vector-core 0.3.0

//! Message sending — NIP-17 gift-wrapped DMs (text and file attachments).
//!
//! This is the core send pipeline used by all Vector interfaces (GUI, CLI, SDK).
//! Clients provide a `SendCallback` for status notifications (pending/sent/failed/progress)
//! and a `SendConfig` for retry/cancel behavior.

use std::sync::Arc;
use std::sync::atomic::{AtomicBool, Ordering};
use nostr_sdk::prelude::*;

use crate::state::{nostr_client, my_public_key, STATE};
use crate::types::{Message, Attachment};
use crate::crypto;

// ============================================================================
// SendCallback — Client notification trait
// ============================================================================

/// Callbacks invoked during the DM send pipeline.
///
/// Each method has a default no-op so simple callers (CLI, bots, tests)
/// implement only what they need. Methods are synchronous and non-fallible
/// by design — they should never block the send pipeline.
///
/// Exception: `on_upload_progress` returns `Result` — return `Err` to cancel.
pub trait SendCallback: Send + Sync {
    /// Message created and added to STATE as pending.
    fn on_pending(&self, _chat_id: &str, _msg: &Message) {}

    /// File upload progress. Return Err("...") to cancel the upload.
    fn on_upload_progress(
        &self,
        _pending_id: &str,
        _percentage: u8,
        _bytes_sent: u64,
    ) -> Result<(), String> {
        Ok(())
    }

    /// Upload complete, attachment URL now available.
    fn on_upload_complete(&self, _chat_id: &str, _pending_id: &str, _attachment_id: &str, _url: &str) {}

    /// Message successfully delivered to at least one relay.
    /// `old_id` is the pending ID, `msg` has the real event ID.
    fn on_sent(&self, _chat_id: &str, _old_id: &str, _msg: &Message) {}

    /// Message delivery failed after all retry attempts.
    fn on_failed(&self, _chat_id: &str, _old_id: &str, _msg: &Message) {}

    /// Persist message to database. Default is no-op.
    /// Tauri implements this to call save_message + save_slim_chat.
    fn on_persist(&self, _chat_id: &str, _msg: &Message) {}
}

/// No-op callback for headless/CLI/test use.
pub struct NoOpSendCallback;
impl SendCallback for NoOpSendCallback {}

// ============================================================================
// SendConfig — Per-call configuration
// ============================================================================

/// Configuration for a send operation.
pub struct SendConfig {
    /// Max gift-wrap send attempts (default: 1).
    pub max_send_attempts: u32,
    /// Delay between send retries (default: 5 seconds).
    pub retry_delay: std::time::Duration,
    /// Send copy to own inbox for recovery/sync (default: false).
    pub self_send: bool,
    /// Cancel token for file uploads — set to true to abort.
    pub cancel_token: Option<Arc<AtomicBool>>,
    /// Max Blossom upload retries per server (default: 3).
    pub upload_retries: u32,
    /// Delay between upload retries (default: 2 seconds).
    pub upload_retry_delay: std::time::Duration,
    /// NIP-40 self-destruct expiry (unix secs) to stamp on the outgoing rumor
    /// and mirror onto the outer wrap. None = permanent. Resolved per-chat by
    /// the caller (the "Self-Destruct Timer" setting).
    pub expiration: Option<u64>,
}

impl Default for SendConfig {
    fn default() -> Self {
        Self {
            max_send_attempts: 1,
            retry_delay: std::time::Duration::from_secs(5),
            self_send: false,
            cancel_token: None,
            upload_retries: 3,
            upload_retry_delay: std::time::Duration::from_secs(2),
            expiration: None,
        }
    }
}

impl SendConfig {
    /// Preset for GUI clients (12 retries, self-send enabled).
    pub fn gui() -> Self {
        Self {
            max_send_attempts: 12,
            self_send: true,
            ..Default::default()
        }
    }

    /// Preset for headless/background mode (3 retries, self-send enabled).
    pub fn headless() -> Self {
        Self {
            max_send_attempts: 3,
            self_send: true,
            ..Default::default()
        }
    }
}

// ============================================================================
// SendResult
// ============================================================================

/// Result of sending a message.
#[derive(serde::Serialize, Clone, Debug)]
pub struct SendResult {
    /// The pending ID used while sending
    pub pending_id: String,
    /// The real event ID after successful send (None if failed)
    pub event_id: Option<String>,
    /// The chat ID (receiver npub for DMs)
    pub chat_id: String,
}

// ============================================================================
// Late-OK confirmation registry
// ============================================================================
//
// A relay's OK can outlive the per-attempt wait: slow links push the
// round-trip past nostr-sdk's OK timeout, and mobile handovers drop the
// socket after the EVENT frame was already delivered. The wrap is then
// on the relay while the sender believes it failed — the user re-sends
// and the recipient sees a double-post.
//
// Every wrap publish registers here before its first attempt. Hosts feed
// relay OKs back via `note_relay_ok` from their notification loop; an
// accepted OK counts as delivery no matter how late it arrives — it wakes
// the in-flight retry loop early, or rescues a message already marked
// Failed back to Sent.

