import type { WireMiniAppHost } from '@farcaster/miniapp-core'
import type { Remote } from 'comlink'
import type { Emitter } from './types.ts'

export type Back = {
  visible: boolean
  show: () => Promise<void>
  hide: () => Promise<void>
  onback: (() => unknown) | null
  enableWebNavigation: () => Promise<void>
  disableWebNavigation: () => Promise<void>
}

export const createBack: (options: {
  emitter: Emitter
  miniAppHost: Remote<WireMiniAppHost>
}) => Back = ({ miniAppHost, emitter }) => {
  let teardownWebNavigation: (() => void) | undefined
  let backCb: (() => unknown) | null = null

  return {
    visible: false,
    get onback() {
      return backCb
    },
    set onback(cb) {
      if (backCb) {
        emitter.removeListener('backNavigationTriggered', backCb)
      }
      backCb = cb
      if (cb) {
        emitter.addListener('backNavigationTriggered', cb)
      }
    },
    async show() {
      await miniAppHost.updateBackState({
        visible: true,
      })
      this.visible = true
    },
    async hide() {
      await miniAppHost.updateBackState({
        visible: false,
      })
      this.visible = false
    },
    async enableWebNavigation() {
      teardownWebNavigation = setupWebBack({
        back: this,
        emitter,
      })
    },
    async disableWebNavigation() {
      teardownWebNavigation?.()
      teardownWebNavigation = undefined
    },
  }
}

function setupWebBack({ emitter, back }: { emitter: Emitter; back: Back }) {
  const navigation = getWebNavigation()
  if (navigation) {
    return setupNavigationApi({ emitter, back, navigation })
  }

  if (typeof window !== 'undefined') {
    return setupFallback({ emitter, back, window })
  }
}

function getWebNavigation(): Navigation | undefined {
  if (typeof window !== 'undefined' && window.navigation !== undefined) {
    return window.navigation
  }
}

function setupNavigationApi({
  emitter,
  back,
  navigation,
}: {
  emitter: Emitter
  back: Back
  navigation: Navigation
}) {
  function handleNavigateSuccess() {
    if (navigation.canGoBack) {
      back.show()
    } else {
      back.hide()
    }
  }

  function handleBackNavigationTriggered() {
    if (back.visible && navigation.canGoBack) {
      navigation.back()
    }
  }

  navigation.addEventListener('navigatesuccess', handleNavigateSuccess)
  emitter.addListener('backNavigationTriggered', handleBackNavigationTriggered)

  return () => {
    navigation.removeEventListener('navigatesuccess', handleNavigateSuccess)
    emitter.removeListener(
      'backNavigationTriggered',
      handleBackNavigationTriggered,
    )
  }
}

function setupFallback({
  emitter,
  back,
  window,
}: {
  emitter: Emitter
  back: Back
  window: Window
}) {
  back.show()

  function handleBackNavigationTriggered() {
    if (back.visible) {
      window.history.back()
    }
  }

  emitter.addListener('backNavigationTriggered', handleBackNavigationTriggered)

  return () => {
    emitter.removeListener(
      'backNavigationTriggered',
      handleBackNavigationTriggered,
    )
  }
}