Extract generic useListData hook for shared list fetching

Docs/Tasks.md

@@ -304,7 +304,9 @@ Issues are grouped by category and ordered roughly by severity. Each entry descr
 
 ---
 
-### TASK-016 — Extract generic `useListData` hook to eliminate duplicated fetch-list pattern
+### TASK-016 — Extract generic `useListData` hook to eliminate duplicated fetch-list pattern (done)
+
+**Where fixed:** `frontend/src/hooks/useListData.ts`, `frontend/src/hooks/useActionList.ts`, `frontend/src/hooks/useFilterList.ts`, `frontend/src/hooks/useJailConfigs.ts`, `frontend/src/hooks/useBlocklists.ts`, `frontend/src/api/config.ts`, `frontend/src/api/blocklist.ts`, `frontend/src/hooks/__tests__/useListData.test.ts`
 
 **Where found:** `frontend/src/hooks/useActionList.ts`, `useFilterList.ts`, `useJailConfigs.ts`, and `useBlocklists.ts` each contain ~40 lines of nearly identical code: `useState` for data/loading/error, a `useRef<AbortController>`, a `refresh` callback with abort-create-set-loading-fetch-set logic, and a `useEffect` that calls `refresh` on mount.
 

frontend/src/api/blocklist.ts

@@ -21,8 +21,8 @@ import type {
 // ---------------------------------------------------------------------------
 
 /** Fetch all configured blocklist sources. */
-export async function fetchBlocklists(): Promise<BlocklistListResponse> {
-  return get<BlocklistListResponse>(ENDPOINTS.blocklists);
+export async function fetchBlocklists(signal?: AbortSignal): Promise<BlocklistListResponse> {
+  return get<BlocklistListResponse>(ENDPOINTS.blocklists, signal);
 }
 
 /** Create a new blocklist source. */

frontend/src/api/config.ts

@@ -51,8 +51,9 @@ import type {
 // ---------------------------------------------------------------------------
 
 export async function fetchJailConfigs(
+signal?: AbortSignal,
 ): Promise<JailConfigListResponse> {
-  return get<JailConfigListResponse>(ENDPOINTS.configJails);
+  return get<JailConfigListResponse>(ENDPOINTS.configJails, signal);
 }
 
 export async function fetchJailConfig(
@@ -344,8 +345,8 @@ export async function assignFilterToJail(
  *
  * @returns FilterListResponse with all discovered filters and status.
  */
-export async function fetchFilters(): Promise<FilterListResponse> {
-  return get<FilterListResponse>(ENDPOINTS.configFilters);
+export async function fetchFilters(signal?: AbortSignal): Promise<FilterListResponse> {
+  return get<FilterListResponse>(ENDPOINTS.configFilters, signal);
 }
 
 /**
@@ -385,8 +386,8 @@ export async function updateParsedAction(
  *
  * @returns ActionListResponse with all discovered actions and status.
  */
-export async function fetchActions(): Promise<ActionListResponse> {
-  return get<ActionListResponse>(ENDPOINTS.configActions);
+export async function fetchActions(signal?: AbortSignal): Promise<ActionListResponse> {
+  return get<ActionListResponse>(ENDPOINTS.configActions, signal);
 }
 
