MAESTRO: integrate browser cache UI

frontend/src/app/page.tsx

@@ -1,15 +1,18 @@
 "use client";
 
-import { useCallback, useState } from "react";
+import { useCallback, useEffect, useMemo, useRef, useState } from "react";
+import { FontAwesomeIcon } from "@fortawesome/react-fontawesome";
+import { faTrash } from "@fortawesome/free-solid-svg-icons";
 
 import AnalyseButton from "../components/AnalyseButton";
-import AnalysisResults from "../components/AnalysisResults";
 import FileDropZone from "../components/FileDropZone";
 import HeaderInput from "../components/HeaderInput";
 import ProgressIndicator from "../components/ProgressIndicator";
+import ReportContainer from "../components/report/ReportContainer";
 import useAnalysis from "../hooks/useAnalysis";
+import useAnalysisCache from "../hooks/useAnalysisCache";
 import { MAX_HEADER_INPUT_BYTES } from "../lib/header-validation";
-import type { AnalysisConfig } from "../types/analysis";
+import type { AnalysisConfig, AnalysisReport } from "../types/analysis";
 
 const defaultConfig: AnalysisConfig = {
   testIds: [],
@@ -18,22 +21,78 @@ const defaultConfig: AnalysisConfig = {
 };
 
 export default function Home() {
-  const [headerInput, setHeaderInput] = useState("");
-  const { status, progress, result, submit } = useAnalysis();
+  const { status, progress, result, submit, cancel } = useAnalysis();
+  const { save, load, clear, isNearLimit } = useAnalysisCache();
+  const initialCache = useMemo(() => load(), [load]);
+  const [headerInput, setHeaderInput] = useState(() => initialCache?.headers ?? "");
+  const [analysisConfig, setAnalysisConfig] = useState<AnalysisConfig>(
+    () => initialCache?.config ?? defaultConfig,
+  );
+  const [cachedReport, setCachedReport] = useState<AnalysisReport | null>(
+    () => initialCache?.result ?? null,
+  );
+  const [cachedTimestamp, setCachedTimestamp] = useState<number | null>(
+    () => initialCache?.timestamp ?? null,
+  );
+  const [isViewCleared, setIsViewCleared] = useState(false);
+  const lastSubmissionRef = useRef<{ headers: string; config: AnalysisConfig } | null>(null);
+
+  useEffect(() => {
+    if (!result) {
+      return;
+    }
+
+    const payload = lastSubmissionRef.current ?? {
+      headers: headerInput,
+      config: analysisConfig,
+    };
+
+    save({ headers: payload.headers, config: payload.config, result });
+  }, [analysisConfig, headerInput, result, save]);
+
   const hasHeaderInput = headerInput.trim().length > 0;
   const isOversized = headerInput.length > MAX_HEADER_INPUT_BYTES;
   const canAnalyse = hasHeaderInput && !isOversized;
   const isLoading = status === "submitting" || status === "analysing";
   const showProgress = status === "analysing" || status === "timeout";
   const incompleteTests = result?.metadata.incompleteTests ?? [];
+  const allowCachedFallback =
+    status === "idle" || status === "complete" || status === "error" || status === "timeout";
+  const report = isViewCleared ? null : (result ?? (allowCachedFallback ? cachedReport : null));
+  const isCachedView = Boolean(!isViewCleared && !result && allowCachedFallback && cachedReport);
+  const hasCache = Boolean(result || cachedReport);
+  const cacheTimestampLabel = useMemo(() => {
+    if (!cachedTimestamp) {
+      return null;
+    }
+
+    return new Date(cachedTimestamp).toLocaleString("en-US", {
+      dateStyle: "medium",
+      timeStyle: "short",
+    });
+  }, [cachedTimestamp]);
 
   const handleAnalyse = useCallback(() => {
     if (!canAnalyse) {
       return;
     }
 
-    void submit({ headers: headerInput, config: defaultConfig });
-  }, [canAnalyse, headerInput, submit]);
+    const payload = { headers: headerInput, config: analysisConfig };
+    lastSubmissionRef.current = payload;
+    setIsViewCleared(false);
+    void submit(payload);
+  }, [analysisConfig, canAnalyse, headerInput, submit]);
+
+  const handleClearCache = useCallback(() => {
+    clear();
+    cancel();
+    setHeaderInput("");
+    setAnalysisConfig(defaultConfig);
+    setCachedReport(null);
+    setCachedTimestamp(null);
+    setIsViewCleared(true);
+    lastSubmissionRef.current = null;
+  }, [cancel, clear]);
 
   return (
     <main className="min-h-screen bg-background text-text">
@@ -90,10 +149,53 @@ export default function Home() {
                   incompleteTests={incompleteTests}
                 />
               ) : null}
+
+              <div className="rounded-2xl border border-info/10 bg-surface p-5">
+                <div className="flex flex-wrap items-center justify-between gap-3">
+                  <p className="text-xs uppercase tracking-[0.2em] text-info/80">Browser Cache</p>
+                  <button
+                    type="button"
+                    className="inline-flex items-center gap-2 rounded-full border border-info/20 bg-background/40 px-4 py-2 text-[11px] font-semibold uppercase tracking-[0.2em] text-text/70 transition hover:border-info/40 hover:text-text focus-visible:outline focus-visible:outline-2 focus-visible:outline-offset-2 focus-visible:outline-info disabled:cursor-not-allowed disabled:opacity-50"
+                    onClick={handleClearCache}
+                    disabled={!hasCache}
+                  >
+                    <FontAwesomeIcon icon={faTrash} className="text-xs" />
+                    Clear Cache
+                  </button>
+                </div>
+                <p className="mt-2 text-xs text-text/60">
+                  {result
+                    ? "Latest analysis cached for this session."
+                    : hasCache
+                      ? `Cached analysis saved ${cacheTimestampLabel ?? "recently"}.`
+                      : "No cached analysis yet. Run an analysis to save this session."}
+                </p>
+                {isNearLimit ? (
+                  <p className="mt-2 text-xs text-suspicious">
+                    Local storage is nearly full. Consider clearing cached data.
+                  </p>
+                ) : null}
+              </div>
             </div>
           </section>
 
-          {result ? <AnalysisResults report={result} /> : null}
+          {report ? (
+            <section className="flex flex-col gap-3">
+              {isCachedView ? (
+                <div className="flex flex-wrap items-center gap-2 text-[11px] text-text/60">
+                  <span className="rounded-full border border-info/20 bg-background/40 px-3 py-1 uppercase tracking-[0.2em] text-info/70">
+                    Cached Result
+                  </span>
+                  {cacheTimestampLabel ? (
+                    <span>Saved {cacheTimestampLabel}</span>
+                  ) : (
+                    <span>Saved recently</span>
+                  )}
+                </div>
+              ) : null}
+              <ReportContainer report={report} />
+            </section>
+          ) : null}
         </div>
       </div>
     </main>