"use client";

import { exportDeck } from "./storage";
import { showToast } from "./toast";
import type { Deck, HomeworkRecord } from "./schemas";
import { t } from "./i18n";

/**
 * Web Share with graceful fallbacks: file share (deck JSON) where the browser
 * supports it, text share otherwise, clipboard copy as the last resort.
 */

type ShareNavigator = Navigator & {
  canShare?: (data: { files?: File[]; text?: string; title?: string }) => boolean;
  share?: (data: { files?: File[]; text?: string; title?: string }) => Promise<void>;
};

function deckFile(deck: Deck): File {
  return new File([exportDeck(deck)], `${deck.title.replace(/[^\p{L}\p{N} _-]/gu, "").trim() || "deck"}.json`, {
    type: "application/json",
  });
}

async function copyText(text: string): Promise<boolean> {
  try {
    if (navigator.clipboard?.writeText) {
      await navigator.clipboard.writeText(text);
      return true;
    }
  } catch {
    /* fall through */
  }
  return false;
}

export async function shareDeck(deck: Deck): Promise<void> {
  const nav = navigator as ShareNavigator;
  const file = deckFile(deck);
  try {
    if (nav.share && nav.canShare?.({ files: [file] })) {
      await nav.share({ files: [file], title: deck.title });
      return;
    }
    if (nav.share) {
      await nav.share({ title: deck.title, text: deck.title });
      return;
    }
  } catch (error) {
    // The user cancelling the share sheet is not an error.
    if (error instanceof DOMException && error.name === "AbortError") return;
  }
  if (await copyText(exportDeck(deck))) showToast({ message: t("share.copied") });
  else showToast({ message: t("share.failed") });
}

export async function shareHomework(record: HomeworkRecord): Promise<void> {
  const nav = navigator as ShareNavigator;
  const text =
    record.mode === "make"
      ? record.answer
      : record.steps.map((step, index) => `${index + 1}. ${step.title}`).join("\n");
  try {
    if (nav.share) {
      await nav.share({ title: record.title, text });
      return;
    }
  } catch (error) {
    if (error instanceof DOMException && error.name === "AbortError") return;
  }
  if (await copyText(text)) showToast({ message: t("share.copied") });
  else showToast({ message: t("share.failed") });
}