import { encodeFunctionData } from 'viem'
import type {
  EVMGasConfig,
  EVMNativeTransferRequest,
  EVMContractCallRequest,
  EVMTransactionParams,
  EVMDataTransferRequest
} from '@meshconnect/uwc-types'
import { parseError } from '../../utils/error-utils'

/**
 * Service for handling Ethereum/EVM transaction operations
 */
export class EthereumTransactionBuilder {
  async getContractTransaction(
    request: EVMContractCallRequest
  ): Promise<EVMTransactionParams> {
    try {
      // Encode function data using viem
      const data = encodeFunctionData({
        abi: request.abi,
        functionName: request.functionName,
        args: request.args || []
      })
      const txRequest: EVMTransactionParams = {
        to: request.contractAddress,
        data,
        value: request.value ?? 0n,
        ...this.formatGasConfig(request.gasConfig)
      }
      return txRequest
    } catch (error) {
      parseError(error)
    }
  }

  async getNativeTransaction(
    request: EVMNativeTransferRequest
  ): Promise<EVMTransactionParams> {
    try {
      return {
        to: request.to,
        value: request.amount,
        ...this.formatGasConfig(request.gasConfig)
      }
    } catch (error) {
      parseError(error)
    }
  }

  async getDataTransaction(
    request: EVMDataTransferRequest
  ): Promise<EVMTransactionParams> {
    try {
      const txRequest: EVMTransactionParams = {
        to: request.to,
        data: request.data,
        value: request.value ?? 0n,
        ...this.formatGasConfig(request.gasConfig)
      }

      return txRequest
    } catch (error) {
      parseError(error)
    }
  }

  /**
   * Helper to format gas configuration for viem
   */
  private formatGasConfig(
    gasConfig?: EVMGasConfig
  ): Partial<EVMTransactionParams> {
    const txOptions: Partial<EVMTransactionParams> = {}
    if (gasConfig?.gasLimit) {
      txOptions.gasLimit = BigInt(Math.floor(gasConfig.gasLimit))
    }
    if (gasConfig?.maxFeePerGas) {
      txOptions.maxFeePerGas = BigInt(Math.floor(gasConfig.maxFeePerGas))
    }
    if (gasConfig?.maxPriorityFeePerGas) {
      txOptions.maxPriorityFeePerGas = BigInt(
        Math.floor(gasConfig.maxPriorityFeePerGas)
      )
    }
    return txOptions
  }
}