 /**

frontend/src/hooks/__tests__/useListData.test.ts

@@ -0,0 +1,79 @@
+import { describe, it, expect, vi } from "vitest";
+import { renderHook, act } from "@testing-library/react";
+import { useListData } from "../useListData";
+
+describe("useListData", () => {
+  it("loads items and updates loading", async () => {
+    const fetcher = vi.fn().mockResolvedValue({ items: ["one", "two"] });
+    const selector = vi.fn((response: { items: string[] }) => response.items);
+
+    const { result } = renderHook(() =>
+      useListData({
+        fetcher,
+        selector,
+        errorMessage: "Failed to load",
+      })
+    );
+
+    expect(result.current.loading).toBe(true);
+    expect(result.current.items).toEqual([]);
+
+    await act(async () => {
+      await Promise.resolve();
+    });
+
+    expect(fetcher).toHaveBeenCalledTimes(1);
+    expect(selector).toHaveBeenCalledWith({ items: ["one", "two"] });
+    expect(result.current.items).toEqual(["one", "two"]);
+    expect(result.current.loading).toBe(false);
+  });
+
+  it("sets error when the fetcher rejects", async () => {
+    const fetcher = vi.fn().mockRejectedValue(new Error("network"));
+    const selector = vi.fn();
+
+    const { result } = renderHook(() =>
+      useListData({
+        fetcher,
+        selector,
+        errorMessage: "Failed to load",
+      })
+    );
+
+    await act(async () => {
+      await Promise.resolve();
+    });
+
+    expect(result.current.error).toBe("network");
+    expect(result.current.loading).toBe(false);
+    expect(result.current.items).toEqual([]);
+  });
+
+  it("refresh triggers a second fetch", async () => {
+    const fetcher = vi.fn()
+      .mockResolvedValueOnce({ items: ["first"] })
+      .mockResolvedValueOnce({ items: ["second"] });
+    const selector = vi.fn((response: { items: string[] }) => response.items);
+
+    const { result } = renderHook(() =>
+      useListData({
+        fetcher,
+        selector,
+        errorMessage: "Failed to load",
+      })
+    );
+
+    await act(async () => {
+      await Promise.resolve();
+    });
+
+    expect(result.current.items).toEqual(["first"]);
+    await act(async () => {
+      result.current.refresh();
+      await Promise.resolve();
+    });
+
+    expect(fetcher).toHaveBeenCalledTimes(2);
+    expect(result.current.items).toEqual(["second"]);
+  });
+});

frontend/src/hooks/useActionList.ts

@@ -1,10 +1,10 @@
 /**
  * React hook for loading action metadata used by the actions tab.
  */
-import { useCallback, useEffect, useRef, useState } from "react";
+import { useCallback } from "react";
 import { fetchActions, removeActionFromJail, createAction, assignActionToJail } from "../api/config";
-import { handleFetchError } from "../utils/fetchError";
-import type { ActionConfig, ActionCreateRequest } from "../types/config";
+import { useListData } from "./useListData";
+import type { ActionConfig, ActionCreateRequest, ActionListResponse } from "../types/config";
 
 export interface UseActionListResult {
   actions: ActionConfig[];
@@ -20,43 +20,18 @@ export interface UseActionListResult {
  * Load the action inventory and expose related action operations.
  */
 export function useActionList(): UseActionListResult {
-  const [actions, setActions] = useState<ActionConfig[]>([]);
-  const [loading, setLoading] = useState(true);
-  const [error, setError] = useState<string | null>(null);
-  const abortRef = useRef<AbortController | null>(null);
+  const fetcher = useCallback(
+    (signal: AbortSignal) => fetchActions(signal),
+    [],
+  );
 
-  const refresh = useCallback((): void => {
-    abortRef.current?.abort();
-    const controller = new AbortController();
-    abortRef.current = controller;
+  const selector = useCallback((response: ActionListResponse) => response.actions, []);
 
-    setLoading(true);
-    setError(null);
-
-    fetchActions()
-      .then((resp) => {
-        if (!controller.signal.aborted) {
-          setActions(resp.actions);
-        }
-      })
-      .catch((err: unknown) => {
-        if (!controller.signal.aborted) {
-          handleFetchError(err, setError, "Failed to load actions");
-        }
-      })
-      .finally(() => {
-        if (!controller.signal.aborted) {
-          setLoading(false);
-        }
-      });
-  }, []);
-
-  useEffect(() => {
-    refresh();
-    return (): void => {
-      abortRef.current?.abort();
-    };
-  }, [refresh]);
+  const { items: actions, loading, error, refresh } = useListData<ActionListResponse, ActionConfig>({
+    fetcher,
+    selector,
+    errorMessage: "Failed to load actions",
+  });
 
