import { useQuery, useMutation, useQueryClient } from "@tanstack/react-query"
import { supabase } from "@/lib/supabase"
import type { QuickAddItem } from "@/lib/types"

// ---------------------------------------------------------------------------
// Query key
// ---------------------------------------------------------------------------

const QUICK_ADD_KEY = ["quick-add"] as const

// ---------------------------------------------------------------------------
// Hook
// ---------------------------------------------------------------------------

/**
 * TanStack Query hook for managing the user's quick-add item library.
 *
 * Provides:
 *   - `items`  — ordered list of QuickAddItem rows
 *   - `loading` — true while the initial fetch is in-flight
 *   - `create`  — mutation to add a new item (name, optional icon)
 *   - `update`  — mutation to rename / change the icon of an existing item
 *   - `remove`  — mutation to delete an item by id
 */
export function useQuickAdd() {
  const queryClient = useQueryClient()

  // ------------------------------------------------------------------
  // Query: list all quick-add items for the current user, by sort_order
  // ------------------------------------------------------------------

  const query = useQuery({
    queryKey: QUICK_ADD_KEY,
    queryFn: async () => {
      const { data, error } = await supabase
        .from("quick_add_items")
        .select("*")
        .order("sort_order")
      if (error) throw error
      return data as QuickAddItem[]
    },
  })

  // ------------------------------------------------------------------
  // Mutation: create a new quick-add item
  // ------------------------------------------------------------------

  const create = useMutation({
    mutationFn: async ({
      name,
      icon,
    }: {
      name: string
      icon?: string | null
    }) => {
      const {
        data: { user },
      } = await supabase.auth.getUser()
      if (!user) throw new Error("Not authenticated")

      // Determine next sort_order as max + 1 (or 0 for the first item)
      const currentItems = queryClient.getQueryData<QuickAddItem[]>(QUICK_ADD_KEY) ?? []
      const nextOrder =
        currentItems.length > 0
          ? Math.max(...currentItems.map((i) => i.sort_order)) + 1
          : 0

      const { data, error } = await supabase
        .from("quick_add_items")
        .insert({
          user_id: user.id,
          name,
          icon: icon ?? null,
          sort_order: nextOrder,
        })
        .select()
        .single()
      if (error) throw error
      return data as QuickAddItem
    },
    onSuccess: () => queryClient.invalidateQueries({ queryKey: QUICK_ADD_KEY }),
  })

  // ------------------------------------------------------------------
  // Mutation: update name and/or icon of an existing item
  // ------------------------------------------------------------------

  const update = useMutation({
    mutationFn: async ({
      id,
      name,
      icon,
    }: {
      id: string
      name: string
      icon: string | null
    }) => {
      const { data, error } = await supabase
        .from("quick_add_items")
        .update({ name, icon })
        .eq("id", id)
        .select()
        .single()
      if (error) throw error
      return data as QuickAddItem
    },
    onSuccess: () => queryClient.invalidateQueries({ queryKey: QUICK_ADD_KEY }),
  })

  // ------------------------------------------------------------------
  // Mutation: delete a quick-add item by id
  // ------------------------------------------------------------------

  const remove = useMutation({
    mutationFn: async (id: string) => {
      const { error } = await supabase
        .from("quick_add_items")
        .delete()
        .eq("id", id)
      if (error) throw error
    },
    onSuccess: () => queryClient.invalidateQueries({ queryKey: QUICK_ADD_KEY }),
  })

  // ------------------------------------------------------------------
  // Exposed API
  // ------------------------------------------------------------------

  return {
    /** All quick-add items for the current user, ordered by sort_order. */
    items: query.data ?? [],
    loading: query.isLoading,
    create,
    update,
    remove,
  }
}