package ethbalanceofhelper

import (
	"context"
	"errors"
	"fmt"
	"math/big"
	"net/http"
	"net/url"
	"strings"

	"github.com/ethereum/go-ethereum"
	"github.com/ethereum/go-ethereum/accounts/abi"
	"github.com/ethereum/go-ethereum/common"
	"github.com/ethereum/go-ethereum/ethclient"
	"github.com/ethereum/go-ethereum/rpc"
	"github.com/shopspring/decimal"
)

// ERC-20 代币合约 ABI (部分，只包含 balanceOf)
// ERC-20 代币合约 ABI (部分，只包含 balanceOf 和 decimals)
const erc20ABI = `[
    {
        "constant": true,
        "inputs": [ { "name": "_owner", "type": "address" } ],
        "name": "balanceOf",
        "outputs": [ { "name": "balance", "type": "uint256" } ],
        "type": "function"
    },
    {
        "constant": true,
        "inputs": [],
        "name": "decimals",
        "outputs": [ { "name": "", "type": "uint8" } ],
        "type": "function"
    }
]`

// GetBalance 查询  余额并转换为正常单位 (使用 decimal)
func GetBalance(client *ethclient.Client, tokenAddress, accountAddress string, decimals int) (decimal.Decimal, error) {
	switch tokenAddress {
	case "0":
		return GetEthBalance(client, accountAddress, decimals)
	default:
		return GetERC20Balance(client, tokenAddress, accountAddress, decimals)
	}
}

// GetEthBalance 查询以太坊余额并转换为正常单位 (使用 decimal)
func GetEthBalance(client *ethclient.Client, accountAddress string, decimals int) (decimal.Decimal, error) {
	account := common.HexToAddress(accountAddress)
	balance, err := client.BalanceAt(context.Background(), account, nil)
	if err != nil {
		return decimal.Zero, fmt.Errorf("查询余额失败 err:%v", err)
	}
	balanceDecimal := decimal.NewFromBigInt(balance, 0) // Create decimal from big.Int
	decimalFactor := decimal.NewFromInt(10).Pow(decimal.NewFromInt(int64(decimals)))
	readableBalance := balanceDecimal.Div(decimalFactor)

	return readableBalance, nil
}

// GetERC20Balance 查询 ERC-20 代币余额并转换为正常单位 (使用 decimal)
// tokenAddress: 代币合约地址
// accountAddress: 账户地址
// decimals: 代币精度
// 返回值: 代币余额 (decimal.Decimal)
func GetERC20Balance(client *ethclient.Client, tokenAddress, accountAddress string, decimals int) (decimal.Decimal, error) {
	// 1. 解析 ABI
	contractABI, err := abi.JSON(strings.NewReader(erc20ABI))
	if err != nil {
		return decimal.Zero, fmt.Errorf("解析 ABI 失败: %w", err)
	}

	// 2. 构造 balanceOf 函数调用数据
	balanceOfCallData, err := contractABI.Pack("balanceOf", common.HexToAddress(accountAddress))
	if err != nil {
		return decimal.Zero, fmt.Errorf("构造 balanceOf 调用数据失败: %w", err)
	}

	address := common.HexToAddress(tokenAddress)
	// 3. 执行 balanceOf 调用
	balanceResult, err := client.CallContract(context.Background(), ethereum.CallMsg{
		To:   &address,
		Data: balanceOfCallData,
	}, nil)
	if err != nil {
		return decimal.Zero, fmt.Errorf("调用 balanceOf 失败: %w", err)
	}

	// 4. 解析 balanceOf 结果
	unpackedBalance, err := contractABI.Unpack("balanceOf", balanceResult)
	if err != nil {
		return decimal.Zero, fmt.Errorf("解析 balanceOf 结果失败: %w", err)
	}

	balance, ok := unpackedBalance[0].(*big.Int)
	if !ok {
		return decimal.Zero, errors.New("解析 balanceOf 结果为 *big.Int 失败")
	}

	// 8. 转换为正常单位 (使用 decimal)
	balanceDecimal := decimal.NewFromBigInt(balance, 0) // Create decimal from big.Int
	decimalFactor := decimal.NewFromInt(10).Pow(decimal.NewFromInt(int64(decimals)))
	readableBalance := balanceDecimal.Div(decimalFactor)

	return readableBalance, nil
}

// 初始化以太坊客户端连接代理
func EthClientWithProxy(rawURL string, proxyURL string) (*ethclient.Client, error) {
	u, err := url.Parse(rawURL)
	if err != nil {
		return nil, fmt.Errorf("invalid URL: %v", err)
	}

	if proxyURL == "" {
		return ethclient.Dial(rawURL)
	}

	proxy, err := url.Parse(proxyURL)
	if err != nil {
		return nil, fmt.Errorf("invalid proxy URL: %v", err)
	}

	httpClient := &http.Client{
		Transport: &http.Transport{
			Proxy: http.ProxyURL(proxy),
		},
	}
	dialOptions := []rpc.ClientOption{
		rpc.WithHTTPClient(httpClient),
	}
	rpcClient, err := rpc.DialOptions(context.Background(), u.String(), dialOptions...)
	if err != nil {
		return nil, fmt.Errorf("failed to dial RPC client with options: %v", err)
	}

	return ethclient.NewClient(rpcClient), nil
}