generate.server.ts

import { ImageResponse, type ImageResponseOptions } from 'takumi-js/response'
import { findLibrary } from '~/libraries'
import type { LibraryId } from '~/libraries'
import { loadOgAssets as loadNodeOgAssets } from './assets.server'
import { getAccentColor } from './colors'
import { buildOgTree } from './template'
import {
  MAX_OG_DESCRIPTION_LENGTH,
  MAX_OG_TITLE_LENGTH,
  clampOgText,
} from '~/utils/og-limits'

const ISLAND_KEY = 'island'

type GenerateInput = {
  libraryId: LibraryId | string
  requestUrl?: string
  title?: string
  description?: string
}

export type OgLibraryNotFoundError = {
  kind: 'library-not-found'
  libraryId: string
}

export async function generateOgImageResponse(
  input: GenerateInput,
  init?: ResponseInit,
): Promise<ImageResponse | OgLibraryNotFoundError> {
  const library = findLibrary(input.libraryId)
  if (!library) {
    return { kind: 'library-not-found', libraryId: input.libraryId }
  }

  const assets = await loadNodeOgAssets(input.requestUrl)
  const tree = buildOgTree({
    libraryName: library.name,
    accentColor: getAccentColor(library.id),
    islandSrc: ISLAND_KEY,
    pitch: clampOgText(library.tagline ?? '', MAX_OG_DESCRIPTION_LENGTH),
    docTitle: input.title?.trim()
      ? clampOgText(input.title, MAX_OG_TITLE_LENGTH)
      : undefined,
    description: input.description?.trim()
      ? clampOgText(input.description, MAX_OG_DESCRIPTION_LENGTH)
      : undefined,
  })

  const options: ImageResponseOptions = {
    width: 1200,
    height: 630,
    format: 'png',
    fonts: [
      {
        name: 'Inter',
        data: assets.interRegular,
        weight: 400,
        style: 'normal',
      },
      {
        name: 'Inter',
        data: assets.interExtraBold,
        weight: 800,
        style: 'normal',
      },
      {
        name: 'Inter',
        data: assets.interBlack,
        weight: 900,
        style: 'normal',
      },
    ],
    images: [{ src: ISLAND_KEY, data: assets.islandPng }],
    ...init,
  }

  return new ImageResponse(tree, options)
}