Separated fetch

src/engine/engine.rs

@@ -1,8 +1,3 @@
-use std::collections::HashMap;
-
-use pulse_wire::terminal::WatchListItem;
-use serde_json::Value;
-
 use crate::terminal::TerminalServer;
 
 const WATCH_LIST_SYMBOLS: &[&str] = &["BTC", "ETH", "SOL", "XRP"];
@@ -38,7 +33,7 @@ impl Engine {
             loop {
                 refresh.tick().await;
 
-                match fetch_watch_list(WATCH_LIST_SYMBOLS).await {
+                match crate::fetch::fetch_watch_list(WATCH_LIST_SYMBOLS).await {
                     Ok(watch_list) => {
                         if let Err(error) = terminal_server
                             .broadcast(
@@ -63,83 +58,3 @@ impl Engine {
         }
     }
 }
-
-async fn fetch_watch_list(symbols: &[&str]) -> Result<Vec<WatchListItem>, String> {
-    let response = hypersdk::hypercore::mainnet()
-        .meta_and_asset_ctxs(None)
-        .await
-        .map_err(|error| format!("Hyperliquid metaAndAssetCtxs request failed: {error}"))?;
-
-    normalize_watch_list(&response, symbols)
-}
-
-fn normalize_watch_list(response: &Value, symbols: &[&str]) -> Result<Vec<WatchListItem>, String> {
-    let response = response
-        .as_array()
-        .ok_or("metaAndAssetCtxs response must be an array")?;
-
-    if response.len() != 2 {
-        return Err(format!(
-            "metaAndAssetCtxs response must contain meta and contexts, got {} entries",
-            response.len()
-        ));
-    }
-
-    let universe = response[0]["universe"]
-        .as_array()
-        .ok_or("metaAndAssetCtxs response is missing meta.universe")?;
-    let contexts = response[1]
-        .as_array()
-        .ok_or("metaAndAssetCtxs response contexts must be an array")?;
-
-    if universe.len() != contexts.len() {
-        return Err(format!(
-            "Hyperliquid returned {} instruments but {} contexts",
-            universe.len(),
-            contexts.len()
-        ));
-    }
-
-    let mut by_symbol = HashMap::with_capacity(universe.len());
-
-    for (meta, context) in universe.iter().zip(contexts) {
-        let symbol = meta["name"]
-            .as_str()
-            .ok_or("instrument metadata is missing a name")?;
-        let price = number(context, "markPx")?;
-        let previous_day_price = number(context, "prevDayPx")?;
-        let volume_24h = number(context, "dayNtlVlm")?;
-
-        if previous_day_price <= 0.0 {
-            return Err(format!("{symbol} has an invalid previous-day price"));
-        }
-
-        by_symbol.insert(
-            symbol,
-            WatchListItem {
-                symbol: symbol.to_owned(),
-                price,
-                trend: ((price / previous_day_price) - 1.0) * 100.0,
-                volume_24h,
-            },
-        );
-    }
-
-    symbols
-        .iter()
-        .map(|symbol| {
-            by_symbol
-                .remove(*symbol)
-                .ok_or_else(|| format!("{symbol} is not in the Hyperliquid perpetual universe"))
-        })
-        .collect()
-}
-
-fn number(value: &Value, field: &str) -> Result<f64, String> {
-    let raw = value[field]
-        .as_str()
-        .ok_or_else(|| format!("asset context field {field} must be a string"))?;
-
-    raw.parse::<f64>()
-        .map_err(|error| format!("could not parse asset context field {field} ({raw}): {error}"))
-}

src/engine/fetch.rs

@@ -0,0 +1,80 @@
+use std::collections::HashMap;
+
+use pulse_wire::terminal::WatchListItem;
+use serde_json::Value;
+
+fn number(value: &Value, field: &str) -> Result<f64, String> {
+    let raw = value[field]
+        .as_str()
+        .ok_or_else(|| format!("asset context field {field} must be a string"))?;
+
+    raw.parse::<f64>()
+        .map_err(|error| format!("could not parse asset context field {field} ({raw}): {error}"))
+}
+
+pub async fn fetch_watch_list(symbols: &[&str]) -> Result<Vec<WatchListItem>, String> {
+    let response = hypersdk::hypercore::mainnet()
+        .meta_and_asset_ctxs(None)
+        .await
+        .map_err(|error| format!("Hyperliquid metaAndAssetCtxs request failed: {error}"))?;
+
+    let response = response
+        .as_array()
+        .ok_or("metaAndAssetCtxs response must be an array")?;
+
+    if response.len() != 2 {
+        return Err(format!(
+            "metaAndAssetCtxs response must contain meta and contexts, got {} entries",
+            response.len()
+        ));
+    }
+
+    let universe = response[0]["universe"]
+        .as_array()
+        .ok_or("metaAndAssetCtxs response is missing meta.universe")?;
+    let contexts = response[1]
+        .as_array()
+        .ok_or("metaAndAssetCtxs response contexts must be an array")?;
+
+    if universe.len() != contexts.len() {
+        return Err(format!(
+            "Hyperliquid returned {} instruments but {} contexts",
+            universe.len(),
+            contexts.len()
+        ));
+    }
+
+    let mut by_symbol = HashMap::with_capacity(universe.len());
+
+    for (meta, context) in universe.iter().zip(contexts) {
+        let symbol = meta["name"]
+            .as_str()
+            .ok_or("instrument metadata is missing a name")?;
+        let price = number(context, "markPx")?;
+        let previous_day_price = number(context, "prevDayPx")?;
+        let volume_24h = number(context, "dayNtlVlm")?;
+
+        if previous_day_price <= 0.0 {
+            return Err(format!("{symbol} has an invalid previous-day price"));
+        }
+
+        by_symbol.insert(
+            symbol,
+            WatchListItem {
+                symbol: symbol.to_owned(),
+                price,
+                trend: ((price / previous_day_price) - 1.0) * 100.0,
+                volume_24h,
+            },
+        );
+    }
+
+    symbols
+        .iter()
+        .map(|symbol| {
+            by_symbol
+                .remove(*symbol)
+                .ok_or_else(|| format!("{symbol} is not in the Hyperliquid perpetual universe"))
+        })
+        .collect()
+}

src/engine/main.rs

@@ -1,4 +1,5 @@
 pub mod engine;
+pub mod fetch;
 pub mod terminal;
 
 #[tokio::main]