import { useNostr } from "@nostrify/react";
import { useMutation, type UseMutationResult } from "@tanstack/react-query";

import { useCurrentUser } from "./useCurrentUser";
import { isOffline, queueSignedEvent } from "@/lib/offlineCache";
import { minePow } from "@/lib/pow";
import { toast } from "@/hooks/useToast";

import type { NostrEvent, NPool } from "@nostrify/nostrify";

/**
 * Keep a signed event for delivery when we're back online. Signing already
 * happened (above), so an interactive signer is NOT prompted again later — we
 * just hand the signature over.
 */
async function queueForLater(event: NostrEvent): Promise<boolean> {
  try {
    await queueSignedEvent(event);
    toast({
      title: 'Saved offline',
      description: "We'll publish it automatically when you're back online.",
    });
    return true;
  } catch {
    return false;
  }
}

/**
 * Publishes a Nostr event with retry logic and improved error handling.
 *
 * If the relays can't be reached, the SIGNED event is queued (see
 * `lib/offlineCache`) and delivered by `useSyncPendingPosts()` on reconnect —
 * so an offline action completes instead of being lost.
 */
export function useNostrPublish(): UseMutationResult<NostrEvent> {
  const { nostr } = useNostr();
  const { user } = useCurrentUser();

  return useMutation({
    mutationFn: async (t: Omit<NostrEvent, 'id' | 'pubkey' | 'sig'> & { pow?: number }) => {
      if (!user) {
        throw new Error("You must be logged in to publish events");
      }

      const tags = [...(t.tags ?? [])];

      // Add the client tag if it doesn't exist
      if (location.protocol === "https:" && !tags.some(([name]) => name === "client")) {
        tags.push(["client", location.hostname]);
      }

      const createdAt = t.created_at ?? Math.floor(Date.now() / 1000);

      // Optional NIP-13 proof of work. Mined on the UNSIGNED event — the id does
      // not depend on the signature — so the signer is still prompted only once.
      let finalTags = tags;
      if (t.pow && t.pow > 0) {
        const { nonce } = await minePow(
          { pubkey: user.pubkey, kind: t.kind, created_at: createdAt, tags, content: t.content ?? "" },
          t.pow,
        );
        finalTags = [...tags.filter(([n]) => n !== "nonce"), ["nonce", nonce, String(t.pow)]];
      }

      // Sign the event
      const event = await user.signer.signEvent({
        kind: t.kind,
        content: t.content ?? "",
        tags: finalTags,
        created_at: createdAt,
      });

      // Offline: don't sit through a 15s publish timeout before giving up.
      if (isOffline()) {
        await queueForLater(event);
        return event;
      }

      try {
        await publishEventWithRetry(nostr, event);
      } catch (err) {
        // Relays unreachable — keep it and deliver later, unless queuing failed
        // (then the real error is the honest thing to surface).
        const queued = await queueForLater(event);
        if (!queued) throw err;
      }

      return event;
    },
    onError: (error) => {
      console.error("Failed to publish event:", error);
    },
  });
}

/**
 * Publishes event with retry logic and partial success handling
 */
async function publishEventWithRetry(
  nostr: NPool,
  event: NostrEvent,
  maxRetries = 1,
  timeoutMs = 15000
): Promise<void> {
  let lastError: Error | null = null;

  // Try publishing with retries
  for (let attempt = 0; attempt <= maxRetries; attempt++) {
    try {
      const controller = new AbortController();
      const timeoutId = setTimeout(() => controller.abort(), timeoutMs);

      try {
        // Attempt to publish
        await nostr.event(event, { signal: controller.signal });
        return; // Success!

      } finally {
        clearTimeout(timeoutId);
      }

    } catch (error) {
      lastError = error instanceof Error ? error : new Error(String(error));

      // If this isn't the last attempt, wait before retrying
      if (attempt < maxRetries) {
        const backoffMs = 1000 * Math.pow(2, attempt);
        await new Promise(resolve => setTimeout(resolve, backoffMs));
      }
    }
  }

  // All retries failed
  if (lastError) {
    // Provide user-friendly error messages
    if (lastError.name === 'AbortError' || lastError.message.includes('timeout')) {
      throw new Error(
        'Publishing timed out. Your relays may be slow or unreachable. ' +
        'Try checking your relay connections in Settings > Relays.'
      );
    } else if (lastError.message.includes('network') || lastError.message.includes('fetch')) {
      throw new Error(
        'Network error while publishing. Please check your internet connection and try again.'
      );
    } else {
      throw new Error(
        `Failed to publish after ${maxRetries + 1} attempts: ${lastError.message}`
      );
    }
  }

  throw new Error('Failed to publish event to any relay');
}