struct WrapConfirm {
    wrap_id: EventId,
    chat_id: String,
    pending_id: String,
    /// Inner rumor id — the message's final id after finalization.
    rumor_event_id: String,
    rumor: UnsignedEvent,
    callback: Arc<dyn SendCallback>,
    self_send: bool,
    confirmed: AtomicBool,
    /// Claimed by whichever path (retry loop or note_relay_ok) performs
    /// the failed→sent rescue, so it happens exactly once.
    rescued: AtomicBool,
    /// Set once the retry loop has exited after marking the message
    /// failed — from then on `note_relay_ok` performs the rescue itself.
    loop_exited: AtomicBool,
    notify: tokio::sync::Notify,
    session: crate::state::SessionGuard,
    registered_at: std::time::Instant,
}

static WRAP_CONFIRMS: std::sync::LazyLock<
    std::sync::Mutex<std::collections::HashMap<EventId, Arc<WrapConfirm>>>,
> = std::sync::LazyLock::new(|| std::sync::Mutex::new(std::collections::HashMap::new()));

/// An OK this long after the last publish attempt is a ghost — drop the
/// entry rather than resurrect a message the user has moved past.
const WRAP_CONFIRM_TTL: std::time::Duration = std::time::Duration::from_secs(15 * 60);

fn register_wrap_confirm(entry: Arc<WrapConfirm>) {
    let mut map = WRAP_CONFIRMS.lock().unwrap();
    map.retain(|_, e| e.registered_at.elapsed() < WRAP_CONFIRM_TTL);
    map.insert(entry.wrap_id, entry);
}

fn remove_wrap_confirm(wrap_id: &EventId) {
    WRAP_CONFIRMS.lock().unwrap().remove(wrap_id);
}

/// Clear on session swap — entries carry per-account chat/message ids.
pub fn clear_wrap_confirms() {
    WRAP_CONFIRMS.lock().unwrap().clear();
}

/// Feed a relay `OK` for an outbound event back into the send pipeline.
///
/// Hosts call this from their notification loop for every
/// `RelayMessage::Ok`. Ids that aren't in-flight wraps miss the registry
/// and return immediately.
pub fn note_relay_ok(event_id: &EventId, accepted: bool) {
    if !accepted {
        return;
    }
    let entry = {
        let map = WRAP_CONFIRMS.lock().unwrap();
        map.get(event_id).cloned()
    };
    let Some(entry) = entry else { return };
    entry.confirmed.store(true, Ordering::SeqCst);
    entry.notify.notify_one();
    if !entry.loop_exited.load(Ordering::SeqCst)
        || entry.rescued.swap(true, Ordering::SeqCst)
    {
        return;
    }
    if !entry.session.is_valid() {
        remove_wrap_confirm(&entry.wrap_id);
        return;
    }
    tokio::spawn(async move {
        rescue_failed_as_sent(&entry).await;
        remove_wrap_confirm(&entry.wrap_id);
    });
}

/// Flip an already-failed message back to Sent — a late relay OK proved
/// the wrap was delivered.
async fn rescue_failed_as_sent(entry: &WrapConfirm) {
    if !entry.session.is_valid() {
        return;
    }
    let finalized = {
        let mut state = STATE.lock().await;
        state.update_message(&entry.pending_id, |msg| {
            msg.set_failed(false);
        });
        state.finalize_pending_message(&entry.chat_id, &entry.pending_id, &entry.rumor_event_id)
    };
    let Some((_old_id, ref msg)) = finalized else { return };
    crate::log_info!(
        "[Send] late relay OK confirmed wrap {} — message {} rescued to sent",
        entry.wrap_id,
        entry.rumor_event_id,
    );
    entry.callback.on_sent(&entry.chat_id, &entry.pending_id, msg);
    entry.callback.on_persist(&entry.chat_id, msg);
    if entry.self_send {
        if let (Some(client), Some(my_pk)) = (nostr_client(), my_public_key()) {
            spawn_self_send(client, my_pk, entry.rumor.clone());
        }
    }
}

/// Fire-and-forget the self-send recovery copy + persist its wrap key.
/// SessionGuard skips publish + DB write on swap; without it account A's
/// wrap key would corrupt account B's nip17_keys delete-history.
fn spawn_self_send(client: Client, my_pk: PublicKey, rumor: UnsignedEvent) {
    let rid_for_self = rumor.id;
    let session = crate::state::SessionGuard::capture();
    tokio::spawn(async move {
        if !session.is_valid() { return; }
        match crate::inbox_relays::send_gift_wrap_retained(
            &client, &my_pk, rumor, [],
        ).await {
            Ok(self_outcome) if !self_outcome.output.success.is_empty() => {
                if !session.is_valid() { return; }
                if let Some(rid) = rid_for_self {
                    if let Err(e) = crate::db::nip17_keys::store_wrap_key(
                        &self_outcome.wrap_event_id,
                        &rid,
                        &my_pk,
                        crate::db::nip17_keys::WrapRole::SelfSend,
                        &self_outcome.wrap_secret,
                        &self_outcome.targeted_relays,
                    ) {
                        eprintln!("[NIP-17] failed to persist self-wrap key: {}", e);
                    }
                }
            }
            _ => {}
        }
    });
}

// ============================================================================
// Internal: retry gift-wrap send
// ============================================================================

