server can now send error messages to clients

musicdb-lib/src/data/database.rs

@@ -232,7 +232,14 @@ impl Database {
         Ok(())
     }
 
-    pub fn apply_command(&mut self, command: Command) {
+    pub fn apply_command(&mut self, mut command: Command) {
+        if !self.is_client() {
+            if let Command::ErrorInfo(t, _) = &mut command {
+                // clients can send ErrorInfo to the server and it will show up on other clients,
+                // BUT only the server can set the Title of the ErrorInfo.
+                t.clear();
+            }
+        }
         // since db.update_endpoints is empty for clients, this won't cause unwanted back and forth
         self.broadcast_update(&command);
         match command {
@@ -349,6 +356,7 @@ impl Database {
             Command::InitComplete => {
                 self.client_is_init = true;
             }
+            Command::ErrorInfo(..) => {}
         }
     }
 }

musicdb-lib/src/data/song.rs

@@ -154,7 +154,7 @@ impl Song {
                 {
                     Ok(data) => Some(data),
                     Err(e) => {
-                        eprintln!("[info] error loading song {id}: {e}");
+                        eprintln!("[WARN] error loading song {id}: {e}");
                         None
                     }
                 }

musicdb-lib/src/player/mod.rs

@@ -139,6 +139,13 @@ impl Player {
                                     db.apply_command(Command::NextSong);
                                 }
                             }
+                        } else {
+                            // couldn't load song bytes
+                            db.broadcast_update(&Command::ErrorInfo(
+                                "NoSongData".to_owned(),
+                                format!("Couldn't load song #{}\n({})", song.id, song.title),
+                            ));
+                            db.apply_command(Command::NextSong);
                         }
                     } else {
                         self.source = None;

musicdb-lib/src/server/mod.rs

@@ -1,7 +1,6 @@
 pub mod get;
 
 use std::{
-    eprintln,
     io::{BufRead, BufReader, Read, Write},
     net::{SocketAddr, TcpListener},
     sync::{mpsc, Arc, Mutex},
@@ -51,6 +50,7 @@ pub enum Command {
     RemoveArtist(ArtistId),
     ModifyArtist(Artist),
     InitComplete,
+    ErrorInfo(String, String),
 }
 impl Command {
     pub fn send_to_server(self, db: &Database) -> Result<(), Self> {
@@ -106,7 +106,6 @@ pub fn run_server(
                         let command_sender = command_sender.clone();
                         let db = Arc::clone(&db);
                         thread::spawn(move || {
-                            eprintln!("[info] TCP connection accepted from {con_addr}.");
                             // each connection first has to send one line to tell us what it wants
                             let mut connection = BufReader::new(connection);
                             let mut line = String::new();
@@ -279,6 +278,11 @@ impl ToFromBytes for Command {
             Self::InitComplete => {
                 s.write_all(&[0b00110001])?;
             }
+            Self::ErrorInfo(t, d) => {
+                s.write_all(&[0b11011011])?;
+                t.to_bytes(s)?;
+                d.to_bytes(s)?;
+            }
         }
         Ok(())
     }
@@ -324,6 +328,7 @@ impl ToFromBytes for Command {
             0b11011100 => Self::RemoveArtist(ToFromBytes::from_bytes(s)?),
             0b01011101 => Self::AddCover(ToFromBytes::from_bytes(s)?),
             0b00110001 => Self::InitComplete,
+            0b11011011 => Self::ErrorInfo(ToFromBytes::from_bytes(s)?, ToFromBytes::from_bytes(s)?),
             _ => {
                 eprintln!("unexpected byte when reading command; stopping playback.");
                 Self::Stop