import { NextResponse } from "next/server"
import { getSessionUser } from "@/lib/session"
import { readFile, contentTypeForKey } from "@/lib/storage"

// Only these image types are safe to render inline from our origin. Everything
// else (including svg, html, documents) is forced to download as an attachment.
const INLINE_EXTENSIONS = ["png", "jpg", "jpeg", "gif", "webp"]

// Auth-gated file serving. Storage keys are namespaced by user id
// (`<userId>/<scope>/<file>`), so a file belongs to the requester iff the key's
// first segment equals their session user id.
export async function GET(_: Request, { params }: { params: Promise<{ key: string[] }> }) {
  const user = await getSessionUser()
  if (!user) return NextResponse.json({ error: "Unauthorized" }, { status: 401 })

  const { key: segments } = await params
  const key = segments.map((s) => decodeURIComponent(s)).join("/")

  if (!key.startsWith(`${user.id}/`)) {
    return NextResponse.json({ error: "Forbidden" }, { status: 403 })
  }

  try {
    const buffer = await readFile(key)

    const ext = key.split(".").pop()?.toLowerCase() ?? ""
    const disposition = INLINE_EXTENSIONS.includes(ext) ? "inline" : "attachment"
    const basename = (key.split("/").pop() ?? "file").replace(/["\\\r\n\x00-\x1f]/g, "")

    return new NextResponse(new Uint8Array(buffer), {
      headers: {
        "Content-Type": contentTypeForKey(key),
        "Content-Disposition": `${disposition}; filename="${basename}"`,
        "X-Content-Type-Options": "nosniff",
        "Cache-Control": "private, max-age=3600",
      },
    })
  } catch {
    return NextResponse.json({ error: "Not found" }, { status: 404 })
  }
}