import { dlopen } from "node:ffi"
import type { ReadStream } from "node:tty"

const STD_INPUT_HANDLE = -10
const ENABLE_PROCESSED_INPUT = 0x0001

const kernel = () =>
  dlopen("kernel32.dll", {
    GetStdHandle: { arguments: ["i32"], return: "pointer" },
    GetConsoleMode: { arguments: ["pointer", "pointer"], return: "i32" },
    SetConsoleMode: { arguments: ["pointer", "u32"], return: "i32" },
    FlushConsoleInputBuffer: { arguments: ["pointer"], return: "i32" },
  }).functions

let k32: ReturnType<typeof kernel> | undefined

function load() {
  if (process.platform !== "win32") return false
  try {
    k32 ??= kernel()
    return true
  } catch {
    return false
  }
}

export function win32DisableProcessedInput() {
  if (process.platform !== "win32" || !process.stdin.isTTY || !load()) return
  const handle = k32!.GetStdHandle(STD_INPUT_HANDLE)
  const buffer = new Uint32Array(1)
  if (k32!.GetConsoleMode(handle, buffer) === 0) return
  const mode = buffer[0]!
  if ((mode & ENABLE_PROCESSED_INPUT) === 0) return
  k32!.SetConsoleMode(handle, mode & ~ENABLE_PROCESSED_INPUT)
}

export function win32FlushInputBuffer() {
  if (process.platform !== "win32" || !process.stdin.isTTY || !load()) return
  k32!.FlushConsoleInputBuffer(k32!.GetStdHandle(STD_INPUT_HANDLE))
}

let unhook: (() => void) | undefined

export function win32InstallCtrlCGuard() {
  if (process.platform !== "win32" || !process.stdin.isTTY || !load() || unhook) return unhook
  const stdin = process.stdin as ReadStream
  const original = stdin.setRawMode
  const handle = k32!.GetStdHandle(STD_INPUT_HANDLE)
  const buffer = new Uint32Array(1)
  if (k32!.GetConsoleMode(handle, buffer) === 0) return
  const initial = buffer[0]!
  const enforce = () => {
    if (k32!.GetConsoleMode(handle, buffer) === 0) return
    const mode = buffer[0]!
    if ((mode & ENABLE_PROCESSED_INPUT) !== 0) k32!.SetConsoleMode(handle, mode & ~ENABLE_PROCESSED_INPUT)
  }
  const later = () => {
    enforce()
    setImmediate(enforce)
  }
  const wrapped: ReadStream["setRawMode"] = (mode) => {
    const result = original.call(stdin, mode)
    later()
    return result
  }
  stdin.setRawMode = wrapped
  later()
  const interval = setInterval(enforce, 100)
  interval.unref()
  unhook = () => {
    clearInterval(interval)
    if (stdin.setRawMode === wrapped) stdin.setRawMode = original
    k32!.SetConsoleMode(handle, initial)
    unhook = undefined
  }
  return unhook
}