/// Shared tail of send_dm / send_file_dm / send_rumor_dm:
/// gift-wrap → retry loop → finalize/fail → self-send.
///
/// The wrap is built ONCE and the identical event republished on every
/// attempt: a relay that already stored it answers the resend with
/// OK-true "duplicate", so a lost OK becomes a delivery confirmation on
/// the next attempt instead of an unconfirmed extra copy. The wrap's
/// ephemeral key is persisted via `db::nip17_keys::store_wrap_key`
/// BEFORE the first publish — a wrap can land without us ever seeing
/// the OK, and the user must still be able to NIP-09 it later.
async fn retry_send_gift_wrap(
    client: &Client,
    receiver: &PublicKey,
    receiver_npub: &str,
    pending_id: &str,
    rumor: UnsignedEvent,
    event_id: &str,
    config: &SendConfig,
    callback: Arc<dyn SendCallback>,
) -> Result<SendResult, String> {
    let my_pk = my_public_key().ok_or("Public key not set")?;
    let inner_rumor_id = rumor.id;

    // Built lazily in-loop so transient signer failures (NIP-46 bunker
    // round-trips) still get the full retry schedule.
    let mut built: Option<crate::inbox_relays::BuiltGiftWrap> = None;
    // Targets resolve once; transient inbox connections live across the
    // whole retry window rather than reconnecting per attempt.
    let mut targets: Option<crate::inbox_relays::GiftWrapTargets> = None;
    let mut confirm: Option<Arc<WrapConfirm>> = None;
    let mut last_error: Option<String> = None;

    let max_attempts = config.max_send_attempts.max(1);

    for attempt in 0..max_attempts {
        if built.is_none() {
            // Mirror any NIP-40 expiry from the rumor onto the outer wrap so
            // relays drop the gift-wrap on schedule (the inner tag is encrypted).
            let wrap_extra: Vec<Tag> = rumor.tags.iter()
                .find(|t| t.as_slice().first().map(|k| k.as_str() == "expiration").unwrap_or(false))
                .cloned()
                .into_iter()
                .collect();
            match crate::inbox_relays::build_gift_wrap_retained(
                client, receiver, rumor.clone(), wrap_extra,
            ).await {
                Ok(b) => built = Some(b),
                Err(e) => {
                    crate::log_warn!(
                        "[Send] attempt {}/{} — building gift-wrap failed: {}",
                        attempt + 1, max_attempts, e,
                    );
                    last_error = Some(e);
                    if attempt + 1 < max_attempts {
                        tokio::time::sleep(config.retry_delay).await;
                    }
                    continue;
                }
            }
        }
        let wrap = built.as_ref().unwrap();

        if confirm.is_none() {
            let entry = Arc::new(WrapConfirm {
                wrap_id: wrap.event.id,
                chat_id: receiver_npub.to_string(),
                pending_id: pending_id.to_string(),
                rumor_event_id: event_id.to_string(),
                rumor: rumor.clone(),
                callback: callback.clone(),
                self_send: config.self_send,
                confirmed: AtomicBool::new(false),
                rescued: AtomicBool::new(false),
                loop_exited: AtomicBool::new(false),
                notify: tokio::sync::Notify::new(),
                session: crate::state::SessionGuard::capture(),
                registered_at: std::time::Instant::now(),
            });
            register_wrap_confirm(entry.clone());
            confirm = Some(entry);
        }
        let confirm_ref = confirm.as_ref().unwrap();

        if targets.is_none() {
            let t = crate::inbox_relays::resolve_gift_wrap_targets(client, receiver).await;
            if let Some(rid) = inner_rumor_id {
                if let Err(e) = crate::db::nip17_keys::store_wrap_key(
                    &wrap.event.id,
                    &rid,
                    receiver,
                    crate::db::nip17_keys::WrapRole::Recipient,
                    &wrap.secret,
                    &t.targeted_relays,
                ) {
                    eprintln!("[NIP-17] failed to persist wrap key: {}", e);
                }
            }
            targets = Some(t);
        } else {
            crate::inbox_relays::reconnect_gift_wrap_targets(targets.as_ref().unwrap()).await;
        }
        let targets_ref = targets.as_ref().unwrap();

        match crate::inbox_relays::publish_gift_wrap_to_targets(
            client, targets_ref, &wrap.event,
        ).await {
            Ok(output) if !output.success.is_empty() => {
                return Ok(finalize_gift_wrap_sent(
                    client, my_pk, receiver_npub, pending_id, event_id,
                    &rumor, config, &callback, confirm_ref, targets_ref,
                ).await);
            }
            Ok(output) => {
                // The publish round-trip ran but no targeted relay confirmed
                // (auth required, kind filter, rate-limit, timed-out OK,
                // etc.). Surface the per-relay failure reasons so the user
                // can see WHY their DMs aren't being accepted.
                let failures: Vec<String> = output.failed.iter()
                    .map(|(url, err)| format!("{}: {}", url, err))
                    .collect();
                crate::log_warn!(
                    "[Send] attempt {}/{} — 0 of {} relays accepted (targeted: {}). Per-relay errors: {}",
                    attempt + 1,
                    max_attempts,
                    targets_ref.targeted_relays.len(),
                    targets_ref.targeted_relays.join(", "),
                    if failures.is_empty() {
                        "(none reported — likely all timed out before responding)".to_string()
                    } else {
                        failures.join(" | ")
                    },
                );
                last_error = None;
            }
            Err(e) => {
                crate::log_warn!(
                    "[Send] attempt {}/{} — publish errored: {}",
                    attempt + 1, max_attempts, e,
                );
                last_error = Some(e);
            }
        }

