import { useMutation, useQuery, useQueryClient } from '@tanstack/vue-query'
import { HttpStatus } from 'http-status-ts'
import { toValue, type MaybeRefOrGetter } from 'vue'

import type {
  CourseTasks,
  CreateTaskBody,
  FocusStart,
  FocusStop,
  Task,
  TaskBody,
  TimetaggerRecord,
} from '@/utils/types'
import { getClient } from './client'

// Every mutation answers with all the tasks of the course (nested, sorted) and the
// deadlines, which replace the cache: no refetch needed.

function tasksKey(courseId: MaybeRefOrGetter<number>) {
  return ['course', courseId, 'tasks']
}

const TODO_KEY = ['todo-tasks']

function unexpected(status: number): never {
  throw new Error(`Unexpected status code received: ${status}`)
}

/** Body replacing `task` by itself, with `changes` applied */
export function toTaskBody(task: Task, changes: Partial<TaskBody> = {}): TaskBody {
  return {
    name: task.name,
    description: task.description,
    links: task.links,
    deadline: task.deadline,
    done: task.done,
    tag_ids: task.tag_ids,
    ...changes,
  }
}

export function useCourseTasks(courseId: MaybeRefOrGetter<number>) {
  return useQuery({
    queryKey: tasksKey(courseId),
    queryFn: async () => {
      const { data, response } = await getClient().GET('/api/courses/{id}/tasks', {
        params: { path: { id: toValue(courseId) } },
      })
      return response.status === HttpStatus.OK && data ? data : unexpected(response.status)
    },
  })
}

/**
 * Tasks and subtasks of every course with a deadline in `[from, to[` (ISO dates), for
 * the calendar
 */
export function useCalendarTasks(period: MaybeRefOrGetter<{ from: string; to: string }>) {
  return useQuery({
    queryKey: ['calendar-tasks', period],
    queryFn: async () => {
      const { data, response } = await getClient().GET('/api/tasks', {
        params: { query: toValue(period) },
      })
      return response.status === HttpStatus.OK && data ? data : unexpected(response.status)
    },
  })
}

/** Tasks not done of every course and association, the closest deadline first */
export function useTodoTasks() {
  return useQuery({
    queryKey: TODO_KEY,
    queryFn: async () => {
      const { data, response } = await getClient().GET('/api/tasks/todo')
      return response.status === HttpStatus.OK && data ? data : unexpected(response.status)
    },
  })
}

/**
 * Mutations of the tasks of any course: the course is given with each call. See
 * `useTaskMutations` for the tasks of a single course.
 */
export function useAnyTaskMutations() {
  const queryClient = useQueryClient()
  const onSuccess = (tasks: CourseTasks, { courseId }: { courseId: number }) => {
    queryClient.setQueryData(tasksKey(courseId), tasks)
    // Refetched when they are shown again
    queryClient.invalidateQueries({ queryKey: ['calendar-tasks'] })
    queryClient.invalidateQueries({ queryKey: TODO_KEY })
  }

  const create = useMutation({
    mutationFn: async ({ courseId, body }: { courseId: number; body: CreateTaskBody }) => {
      const { data, response } = await getClient().POST('/api/courses/{id}/tasks', {
        params: { path: { id: courseId } },
        body,
      })
      return response.status === HttpStatus.OK && data ? data : unexpected(response.status)
    },
    onSuccess,
  })

  const update = useMutation({
    mutationFn: async ({ id, body }: { courseId: number; id: number; body: TaskBody }) => {
      const { data, response } = await getClient().PUT('/api/tasks/{id}', {
        params: { path: { id } },
        body,
      })
      return response.status === HttpStatus.OK && data ? data : unexpected(response.status)
    },
    onSuccess,
  })

  const remove = useMutation({
    mutationFn: async ({ id }: { courseId: number; id: number }) => {
      const { data, response } = await getClient().DELETE('/api/tasks/{id}', {
        params: { path: { id } },
      })
      return response.status === HttpStatus.OK && data ? data : unexpected(response.status)
    },
    onSuccess,
  })

  return { create, update, remove }
}

/** Mutations of the tasks of a single course */
export function useTaskMutations(courseId: MaybeRefOrGetter<number>) {
  const { create, update, remove } = useAnyTaskMutations()
  return {
    create: {
      ...create,
      mutateAsync: (body: CreateTaskBody) =>
        create.mutateAsync({ courseId: toValue(courseId), body }),
    },
    update: {
      ...update,
      mutateAsync: ({ id, body }: { id: number; body: TaskBody }) =>
        update.mutateAsync({ courseId: toValue(courseId), id, body }),
    },
    remove: {
      ...remove,
      mutateAsync: (id: number) => remove.mutateAsync({ courseId: toValue(courseId), id }),
    },
  }
}

/** Starts a focus session on a task, and its TimeTagger record */
export async function startFocus(taskId: number): Promise<FocusStart> {
  const { data, response } = await getClient().POST('/api/tasks/{id}/focus', {
    params: { path: { id: taskId } },
  })
  return response.status === HttpStatus.OK && data ? data : unexpected(response.status)
}

/** Ends (or pauses) a focus session: its time is added to the task */
export async function stopFocus(
  taskId: number,
  seconds: number,
  timetagger: TimetaggerRecord | null,
): Promise<FocusStop> {
  const { data, response } = await getClient().POST('/api/tasks/{id}/focus/stop', {
    params: { path: { id: taskId } },
    body: { seconds, timetagger },
  })
  return response.status === HttpStatus.OK && data ? data : unexpected(response.status)
}

/** The time spent on the tasks changed: shown again from the server */
export function useRefreshTasks() {
  const queryClient = useQueryClient()
  return (courseId: number) => {
    queryClient.invalidateQueries({ queryKey: tasksKey(courseId) })
    queryClient.invalidateQueries({ queryKey: TODO_KEY })
  }
}