   const handleRemoveActionFromJail = useCallback(
     async (jailName: string, actionName: string): Promise<void> => {

frontend/src/hooks/useBlocklists.ts

@@ -2,7 +2,7 @@
  * React hook for listing and mutating blocklist sources.
  */
 
-import { useCallback, useEffect, useRef, useState } from "react";
+import { useCallback } from "react";
 import {
   createBlocklist,
   deleteBlocklist,
@@ -10,11 +10,12 @@ import {
   previewBlocklist,
   updateBlocklist,
 } from "../api/blocklist";
-import { handleFetchError } from "../utils/fetchError";
+import { useListData } from "./useListData";
 import type {
   BlocklistSource,
   BlocklistSourceCreate,
   BlocklistSourceUpdate,
+  BlocklistListResponse,
   PreviewResponse,
 } from "../types/blocklist";
 
@@ -33,63 +34,44 @@ export interface UseBlocklistsReturn {
  * Load all blocklist sources and expose CRUD operations.
  */
 export function useBlocklists(): UseBlocklistsReturn {
-  const [sources, setSources] = useState<BlocklistSource[]>([]);
-  const [loading, setLoading] = useState(true);
-  const [error, setError] = useState<string | null>(null);
-  const abortRef = useRef<AbortController | null>(null);
+  const fetcher = useCallback(
+    (signal: AbortSignal) => fetchBlocklists(signal),
+    [],
+  );
 
-  const load = useCallback((): void => {
-    abortRef.current?.abort();
-    const ctrl = new AbortController();
-    abortRef.current = ctrl;
+  const selector = useCallback((response: BlocklistListResponse) => response.sources, []);
 
-    setLoading(true);
-    setError(null);
-
-    fetchBlocklists()
-      .then((data) => {
-        if (!ctrl.signal.aborted) {
-          setSources(data.sources);
-          setLoading(false);
-        }
-      })
-      .catch((err: unknown) => {
-        if (!ctrl.signal.aborted) {
-          handleFetchError(err, setError, "Failed to load blocklists");
-          setLoading(false);
-        }
-      });
-  }, []);
-
-  useEffect(() => {
-    load();
-    return (): void => {
-      abortRef.current?.abort();
-    };
-  }, [load]);
+  const { items: sources, loading, error, refresh } = useListData<BlocklistListResponse, BlocklistSource>({
+    fetcher,
+    selector,
+    errorMessage: "Failed to load blocklists",
+  });
 
   const createSource = useCallback(
     async (payload: BlocklistSourceCreate): Promise<BlocklistSource> => {
       const created = await createBlocklist(payload);
-      setSources((prev) => [...prev, created]);
+      refresh();
       return created;
     },
-    [],
+    [refresh],
   );
 
   const updateSource = useCallback(
     async (id: number, payload: BlocklistSourceUpdate): Promise<BlocklistSource> => {
       const updated = await updateBlocklist(id, payload);
-      setSources((prev) => prev.map((s) => (s.id === id ? updated : s)));
+      refresh();
       return updated;
     },
-    [],
+    [refresh],
   );
 
-  const removeSource = useCallback(async (id: number): Promise<void> => {
-    await deleteBlocklist(id);
-    setSources((prev) => prev.filter((s) => s.id !== id));
-  }, []);
+  const removeSource = useCallback(
+    async (id: number): Promise<void> => {
+      await deleteBlocklist(id);
+      refresh();
+    },
+    [refresh],
+  );
 
   const previewSource = useCallback(async (id: number): Promise<PreviewResponse> => {
     return previewBlocklist(id);
@@ -99,7 +81,7 @@ export function useBlocklists(): UseBlocklistsReturn {
     sources,
     loading,
     error,
-    refresh: load,
+    refresh,
     createSource,
     updateSource,
     removeSource,

