"use client";

import { useEffect, useState, useCallback, useRef } from "react";
import { getWebSocketClient } from "@/lib/ws/connection";
import {
  requestFileTree,
  requestFileContent,
  searchWorkspaceFiles,
} from "@/lib/ws/workspace-files";
import type { FileTreeNode, FileContentResponse, OpenFileTab } from "@/lib/types/backend";
import { useSessionAgentctl } from "@/hooks/domains/session/use-session-agentctl";
import {
  getFilesPanelExpandedPaths,
  setFilesPanelExpandedPaths,
  getFilesPanelScrollPosition,
  setFilesPanelScrollPosition,
} from "@/lib/local-storage";
import type { useToast } from "@/components/toast-provider";
import { mergeTreeNodes } from "./file-browser-parts";

const MAX_RETRY_ATTEMPTS = 4;
const RETRY_DELAYS_MS = [1000, 2000, 5000, 10000];

export type LoadState = "loading" | "waiting" | "loaded" | "manual" | "error";

/** Hook encapsulating file search state and handlers. */
export function useFileBrowserSearch(sessionId: string) {
  const [isSearchActive, setIsSearchActive] = useState(false);
  const [localSearchQuery, setLocalSearchQuery] = useState("");
  const [searchResults, setSearchResults] = useState<string[] | null>(null);
  const [isSearching, setIsSearching] = useState(false);
  const searchTimeoutRef = useRef<NodeJS.Timeout | null>(null);
  const searchInputRef = useRef<HTMLInputElement>(null);

  // Focus search input when search opens
  useEffect(() => {
    if (isSearchActive && searchInputRef.current) {
      searchInputRef.current.focus();
    }
  }, [isSearchActive]);

  // Clear search when closing
  useEffect(() => {
    if (!isSearchActive) {
      setLocalSearchQuery("");
      setSearchResults(null);
      setIsSearching(false);
      if (searchTimeoutRef.current) clearTimeout(searchTimeoutRef.current);
    }
  }, [isSearchActive]);

  // Cleanup on unmount
  useEffect(() => {
    return () => {
      if (searchTimeoutRef.current) clearTimeout(searchTimeoutRef.current);
    };
  }, []);

  const handleSearchChange = useCallback(
    (e: React.ChangeEvent<HTMLInputElement>) => {
      const value = e.target.value;
      setLocalSearchQuery(value);
      if (searchTimeoutRef.current) clearTimeout(searchTimeoutRef.current);
      if (!value.trim()) {
        setSearchResults(null);
        setIsSearching(false);
        return;
      }
      setIsSearching(true);
      searchTimeoutRef.current = setTimeout(async () => {
        try {
          const client = getWebSocketClient();
          if (!client) return;
          const response = await searchWorkspaceFiles(client, sessionId, value, 50);
          setSearchResults(response.files || []);
        } catch (error) {
          console.error("Failed to search files:", error);
          setSearchResults([]);
        } finally {
          setIsSearching(false);
        }
      }, 300);
    },
    [sessionId],
  );

  const handleCloseSearch = useCallback(() => {
    setIsSearchActive(false);
    setLocalSearchQuery("");
    setSearchResults(null);
    setIsSearching(false);
    if (searchTimeoutRef.current) clearTimeout(searchTimeoutRef.current);
  }, []);

  return {
    isSearchActive,
    setIsSearchActive,
    localSearchQuery,
    searchResults,
    isSearching,
    searchInputRef,
    handleSearchChange,
    handleCloseSearch,
  };
}

/** Apply incoming file changes to the tree by refreshing affected folders. */
function applyFileChanges(ctx: {
  client: ReturnType<typeof getWebSocketClient>;
  sessionId: string;
  expandedPaths: Set<string>;
  changes: Array<{ path: string }>;
  setTree: React.Dispatch<React.SetStateAction<FileTreeNode | null>>;
  setLoadState: React.Dispatch<React.SetStateAction<LoadState>>;
}) {
  const { client, sessionId, expandedPaths, changes, setTree, setLoadState } = ctx;
  const candidates = new Set<string>();
  for (const change of changes) {
    const p = change.path;
    const lastSlash = p.lastIndexOf("/");
    candidates.add(lastSlash === -1 ? "" : p.substring(0, lastSlash));
    candidates.add(p);
  }
  const foldersToRefresh = new Set<string>();
  for (const c of candidates) {
    if (c === "" || expandedPaths.has(c)) foldersToRefresh.add(c);
  }
  if (foldersToRefresh.size === 0) return;

