"use client"

import { useEffect, useRef } from "react"
import { cn } from "@/lib/utils"

declare global {
  interface Window {
    turnstile?: {
      render: (el: HTMLElement, opts: Record<string, unknown>) => string
      remove: (id: string) => void
      reset: (id?: string) => void
    }
  }
}

const SCRIPT_ID = "cf-turnstile-script"
const SCRIPT_SRC = "https://challenges.cloudflare.com/turnstile/v0/api.js?render=explicit"

/**
 * Cloudflare Turnstile widget (explicit render).
 *
 * Renders inside the enclosing <form>; on success Turnstile injects a hidden
 * <input name="cf-turnstile-response"> that is submitted with the form and
 * verified server-side by verifyTurnstile(). Renders nothing when the public
 * site key is not configured, so the forms still work without Turnstile.
 */
export function TurnstileWidget({ className }: { className?: string }) {
  const siteKey = process.env.NEXT_PUBLIC_TURNSTILE_SITE_KEY
  const containerRef = useRef<HTMLDivElement>(null)
  const widgetIdRef = useRef<string | null>(null)

  useEffect(() => {
    if (!siteKey) return
    let cancelled = false

    const render = () => {
      if (cancelled || widgetIdRef.current || !containerRef.current || !window.turnstile) return
      widgetIdRef.current = window.turnstile.render(containerRef.current, {
        sitekey: siteKey,
        theme: "dark",
        // A Turnstile token is only valid for ~5 minutes. Without these the
        // widget goes quietly stale on a form left open, and the submit fails
        // server-side with "complete the verification challenge" even though
        // the challenge visibly passed. Re-running it keeps the hidden
        // cf-turnstile-response input fresh.
        "refresh-expired": "auto",
        "expired-callback": () => {
          if (widgetIdRef.current) window.turnstile?.reset(widgetIdRef.current)
        },
        "timeout-callback": () => {
          if (widgetIdRef.current) window.turnstile?.reset(widgetIdRef.current)
        },
        "error-callback": () => {
          // Returning false lets Turnstile surface its own error UI rather than
          // leaving an empty box the user can't act on.
          return false
        },
      })
    }

    if (!document.getElementById(SCRIPT_ID)) {
      const script = document.createElement("script")
      script.id = SCRIPT_ID
      script.src = SCRIPT_SRC
      script.async = true
      script.defer = true
      script.onload = render
      document.head.appendChild(script)
    } else {
      render()
    }

    // Fallback: the script may already be cached/loaded so onload won't fire.
    const poll = window.setInterval(() => {
      if (window.turnstile) {
        render()
        window.clearInterval(poll)
      }
    }, 150)

    return () => {
      cancelled = true
      window.clearInterval(poll)
      if (widgetIdRef.current && window.turnstile) {
        try {
          window.turnstile.remove(widgetIdRef.current)
        } catch {
          // widget already removed
        }
        widgetIdRef.current = null
      }
    }
  }, [siteKey])

  if (!siteKey) return null
  return <div ref={containerRef} className={cn("min-h-[65px]", className)} />
}