        // A late OK for an earlier attempt may have arrived while this one
        // was publishing.
        if confirm_ref.confirmed.load(Ordering::SeqCst) {
            return Ok(finalize_gift_wrap_sent(
                client, my_pk, receiver_npub, pending_id, event_id,
                &rumor, config, &callback, confirm_ref, targets_ref,
            ).await);
        }

        if attempt + 1 < max_attempts {
            // Sleep out the retry delay, waking instantly on a late OK
            // (notify_one stores a permit, so an OK landing before this
            // line still wakes us).
            let _ = tokio::time::timeout(
                config.retry_delay,
                confirm_ref.notify.notified(),
            ).await;
            if confirm_ref.confirmed.load(Ordering::SeqCst) {
                return Ok(finalize_gift_wrap_sent(
                    client, my_pk, receiver_npub, pending_id, event_id,
                    &rumor, config, &callback, confirm_ref, targets_ref,
                ).await);
            }
        }
    }

    // Exhausted every attempt with no OK observed. Mark failed, but leave
    // the confirmation entry armed: a straggler OK can still rescue this
    // message to Sent (see note_relay_ok).
    if let Some(t) = targets.as_ref() {
        crate::inbox_relays::teardown_gift_wrap_targets(client, t).await;
    }
    let failed_msg = {
        let mut state = STATE.lock().await;
        state.update_message(pending_id, |msg| {
            msg.set_failed(true);
            msg.set_pending(false);
        })
    };
    if let Some((_chat_id, ref msg)) = failed_msg {
        callback.on_failed(receiver_npub, pending_id, msg);
        callback.on_persist(receiver_npub, msg);
    }
    if let Some(entry) = confirm.as_ref() {
        entry.loop_exited.store(true, Ordering::SeqCst);
        // An OK that landed between the last attempt and loop_exited going
        // up would see loop_exited=false and skip its rescue — catch it here.
        if entry.confirmed.load(Ordering::SeqCst)
            && !entry.rescued.swap(true, Ordering::SeqCst)
        {
            rescue_failed_as_sent(entry).await;
            remove_wrap_confirm(&entry.wrap_id);
            return Ok(SendResult {
                pending_id: pending_id.to_string(),
                event_id: Some(event_id.to_string()),
                chat_id: receiver_npub.to_string(),
            });
        }
    }
    match last_error {
        Some(e) => Err(format!("Failed to send DM after {} attempts: {}", max_attempts, e)),
        None => Err(format!(
            "Failed to send DM after {} attempts (no relays accepted the gift-wrap)",
            max_attempts
        )),
    }
}

/// Success epilogue shared by every confirmed path in the retry loop:
/// finalize the pending message, notify, persist, fire the self-send.
async fn finalize_gift_wrap_sent(
    client: &Client,
    my_pk: PublicKey,
    receiver_npub: &str,
    pending_id: &str,
    event_id: &str,
    rumor: &UnsignedEvent,
    config: &SendConfig,
    callback: &Arc<dyn SendCallback>,
    confirm: &Arc<WrapConfirm>,
    targets: &crate::inbox_relays::GiftWrapTargets,
) -> SendResult {
    remove_wrap_confirm(&confirm.wrap_id);
    crate::inbox_relays::teardown_gift_wrap_targets(client, targets).await;

    let finalized = {
        let mut state = STATE.lock().await;
        state.finalize_pending_message(receiver_npub, pending_id, event_id)
    };
    if let Some((_old_id, ref finalized_msg)) = finalized {
        callback.on_sent(receiver_npub, pending_id, finalized_msg);
        callback.on_persist(receiver_npub, finalized_msg);
    }

    if config.self_send {
        spawn_self_send(client.clone(), my_pk, rumor.clone());
    }

    SendResult {
        pending_id: pending_id.to_string(),
        event_id: Some(event_id.to_string()),
        chat_id: receiver_npub.to_string(),
    }
}

// ============================================================================
// send_dm — Text DMs
// ============================================================================

/// Send a NIP-17 gift-wrapped text DM.
///
/// Flow: pending msg → callback.on_pending → build Kind 14 rumor →
/// gift-wrap with retry → finalize → callback.on_sent → optional self-send.
pub async fn send_dm(
    receiver_npub: &str,
    content: &str,
    reply_to: Option<&str>,
    config: &SendConfig,
    callback: Arc<dyn SendCallback>,
) -> Result<SendResult, String> {
    let client = nostr_client().ok_or("Not logged in")?;
    let my_pk = my_public_key().ok_or("Public key not set")?;

    let now = std::time::SystemTime::now()
        .duration_since(std::time::UNIX_EPOCH).unwrap();
    let pending_id = format!("pending-{}", now.as_nanos());

    let receiver = PublicKey::from_bech32(receiver_npub)
        .map_err(|e| format!("Invalid npub: {}", e))?;

    // NIP-30: resolve any `:shortcode:` in the outbound text against the
    // user's subscribed packs so the rumor carries `["emoji", ...]` tags.
    // Recipients without the pack subscribed still render correctly, and
    // our own-view echo populates `emoji_tags` for the renderer.
    let emoji_tags = crate::emoji_packs::resolve_outbound_emoji_tags(content);

