refactor: replace magic indices with RtorrentField enum for type-safe parsing

backend/Cargo.toml

@@ -42,3 +42,4 @@ anyhow = "1.0.101"
 time = { version = "0.3.47", features = ["serde", "formatting", "parsing"] }
 tower_governor = "0.8.0"
 governor = "0.10.4"
+strum = { version = "0.25", features = ["derive", "strum_macros"] }

backend/src/sse.rs

@@ -7,95 +7,80 @@ use axum::response::sse::{Event, Sse};
 use futures::stream::{self, Stream};
 use shared::{AppEvent, GlobalStats, Torrent, TorrentStatus};
 use std::convert::Infallible;
+use strum::{Display, EnumString};
 use tokio_stream::StreamExt;
 
-// Field definitions to keep query and parser in sync
-mod fields {
-    pub const IDX_HASH: usize = 0;
-    pub const CMD_HASH: &str = "d.hash=";
-
-    pub const IDX_NAME: usize = 1;
-    pub const CMD_NAME: &str = "d.name=";
-
-    pub const IDX_SIZE: usize = 2;
-    pub const CMD_SIZE: &str = "d.size_bytes=";
-
-    pub const IDX_COMPLETED: usize = 3;
-    pub const CMD_COMPLETED: &str = "d.bytes_done=";
-
-    pub const IDX_DOWN_RATE: usize = 4;
-    pub const CMD_DOWN_RATE: &str = "d.down.rate=";
-
-    pub const IDX_UP_RATE: usize = 5;
-    pub const CMD_UP_RATE: &str = "d.up.rate=";
-
-    pub const IDX_STATE: usize = 6;
-    pub const CMD_STATE: &str = "d.state=";
-
-    pub const IDX_COMPLETE: usize = 7;
-    pub const CMD_COMPLETE: &str = "d.complete=";
-
-    pub const IDX_MESSAGE: usize = 8;
-    pub const CMD_MESSAGE: &str = "d.message=";
-
-    pub const IDX_LEFT_BYTES: usize = 9;
-    pub const CMD_LEFT_BYTES: &str = "d.left_bytes=";
-
-    pub const IDX_CREATION_DATE: usize = 10;
-    pub const CMD_CREATION_DATE: &str = "d.creation_date=";
-
-    pub const IDX_HASHING: usize = 11;
-    pub const CMD_HASHING: &str = "d.hashing=";
-
-    pub const IDX_LABEL: usize = 12;
-    pub const CMD_LABEL: &str = "d.custom1=";
+#[derive(Debug, Clone, Copy, EnumString, Display, PartialEq)]
+enum RtorrentField {
+    #[strum(serialize = "d.hash=")]
+    Hash,
+    #[strum(serialize = "d.name=")]
+    Name,
+    #[strum(serialize = "d.size_bytes=")]
+    Size,
+    #[strum(serialize = "d.bytes_done=")]
+    Completed,
+    #[strum(serialize = "d.down.rate=")]
+    DownRate,
+    #[strum(serialize = "d.up.rate=")]
+    UpRate,
+    #[strum(serialize = "d.state=")]
+    State,
+    #[strum(serialize = "d.complete=")]
+    Complete,
+    #[strum(serialize = "d.message=")]
+    Message,
+    #[strum(serialize = "d.left_bytes=")]
+    LeftBytes,
+    #[strum(serialize = "d.creation_date=")]
+    CreationDate,
+    #[strum(serialize = "d.hashing=")]
+    Hashing,
+    #[strum(serialize = "d.custom1=")]
+    Label,
 }
 
-use fields::*;
-
-// Constants for rTorrent fields to ensure query and parser stay in sync
-const RTORRENT_FIELDS: &[&str] = &[
-    "",     // Ignored by multicall pattern
-    "main", // View
-    CMD_HASH,
-    CMD_NAME,
-    CMD_SIZE,
-    CMD_COMPLETED,
-    CMD_DOWN_RATE,
-    CMD_UP_RATE,
-    CMD_STATE,
-    CMD_COMPLETE,
-    CMD_MESSAGE,
-    CMD_LEFT_BYTES,
-    CMD_CREATION_DATE,
-    CMD_HASHING,
-    CMD_LABEL,
+const RTORRENT_FIELDS: &[RtorrentField] = &[
+    RtorrentField::Hash,
+    RtorrentField::Name,
+    RtorrentField::Size,
+    RtorrentField::Completed,
+    RtorrentField::DownRate,
+    RtorrentField::UpRate,
+    RtorrentField::State,
+    RtorrentField::Complete,
+    RtorrentField::Message,
+    RtorrentField::LeftBytes,
+    RtorrentField::CreationDate,
+    RtorrentField::Hashing,
+    RtorrentField::Label,
 ];
 