frontend/src/hooks/useFilterList.ts

@@ -1,10 +1,10 @@
 /**
  * React hook for loading filter config metadata used by the filter tab.
  */
-import { useCallback, useEffect, useRef, useState } from "react";
+import { useCallback } from "react";
 import { fetchFilters, createFilter, assignFilterToJail } from "../api/config";
-import { handleFetchError } from "../utils/fetchError";
-import type { FilterConfig, FilterCreateRequest } from "../types/config";
+import { useListData } from "./useListData";
+import type { FilterConfig, FilterCreateRequest, FilterListResponse } from "../types/config";
 
 export interface UseFilterListResult {
   filters: FilterConfig[];
@@ -19,43 +19,18 @@ export interface UseFilterListResult {
  * Load the filter inventory and expose refresh semantics.
  */
 export function useFilterList(): UseFilterListResult {
-  const [filters, setFilters] = useState<FilterConfig[]>([]);
-  const [loading, setLoading] = useState(true);
-  const [error, setError] = useState<string | null>(null);
-  const abortRef = useRef<AbortController | null>(null);
+  const fetcher = useCallback(
+    (signal: AbortSignal) => fetchFilters(signal),
+    [],
+  );
 
-  const refresh = useCallback((): void => {
-    abortRef.current?.abort();
-    const controller = new AbortController();
-    abortRef.current = controller;
+  const selector = useCallback((response: FilterListResponse) => response.filters, []);
 
-    setLoading(true);
-    setError(null);
-
-    fetchFilters()
-      .then((resp) => {
-        if (!controller.signal.aborted) {
-          setFilters(resp.filters);
-        }
-      })
-      .catch((err: unknown) => {
-        if (!controller.signal.aborted) {
-          handleFetchError(err, setError, "Failed to load filters");
-        }
-      })
-      .finally(() => {
-        if (!controller.signal.aborted) {
-          setLoading(false);
-        }
-      });
-  }, []);
-
-  useEffect(() => {
-    refresh();
-    return (): void => {
-      abortRef.current?.abort();
-    };
-  }, [refresh]);
+  const { items: filters, loading, error, refresh } = useListData<FilterListResponse, FilterConfig>({
+    fetcher,
+    selector,
+    errorMessage: "Failed to load filters",
+  });
 
   const handleCreateFilter = useCallback(
     async (payload: FilterCreateRequest): Promise<FilterConfig> => {

frontend/src/hooks/useJailConfigs.ts

@@ -2,10 +2,10 @@
  * React hook for loading the jail config inventory.
  */
 
-import { useCallback, useEffect, useRef, useState } from "react";
+import { useCallback, useState } from "react";
 import { fetchJailConfigs, reloadConfig, updateJailConfig } from "../api/config";
-import { handleFetchError } from "../utils/fetchError";
-import type { JailConfig, JailConfigUpdate } from "../types/config";
+import { useListData } from "./useListData";
+import type { JailConfig, JailConfigUpdate, JailConfigListResponse } from "../types/config";
 
 export interface UseJailConfigsResult {
   jails: JailConfig[];
@@ -21,57 +21,36 @@ export interface UseJailConfigsResult {
  * Load all jail configs and expose update controls.
  */
 export function useJailConfigs(): UseJailConfigsResult {
-  const [jails, setJails] = useState<JailConfig[]>([]);
   const [total, setTotal] = useState(0);
-  const [loading, setLoading] = useState(true);
-  const [error, setError] = useState<string | null>(null);
-  const abortRef = useRef<AbortController | null>(null);
 
-  const load = useCallback((): void => {
-    abortRef.current?.abort();
-    const ctrl = new AbortController();
-    abortRef.current = ctrl;
-    setLoading(true);
-    setError(null);
+  const fetcher = useCallback(
+    (signal: AbortSignal) => fetchJailConfigs(signal),
+    [],
+  );
 
