"use client"

import React, { createContext, useContext, useState, useEffect, useCallback } 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
  result?: any
  error?: string
  files?: { [key: string]: any }
}

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 [trackedTaskIds, setTrackedTaskIds] = useState<Set<string>>(new Set())
  const { isAuthenticated } = useAuth()

  const fetchTasks = useCallback(async () => {
    if (!isAuthenticated) 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),
                  },
                })
              } 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]) // Removed 'tasks' from dependencies to prevent infinite loop!

  const addTask = useCallback((taskId: string) => {
    setTrackedTaskIds(prev => new Set(prev).add(taskId))
    
    // 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) => {
    setTrackedTaskIds(prev => {
      const newSet = new Set(prev)
      newSet.delete(taskId)
      return newSet
    })
  }, [])

  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) 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, 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
}