const axios = require('axios')
const bolt11 = require('bolt11')
const _ = require('lodash/fp')
const BN = require('../../../bn')

const NAME = 'LNBits'
const SUPPORTED_COINS = ['LN']

function checkCryptoCode(cryptoCode) {
  if (!SUPPORTED_COINS.includes(cryptoCode)) {
    return Promise.reject(new Error(`Unsupported crypto: ${cryptoCode}`))
  }
  return Promise.resolve()
}

function validateConfig(account) {
  const required = ['endpoint', 'adminKey']
  for (const field of required) {
    if (!account[field]) {
      throw new Error(`LNBits configuration missing: ${field}`)
    }
  }
  
  try {
    new URL(account.endpoint)
  } catch (error) {
    throw new Error(`Invalid LNBits endpoint URL: ${account.endpoint}`)
  }
}

async function request(endpoint, method = 'GET', data = null, apiKey) {
  const config = {
    method,
    url: endpoint,
    headers: {
      'Content-Type': 'application/json',
      'X-API-KEY': apiKey
    },
    timeout: 30000
  }
  
  if (data) {
    config.data = data
  }
  
  try {
    const response = await axios(config)
    return response.data
  } catch (error) {
    if (error.response) {
      const detail = error.response.data?.detail || error.response.statusText
      throw new Error(`LNBits API Error: ${detail} (${error.response.status})`)
    }
    throw new Error(`LNBits Network Error: ${error.message}`)
  }
}

function extractPaymentHash(bolt11Invoice) {
  try {
    const decoded = bolt11.decode(bolt11Invoice)
    return decoded.tagsObject.payment_hash
  } catch (error) {
    throw new Error(`Invalid Lightning invoice: ${error.message}`)
  }
}

function isLnInvoice(address) {
  if (!address || typeof address !== 'string') return false
  return address.toLowerCase().startsWith('lnbc') || 
         address.toLowerCase().startsWith('lntb') ||
         address.toLowerCase().startsWith('lnbcrt')
}

function isLnurl(address) {
  if (!address || typeof address !== 'string') return false
  return address.toLowerCase().startsWith('lnurl')
}

async function newAddress(account, info, tx) {
  validateConfig(account)
  const { cryptoAtoms, cryptoCode } = tx
  
  await checkCryptoCode(cryptoCode)
  
  const invoiceData = {
    out: false,
    amount: parseInt(cryptoAtoms.toString()),
    unit: 'sat',
    memo: `Lamassu ATM - ${new Date().toISOString()}`,
    expiry: 3600
  }
  
  const endpoint = `${account.endpoint}/api/v1/payments`
  const result = await request(endpoint, 'POST', invoiceData, account.adminKey)
  
  if (!result.payment_request) {
    throw new Error('LNBits did not return a payment request')
  }
  
  return result.payment_request
}

async function getStatus(account, tx) {
  validateConfig(account)
  const { toAddress, cryptoCode } = tx
  
  await checkCryptoCode(cryptoCode)
  
  if (!isLnInvoice(toAddress)) {
    return { status: 'notSeen' }
  }
  
  const paymentHash = extractPaymentHash(toAddress)
  const endpoint = `${account.endpoint}/api/v1/payments/${paymentHash}`
  
  try {
    const result = await request(endpoint, 'GET', null, account.adminKey)
    
    if (result.paid === true) {
      return { status: 'confirmed' }
    } else if (result.paid === false && result.pending === true) {
      return { status: 'pending' }
    } else {
      return { status: 'notSeen' }
    }
  } catch (error) {
    if (error.message.includes('404')) {
      return { status: 'notSeen' }
    }
    throw error
  }
}

async function sendCoins(account, tx) {
  validateConfig(account)
  const { toAddress, cryptoAtoms, cryptoCode } = tx
  
  await checkCryptoCode(cryptoCode)
  
  const paymentData = {
    out: true,
    bolt11: toAddress
  }
  
  const decoded = bolt11.decode(toAddress)
  const invoiceAmount = decoded.satoshis
  
  if (!invoiceAmount || invoiceAmount === 0) {
    paymentData.amount = parseInt(cryptoAtoms.toString())
  }
  
  const endpoint = `${account.endpoint}/api/v1/payments`
  const result = await request(endpoint, 'POST', paymentData, account.adminKey)
  
  if (!result.payment_hash) {
    throw new Error('LNBits payment failed: No payment hash returned')
  }
  
  return {
    txid: result.payment_hash,
    fee: result.fee_msat ? Math.ceil(result.fee_msat / 1000) : 0
  }
}

async function balance(account, cryptoCode) {
  validateConfig(account)
  await checkCryptoCode(cryptoCode)
  
  const endpoint = `${account.endpoint}/api/v1/wallet`
  const result = await request(endpoint, 'GET', null, account.adminKey)
  
  if (result.balance === undefined) {
    throw new Error('LNBits did not return wallet balance')
  }
  
  const balanceSats = Math.floor(result.balance / 1000)
  return new BN(balanceSats)
}

async function newFunding(account, cryptoCode) {
  await checkCryptoCode(cryptoCode)
  validateConfig(account)
  
  const promises = [
    balance(account, cryptoCode),
    newAddress(account, { cryptoCode }, { cryptoCode, cryptoAtoms: new BN(100000) })
  ]
  
  const [walletBalance, fundingAddress] = await Promise.all(promises)
  
  return {
    fundingAddress,
    fundingAddressQr: fundingAddress,
    confirmed: walletBalance.gte(0),
    confirmedBalance: walletBalance.toString()
  }
}

async function probeLN(account, cryptoCode, invoice) {
  validateConfig(account)
  await checkCryptoCode(cryptoCode)
  
  if (!isLnInvoice(invoice)) {
    throw new Error('Invalid Lightning invoice provided for probe')
  }
  
  const endpoint = `${account.endpoint}/api/v1/payments/decode`
  const decodeData = { data: invoice }
  
  try {
    const result = await request(endpoint, 'POST', decodeData, account.adminKey)
    
    const amountSats = result.amount_msat ? Math.floor(result.amount_msat / 1000) : 0
    
    const limits = [200000, 1000000, 2000000]
    const probeResults = limits.map(limit => amountSats <= limit)
    
    return probeResults
  } catch (error) {
    console.error('LNBits probe error:', error.message)
    return [false, false, false]
  }
}

function cryptoNetwork(account, cryptoCode) {
  const endpoint = account.endpoint || ''
  if (endpoint.includes('testnet') || endpoint.includes('test')) {
    return 'test'
  }
  if (endpoint.includes('regtest') || endpoint.includes('local')) {
    return 'regtest'
  }
  return 'main'
}

module.exports = {
  NAME,
  balance,
  sendCoins,
  newAddress,
  getStatus,
  newFunding,
  probeLN,
  cryptoNetwork,
  isLnInvoice,
  isLnurl
}