    // Build pending message and add to state
    let msg = Message {
        id: pending_id.clone(),
        content: content.to_string(),
        replied_to: reply_to.unwrap_or("").to_string(),
        at: now.as_millis() as u64,
        pending: true,
        mine: true,
        npub: my_pk.to_bech32().ok(),
        emoji_tags: emoji_tags.clone(),
        expiration: config.expiration,
        ..Default::default()
    };

    {
        let mut state = STATE.lock().await;
        state.add_message_to_participant(receiver_npub, msg.clone());
    }

    callback.on_pending(receiver_npub, &msg);

    // Build the rumor
    let milliseconds = now.as_millis() % 1000;
    let mut rumor = EventBuilder::private_msg_rumor(receiver, content);

    if let Some(reply_id) = reply_to {
        if !reply_id.is_empty() {
            rumor = rumor.tag(Tag::custom(
                TagKind::e(),
                [reply_id.to_string(), String::new(), "reply".to_string()],
            ));
        }
    }

    let mut rumor = rumor.tag(Tag::custom(TagKind::custom("ms"), [milliseconds.to_string()]));
    for et in &emoji_tags {
        rumor = rumor.tag(Tag::custom(
            TagKind::custom("emoji"),
            [et.shortcode.clone(), et.url.clone()],
        ));
    }
    // NIP-40 self-destruct: stamp the rumor so compliant receivers honor the
    // expiry; retry_send_gift_wrap mirrors it onto the outer wrap for relays.
    if let Some(exp) = config.expiration {
        rumor = rumor.tag(Tag::expiration(Timestamp::from_secs(exp)));
    }
    let built_rumor = rumor.build(my_pk);
    let event_id = built_rumor.id.ok_or("Rumor has no id")?.to_hex();

    // Send via gift-wrap with retry
    retry_send_gift_wrap(
        &client, &receiver, receiver_npub, &pending_id,
        built_rumor, &event_id, config, callback,
    ).await
}

// ============================================================================
// send_rumor_dm — Pre-built rumor (custom events)
// ============================================================================

/// Send a pre-built rumor via NIP-17 gift-wrap.
///
/// Used when the caller has already built the rumor. Skips encryption/upload.
pub async fn send_rumor_dm(
    receiver_npub: &str,
    pending_id: &str,
    rumor: UnsignedEvent,
    config: &SendConfig,
    callback: Arc<dyn SendCallback>,
) -> Result<SendResult, String> {
    let client = nostr_client().ok_or("Not logged in")?;

    let receiver = PublicKey::from_bech32(receiver_npub)
        .map_err(|e| format!("Invalid npub: {}", e))?;

    let event_id = rumor.id.ok_or("Rumor has no id")?.to_hex();

    retry_send_gift_wrap(
        &client, &receiver, receiver_npub, pending_id,
        rumor, &event_id, config, callback,
    ).await
}

// ============================================================================
// send_file_dm — File Attachment DMs
// ============================================================================

/// Send a NIP-17 gift-wrapped file attachment DM.
///
/// Flow: hash → save locally → encrypt → upload → build Kind 15 rumor → gift-wrap + send.
pub async fn send_file_dm(
    receiver_npub: &str,
    file_bytes: Arc<Vec<u8>>,
    filename: &str,
    extension: &str,
    content: Option<&str>,
    config: &SendConfig,
    callback: Arc<dyn SendCallback>,
) -> Result<SendResult, String> {
    let client = nostr_client().ok_or("Not logged in")?;
    let my_pk = my_public_key().ok_or("Public key not set")?;
    // Sign the Blossom auth event via the active client signer so bunker
    // accounts route through NostrConnect (the user's identity key lives on
    // the remote signer; MY_SECRET_KEY only holds the NIP-46 client key).
    let signer = client.signer().await
        .map_err(|e| format!("Signer unavailable: {}", e))?;

    let now = std::time::SystemTime::now()
        .duration_since(std::time::UNIX_EPOCH).unwrap();
    let pending_id = format!("pending-{}", now.as_nanos());
    let milliseconds = now.as_millis() % 1000;

    let receiver = PublicKey::from_bech32(receiver_npub)
        .map_err(|e| format!("Invalid npub: {}", e))?;

    let file_hash = crypto::sha256_hex(&file_bytes);
    let mime_type = crypto::mime_from_extension(extension);

    // WebXDC Mini Apps: mint the realtime-channel topic at send time and carry
    // it on the rumor — locally-derived topics are asymmetric in DMs (each
    // side's chat_id is the other party's npub), splitting players onto
    // disjoint gossip topics.
    let webxdc_topic = (extension.eq_ignore_ascii_case("xdc"))
        .then(|| crate::webxdc::mint_topic_id(&file_hash, &my_pk.to_hex()));

