flotilla/src/app/push/adapters/common.ts

import type {Subscriber, Unsubscriber} from "svelte/store"
import {Capacitor} from "@capacitor/core"
import {call, ms, now, on, parseJson, poll, spec, throttle, uniq} from "@welshman/lib"
import {LOCAL_RELAY_URL} from "@welshman/net"
import type {RepositoryUpdate} from "@welshman/net"
import {
  getIdFilters,
  matchFilters,
  tagSpec,
  tagValue,
  verifyEvent,
  MESSAGE,
  WRAP,
  type Filter,
  type TrustedEvent,
} from "@welshman/util"
import {merged, synced, withGetter} from "@welshman/store"
import {User} from "@welshman/app"
import {navigate} from "@app/modal"
import {app, messagingRelayLists, network, roomLists} from "@app/core"
import {DM_KINDS} from "@app/content"
import {getMutedRooms, shouldNotify, userSettingsValues} from "@app/settings"
import {makeEventPath, goToChat, goToSpace} from "@app/routes"
import {kv} from "@app/storage"

export type PushSubscription = {
  key: string
  callback: string
}

export type PushState = {
  token?: string
  useFallback?: boolean
  subscription?: PushSubscription
}

// The F-Droid build ships without the push plugin, so those installs can only ever poll
export const requiresFallback =
  Capacitor.getPlatform() === "android" && !Capacitor.isPluginAvailable("PushNotifications")

export const pushState = withGetter(
  synced<PushState>({
    key: "notificationState",
    storage: kv,
    defaultValue: {useFallback: requiresFallback},
  }),
)

const defaultNotificationSettings = {
  push: false,
  sound: true,
  badge: false,
  spaces: true,
  mentions: true,
  messages: true,
  events: true,
  reminder_minutes: [5],
}

export const notificationSettings = withGetter(
  synced({
    key: "notificationSettings",
    storage: kv,
    defaultValue: defaultNotificationSettings,
  }),
)

// synced restores the saved object whole, so fill in fields added since it was saved.
notificationSettings.ready.then(() =>
  notificationSettings.update(settings => ({...defaultNotificationSettings, ...settings})),
)

export interface IPushAdapter {
  request: (prompt?: boolean) => Promise<string>
  disable: () => Promise<void>
  enable: () => Promise<void>
}

export const onNotification = call(() => {
  const subscribers: Subscriber<TrustedEvent>[] = []

  let unsubscribe: Unsubscriber | undefined

  return (f: (event: TrustedEvent) => void) => {
    subscribers.push(f)

    if (!unsubscribe) {
      let unsubscribeRepository: Unsubscriber | undefined
      const unsubscribeApp = app.subscribe($app => {
        unsubscribeRepository?.()
        const filters = [{kinds: [MESSAGE, ...DM_KINDS], since: now()}]
        unsubscribeRepository = on($app.repository, "update", ({added}: RepositoryUpdate) => {
          const $pubkey = $app.user?.pubkey

          for (const event of added) {
            if (event.pubkey == $pubkey) {
              continue
            }

            const h = tagValue(tagSpec("h"), event.tags)

            if (Array.from($app.tracker.getRelays(event.id)).every(url => !shouldNotify(url, h))) {
              continue
            }

            if (matchFilters(filters, event)) {
              for (const f of subscribers) {
                f(event)
              }
            }
          }
        })
      })
      unsubscribe = () => {
        unsubscribeApp()
        unsubscribeRepository?.()
      }
    }

    return () => {
      subscribers.splice(subscribers.indexOf(f), 1)

      if (subscribers.length === 0) {
        unsubscribe?.()
        unsubscribe = undefined
      }
    }
  }
})

const ingestNotification = async (relay: string, id: string, json?: string) => {
  const pushed = parseJson<TrustedEvent>(json)

  if (pushed && verifyEvent(pushed)) {
    app.get().tracker.track(pushed.id, relay)
    app.get().repository.publish(pushed)

    return pushed
  } else {
    const events = await network.get().request({
      filters: getIdFilters([id]),
      relays: [relay, LOCAL_RELAY_URL],
      // The local relay eoses immediately, so anything less waits on it alone
      threshold: 1,
      autoClose: true,
      signal: AbortSignal.timeout(ms(5)),
    })

    return events[0]
  }
}

// Wraps are ingested into the repository and unwrapped in the background, so wait for the rumor
const loadNotificationRumor = async (wrap: TrustedEvent) => {
  const getRumor = () => app.get().wrapManager.getRumor(wrap.id)

  await poll({condition: () => Boolean(getRumor()), signal: AbortSignal.timeout(ms(5))})

  return getRumor()
}

export const onPushNotificationAction = async (action: {
  notification: {data: {relay: string; id: string; event?: string}}
}) => {
  const {relay, id, event: json} = action.notification.data
  const event = await ingestNotification(relay, id, json)
  const target = event?.kind === WRAP ? await loadNotificationRumor(event) : event
  const path = target && makeEventPath(target, [relay])

  if (path) {
    navigate(path)
  } else if (event?.kind === WRAP) {
    goToChat()
  } else {
    goToSpace(relay)
  }
}

export const syncRelaySubscriptions = (
  signal: AbortSignal,
  sync: (url: string, key: string, filters: Filter[], ignore: Filter[]) => void,
) => {
  const $pubkey = User.require(app.get()).pubkey

  const unsubscribeSpaces = merged([
    roomLists.get().urls($pubkey).$,
    notificationSettings,
    userSettingsValues,
  ]).subscribe(
    throttle(3000, ([$spaceUrls, {spaces, mentions}, $settings]) => {
      const baseFilter = {kinds: [MESSAGE]}

      for (const url of $spaceUrls) {
        const {notify = true, exceptions = []} = $settings.alerts.find(spec({url})) || {}
        const muted = getMutedRooms($settings, url)
        const filters: Filter[] = []
        const ignore: Filter[] = []

        if (spaces) {
          if (notify) {
            const skipped = uniq([...exceptions, ...muted])

            if (skipped.length > 0) {
              ignore.push({"#h": skipped})
            }
            filters.push(baseFilter)
          } else {
            const included = exceptions.filter(h => !muted.includes(h))

            if (included.length > 0) {
              filters.push({...baseFilter, "#h": included})
            }
          }
        }

        if (mentions) {
          filters.push({...baseFilter, "#p": [$pubkey]})
        }

        sync(url, "spaces", filters, ignore)
      }
    }),
  )

  const unsubscribeMessages = merged([
    messagingRelayLists.get().urls($pubkey).$,
    notificationSettings,
  ]).subscribe(
    throttle(3000, ([$messagingUrls, {messages}]) => {
      for (const url of $messagingUrls) {
        const filters: Filter[] = []

        if (messages) {
          filters.push({kinds: [WRAP], "#p": [$pubkey]})
        }

        sync(url, "messages", filters, [])
      }
    }),
  )

  signal.addEventListener("abort", () => {
    unsubscribeSpaces()
    unsubscribeMessages()
  })
}