degmods.com/src/pages/blog/loader.ts

import { filterForEventsTaggingId, NDKFilter } from '@nostr-dev-kit/ndk'
import { NDKContextType } from 'contexts/NDKContext'
import { kinds, nip19 } from 'nostr-tools'
import { LoaderFunctionArgs, redirect } from 'react-router-dom'
import { toast } from 'react-toastify'
import { appRoutes } from 'routes'
import { BlogPageLoaderResult, FilterOptions, NSFWFilter } from 'types'
import {
  DEFAULT_FILTER_OPTIONS,
  getLocalStorageItem,
  log,
  LogType
} from 'utils'
import { extractBlogCardDetails, extractBlogDetails } from 'utils/blog'

export const blogRouteLoader =
  (ndkContext: NDKContextType) =>
  async ({ params }: LoaderFunctionArgs) => {
    const { naddr } = params
    if (!naddr) {
      log(true, LogType.Error, 'Required naddr.')
      return redirect(appRoutes.blogs)
    }

    // Decode author from naddr
    const decoded = nip19.decode<'naddr'>(naddr as `naddr1${string}`)
    const { pubkey } = decoded.data

    try {
      // Get the filter with #a from naddr for the main blog content
      const filter = filterForEventsTaggingId(naddr)
      if (!filter) {
        log(true, LogType.Error, 'Unable to create filter from blog naddr.')
        return redirect(appRoutes.blogs)
      }

      // Get the blog filter options for latest blogs
      const filterOptions = JSON.parse(
        getLocalStorageItem('filter-blog', DEFAULT_FILTER_OPTIONS)
      ) as FilterOptions

      // Fetch 4 in case the current blog is included in the latest
      const latestModsFilter: NDKFilter = {
        authors: [pubkey],
        kinds: [kinds.LongFormArticle],
        limit: 4
      }
      // Add source filter
      if (filterOptions.source === window.location.host) {
        latestModsFilter['#r'] = [filterOptions.source]
      }
      // Filter by NSFW tag
      // NSFWFilter.Show_NSFW -> filter not needed
      // NSFWFilter.Only_NSFW -> true
      // NSFWFilter.Hide_NSFW -> false
      if (filterOptions.nsfw !== NSFWFilter.Show_NSFW) {
        latestModsFilter['#nsfw'] = [
          (filterOptions.nsfw === NSFWFilter.Only_NSFW).toString()
        ]
      }

      // Parallel fetch blog event and latest events
      const settled = await Promise.allSettled([
        ndkContext.fetchEvent(filter),
        ndkContext.fetchEvents(latestModsFilter)
      ])

      const result: BlogPageLoaderResult = {
        blog: undefined,
        latest: []
      }

      // Check the blog event result
      const fetchEventResult = settled[0]
      if (fetchEventResult.status === 'fulfilled' && fetchEventResult.value) {
        // Extract the blog details from the event
        result.blog = extractBlogDetails(fetchEventResult.value)
      } else if (fetchEventResult.status === 'rejected') {
        log(
          true,
          LogType.Error,
          'Unable to fetch the blog event.',
          fetchEventResult.reason
        )
      }

      // Check the lateast blog events
      const fetchEventsResult = settled[1]
      if (fetchEventsResult.status === 'fulfilled' && fetchEventsResult.value) {
        // Extract the blog card details from the events
        result.latest = fetchEventsResult.value
          .map(extractBlogCardDetails)
          .filter((b) => b.id !== result.blog?.id) // Filter out current blog if present
          .slice(0, 3) // Take only three
      } else if (fetchEventsResult.status === 'rejected') {
        log(
          true,
          LogType.Error,
          'Unable to fetch the latest blog events.',
          fetchEventsResult.reason
        )
      }

      return result
    } catch (error) {
      log(
        true,
        LogType.Error,
        'An error occurred in fetching blog details from relays',
        error
      )
      toast.error('An error occurred in fetching blog details from relays')
      return redirect(appRoutes.blogs)
    }
  }