  void (async () => {
    try {
      const folderUpdates = new Map<string, FileTreeNode[] | undefined>();
      await Promise.all(
        Array.from(foldersToRefresh).map(async (folder) => {
          try {
            const res = await requestFileTree(client!, sessionId, folder || "", 1);
            folderUpdates.set(folder, res.root?.children);
          } catch {
            /* Folder may have been removed */
          }
        }),
      );
      setTree((prev) => {
        if (!prev) return prev;
        let updated = prev;
        if (folderUpdates.has("")) {
          const freshRootChildren = folderUpdates.get("");
          const existingByPath = new Map((updated.children ?? []).map((c) => [c.path, c]));
          const mergedRootChildren = freshRootChildren?.map((incoming) => {
            const existing = existingByPath.get(incoming.path);
            return existing && existing.is_dir && incoming.is_dir
              ? mergeTreeNodes(existing, incoming)
              : incoming;
          });
          updated = { ...updated, children: mergedRootChildren };
        }
        const subFolders = Array.from(folderUpdates.keys()).filter((k) => k !== "");
        if (subFolders.length === 0) return updated;
        const patchNode = (node: FileTreeNode): FileTreeNode => {
          if (node.is_dir && folderUpdates.has(node.path)) {
            return { ...node, children: folderUpdates.get(node.path)?.map(patchNode) };
          }
          return node.children ? { ...node, children: node.children.map(patchNode) } : node;
        };
        return patchNode(updated);
      });
      setLoadState("loaded");
    } catch (error) {
      console.error("[FileBrowser] Failed to refresh file tree:", error);
    }
  })();
}

function useLoadingTimers() {
  const loadingTimersRef = useRef<Map<string, NodeJS.Timeout>>(new Map());
  const [visibleLoadingPaths, setVisibleLoadingPaths] = useState<Set<string>>(new Set());

  const showLoading = useCallback((path: string) => {
    const timer = setTimeout(() => {
      setVisibleLoadingPaths((prev) => new Set(prev).add(path));
      loadingTimersRef.current.delete(path);
    }, 150);
    loadingTimersRef.current.set(path, timer);
  }, []);

  const hideLoading = useCallback((path: string) => {
    const timer = loadingTimersRef.current.get(path);
    if (timer) {
      clearTimeout(timer);
      loadingTimersRef.current.delete(path);
    }
    setVisibleLoadingPaths((prev) => {
      const next = new Set(prev);
      next.delete(path);
      return next;
    });
  }, []);

  return { visibleLoadingPaths, showLoading, hideLoading };
}

type TreeLoaderContext = {
  sessionId: string;
  clearRetryTimer: () => void;
  retryAttemptRef: React.MutableRefObject<number>;
  retryTimerRef: React.MutableRefObject<NodeJS.Timeout | null>;
  setTree: React.Dispatch<React.SetStateAction<FileTreeNode | null>>;
  setIsLoadingTree: React.Dispatch<React.SetStateAction<boolean>>;
  setLoadState: React.Dispatch<React.SetStateAction<LoadState>>;
  setLoadError: React.Dispatch<React.SetStateAction<string | null>>;
};

function useTreeLoader(ctx: TreeLoaderContext) {
  const {
    clearRetryTimer,
    retryAttemptRef,
    retryTimerRef,
    setTree,
    setIsLoadingTree,
    setLoadState,
    setLoadError,
  } = ctx;
  // Use ref for sessionId so loadTree stays stable across session switches.
  // This prevents the tree-clearing effect from re-firing when only sessionId changes.
  const sessionIdRef = useRef(ctx.sessionId);
  sessionIdRef.current = ctx.sessionId;
  const loadInFlightRef = useRef(false);
  const loadTree = useCallback(
    async (options?: { resetRetry?: boolean }) => {
      if (loadInFlightRef.current) return;
      loadInFlightRef.current = true;
      setIsLoadingTree(true);
      setLoadState("loading");
      setLoadError(null);
      if (options?.resetRetry) {
        retryAttemptRef.current = 0;
        clearRetryTimer();
      }
      try {
        const client = getWebSocketClient();
        if (!client) throw new Error("WebSocket client not available");
        const response = await requestFileTree(client, sessionIdRef.current, "", 1);
        setTree(response.root ?? null);
        setLoadState("loaded");
        retryAttemptRef.current = 0;
        clearRetryTimer();
      } catch (error) {
        const message = error instanceof Error ? error.message : "Failed to load file tree";
        setLoadError(message);
        if (retryAttemptRef.current < MAX_RETRY_ATTEMPTS) {
          const delay =
            RETRY_DELAYS_MS[Math.min(retryAttemptRef.current, RETRY_DELAYS_MS.length - 1)];
          retryAttemptRef.current += 1;
          setLoadState("waiting");
          clearRetryTimer();
          retryTimerRef.current = setTimeout(() => {
            void loadTree();
          }, delay);
        } else {
          setLoadState("manual");
        }
      } finally {
        setIsLoadingTree(false);
        loadInFlightRef.current = false;
      }
    },
    [
      clearRetryTimer,
      retryAttemptRef,
      retryTimerRef,
      setIsLoadingTree,
      setLoadError,
      setLoadState,
      setTree,
    ],
  );
  return loadTree;
}

