
+                unsafe {
+                    printf(format_str.as_ptr().cast(), cstr.as_ptr());
+                }
+            }
+        }
+        Ok(buf.len())
+    }
+
+    fn flush(&mut self) -> io::Result<()> {
+        Ok(())
+    }
 }
 
 #[allow(dead_code)]
@@ -44,18 +80,13 @@ pub fn get_canvas_size() -> Option<(u32, u32)> {
 }
 
 pub fn get_asset_bytes(asset: Asset) -> Result<Cow<'static, [u8]>, AssetError> {
-    use sdl2::rwops::RWops;
-    use std::io::Read;
-
     let path = format!("assets/game/{}", asset.path());
     let mut rwops = RWops::from_file(&path, "rb").map_err(|_| AssetError::NotFound(asset.path().to_string()))?;
 
     let len = rwops.len().ok_or_else(|| AssetError::NotFound(asset.path().to_string()))?;
 
     let mut buf = vec![0u8; len];
-    rwops
-        .read_exact(&mut buf)
-        .map_err(|e| AssetError::Io(std::io::Error::other(e)))?;
+    rwops.read_exact(&mut buf).map_err(|e| AssetError::Io(io::Error::other(e)))?;
 
     Ok(Cow::Owned(buf))
 }