import type { Plugin } from 'payload'
import { s3Storage } from '@payloadcms/storage-s3'

/**
 * Cloudflare R2 media storage — configured from environment variables (agency
 * infrastructure, not per-project panel data). R2 is S3-compatible, so we use
 * @payloadcms/storage-s3 pointed at the R2 endpoint.
 *
 * Storage is infrastructure (like the database or PAYLOAD_SECRET): it binds at
 * boot, and its credentials are agency-owned — so it lives in .env, not the
 * panel. See docs/storage.md for the required variables.
 *
 * Returns the storage plugin when all R2 vars are present; otherwise returns a
 * no-op passthrough so the project falls back to Payload's default local disk
 * storage (useful in dev without R2). This mirrors how mailAdapter degrades
 * gracefully when a transport isn't configured.
 *
 * @param collections - slugs of upload collections to offload to R2 (e.g. ['media'])
 */
export const buildR2Storage = (collections: string[] = ['media']): Plugin => {
  const bucket = process.env.R2_BUCKET
  const endpoint = process.env.R2_ENDPOINT
  const accessKeyId = process.env.R2_ACCESS_KEY_ID
  const secretAccessKey = process.env.R2_SECRET_ACCESS_KEY

  // Any missing → skip R2, fall back to local disk. Warn so it's not silent.
  if (!bucket || !endpoint || !accessKeyId || !secretAccessKey) {
    return (config) => {
      // Only warn when SOME vars are set (partial config = likely a mistake).
      if (bucket || endpoint || accessKeyId || secretAccessKey) {
        console.warn(
          '[ipal] R2 storage: incomplete env (need R2_BUCKET, R2_ENDPOINT, ' +
            'R2_ACCESS_KEY_ID, R2_SECRET_ACCESS_KEY). Falling back to local disk.',
        )
      }
      return config
    }
  }

  const collectionsConfig = Object.fromEntries(collections.map((slug) => [slug, true]))

  return s3Storage({
    collections: collectionsConfig,
    bucket,
    config: {
      endpoint,
      region: 'auto', // R2 uses 'auto'
      credentials: { accessKeyId, secretAccessKey },
      // R2 requires path-style addressing for S3 compatibility.
      forcePathStyle: true,
    },
  })
}