function useFileChangeSubscription({
  sessionIdRef,
  expandedPaths,
  setTree,
  setLoadState,
}: {
  sessionIdRef: React.MutableRefObject<string>;
  expandedPaths: Set<string>;
  setTree: React.Dispatch<React.SetStateAction<FileTreeNode | null>>;
  setLoadState: React.Dispatch<React.SetStateAction<LoadState>>;
}) {
  useEffect(() => {
    const client = getWebSocketClient();
    if (!client) return;
    return client.on("session.workspace.file.changes", (msg) => {
      const changes = msg.payload?.changes;
      if (!changes || changes.length === 0) return;
      applyFileChanges({
        client,
        sessionId: sessionIdRef.current,
        expandedPaths,
        changes,
        setTree,
        setLoadState,
      });
    });
    // eslint-disable-next-line react-hooks/exhaustive-deps
  }, [expandedPaths]);
}

/**
 * Hook for tree loading with retry logic, file-change subscription, and expanded state.
 * @param sessionId - Session ID for API calls (agentctl routing).
 * @param resetKey - Optional stable key (e.g. environmentId) that controls when the tree
 *   does a full reset. When sessions share the same environment, this prevents the tree
 *   from flashing on tab switch.
 */
export function useFileBrowserTree(sessionId: string, resetKey?: string) {
  const effectiveResetKey = resetKey ?? sessionId;
  const [tree, setTree] = useState<FileTreeNode | null>(null);
  const [expandedPaths, setExpandedPaths] = useState<Set<string>>(new Set());
  const [isLoadingTree, setIsLoadingTree] = useState(true);
  const [loadState, setLoadState] = useState<LoadState>("loading");
  const [loadError, setLoadError] = useState<string | null>(null);
  const hasInitializedExpandedRef = useRef<string | null>(null);
  const retryAttemptRef = useRef(0);
  const retryTimerRef = useRef<NodeJS.Timeout | null>(null);
  const sessionIdRef = useRef(sessionId);
  sessionIdRef.current = sessionId;
  const agentctlStatus = useSessionAgentctl(sessionId);
  const { visibleLoadingPaths, showLoading, hideLoading } = useLoadingTimers();

  const clearRetryTimer = useCallback(() => {
    if (retryTimerRef.current) {
      clearTimeout(retryTimerRef.current);
      retryTimerRef.current = null;
    }
  }, []);

  const loadTree = useTreeLoader({
    sessionId,
    clearRetryTimer,
    retryAttemptRef,
    retryTimerRef,
    setTree,
    setIsLoadingTree,
    setLoadState,
    setLoadError,
  });

  // Refs for effects below to read without adding deps — avoids infinite
  // retry loops and wipe-on-reconnect when `isReady`/`loadState`/`tree` tick.
  const agentctlIsReadyRef = useRef(agentctlStatus.isReady);
  const loadStateRef = useRef(loadState);
  const treeRef = useRef(tree);
  agentctlIsReadyRef.current = agentctlStatus.isReady;
  loadStateRef.current = loadState;
  treeRef.current = tree;
  useEffect(() => {
    setTree(null);
    setIsLoadingTree(true);
    setLoadState(agentctlIsReadyRef.current ? "loading" : "waiting");
    setLoadError(null);
    retryAttemptRef.current = 0;
    clearRetryTimer();
    hasInitializedExpandedRef.current = null;
    const savedPaths = getFilesPanelExpandedPaths(effectiveResetKey);
    setExpandedPaths(savedPaths.length > 0 ? new Set(savedPaths) : new Set());
    if (savedPaths.length > 0) hasInitializedExpandedRef.current = effectiveResetKey;
    // Only load now if agentctl is ready; otherwise the sibling effect fires
    // on the ready flip. Prevents burning the retry budget during slow prepare.
    if (agentctlIsReadyRef.current) void loadTree({ resetRetry: true });
    else setIsLoadingTree(false);
    return () => {
      clearRetryTimer();
    };
  }, [clearRetryTimer, loadTree, effectiveResetKey]);