    // Save file locally so the attachment is immediately viewable
    let download_dir = crate::db::get_download_dir();
    let _ = std::fs::create_dir_all(&download_dir);
    // Save with an extension matching the actual content. The caller's
    // `extension` argument is post-compression (e.g. JPEG when an
    // original PNG was compressed), but `filename` is the user-facing
    // name which may still carry the pre-compression extension. If we
    // honored `filename` verbatim we'd save JPEG bytes as `.png` and
    // poison any future re-upload with a MIP-04 mismatch.
    let local_name = if filename.is_empty() {
        format!("{}.{}", &file_hash, extension)
    } else {
        let stem = filename.rsplit_once('.').map(|(s, _)| s).unwrap_or(filename);
        format!("{}.{}", stem, extension)
    };
    // Resolve unique path (pasted_image.png → pasted_image-1.png on collision)
    let local_path = crypto::resolve_unique_filename(&download_dir, &local_name);
    // Atomic write: temp file then rename
    let tmp = download_dir.join(format!(".{}.tmp", &file_hash));
    let _ = std::fs::write(&tmp, &*file_bytes);
    let _ = std::fs::rename(&tmp, &local_path);
    let local_path_str = local_path.to_string_lossy().to_string();

    // === Generate image metadata (thumbhash + dimensions) for image files ===
    let img_meta = crypto::generate_image_metadata(&file_bytes);

    // === Encrypt → upload → build rumor → send ===
    let params = crypto::generate_encryption_params();
    let encrypted = crypto::encrypt_data(&file_bytes, &params)?;
    let encrypted_size = encrypted.len() as u64;

    let attachment = Attachment {
        id: file_hash.clone(), key: params.key.clone(), nonce: params.nonce.clone(),
        extension: extension.to_string(), name: filename.to_string(),
        url: String::new(), path: local_path_str.clone(), size: encrypted_size,
        img_meta: img_meta.clone(), downloading: false, downloaded: true,
        webxdc_topic: webxdc_topic.clone(),
        ..Default::default()
    };
    let msg = Message {
        id: pending_id.clone(), content: content.unwrap_or("").to_string(),
        at: now.as_millis() as u64, pending: true, mine: true,
        npub: my_pk.to_bech32().ok(), attachments: vec![attachment],
        expiration: config.expiration,
        ..Default::default()
    };
    {
        let mut state = STATE.lock().await;
        state.add_message_to_participant(receiver_npub, msg.clone());
    }
    callback.on_pending(receiver_npub, &msg);

    // Upload to Blossom — bridge SendCallback.on_upload_progress to Blossom ProgressCallback
    let servers = crate::state::get_blossom_servers();
    let cb_for_progress = callback.clone();
    let pid_for_progress = pending_id.clone();
    let progress_cb: crate::blossom::ProgressCallback = Arc::new(move |percentage, bytes| {
        cb_for_progress.on_upload_progress(
            &pid_for_progress,
            percentage.unwrap_or(0),
            bytes.unwrap_or(0),
        )
    });

    // Send the original MIME even though bytes are ciphertext: many
    // Blossom servers reject `application/octet-stream` but accept the
    // same bytes under their original type.
    let upload_url = match crate::blossom::upload_blob_with_progress_and_failover(
        signer.clone(), servers, Arc::new(encrypted), Some(mime_type),
        /* is_encrypted */ true,
        progress_cb, Some(config.upload_retries), Some(config.upload_retry_delay),
        config.cancel_token.clone(),
    ).await {
        Ok(url) => url,
        Err(e) => {
            let failed_msg = {
                let mut state = STATE.lock().await;
                state.update_message(&pending_id, |msg| {
                    msg.set_failed(true);
                    msg.set_pending(false);
                })
            };
            if let Some((_chat_id, ref msg)) = failed_msg {
                callback.on_failed(receiver_npub, &pending_id, msg);
                callback.on_persist(receiver_npub, msg);
            }
            return Err(format!("Upload failed: {}", e));
        }
    };

    {
        let mut state = STATE.lock().await;
        state.update_message(&pending_id, |msg| {
            if let Some(att) = msg.attachments.last_mut() {
                att.url = upload_url.clone().into_boxed_str();
            }
        });
    }
    callback.on_upload_complete(receiver_npub, &pending_id, &file_hash, &upload_url);

    // Build Kind 15
    let mut file_rumor = EventBuilder::new(Kind::from_u16(15), &upload_url)
        .tag(Tag::public_key(receiver))
        .tag(Tag::custom(TagKind::custom("file-type"), [mime_type]))
        .tag(Tag::custom(TagKind::custom("size"), [encrypted_size.to_string()]))
        .tag(Tag::custom(TagKind::custom("encryption-algorithm"), ["aes-gcm"]))
        .tag(Tag::custom(TagKind::custom("decryption-key"), [params.key.as_str()]))
        .tag(Tag::custom(TagKind::custom("decryption-nonce"), [params.nonce.as_str()]))
        .tag(Tag::custom(TagKind::custom("ox"), [file_hash.clone()]));
    if !filename.is_empty() {
        file_rumor = file_rumor.tag(Tag::custom(TagKind::custom("name"), [filename]));
    }
    if let Some(ref topic) = webxdc_topic {
        file_rumor = file_rumor.tag(Tag::custom(TagKind::custom("webxdc-topic"), [topic.as_str()]));
    }
    // Include image preview metadata for compatible rendering across all clients
    if let Some(ref meta) = img_meta {
        if !meta.thumbhash.is_empty() {
            file_rumor = file_rumor.tag(Tag::custom(TagKind::custom("thumb"), [meta.thumbhash.as_str()]));
        }
        file_rumor = file_rumor.tag(Tag::custom(TagKind::custom("dim"), [format!("{}x{}", meta.width, meta.height)]));
    }
    file_rumor = file_rumor.tag(Tag::custom(TagKind::custom("ms"), [milliseconds.to_string()]));
    if let Some(exp) = config.expiration {
        file_rumor = file_rumor.tag(Tag::expiration(Timestamp::from_secs(exp)));
    }

    let built_rumor = file_rumor.build(my_pk);
    let event_id = built_rumor.id.ok_or("Rumor has no id")?.to_hex();

    retry_send_gift_wrap(
        &client, &receiver, receiver_npub, &pending_id,
        built_rumor, &event_id, config, callback,
    ).await
}

