import { ref, computed } from 'vue'
import type { Expense, SettlementActivityCreate } from '@/types/expense'
import type { CreateExpenseData, UpdateExpenseData } from '@/services/expenseService'
import { expenseService } from '@/services/expenseService'

export function useExpenses() {
  const expenses = ref<Expense[]>([])
  const loading = ref(false)
  const error = ref<string | null>(null)

  const recurringExpenses = computed(() => expenses.value.filter((expense) => expense.isRecurring))

  const fetchExpenses = async (params?: {
    list_id?: number
    group_id?: number
    isRecurring?: boolean
  }) => {
    loading.value = true
    error.value = null
    try {
      expenses.value = await expenseService.getExpenses(params)
    } catch (err) {
      error.value = err instanceof Error ? err.message : 'Failed to fetch expenses'
      throw err
    } finally {
      loading.value = false
    }
  }

  const createExpense = async (data: CreateExpenseData) => {
    loading.value = true
    error.value = null
    try {
      const newExpense = await expenseService.createExpense(data)
      expenses.value.push(newExpense)
      return newExpense
    } catch (err) {
      error.value = err instanceof Error ? err.message : 'Failed to create expense'
      throw err
    } finally {
      loading.value = false
    }
  }

  const updateExpense = async (id: number, data: UpdateExpenseData) => {
    loading.value = true
    error.value = null
    try {
      const updatedExpense = await expenseService.updateExpense(id, data)
      const index = expenses.value.findIndex((e) => e.id === id)
      if (index !== -1) {
        expenses.value[index] = updatedExpense
      }
      return updatedExpense
    } catch (err) {
      error.value = err instanceof Error ? err.message : 'Failed to update expense'
      throw err
    } finally {
      loading.value = false
    }
  }

  const deleteExpense = async (id: number) => {
    loading.value = true
    error.value = null
    try {
      await expenseService.deleteExpense(id)
      expenses.value = expenses.value.filter((e) => e.id !== id)
    } catch (err) {
      error.value = err instanceof Error ? err.message : 'Failed to delete expense'
      throw err
    } finally {
      loading.value = false
    }
  }

  const settleExpenseSplit = async (expense_split_id: number, activity: SettlementActivityCreate) => {
    try {
      await expenseService.settleExpenseSplit(expense_split_id, activity)
      // refetch or update locally later
    } catch (err) {
      error.value = err instanceof Error ? err.message : 'Failed to settle split'
      throw err
    }
  }

  const getExpense = async (id: number) => {
    loading.value = true
    error.value = null
    try {
      return await expenseService.getExpense(id)
    } catch (err) {
      error.value = err instanceof Error ? err.message : 'Failed to fetch expense'
      throw err
    } finally {
      loading.value = false
    }
  }

  return {
    expenses,
    recurringExpenses,
    loading,
    error,
    fetchExpenses,
    createExpense,
    updateExpense,
    deleteExpense,
    settleExpenseSplit,
    getExpense,
  }
}