import { useQuery, useMutation, useQueryClient } from '@tanstack/react-query';
import { planningService } from '@/services/planningService';
import { Sprint, Task, TaskStatus } from '@/types/planning';
import { useToast } from '@/hooks/use-toast';

const QUERY_KEYS = {
  sprints: ['planning', 'sprints'],
  tasks: ['planning', 'tasks'],
  task: (id: string) => ['planning', 'task', id],
  backlog: ['planning', 'backlog'],
  sprintTasks: (sprintId: string) => ['planning', 'sprint-tasks', sprintId],
  allData: ['planning', 'all'],
};

// ==================== SPRINT HOOKS ====================

export const useSprints = () => {
  return useQuery({
    queryKey: QUERY_KEYS.sprints,
    queryFn: planningService.getSprints,
  });
};

export const useCreateSprint = () => {
  const queryClient = useQueryClient();
  const { toast } = useToast();

  return useMutation({
    mutationFn: planningService.createSprint,
    onSuccess: () => {
      queryClient.invalidateQueries({ queryKey: QUERY_KEYS.sprints });
      toast({ title: 'Sprint created successfully' });
    },
    onError: (error: Error) => {
      toast({ title: 'Failed to create sprint', description: error.message, variant: 'destructive' });
    },
  });
};

export const useUpdateSprint = () => {
  const queryClient = useQueryClient();

  return useMutation({
    mutationFn: ({ id, updates }: { id: string; updates: Partial<Sprint> }) =>
      planningService.updateSprint(id, updates),
    onSuccess: () => {
      queryClient.invalidateQueries({ queryKey: QUERY_KEYS.sprints });
    },
  });
};

export const useDeleteSprint = () => {
  const queryClient = useQueryClient();
  const { toast } = useToast();

  return useMutation({
    mutationFn: planningService.deleteSprint,
    onSuccess: () => {
      queryClient.invalidateQueries({ queryKey: QUERY_KEYS.sprints });
      queryClient.invalidateQueries({ queryKey: QUERY_KEYS.tasks });
      toast({ title: 'Sprint deleted' });
    },
  });
};

export const useStartSprint = () => {
  const queryClient = useQueryClient();
  const { toast } = useToast();

  return useMutation({
    mutationFn: planningService.startSprint,
    onSuccess: () => {
      queryClient.invalidateQueries({ queryKey: QUERY_KEYS.sprints });
      toast({ title: 'Sprint started!' });
    },
    onError: (error: Error) => {
      toast({ title: 'Cannot start sprint', description: error.message, variant: 'destructive' });
    },
  });
};

export const useCompleteSprint = () => {
  const queryClient = useQueryClient();
  const { toast } = useToast();

  return useMutation({
    mutationFn: planningService.completeSprint,
    onSuccess: ({ returnedTasks }) => {
      queryClient.invalidateQueries({ queryKey: QUERY_KEYS.sprints });
      queryClient.invalidateQueries({ queryKey: QUERY_KEYS.tasks });
      if (returnedTasks.length > 0) {
        toast({ 
          title: 'Sprint completed', 
          description: `${returnedTasks.length} unfinished task(s) moved to backlog` 
        });
      } else {
        toast({ title: 'Sprint completed successfully!' });
      }
    },
  });
};

// ==================== TASK HOOKS ====================

export const useTasks = () => {
  return useQuery({
    queryKey: QUERY_KEYS.tasks,
    queryFn: planningService.getTasks,
  });
};

export const useTask = (id: string) => {
  return useQuery({
    queryKey: QUERY_KEYS.task(id),
    queryFn: () => planningService.getTask(id),
    enabled: !!id,
  });
};

export const useBacklogTasks = () => {
  return useQuery({
    queryKey: QUERY_KEYS.backlog,
    queryFn: planningService.getBacklogTasks,
  });
};

