const {
  buildReadFrame,
  getMaxReadQuantity
} = require('./modbus-rtu')
const controlState = require('./control-page-state')
const controlService = require('./control-service')
const paramsPageState = require('./params-page-state')
const transport = require('./ble-transport')
const {
  notifyPageToast
} = require('./page-toast')
const {
  addCoilReadValues,
  addWordReadValues
} = require('./register-value-utils')

const readValues = {
  coils: {},
  words: {}
}

let paramsSnapshot = paramsPageState.createInitialState()
let paramsSnapshotVersion = 0

const READ_STEPS = [
  {
    address: 0x00,
    functionCode: 0x01,
    label: '同步线圈 00-10',
    quantity: 17,
    onResponse(response, step) {
      addCoilReadValues(readValues, step.address, step.quantity, response)
      controlService.applyControlReadValues(readValues.coils)
    }
  },
  {
    address: 0x30,
    functionCode: 0x03,
    label: '同步估算器参数 30-4A',
    quantity: 27,
    onResponse(response, step) {
      addWordReadValues(readValues, step.address, response)
    }
  },
  {
    address: 0x60,
    functionCode: 0x03,
    label: '同步参数配置 60-8D',
    quantity: 46,
    onResponse(response, step) {
      addWordReadValues(readValues, step.address, response)
      controlService.applyMotorReadWords(response.words || [], step.address)
    }
  },
  {
    address: controlState.DRIVER_PARAM_START_ADDRESS,
    functionCode: 0x04,
    label: '同步驱动器硬件参数 A0-B3',
    quantity: controlState.DRIVER_PARAM_WORD_COUNT,
    onResponse(response, step) {
      addWordReadValues(readValues, step.address, response)
      controlService.applyDriverReadWords(response.words || [])
    }
  },
  {
    address: controlState.STATUS_START_ADDRESS,
    functionCode: 0x04,
    label: '同步状态 C0-DC',
    quantity: controlState.STATUS_WORD_COUNT,
    onResponse(response, step) {
      addWordReadValues(readValues, step.address, response)
      controlService.applyStatusReadWords(response.words || [], step.address)
    }
  }
]

function splitReadStep(step) {
  const maxQuantity = getMaxReadQuantity(step.functionCode)
  if (!maxQuantity || step.quantity <= maxQuantity) return [step]

  const chunks = []
  let offset = 0

  while (offset < step.quantity) {
    const quantity = Math.min(step.quantity - offset, maxQuantity)
    const address = step.address + offset

    chunks.push({
      ...step,
      address,
      label: `${step.label} ${address.toString(16).toUpperCase()}-${(address + quantity - 1).toString(16).toUpperCase()}`,
      quantity
    })
    offset += quantity
  }

  return chunks
}

let syncing = false
const subscribers = []

function getState() {
  return {
    isSyncing: syncing,
    syncVersion: paramsSnapshotVersion
  }
}

function notify() {
  const state = getState()

  subscribers.slice().forEach((subscriber) => {
    subscriber(state)
  })
}

function setSyncing(value) {
  syncing = !!value
  notify()
}

transport.subscribe((transportState) => {
  if (!transportState.connectedDevice && syncing) {
    setSyncing(false)
  }
})

function subscribe(subscriber) {
  if (typeof subscriber !== 'function') return () => {}

  subscribers.push(subscriber)
  subscriber(getState())

  return () => {
    const index = subscribers.indexOf(subscriber)
    if (index >= 0) subscribers.splice(index, 1)
  }
}

function getSharedSlaveAddress() {
  try {
    return transport.getSlaveAddress()
  } catch (error) {
    transport.showCommandAlert('从机地址错误', error.message)
    return null
  }
}

function resetReadValues() {
  readValues.coils = {}
  readValues.words = {}
}

function getParamsSnapshot() {
  return {
    ...paramsSnapshot,
    syncVersion: paramsSnapshotVersion
  }
}

async function syncAllRegisters() {
  if (syncing) return false

  const transportState = transport.getState()
  if (!transportState.connectedDevice) return false

  const slaveAddress = getSharedSlaveAddress()
  if (slaveAddress === null) return false

  setSyncing(true)
  resetReadValues()

  try {
    for (const step of READ_STEPS) {
      for (const chunk of splitReadStep(step)) {
        const response = await transport.sendManagedFrame(
          buildReadFrame(slaveAddress, chunk.functionCode, chunk.address, chunk.quantity),
          chunk.label,
          {
            address: chunk.address,
            functionCode: chunk.functionCode,
            kind: 'sync-read',
            quantity: chunk.quantity,
            slaveAddress
          }
        )

        if (!response) return false
        if (typeof chunk.onResponse === 'function') {
          chunk.onResponse(response, chunk)
        }
      }
    }

    paramsSnapshot = paramsPageState.applyReadValues(paramsSnapshot, readValues)
    paramsSnapshotVersion += 1
    notify()
    notifyPageToast('同步完成')
    return true
  } finally {
    setSyncing(false)
  }
}

module.exports = {
  getParamsSnapshot,
  getState,
  subscribe,
  syncAllRegisters
}