import { defineStore } from 'pinia'
import { ref, computed } from 'vue'

export interface CartItem {
  id: number
  productId: number
  name: string
  image: string
  price: number
  quantity: number
  product_number: string
}

export interface DeliveryMethod {
  id: number
  name: string
  price: number
  description: string
}

export interface Cart {
  id: string
  name: string
  items: CartItem[]
}

export const useCartStore = defineStore('cart', () => {
  const carts = ref<Cart[]>([])
  const activeCartId = ref<string | null>(null)

  const selectedAddressId = ref<number | null>(null)
  const selectedDeliveryMethodId = ref<number | null>(null)
  const shippingCost = ref(0)
  const vatRate = ref(0.23) // 23% VAT
  const currentPage = ref(1)
  const deliveryMethods = ref<DeliveryMethod[]>([
    { id: 1, name: 'Standard Delivery', price: 0, description: '5-7 business days' },
    { id: 2, name: 'Express Delivery', price: 15, description: '2-3 business days' },
    { id: 3, name: 'Priority Delivery', price: 30, description: 'Next business day' }
  ])

  const items = computed(() => {
    if (!activeCartId.value) return []
    const cart = carts.value.find(c => c.id === activeCartId.value)
    return cart ? cart.items : []
  })

  const activeCart = computed(() => {
    return carts.value.find(c => c.id === activeCartId.value) || null
  })

  const productsTotal = computed(() => {
    return items.value.reduce((sum, item) => sum + (item.price * item.quantity), 0)
  })

  const vatAmount = computed(() => {
    return productsTotal.value * vatRate.value
  })

  const orderTotal = computed(() => {
    return productsTotal.value + shippingCost.value + vatAmount.value
  })

  const itemCount = computed(() => {
    return items.value.reduce((sum, item) => sum + item.quantity, 0)
  })

  function createCart(name: string): Cart {
    const newCart: Cart = {
      id: `cart-${Date.now()}`,
      name,
      items: []
    }
    carts.value.push(newCart)
    activeCartId.value = newCart.id

    return newCart
  }

  function deleteCart(cartId: string) {
    const index = carts.value.findIndex(c => c.id === cartId)
    if (index !== -1) {
      carts.value.splice(index, 1)
        if (activeCartId.value === cartId) {
          const firstCart = carts.value[0]
          activeCartId.value = firstCart ? firstCart.id : null
        }
    }
  }

  function renameCart(cartId: string, newName: string) {
    const cart = carts.value.find(c => c.id === cartId)
    if (cart) {
      cart.name = newName
    }
  }

  function setActiveCart(cartId: string) {
    const cart = carts.value.find(c => c.id === cartId)
    if (cart) {
      activeCartId.value = cartId
    }
  }

  function addItemToActiveCart(item: CartItem) {
    if (!activeCartId.value) {
      createCart('Cart 1')
    }
    const cart = carts.value.find(c => c.id === activeCartId.value)
    if (cart) {
      const existingItem = cart.items.find(i => i.productId === item.productId)
      if (existingItem) {
        existingItem.quantity += item.quantity
      } else {
        cart.items.push(item)
      }
    }
  }

  function updateQuantity(itemId: number, quantity: number) {
    const cart = carts.value.find(c => c.id === activeCartId.value)
    if (!cart) return
    
    const item = cart.items.find(i => i.id === itemId)
    if (item) {
      if (quantity <= 0) {
        removeItem(itemId)
      } else {
        item.quantity = quantity
      }
    }
  }

  function deleteProduct(id: number): boolean {
    const cart = carts.value.find(c => c.id === activeCartId.value)
    if (!cart) return false
    
    const index = cart.items.findIndex(a => a.id === id)
    if (index === -1) return false

    cart.items.splice(index, 1)
    resetProductPagination()
    return true
  }

  function resetProductPagination() {
    currentPage.value = 1
  }

  function removeItem(itemId: number) {
    const cart = carts.value.find(c => c.id === activeCartId.value)
    if (!cart) return
    
    const index = cart.items.findIndex(i => i.id === itemId)
    if (index !== -1) {
      cart.items.splice(index, 1)
    }
  }

  function clearCart() {
    const cart = carts.value.find(c => c.id === activeCartId.value)
    if (cart) {
      cart.items = []
    }
    selectedAddressId.value = null
    selectedDeliveryMethodId.value = null
    shippingCost.value = 0
  }

  function setSelectedAddress(addressId: number | null) {
    selectedAddressId.value = addressId
  }

  function setDeliveryMethod(methodId: number) {
    selectedDeliveryMethodId.value = methodId
    const method = deliveryMethods.value.find(m => m.id === methodId)
    if (method) {
      shippingCost.value = method.price
    }
  }

  function initMockData() {
    const cart1: Cart = {
      id: 'cart-1',
      name: 'Cart 1',
      items: [
        { id: 1, productId: 101, name: 'Premium Widget Pro', product_number: 'NC209/7000', image: '/img/product-1.jpg', price: 129.99, quantity: 2 },
        { id: 2, productId: 102, name: 'Ultra Gadget X', product_number: 'NC234/6453', image: '/img/product-2.jpg', price: 89.50, quantity: 1 }
      ]
    }
    
    const cart2: Cart = {
      id: 'cart-2',
      name: 'Cart 2',
      items: [
        { id: 3, productId: 103, name: 'Mega Tool Set', product_number: 'NC324/9030', image: '/img/product-3.jpg', price: 249.00, quantity: 3 }
      ]
    }
    
    const cart3: Cart = {
      id: 'cart-3',
      name: 'Cart 3',
      items: []
    }

    carts.value = [cart1, cart2, cart3]
    activeCartId.value = 'cart-1'
  }

  initMockData()

  return {
    carts,
    activeCartId,
    activeCart,
    items,
    selectedAddressId,
    selectedDeliveryMethodId,
    shippingCost,
    vatRate,
    deliveryMethods,
    productsTotal,
    vatAmount,
    orderTotal,
    itemCount,
    
    createCart,
    deleteCart,
    renameCart,
    setActiveCart,
    addItemToActiveCart,
    updateQuantity,
    deleteProduct,
    removeItem,
    clearCart,
    setSelectedAddress,
    setDeliveryMethod
  }
})