export const useSprintTasks = (sprintId: string) => {
  return useQuery({
    queryKey: QUERY_KEYS.sprintTasks(sprintId),
    queryFn: () => planningService.getSprintTasks(sprintId),
    enabled: !!sprintId,
  });
};

export const useCreateTask = () => {
  const queryClient = useQueryClient();
  const { toast } = useToast();

  return useMutation({
    mutationFn: planningService.createTask,
    onSuccess: () => {
      queryClient.invalidateQueries({ queryKey: QUERY_KEYS.tasks });
      queryClient.invalidateQueries({ queryKey: QUERY_KEYS.backlog });
      toast({ title: 'Task created' });
    },
  });
};

export const useUpdateTask = () => {
  const queryClient = useQueryClient();

  return useMutation({
    mutationFn: ({ id, updates }: { id: string; updates: Partial<Task> }) =>
      planningService.updateTask(id, updates),
    onSuccess: () => {
      queryClient.invalidateQueries({ queryKey: QUERY_KEYS.tasks });
      queryClient.invalidateQueries({ queryKey: QUERY_KEYS.backlog });
    },
  });
};

export const useDeleteTask = () => {
  const queryClient = useQueryClient();
  const { toast } = useToast();

  return useMutation({
    mutationFn: planningService.deleteTask,
    onSuccess: () => {
      queryClient.invalidateQueries({ queryKey: QUERY_KEYS.tasks });
      queryClient.invalidateQueries({ queryKey: QUERY_KEYS.backlog });
      toast({ title: 'Task deleted' });
    },
  });
};

export const useMoveTask = () => {
  const queryClient = useQueryClient();

  return useMutation({
    mutationFn: ({ taskId, sprintId }: { taskId: string; sprintId: string | null }) =>
      planningService.moveTaskToSprint(taskId, sprintId),
    onMutate: async ({ taskId, sprintId }) => {
      // Cancel outgoing refetches
      await queryClient.cancelQueries({ queryKey: QUERY_KEYS.tasks });
      
      // Snapshot previous value
      const previousTasks = queryClient.getQueryData<Task[]>(QUERY_KEYS.tasks);
      
      // Optimistically update
      queryClient.setQueryData<Task[]>(QUERY_KEYS.tasks, (old) =>
        old?.map(task => task.id === taskId ? { ...task, sprintId } : task) ?? []
      );
      
      return { previousTasks };
    },
    onError: (_err, _vars, context) => {
      // Rollback on error
      if (context?.previousTasks) {
        queryClient.setQueryData(QUERY_KEYS.tasks, context.previousTasks);
      }
    },
    onSettled: () => {
      queryClient.invalidateQueries({ queryKey: QUERY_KEYS.tasks });
      queryClient.invalidateQueries({ queryKey: QUERY_KEYS.backlog });
    },
  });
};

export const useUpdateTaskStatus = () => {
  const queryClient = useQueryClient();

  return useMutation({
    mutationFn: ({ taskId, status }: { taskId: string; status: TaskStatus }) =>
      planningService.updateTaskStatus(taskId, status),
    onMutate: async ({ taskId, status }) => {
      await queryClient.cancelQueries({ queryKey: QUERY_KEYS.tasks });
      
      const previousTasks = queryClient.getQueryData<Task[]>(QUERY_KEYS.tasks);
      
      queryClient.setQueryData<Task[]>(QUERY_KEYS.tasks, (old) =>
        old?.map(task => task.id === taskId ? { ...task, status } : task) ?? []
      );
      
      return { previousTasks };
    },
    onError: (_err, _vars, context) => {
      if (context?.previousTasks) {
        queryClient.setQueryData(QUERY_KEYS.tasks, context.previousTasks);
      }
    },
    onSettled: () => {
      queryClient.invalidateQueries({ queryKey: QUERY_KEYS.tasks });
    },
  });
};

// ==================== COMBINED DATA ====================

export const usePlanningData = () => {
  return useQuery({
    queryKey: QUERY_KEYS.allData,
    queryFn: planningService.getAllData,
  });
};