// ============================================================================
// Tests
// ============================================================================

#[cfg(test)]
mod tests {
    use super::*;
    use std::sync::Mutex;

    #[derive(Debug, Clone, PartialEq)]
    enum CbEvent {
        Pending(String),
        UploadProgress(String, u8, u64),
        UploadComplete(String, String),
        Sent(String, String),
        Failed(String, String),
        Persist(String),
    }

    struct MockCallback {
        events: Mutex<Vec<CbEvent>>,
        cancel_at: Option<u8>,
    }

    impl MockCallback {
        fn new() -> Self { Self { events: Mutex::new(vec![]), cancel_at: None } }
        fn with_cancel(pct: u8) -> Self { Self { events: Mutex::new(vec![]), cancel_at: Some(pct) } }
        fn events(&self) -> Vec<CbEvent> { self.events.lock().unwrap().clone() }
    }

    impl SendCallback for MockCallback {
        fn on_pending(&self, cid: &str, _: &Message) {
            self.events.lock().unwrap().push(CbEvent::Pending(cid.into()));
        }
        fn on_upload_progress(&self, pid: &str, pct: u8, bytes: u64) -> Result<(), String> {
            self.events.lock().unwrap().push(CbEvent::UploadProgress(pid.into(), pct, bytes));
            if self.cancel_at.map_or(false, |c| pct >= c) { return Err("Cancelled".into()); }
            Ok(())
        }
        fn on_upload_complete(&self, cid: &str, _: &str, _: &str, url: &str) {
            self.events.lock().unwrap().push(CbEvent::UploadComplete(cid.into(), url.into()));
        }
        fn on_sent(&self, cid: &str, old: &str, _: &Message) {
            self.events.lock().unwrap().push(CbEvent::Sent(cid.into(), old.into()));
        }
        fn on_failed(&self, cid: &str, old: &str, _: &Message) {
            self.events.lock().unwrap().push(CbEvent::Failed(cid.into(), old.into()));
        }
        fn on_persist(&self, cid: &str, _: &Message) {
            self.events.lock().unwrap().push(CbEvent::Persist(cid.into()));
        }
    }

    #[test]
    fn config_default() {
        let c = SendConfig::default();
        assert_eq!(c.max_send_attempts, 1);
        assert!(!c.self_send);
        assert!(c.cancel_token.is_none());
        assert_eq!(c.upload_retries, 3);
    }

    #[test]
    fn config_gui() {
        let c = SendConfig::gui();
        assert_eq!(c.max_send_attempts, 12);
        assert!(c.self_send);
    }

    #[test]
    fn config_headless() {
        let c = SendConfig::headless();
        assert_eq!(c.max_send_attempts, 3);
        assert!(c.self_send);
    }

    #[test]
    fn config_custom_override() {
        let c = SendConfig { max_send_attempts: 5, ..SendConfig::gui() };
        assert_eq!(c.max_send_attempts, 5);
        assert!(c.self_send);
    }

    #[test]
    fn noop_callback_all_methods() {
        let cb = NoOpSendCallback;
        let msg = Message::default();
        cb.on_pending("c", &msg);

        assert!(cb.on_upload_progress("p", 50, 1024).is_ok());
        cb.on_upload_complete("c", "p", "a", "url");
        cb.on_sent("c", "o", &msg);
        cb.on_failed("c", "o", &msg);
        cb.on_persist("c", &msg);
    }

    #[test]
    fn text_dm_sequence() {
        let cb = MockCallback::new();
        let msg = Message::default();
        cb.on_pending("r", &msg);
        cb.on_sent("r", "p-1", &msg);
        cb.on_persist("r", &msg);
        assert_eq!(cb.events(), vec![
            CbEvent::Pending("r".into()),
            CbEvent::Sent("r".into(), "p-1".into()),
            CbEvent::Persist("r".into()),
        ]);
    }

    #[test]
    fn file_dm_sequence() {
        let cb = MockCallback::new();
        let msg = Message::default();
        cb.on_pending("r", &msg);

        cb.on_upload_progress("p", 0, 0).ok();
        cb.on_upload_progress("p", 50, 5000).ok();
        cb.on_upload_progress("p", 100, 10000).ok();
        cb.on_upload_complete("r", "p", "h", "https://blossom/h");
        cb.on_sent("r", "p", &msg);
        cb.on_persist("r", &msg);
        let e = cb.events();
        assert_eq!(e.len(), 7);
        assert!(matches!(&e[4], CbEvent::UploadComplete(_, url) if url.contains("blossom")));
    }