-    fetchJailConfigs()
-      .then((resp) => {
-        if (!ctrl.signal.aborted) {
-          setJails(resp.jails);
-          setTotal(resp.total);
-        }
-      })
-      .catch((err: unknown) => {
-        if (!ctrl.signal.aborted) {
-          handleFetchError(err, setError, "Failed to fetch jail configs");
-        }
-      })
-      .finally(() => {
-        if (!abortRef.current?.signal.aborted) {
-          setLoading(false);
-        }
-      });
-  }, []);
+  const selector = useCallback((response: JailConfigListResponse) => response.jails, []);
 
-  useEffect(() => {
-    load();
-    return (): void => {
-      abortRef.current?.abort();
-    };
-  }, [load]);
+  const { items: jails, loading, error, refresh } = useListData<JailConfigListResponse, JailConfig>({
+    fetcher,
+    selector,
+    errorMessage: "Failed to fetch jail configs",
+    onSuccess: (response) => {
+      setTotal(response.total);
+    },
+  });
 
   const updateJail = useCallback(
     async (name: string, update: JailConfigUpdate): Promise<void> => {
       await updateJailConfig(name, update);
-      load();
+      refresh();
     },
-    [load],
+    [refresh],
   );
 
   const reloadAll = useCallback(async (): Promise<void> => {
     await reloadConfig();
-    load();
-  }, [load]);
+    refresh();
+  }, [refresh]);
 
-  return { jails, total, loading, error, refresh: load, updateJail, reloadAll };
+  return { jails, total, loading, error, refresh, updateJail, reloadAll };
 }

frontend/src/hooks/useListData.ts

@@ -0,0 +1,70 @@
+/**
+ * Generic hook for loading list data from an API endpoint.
+ */
+import { useCallback, useEffect, useRef, useState } from "react";
+import { handleFetchError } from "../utils/fetchError";
+
+export interface UseListDataOptions<TResponse, TItem> {
+  fetcher: (signal: AbortSignal) => Promise<TResponse>;
+  selector: (response: TResponse) => TItem[];
+  errorMessage: string;
+  onSuccess?: (response: TResponse) => void;
+  initialItems?: TItem[];
+}
+
+export interface UseListDataResult<TItem> {
+  items: TItem[];
+  loading: boolean;
+  error: string | null;
+  refresh: () => void;
+}
+
+/**
+ * Load a list response and expose refresh semantics with abort support.
+ */
+export function useListData<TResponse, TItem>(
+  options: UseListDataOptions<TResponse, TItem>,
+): UseListDataResult<TItem> {
+  const { fetcher, selector, errorMessage, onSuccess, initialItems } = options;
+  const [items, setItems] = useState<TItem[]>(initialItems ?? []);
+  const [loading, setLoading] = useState(true);
+  const [error, setError] = useState<string | null>(null);
+  const abortRef = useRef<AbortController | null>(null);
+
+  const refresh = useCallback((): void => {
+    abortRef.current?.abort();
+    const controller = new AbortController();
+    abortRef.current = controller;
+
+    setLoading(true);
+    setError(null);
+
+    fetcher(controller.signal)
+      .then((response) => {
+        if (controller.signal.aborted) return;
+        setItems(selector(response));
+        if (onSuccess) {
+          onSuccess(response);
+        }
+      })
+      .catch((err: unknown) => {
+        if (controller.signal.aborted) return;
+        handleFetchError(err, setError, errorMessage);
+      })
+      .finally(() => {
+        if (!controller.signal.aborted) {
+          setLoading(false);
+        }
+      });
+  }, [fetcher, selector, errorMessage, onSuccess]);
+
+  useEffect(() => {
+    refresh();
+
+    return (): void => {
+      abortRef.current?.abort();
+    };
+  }, [refresh]);
+
+  return { items, loading, error, refresh };
+}