import { readFile } from 'fs/promises'
import path from 'path'
import { prisma } from './prisma'

const NOTES_UPLOAD_ROOT = path.join(process.cwd(), 'data', 'uploads', 'notes')

export type UploadMeta = {
  userId: string
  createdAt: number
}

/**
 * Canonical URL form:
 *   /uploads/notes/{userId}/{filename}  ← preferred (ownership in path)
 * Legacy:
 *   /uploads/notes/{filename}           ← meta sidecar or note content
 */

export function uploadMetaPathForRelative(relativeUnderNotes: string): string {
  // relativeUnderNotes e.g. "userId/uuid.png" or "uuid.png"
  return path.join(NOTES_UPLOAD_ROOT, `${relativeUnderNotes}.meta.json`)
}

export async function writeUploadMeta(relativeUnderNotes: string, userId: string): Promise<void> {
  const { writeFile, mkdir } = await import('fs/promises')
  const full = uploadMetaPathForRelative(relativeUnderNotes)
  await mkdir(path.dirname(full), { recursive: true })
  const meta: UploadMeta = { userId, createdAt: Date.now() }
  await writeFile(full, JSON.stringify(meta), 'utf8')
}

async function readUploadMeta(relativeUnderNotes: string): Promise<UploadMeta | null> {
  try {
    const raw = await readFile(uploadMetaPathForRelative(relativeUnderNotes), 'utf8')
    const parsed = JSON.parse(raw) as UploadMeta
    if (parsed?.userId && typeof parsed.userId === 'string') return parsed
    return null
  } catch {
    return null
  }
}

/**
 * @param pathSegments path after `/uploads/` e.g. `['notes', userId, 'file.png']` or `['notes', 'file.png']`
 */
export async function canAccessUploadedNoteImage(
  pathSegments: string[],
  userId: string | null | undefined,
): Promise<boolean> {
  if (pathSegments.length < 2 || pathSegments[0] !== 'notes') return false

  // notes/{userId}/{filename}
  if (pathSegments.length >= 3) {
    const ownerId = pathSegments[1]
    const filename = pathSegments[pathSegments.length - 1]
    const relative = pathSegments.slice(1).join('/') // userId/file.png
    const imagePath = `/uploads/notes/${relative}`

    // 1) Path ownership — definitive for new uploads
    if (userId && ownerId === userId) return true

    // 2) Meta (redundant but safe)
    if (userId) {
      const meta = await readUploadMeta(relative)
      if (meta?.userId === userId) return true
    }

    // 3) Public note embeds this URL
    const published = await noteContainsImage({ imagePath, filename, isPublic: true })
    if (published) return true

    if (!userId) return false

    // 4) Private note owned by user embeds this URL
    return noteContainsImage({ imagePath, filename, userId })
  }

  // Legacy: notes/{filename}
  const filename = pathSegments[1]
  const imagePath = `/uploads/notes/${filename}`

  if (userId) {
    const meta = await readUploadMeta(filename)
    if (meta?.userId === userId) return true
  }

  const published = await noteContainsImage({ imagePath, filename, isPublic: true })
  if (published) return true

  if (!userId) return false
  return noteContainsImage({ imagePath, filename, userId })
}

async function noteContainsImage(opts: {
  imagePath: string
  filename: string
  userId?: string
  isPublic?: boolean
}): Promise<boolean> {
  // Match full URL only (not bare filename) to avoid accidental cross-access
  const where: Record<string, unknown> = {
    trashedAt: null,
    OR: [
      { content: { contains: opts.imagePath } },
      { images: { contains: opts.imagePath } },
      // images JSON sometimes stored without leading path prefix
      { images: { contains: opts.filename } },
    ],
  }
  if (opts.isPublic) where.isPublic = true
  if (opts.userId) where.userId = opts.userId

  const row = await prisma.note.findFirst({
    where,
    select: { id: true },
  })
  return !!row
}