Add logging with filters

src/components/Logging/useLogs.ts

@@ -0,0 +1,146 @@
+import {useCallback, useEffect, useRef, useState} from "react";
+
+import {applyPriorityPredicates, type PriorityFilterPredicate} from "../../utils/priorityFiltering.ts";
+import {cell, type Cell} from "../../utils/cellStore.ts";
+
+export type LogRecord = {
+  name: string;
+  message: string;
+  levelname: 'DEBUG' | 'INFO' | 'WARNING' | 'ERROR' | 'CRITICAL' | string;
+  levelno: number;
+  created: number;
+  relativeCreated: number;
+  reference?: string;
+  firstCreated: number;
+  firstRelativeCreated: number;
+};
+
+// eslint-disable-next-line @typescript-eslint/no-explicit-any
+export type LogFilterPredicate = PriorityFilterPredicate<LogRecord> & { value: any };
+
+export function useLogs(filterPredicates: Map<string, LogFilterPredicate>) {
+  const [distinctNames, setDistinctNames] = useState<Set<string>>(new Set());
+  const [filtered, setFiltered] = useState<Cell<LogRecord>[]>([]);
+
+  const sseRef = useRef<EventSource | null>(null);
+  const filtersRef = useRef(filterPredicates);
+  const logsRef = useRef<LogRecord[]>([]);
+
+  /** Map to store the first message for each reference, instance can be updated to change contents. */
+  const firstByRefRef = useRef<Map<string, Cell<LogRecord>>>(new Map());
+
+  /**
+   * Apply the filter predicates to a log record.
+   * @param log The log record to apply the filters to.
+   * @returns `true` if the record passes.
+   */
+  const applyFilters = useCallback((log: LogRecord) =>
+    applyPriorityPredicates(log, [...filtersRef.current.values()]), []);
+
+  /** Recomputes the entire filtered list. Use when filter predicates change. */
+  const recomputeFiltered = useCallback(() => {
+    const newFiltered: Cell<LogRecord>[] = [];
+    firstByRefRef.current = new Map();
+
+    for (const message of logsRef.current) {
+      const messageCell = cell<LogRecord>({
+        ...message,
+        firstCreated: message.created,
+        firstRelativeCreated: message.relativeCreated,
+      });
+
+      if (message.reference) {
+        const first = firstByRefRef.current.get(message.reference);
+        if (first) {
+          // Update the first's contents
+          first.set((prev) => ({
+            ...message,
+            firstCreated: prev.firstCreated ?? prev.created,
+            firstRelativeCreated: prev.firstRelativeCreated ?? prev.relativeCreated,
+          }));
+
+          // Don't add it to the list again
+          continue;
+        } else {
+          // Add the first message with this reference to the registry
+          firstByRefRef.current.set(message.reference, messageCell);
+        }
+      }
+
+      if (applyFilters(message)) {
+        newFiltered.push(messageCell);
+      }
+    }
+
+    setFiltered(newFiltered);
+  }, [applyFilters, setFiltered]);
+
+  // Reapply filters to all logs, only when filters change
+  useEffect(() => {
+    filtersRef.current = filterPredicates;
+    recomputeFiltered();
+  }, [filterPredicates, recomputeFiltered]);
+
+  /**
+   * Handle a new log message. Updates the filtered list and to the full history.
+   * @param message The new log message.
+   */
+  const handleNewMessage = useCallback((message: LogRecord) => {
+    // Add to the full history for re-filtering on filter changes
+    logsRef.current.push(message);
+
+    setDistinctNames((prev) => {
+      if (prev.has(message.name)) return prev;
+      const newSet = new Set(prev);
+      newSet.add(message.name);
+      return newSet;
+    });
+
+    const messageCell = cell<LogRecord>({
+      ...message,
+      firstCreated: message.created,
+      firstRelativeCreated: message.relativeCreated,
+    });
+
+    if (message.reference) {
+      const first = firstByRefRef.current.get(message.reference);
+      if (first) {
+        // Update the first's contents
+        first.set((prev) => ({
+          ...message,
+          firstCreated: prev.firstCreated ?? prev.created,
+          firstRelativeCreated: prev.firstRelativeCreated ?? prev.relativeCreated,
+        }));
+
+        // Don't add it to the list again
+        return;
+      } else {
+        // Add the first message with this reference to the registry
+        firstByRefRef.current.set(message.reference, messageCell);
+      }
+    }
+
+    if (applyFilters(message)) {
+      setFiltered((curr) => [...curr, messageCell]);
+    }
+  }, [applyFilters, setFiltered]);
+
+  useEffect(() => {
+    if (sseRef.current) return;
+
+    const es = new EventSource("http://localhost:8000/logs/stream");
+    sseRef.current = es;
+
+    es.onmessage = (event) => {
+      const data: LogRecord = JSON.parse(event.data);
+      handleNewMessage(data);
+    };
+
+    return () => {
+      es.close();
+      sseRef.current = null;
+    };
+  }, [handleNewMessage]);
+
+  return {filteredLogs: filtered, distinctNames};
+}