-fn parse_long(s: Option<&String>) -> i64 {
-    s.map(|v| v.parse().unwrap_or(0)).unwrap_or(0)
+fn get_field_value(row: &Vec<String>, field: RtorrentField) -> String {
+    let idx = RTORRENT_FIELDS.iter().position(|&f| f == field).unwrap_or(0);
+    row.get(idx).cloned().unwrap_or_default()
 }
 
-fn parse_string(s: Option<&String>) -> String {
-    s.cloned().unwrap_or_default()
+fn parse_long(s: &str) -> i64 {
+    s.parse().unwrap_or(0)
 }
 
 /// Converts a raw row of strings from rTorrent XML-RPC into a generic Torrent struct
-fn from_rtorrent_row(row: Vec<String>) -> Torrent {
-    let hash = parse_string(row.get(IDX_HASH));
-    let name = parse_string(row.get(IDX_NAME));
-    let size = parse_long(row.get(IDX_SIZE));
-    let completed = parse_long(row.get(IDX_COMPLETED));
-    let down_rate = parse_long(row.get(IDX_DOWN_RATE));
-    let up_rate = parse_long(row.get(IDX_UP_RATE));
+fn from_rtorrent_row(row: &Vec<String>) -> Torrent {
+    let hash = get_field_value(row, RtorrentField::Hash);
+    let name = get_field_value(row, RtorrentField::Name);
+    let size = parse_long(&get_field_value(row, RtorrentField::Size));
+    let completed = parse_long(&get_field_value(row, RtorrentField::Completed));
+    let down_rate = parse_long(&get_field_value(row, RtorrentField::DownRate));
+    let up_rate = parse_long(&get_field_value(row, RtorrentField::UpRate));
 
-    let state = parse_long(row.get(IDX_STATE));
-    let is_complete = parse_long(row.get(IDX_COMPLETE));
-    let message = parse_string(row.get(IDX_MESSAGE));
-    let left_bytes = parse_long(row.get(IDX_LEFT_BYTES));
-    let added_date = parse_long(row.get(IDX_CREATION_DATE));
-    let is_hashing = parse_long(row.get(IDX_HASHING));
-    let label_raw = parse_string(row.get(IDX_LABEL));
+    let state = parse_long(&get_field_value(row, RtorrentField::State));
+    let is_complete = parse_long(&get_field_value(row, RtorrentField::Complete));
+    let message = get_field_value(row, RtorrentField::Message);
+    let left_bytes = parse_long(&get_field_value(row, RtorrentField::LeftBytes));
+    let added_date = parse_long(&get_field_value(row, RtorrentField::CreationDate));
+    let is_hashing = parse_long(&get_field_value(row, RtorrentField::Hashing));
+    let label_raw = get_field_value(row, RtorrentField::Label);
 
     let label = if label_raw.is_empty() {
         None
@@ -146,7 +131,10 @@ fn from_rtorrent_row(row: Vec<String>) -> Torrent {
 }
 
 pub async fn fetch_torrents(client: &RtorrentClient) -> Result<Vec<Torrent>, XmlRpcError> {
-    let params: Vec<RpcParam> = RTORRENT_FIELDS.iter().map(|s| RpcParam::from(*s)).collect();
+    let params: Vec<RpcParam> = RTORRENT_FIELDS
+        .iter()
+        .map(|&f| RpcParam::from(f.to_string()))
+        .collect();
     let xml = client.call("d.multicall2", &params).await?;
 
     if xml.trim().is_empty() {
@@ -155,7 +143,7 @@ pub async fn fetch_torrents(client: &RtorrentClient) -> Result<Vec<Torrent>, Xml
 
     let rows = parse_multicall_response(&xml)?;
 
-    let torrents = rows.into_iter().map(from_rtorrent_row).collect();
+    let torrents = rows.iter().map(from_rtorrent_row).collect();
 
     Ok(torrents)
 }