import { NextResponse } from "next/server"
import { readFile } from "node:fs/promises"
import { existsSync } from "node:fs"
import { join } from "node:path"
import { getManualsFilesRoot } from "@/lib/manuals-paths"
import { getManualAssetFromStorage } from "@/lib/manuals-object-storage"

export const dynamic = "force-dynamic"

function decodeSegments(pathArray: string[]) {
  return pathArray.map((segment) => {
    try {
      let decoded = segment
      while (decoded !== decodeURIComponent(decoded)) {
        decoded = decodeURIComponent(decoded)
      }
      return decoded
    } catch {
      return segment
    }
  })
}

function invalidPath(pathValue: string) {
  return pathValue.includes("..") || pathValue.startsWith("/")
}

export async function GET(
  _request: Request,
  { params }: { params: Promise<{ path: string[] }> },
) {
  try {
    const { path: pathArray } = await params
    const decodedPath = decodeSegments(pathArray)
    const filePath = decodedPath.join("/")

    if (invalidPath(filePath) || !filePath.toLowerCase().endsWith(".pdf")) {
      return new NextResponse("Invalid path", { status: 400 })
    }

    const storageObject = await getManualAssetFromStorage("manuals", filePath)
    if (storageObject) {
      return new NextResponse(Buffer.from(storageObject.body), {
        headers: {
          "Content-Type": storageObject.contentType || "application/pdf",
          "Content-Disposition": `inline; filename="${encodeURIComponent(decodedPath.at(-1) || "manual.pdf")}"`,
          "Cache-Control": "public, max-age=31536000, immutable",
          "X-Content-Type-Options": "nosniff",
        },
      })
    }

    const manualsDir = getManualsFilesRoot()
    const fullPath = join(manualsDir, filePath)
    const normalizedFullPath = fullPath.replace(/\\/g, "/")
    const normalizedManualsDir = manualsDir.replace(/\\/g, "/")

    if (!existsSync(normalizedFullPath) && !existsSync(fullPath)) {
      return new NextResponse("File not found", { status: 404 })
    }

    const fileToRead = existsSync(normalizedFullPath) ? normalizedFullPath : fullPath
    const resolvedPath = fileToRead.replace(/\\/g, "/")
    if (!resolvedPath.startsWith(normalizedManualsDir)) {
      return new NextResponse("Invalid path", { status: 400 })
    }

    const fileBuffer = await readFile(fileToRead)
    return new NextResponse(fileBuffer, {
      headers: {
        "Content-Type": "application/pdf",
        "Content-Disposition": `inline; filename="${encodeURIComponent(decodedPath.at(-1) || "manual.pdf")}"`,
        "Cache-Control": "public, max-age=31536000, immutable",
        "X-Content-Type-Options": "nosniff",
      },
    })
  } catch (error) {
    console.error("[manuals-api] failed to serve manual", error)
    return new NextResponse("Internal server error", { status: 500 })
  }
}