/**
 * useGasEstimate Hook
 *
 * Estimates gas costs for blockchain transactions before execution.
 *
 * Features:
 * - Fetch current gas price
 * - Estimate gas limit for specific operations
 * - Calculate total cost in ETH and USD
 * - Real-time gas price updates
 *
 * NOTE: This is pseudocode/skeleton showing the architecture.
 */

import { useState, useEffect, useCallback } from 'react'
import { useWeb3Wallet } from './useWeb3Wallet'

interface GasEstimate {
  gasLimit: number
  gasPrice: number // in wei
  gasPriceGwei: number
  costEth: string
  costUsd: string
  isLoading: boolean
  error: string | null
}

interface UseGasEstimateReturn extends GasEstimate {
  refresh: () => Promise<void>
}

type TransactionType = 'create_bet' | 'accept_bet' | 'settle_bet' | 'dispute_bet'

/**
 * Hook to estimate gas costs for transactions
 */
export const useGasEstimate = (
  transactionType: TransactionType,
  params?: any
): UseGasEstimateReturn => {
  const { isConnected, chainId } = useWeb3Wallet()
  const [estimate, setEstimate] = useState<GasEstimate>({
    gasLimit: 0,
    gasPrice: 0,
    gasPriceGwei: 0,
    costEth: '0',
    costUsd: '0',
    isLoading: true,
    error: null
  })

  /**
   * Fetch gas estimate from backend
   */
  const fetchEstimate = useCallback(async () => {
    // For MVP: Skip wallet requirement, just return mock estimates
    setEstimate(prev => ({ ...prev, isLoading: true, error: null }))

    try {
      // Placeholder estimates for different transaction types
      const estimates: Record<TransactionType, { gasLimit: number; gasPriceGwei: number }> = {
        'create_bet': { gasLimit: 120000, gasPriceGwei: 50 },
        'accept_bet': { gasLimit: 180000, gasPriceGwei: 50 },
        'settle_bet': { gasLimit: 150000, gasPriceGwei: 50 },
        'dispute_bet': { gasLimit: 100000, gasPriceGwei: 50 }
      }

      const { gasLimit, gasPriceGwei } = estimates[transactionType]
      const gasPrice = gasPriceGwei * 1e9 // Convert to wei
      const costWei = gasLimit * gasPrice
      const costEth = (costWei / 1e18).toFixed(6)
      const ethPriceUsd = 2000 // Placeholder - would fetch from price oracle
      const costUsd = (parseFloat(costEth) * ethPriceUsd).toFixed(2)

      setEstimate({
        gasLimit,
        gasPrice,
        gasPriceGwei,
        costEth,
        costUsd,
        isLoading: false,
        error: null
      })
    } catch (error: any) {
      console.error('[Gas] Failed to fetch estimate:', error)
      setEstimate(prev => ({
        ...prev,
        isLoading: false,
        error: 'Failed to estimate gas'
      }))
    }
  }, [transactionType])

  /**
   * Fetch estimate on mount and when transaction type changes
   */
  useEffect(() => {
    fetchEstimate()
  }, [transactionType])

  return {
    ...estimate,
    refresh: fetchEstimate
  }
}

/**
 * Hook to get current gas price (without specific transaction estimate)
 */
export const useGasPrice = () => {
  const [gasPrice, setGasPrice] = useState<{
    gwei: number
    wei: number
    isLoading: boolean
  }>({
    gwei: 0,
    wei: 0,
    isLoading: true
  })

  useEffect(() => {
    const fetchGasPrice = async () => {
      // Pseudocode: Fetch from RPC
      // const provider = new ethers.providers.Web3Provider(window.ethereum)
      // const price = await provider.getGasPrice()
      // const gwei = parseFloat(ethers.utils.formatUnits(price, 'gwei'))

      // Placeholder
      const gwei = 50
      const wei = gwei * 1e9

      setGasPrice({
        gwei,
        wei,
        isLoading: false
      })
    }

    fetchGasPrice()

    const interval = setInterval(fetchGasPrice, 30000)
    return () => clearInterval(interval)
  }, [])

  return gasPrice
}