  // Fire the initial load on the waiting → ready transition. `loadState` is
  // read via a ref so a failed load (which sets state back to "waiting") does
  // not re-fire this effect and cancel the retry timer via `resetRetry: true`.
  // "loaded" only counts when a tree is actually present — `applyFileChanges`
  // can flip state to "loaded" while the tree is still null.
  useEffect(() => {
    if (!agentctlStatus.isReady) return;
    if (loadStateRef.current === "loading") return;
    if (loadStateRef.current === "loaded" && treeRef.current) return;
    void loadTree({ resetRetry: true });
  }, [agentctlStatus.isReady, loadTree]);

  useEffect(() => {
    if (!tree || isLoadingTree || hasInitializedExpandedRef.current === effectiveResetKey) return;
    hasInitializedExpandedRef.current = effectiveResetKey;
    setExpandedPaths(new Set());
    // eslint-disable-next-line react-hooks/exhaustive-deps
  }, [tree?.children?.length, isLoadingTree, effectiveResetKey]);

  useEffect(() => {
    if (expandedPaths.size > 0 || hasInitializedExpandedRef.current === effectiveResetKey) {
      setFilesPanelExpandedPaths(effectiveResetKey, Array.from(expandedPaths));
    }
  }, [expandedPaths, effectiveResetKey]);

  useFileChangeSubscription({ sessionIdRef, expandedPaths, setTree, setLoadState });

  const collapseAll = useCallback(() => {
    setExpandedPaths(new Set());
  }, []);

  return {
    tree,
    setTree,
    expandedPaths,
    setExpandedPaths,
    visibleLoadingPaths,
    isLoadingTree,
    loadState,
    loadError,
    loadTree,
    showLoading,
    hideLoading,
    collapseAll,
  };
}

/** Hook for scroll position persistence in the file browser. */
export function useScrollPersistence(
  sessionId: string,
  isTreeLoaded: boolean,
  scrollAreaRef: React.RefObject<HTMLDivElement | null>,
  tree: FileTreeNode | null,
) {
  const scrollSaveTimeoutRef = useRef<NodeJS.Timeout | null>(null);
  const hasRestoredScrollRef = useRef<string | null>(null);

  // Restore scroll position after tree loads
  useEffect(() => {
    if (!isTreeLoaded || hasRestoredScrollRef.current === sessionId) return;
    const savedScroll = getFilesPanelScrollPosition(sessionId);
    if (savedScroll > 0 && scrollAreaRef.current) {
      const viewport = scrollAreaRef.current.querySelector("[data-radix-scroll-area-viewport]");
      if (viewport) {
        viewport.scrollTop = savedScroll;
        hasRestoredScrollRef.current = sessionId;
      }
    } else {
      hasRestoredScrollRef.current = sessionId;
    }
  }, [isTreeLoaded, sessionId, scrollAreaRef]);

  // Attach scroll listener to ScrollArea viewport
  useEffect(() => {
    const el = scrollAreaRef.current;
    if (!el) return;
    const viewport = el.querySelector("[data-radix-scroll-area-viewport]");
    if (!viewport) return;
    const onScroll = (event: Event) => {
      const target = event.target as HTMLElement;
      if (scrollSaveTimeoutRef.current) clearTimeout(scrollSaveTimeoutRef.current);
      scrollSaveTimeoutRef.current = setTimeout(() => {
        setFilesPanelScrollPosition(sessionId, target.scrollTop);
      }, 150);
    };
    viewport.addEventListener("scroll", onScroll);
    return () => {
      viewport.removeEventListener("scroll", onScroll);
      if (scrollSaveTimeoutRef.current) clearTimeout(scrollSaveTimeoutRef.current);
    };
  }, [sessionId, tree, scrollAreaRef]);
}

/** Fetch children for a folder node if not already loaded. */
export async function loadNodeChildren(
  node: FileTreeNode,
  sessionId: string,
  treeState: ReturnType<typeof useFileBrowserTree>,
) {
  if (node.children && node.children.length > 0) return;
  treeState.showLoading(node.path);
  try {
    const client = getWebSocketClient();
    if (!client) return;
    const response = await requestFileTree(client, sessionId, node.path, 1);
    const updateNode = (n: FileTreeNode): FileTreeNode => {
      if (n.path === node.path) return { ...n, children: response.root.children };
      return n.children ? { ...n, children: n.children.map(updateNode) } : n;
    };
    if (treeState.tree) treeState.setTree(updateNode(treeState.tree));
  } catch (error) {
    console.error("Failed to load children:", error);
  } finally {
    treeState.hideLoading(node.path);
  }
}

/** Fetch and open a file by path. */
export async function fetchAndOpenFile(
  sessionId: string,
  path: string,
  onOpenFile: (file: OpenFileTab) => void,
  toast: ReturnType<typeof useToast>["toast"],
) {
  try {
    const client = getWebSocketClient();
    if (!client) return;
    const response: FileContentResponse = await requestFileContent(client, sessionId, path);
    const { calculateHash } = await import("@/lib/utils/file-diff");
    const hash = await calculateHash(response.content);
    const name = path.split("/").pop() || path;
    onOpenFile({
      path,
      name,
      content: response.content,
      originalContent: response.content,
      originalHash: hash,
      isDirty: false,
      isBinary: response.is_binary,
    });
  } catch (error) {
    const reason = error instanceof Error ? error.message : "Unknown error";
    toast({ title: "Failed to open file", description: reason, variant: "error" });
  }
}