import { ref, onBeforeUnmount, type Ref } from "vue";
import { invoke } from "@tauri-apps/api/core";
import { listen, type UnlistenFn } from "@tauri-apps/api/event";

export interface FileEntry {
  name: string;
  path: string;
  size: number;
  isDir: boolean;
  permissions: string;
  modTime: string;
}

export interface UseSftpReturn {
  currentPath: Ref<string>;
  entries: Ref<FileEntry[]>;
  isLoading: Ref<boolean>;
  followTerminal: Ref<boolean>;
  navigateTo: (path: string) => Promise<void>;
  goUp: () => Promise<void>;
  refresh: () => Promise<void>;
}

/**
 * Composable that manages SFTP file browsing state.
 * Calls the Rust SFTP commands via Tauri invoke.
 */
export function useSftp(sessionId: string): UseSftpReturn {
  const currentPath = ref("/");
  const entries = ref<FileEntry[]>([]);
  const isLoading = ref(false);
  const followTerminal = ref(true);

  // Holds the unlisten function returned by listen() — called on cleanup.
  let unlistenCwd: UnlistenFn | null = null;

  async function listDirectory(path: string): Promise<FileEntry[]> {
    try {
      const result = await invoke<FileEntry[]>("sftp_list", { sessionId, path });
      return result ?? [];
    } catch (err) {
      console.error("SFTP list error:", err);
      return [];
    }
  }

  async function navigateTo(path: string): Promise<void> {
    isLoading.value = true;
    try {
      currentPath.value = path;
      entries.value = await listDirectory(path);
    } finally {
      isLoading.value = false;
    }
  }

  async function goUp(): Promise<void> {
    const parts = currentPath.value.split("/").filter(Boolean);
    if (parts.length <= 1) {
      await navigateTo("/");
      return;
    }
    parts.pop();
    await navigateTo("/" + parts.join("/"));
  }

  async function refresh(): Promise<void> {
    await navigateTo(currentPath.value);
  }

  // Listen for CWD changes from the Rust backend (OSC 7 tracking).
  // listen() returns Promise<UnlistenFn> — store it for cleanup.
  listen<string>(`ssh:cwd:${sessionId}`, (event) => {
    if (!followTerminal.value) return;
    const newPath = event.payload;
    if (newPath && newPath !== currentPath.value) {
      navigateTo(newPath);
    }
  }).then((unlisten) => {
    unlistenCwd = unlisten;
  });

  onBeforeUnmount(() => {
    if (unlistenCwd) unlistenCwd();
  });

  // Load home directory on init
  navigateTo("/home");

  return {
    currentPath,
    entries,
    isLoading,
    followTerminal,
    navigateTo,
    goUp,
    refresh,
  };
}