import type { Purchase, PurchaseInsert, EquipmentCategory } from '~/types/purchase'

export function usePurchases() {
  const client = useSupabaseClient()
  const user = useSupabaseUser()

  const purchases = ref<Purchase[]>([])
  const loading = ref(false)
  const error = ref<string | null>(null)

  const totalSpent = computed(() =>
    purchases.value.reduce((sum, p) => sum + p.price, 0)
  )

  const categoryBreakdown = computed(() => {
    const breakdown: Record<string, number> = {}
    for (const p of purchases.value) {
      breakdown[p.category] = (breakdown[p.category] ?? 0) + p.price
    }
    return breakdown
  })

  async function fetchPurchases() {
    if (!user.value) return
    loading.value = true
    error.value = null
    try {
      const { data, error: err } = await client
        .from('purchases')
        .select('*')
        .eq('user_id', user.value.id)
        .order('purchase_date', { ascending: false })
      if (err) throw err
      purchases.value = data as Purchase[]
    } catch (e: unknown) {
      error.value = e instanceof Error ? e.message : '오류가 발생했습니다'
    } finally {
      loading.value = false
    }
  }

  async function createPurchase(payload: PurchaseInsert) {
    if (!user.value) return
    loading.value = true
    error.value = null
    try {
      const { data, error: err } = await client
        .from('purchases')
        .insert({ ...payload, user_id: user.value.id })
        .select()
        .single()
      if (err) throw err
      purchases.value.unshift(data as Purchase)
      return data as Purchase
    } catch (e: unknown) {
      error.value = e instanceof Error ? e.message : '저장에 실패했습니다'
    } finally {
      loading.value = false
    }
  }

  async function updatePurchase(id: string, payload: Partial<PurchaseInsert>) {
    if (!user.value) return
    loading.value = true
    error.value = null
    try {
      const { data, error: err } = await client
        .from('purchases')
        .update(payload)
        .eq('id', id)
        .eq('user_id', user.value.id)
        .select()
        .single()
      if (err) throw err
      const idx = purchases.value.findIndex(p => p.id === id)
      if (idx !== -1) purchases.value[idx] = data as Purchase
      return data as Purchase
    } catch (e: unknown) {
      error.value = e instanceof Error ? e.message : '수정에 실패했습니다'
    } finally {
      loading.value = false
    }
  }

  async function deletePurchase(id: string) {
    if (!user.value) return
    loading.value = true
    error.value = null
    try {
      const { error: err } = await client
        .from('purchases')
        .delete()
        .eq('id', id)
        .eq('user_id', user.value.id)
      if (err) throw err
      purchases.value = purchases.value.filter(p => p.id !== id)
    } catch (e: unknown) {
      error.value = e instanceof Error ? e.message : '삭제에 실패했습니다'
    } finally {
      loading.value = false
    }
  }

  async function getPurchase(id: string): Promise<Purchase | null> {
    if (!user.value) return null
    try {
      const { data, error: err } = await client
        .from('purchases')
        .select('*')
        .eq('id', id)
        .eq('user_id', user.value.id)
        .single()
      if (err) throw err
      return data as Purchase
    } catch {
      return null
    }
  }

  async function bulkCreatePurchases(payloads: PurchaseInsert[]): Promise<number> {
    if (!user.value || payloads.length === 0) return 0
    loading.value = true
    error.value = null
    try {
      const rows = payloads.map(p => ({ ...p, user_id: user.value!.id }))
      const { data, error: err } = await client.from('purchases').insert(rows).select()
      if (err) throw err
      purchases.value.unshift(...(data as Purchase[]))
      return data.length
    } catch (e: unknown) {
      error.value = e instanceof Error ? e.message : '일괄 저장에 실패했습니다'
      return 0
    } finally {
      loading.value = false
    }
  }

  return {
    purchases: readonly(purchases),
    loading: readonly(loading),
    error: readonly(error),
    totalSpent,
    categoryBreakdown,
    fetchPurchases,
    createPurchase,
    updatePurchase,
    deletePurchase,
    getPurchase,
    bulkCreatePurchases
  }
}