"use client"

import { useEffect, useMemo, useState } from "react"
import { IPSEC_MIN_PASSPHRASE, type IpsecCertBundle } from "@mmapp/contracts/ipsec"
import { FormField, SectionTitle } from "@/components/form-kit"
import { Button } from "@/components/ui/button"
import { Input } from "@/components/ui/input"
import {
  Sheet, SheetContent, SheetHeader, SheetTitle,
  SheetDescription, SheetFooter, SheetClose,
} from "@/components/ui/sheet"
import { toast } from "sonner"
import { DownloadIcon, CopyIcon, RefreshCwIcon } from "lucide-react"

function downloadBlob(filename: string, blob: Blob) {
  const url = URL.createObjectURL(blob)
  const a = document.createElement("a")
  a.href = url
  a.download = filename
  a.click()
  URL.revokeObjectURL(url)
}

function downloadText(filename: string, content: string) {
  downloadBlob(filename, new Blob([content], { type: "text/plain;charset=utf-8" }))
}

function downloadB64(filename: string, b64: string, mime: string) {
  const bin = atob(b64)
  const bytes = new Uint8Array(bin.length)
  for (let i = 0; i < bin.length; i++) bytes[i] = bin.charCodeAt(i)
  downloadBlob(filename, new Blob([bytes], { type: mime }))
}

function randomPassphrase(): string {
  // RouterOS требует ≥ IPSEC_MIN_PASSPHRASE символов
  const bytes = new Uint8Array(IPSEC_MIN_PASSPHRASE + 1)
  crypto.getRandomValues(bytes)
  let s = ""
  for (const b of bytes) s += "abcdefghijkmnopqrstuvwxyzABCDEFGHJKLMNPQRSTUVWXYZ23456789"[b % 56]
  return s
}

function IpsecCertSheet({
  open,
  onOpenChange,
  bundle,
  busy,
  onReexport,
}: {
  open: boolean
  onOpenChange: (v: boolean) => void
  bundle: IpsecCertBundle | null
  busy?: boolean
  /** Перекачка с новой passphrase (серийник ключа остаётся на роутере). */
  onReexport?: (passphrase: string) => void | Promise<void>
}) {
  const [passphrase, setPassphrase] = useState("")

  useEffect(() => {
    if (!open) return
    const initial = bundle?.passphrase ?? ""
    queueMicrotask(() => setPassphrase(initial))
  }, [open, bundle])

  const canDownload = useMemo(
    () => Boolean(bundle && passphrase.trim().length >= IPSEC_MIN_PASSPHRASE),
    [bundle, passphrase],
  )

  return (
    <Sheet open={open} onOpenChange={onOpenChange}>
      <SheetContent side="right" className="w-full sm:max-w-md flex flex-col gap-0 p-0">
        <SheetHeader className="px-6 pt-6 pb-4 border-b shrink-0">
          <SheetTitle>Сертификат клиента {bundle ? `«${bundle.user}»` : ""}</SheetTitle>
          <SheetDescription>
            .p12 для Windows/macOS/iOS · .sswan для strongSwan (Android/iOS)
          </SheetDescription>
        </SheetHeader>

        <div className="flex-1 overflow-y-auto px-6 py-5 flex flex-col gap-5">
          {!bundle ? (
            <p className="text-sm text-muted-foreground">
              Бандл сертификата пуст — перезапустите экспорт с новой парольной фразой.
            </p>
          ) : (
            <>
              <div className="flex flex-col gap-4">
                <SectionTitle>Пароль архива .p12</SectionTitle>
                <FormField
                  label="Passphrase"
                  required
                  hint={
                    passphrase.trim().length > 0 && passphrase.trim().length < IPSEC_MIN_PASSPHRASE
                      ? `Минимум ${IPSEC_MIN_PASSPHRASE} символов — требование RouterOS`
                      : `Нужна при импорте .p12 на устройстве (минимум ${IPSEC_MIN_PASSPHRASE} символов)`
                  }
                >
                  <div className="flex gap-2">
                    <Input
                      className="font-mono"
                      value={passphrase}
                      onChange={(e) => setPassphrase(e.target.value)}
                    />
                    <Button
                      type="button"
                      size="icon"
                      variant="outline"
                      title="Сгенерировать и перекачать"
                      disabled={busy}
                      onClick={() => {
                        const next = randomPassphrase()
                        setPassphrase(next)
                        if (onReexport) void onReexport(next)
                      }}
                    >
                      <RefreshCwIcon className={`size-4 ${busy ? "animate-spin" : ""}`} />
                    </Button>
                  </div>
                </FormField>
                {bundle.serverEndpoint ? (
                  <p className="text-xs text-muted-foreground">
                    Сервер: <span className="font-mono">{bundle.serverEndpoint}</span>
                  </p>
                ) : null}
              </div>

              <div className="flex flex-col gap-4">
                <SectionTitle>Файлы</SectionTitle>
                <Button
                  variant="outline"
                  className="justify-start"
                  disabled={!canDownload}
                  onClick={() => {
                    if (!bundle) return
                    downloadB64(bundle.filename, bundle.contentB64, bundle.mime)
                    toast.success(`Скачан ${bundle.filename}`)
                  }}
                >
                  <DownloadIcon className="size-4" />
                  {bundle.filename} (.p12, сертификат + ключ)
                </Button>
                {bundle.sswanContent && bundle.sswanFilename ? (
                  <Button
                    variant="outline"
                    className="justify-start"
                    disabled={!canDownload}
                    onClick={() => {
                      if (!bundle.sswanContent || !bundle.sswanFilename) return
                      downloadText(bundle.sswanFilename, bundle.sswanContent)
                      toast.success(`Скачан ${bundle.sswanFilename}`)
                    }}
                  >
                    <DownloadIcon className="size-4" />
                    {bundle.sswanFilename} (strongSwan)
                  </Button>
                ) : null}
                {bundle.instructions ? (
                  <Button
                    variant="ghost"
                    className="justify-start text-muted-foreground"
                    onClick={() => {
                      if (!bundle.instructions) return
                      void navigator.clipboard?.writeText(bundle.instructions)
                      toast.success("Инструкция скопирована")
                    }}
                  >
                    <CopyIcon className="size-4" />
                    Скопировать инструкцию по подключению
                  </Button>
                ) : null}
              </div>

              {bundle.instructions ? (
                <pre className="max-h-72 overflow-auto rounded-md border bg-muted/40 p-3 text-[11px] leading-relaxed whitespace-pre-wrap">
                  {bundle.instructions}
                </pre>
              ) : null}
            </>
          )}
        </div>

        <SheetFooter className="px-6 py-4 border-t shrink-0">
          <SheetClose render={<Button variant="outline" className="w-full" />}>
            Закрыть
          </SheetClose>
        </SheetFooter>
      </SheetContent>
    </Sheet>
  )
}

export { IpsecCertSheet, downloadText, downloadB64 }