"use client";

import { useQueryClient } from "@tanstack/react-query";
import type React from "react";
import {
  createContext,
  useCallback,
  useContext,
  useEffect,
  useState,
} from "react";
import { toast } from "sonner";
import { useAuth } from "@/contexts/auth-context";

export interface Task {
  task_id: string;
  status:
    | "pending"
    | "running"
    | "processing"
    | "completed"
    | "failed"
    | "error";
  total_files?: number;
  processed_files?: number;
  successful_files?: number;
  failed_files?: number;
  created_at: string;
  updated_at: string;
  duration_seconds?: number;
  result?: Record<string, unknown>;
  error?: string;
  files?: Record<string, Record<string, unknown>>;
}

interface TaskContextType {
  tasks: Task[];
  addTask: (taskId: string) => void;
  removeTask: (taskId: string) => void;
  refreshTasks: () => Promise<void>;
  cancelTask: (taskId: string) => Promise<void>;
  isPolling: boolean;
  isFetching: boolean;
  isMenuOpen: boolean;
  toggleMenu: () => void;
}

const TaskContext = createContext<TaskContextType | undefined>(undefined);

export function TaskProvider({ children }: { children: React.ReactNode }) {
  const [tasks, setTasks] = useState<Task[]>([]);
  const [isPolling, setIsPolling] = useState(false);
  const [isFetching, setIsFetching] = useState(false);
  const [isMenuOpen, setIsMenuOpen] = useState(false);
  const { isAuthenticated, isNoAuthMode } = useAuth();

  const queryClient = useQueryClient();

  const refetchSearch = () => {
    queryClient.invalidateQueries({
      queryKey: ["search"],
      exact: false,
    });
  };

  const fetchTasks = useCallback(async () => {
    if (!isAuthenticated && !isNoAuthMode) return;

    setIsFetching(true);
    try {
      const response = await fetch("/api/tasks");
      if (response.ok) {
        const data = await response.json();
        const newTasks = data.tasks || [];

        // Update tasks and check for status changes in the same state update
        setTasks(prevTasks => {
          // Check for newly completed tasks to show toasts
          if (prevTasks.length > 0) {
            newTasks.forEach((newTask: Task) => {
              const oldTask = prevTasks.find(
                t => t.task_id === newTask.task_id
              );
              if (
                oldTask &&
                oldTask.status !== "completed" &&
                newTask.status === "completed"
              ) {
                // Task just completed - show success toast
                toast.success("Task completed successfully!", {
                  description: `Task ${newTask.task_id} has finished processing.`,
                  action: {
                    label: "View",
                    onClick: () => console.log("View task", newTask.task_id),
                  },
                });
                refetchSearch();
                // Dispatch knowledge updated event for all knowledge-related pages
                console.log(
                  "Task completed successfully, dispatching knowledgeUpdated event"
                );
                window.dispatchEvent(new CustomEvent("knowledgeUpdated"));
              } else if (
                oldTask &&
                oldTask.status !== "failed" &&
                oldTask.status !== "error" &&
                (newTask.status === "failed" || newTask.status === "error")
              ) {
                // Task just failed - show error toast
                toast.error("Task failed", {
                  description: `Task ${newTask.task_id} failed: ${
                    newTask.error || "Unknown error"
                  }`,
                });
              }
            });
          }

          return newTasks;
        });
      }
    } catch (error) {
      console.error("Failed to fetch tasks:", error);
    } finally {
      setIsFetching(false);
    }
  }, [isAuthenticated, isNoAuthMode]); // Removed 'tasks' from dependencies to prevent infinite loop!

  const addTask = useCallback((taskId: string) => {
    // Immediately start aggressive polling for the new task
    let pollAttempts = 0;
    const maxPollAttempts = 30; // Poll for up to 30 seconds

    const aggressivePoll = async () => {
      try {
        const response = await fetch("/api/tasks");
        if (response.ok) {
          const data = await response.json();
          const newTasks = data.tasks || [];
          const foundTask = newTasks.find(
            (task: Task) => task.task_id === taskId
          );

          if (foundTask) {
            // Task found! Update the tasks state
            setTasks(prevTasks => {
              // Check if task is already in the list
              const exists = prevTasks.some(t => t.task_id === taskId);
              if (!exists) {
                return [...prevTasks, foundTask];
              }
              // Update existing task
              return prevTasks.map(t => (t.task_id === taskId ? foundTask : t));
            });
            return; // Stop polling, we found it
          }
        }
      } catch (error) {
        console.error("Aggressive polling failed:", error);
      }

      pollAttempts++;
      if (pollAttempts < maxPollAttempts) {
        // Continue polling every 1 second for new tasks
        setTimeout(aggressivePoll, 1000);
      }
    };

    // Start aggressive polling after a short delay to allow backend to process
    setTimeout(aggressivePoll, 500);
  }, []);

  const refreshTasks = useCallback(async () => {
    await fetchTasks();
  }, [fetchTasks]);

  const removeTask = useCallback((taskId: string) => {
    setTasks(prev => prev.filter(task => task.task_id !== taskId));
  }, []);

  const cancelTask = useCallback(
    async (taskId: string) => {
      try {
        const response = await fetch(`/api/tasks/${taskId}/cancel`, {
          method: "POST",
        });

        if (response.ok) {
          // Immediately refresh tasks to show the updated status
          await fetchTasks();
          toast.success("Task cancelled", {
            description: `Task ${taskId.substring(0, 8)}... has been cancelled`,
          });
        } else {
          const errorData = await response.json().catch(() => ({}));
          throw new Error(errorData.error || "Failed to cancel task");
        }
      } catch (error) {
        console.error("Failed to cancel task:", error);
        toast.error("Failed to cancel task", {
          description: error instanceof Error ? error.message : "Unknown error",
        });
      }
    },
    [fetchTasks]
  );

  const toggleMenu = useCallback(() => {
    setIsMenuOpen(prev => !prev);
  }, []);

  // Periodic polling for task updates
  useEffect(() => {
    if (!isAuthenticated && !isNoAuthMode) return;

    setIsPolling(true);

    // Initial fetch
    fetchTasks();

    // Set up polling interval - every 3 seconds (more responsive for active tasks)
    const interval = setInterval(fetchTasks, 3000);

    return () => {
      clearInterval(interval);
      setIsPolling(false);
    };
  }, [isAuthenticated, isNoAuthMode, fetchTasks]);

  const value: TaskContextType = {
    tasks,
    addTask,
    removeTask,
    refreshTasks,
    cancelTask,
    isPolling,
    isFetching,
    isMenuOpen,
    toggleMenu,
  };

  return <TaskContext.Provider value={value}>{children}</TaskContext.Provider>;
}

export function useTask() {
  const context = useContext(TaskContext);
  if (context === undefined) {
    throw new Error("useTask must be used within a TaskProvider");
  }
  return context;
}