    #[test]
    fn failed_sequence() {
        let cb = MockCallback::new();
        let msg = Message::default();
        cb.on_pending("r", &msg);
        cb.on_failed("r", "p", &msg);
        cb.on_persist("r", &msg);
        assert_eq!(cb.events(), vec![
            CbEvent::Pending("r".into()),
            CbEvent::Failed("r".into(), "p".into()),
            CbEvent::Persist("r".into()),
        ]);
    }

    #[test]
    fn cancel_upload_at_threshold() {
        let cb = MockCallback::with_cancel(50);
        assert!(cb.on_upload_progress("p", 25, 512).is_ok());
        assert!(cb.on_upload_progress("p", 50, 1024).is_err());
        assert_eq!(cb.events().len(), 2);
    }

    #[test]
    fn cancel_triggers_failed() {
        let cb = MockCallback::with_cancel(30);
        let msg = Message::default();
        cb.on_pending("r", &msg);

        cb.on_upload_progress("p", 10, 1000).ok();
        assert!(cb.on_upload_progress("p", 30, 3000).is_err());
        cb.on_failed("r", "p", &msg);
        assert!(matches!(cb.events().last(), Some(CbEvent::Failed(..))));
    }

    #[test]
    fn send_result_serialize() {
        let r = SendResult { pending_id: "p".into(), event_id: Some("e".into()), chat_id: "c".into() };
        let j = serde_json::to_string(&r).unwrap();
        assert!(j.contains("\"pending_id\":\"p\""));
    }

    #[test]
    fn send_result_none_event() {
        let r = SendResult { pending_id: "p".into(), event_id: None, chat_id: "c".into() };
        let j = serde_json::to_string(&r).unwrap();
        assert!(j.contains("null"));
    }

    // ========================================================================
    // File DM callback sequences
    // ========================================================================

    #[test]
    fn file_dm_fresh_upload_full_sequence() {
        let cb = MockCallback::new();
        let msg = Message::default();

        // 1. Pending message created
        cb.on_pending("npub1recv", &msg);
        // 2. Attachment preview added

        // 3. Upload progress (0% → 25% → 50% → 75% → 100%)
        cb.on_upload_progress("pending-42", 0, 0).unwrap();
        cb.on_upload_progress("pending-42", 25, 2500).unwrap();
        cb.on_upload_progress("pending-42", 50, 5000).unwrap();
        cb.on_upload_progress("pending-42", 75, 7500).unwrap();
        cb.on_upload_progress("pending-42", 100, 10000).unwrap();
        // 4. Upload complete
        cb.on_upload_complete("npub1recv", "pending-42", "deadbeef", "https://blossom.example/deadbeef");
        // 5. Gift-wrap sent successfully
        cb.on_sent("npub1recv", "pending-42", &msg);
        // 6. Persisted to DB
        cb.on_persist("npub1recv", &msg);

        let e = cb.events();
        assert_eq!(e.len(), 9);
        assert!(matches!(&e[0], CbEvent::Pending(c) if c == "npub1recv"));
        assert!(matches!(&e[1], CbEvent::UploadProgress(_, 0, 0)));
        assert!(matches!(&e[5], CbEvent::UploadProgress(_, 100, 10000)));
        assert!(matches!(&e[6], CbEvent::UploadComplete(_, url) if url.contains("deadbeef")));
        assert!(matches!(&e[7], CbEvent::Sent(..)));
        assert!(matches!(&e[8], CbEvent::Persist(..)));
    }

    #[test]
    fn file_dm_skip_upload_sequence() {
        let cb = MockCallback::new();
        let msg = Message::default();

        // Dedup hit: no upload, existing URL reused
        // 1. Pending message
        cb.on_pending("npub1recv", &msg);
        // 2. Attachment preview (with reused URL already set)

        // 3. Upload complete (immediate — URL was already known)
        cb.on_upload_complete("npub1recv", "pending-99", "existinghash", "https://blossom.example/existing");
        // 4. Gift-wrap sent
        cb.on_sent("npub1recv", "pending-99", &msg);
        // 5. Persisted
        cb.on_persist("npub1recv", &msg);

        let e = cb.events();
        assert_eq!(e.len(), 4);
        // No UploadProgress events — upload was skipped
        assert!(!e.iter().any(|ev| matches!(ev, CbEvent::UploadProgress(..))));
        assert!(matches!(&e[1], CbEvent::UploadComplete(..)));
    }

    #[test]
    fn file_dm_upload_cancelled_at_30pct() {
        let cb = MockCallback::with_cancel(30);
        let msg = Message::default();

        cb.on_pending("npub1recv", &msg);

        assert!(cb.on_upload_progress("p", 10, 1000).is_ok());
        assert!(cb.on_upload_progress("p", 20, 2000).is_ok());
        // Cancel triggers at 30%
        let err = cb.on_upload_progress("p", 30, 3000);
        assert!(err.is_err());
        assert!(err.unwrap_err().contains("Cancelled"));
        // Pipeline marks as failed
        cb.on_failed("npub1recv", "p", &msg);

        let e = cb.events();
        assert_eq!(e.len(), 5);
        // No Sent, no Persist after cancel — just Failed
        assert!(!e.iter().any(|ev| matches!(ev, CbEvent::Sent(..))));
        assert!(matches!(e.last(), Some(CbEvent::Failed(..))));
    }

    #[test]
    fn file_dm_upload_fails_marks_failed() {
        let cb = MockCallback::new();
        let msg = Message::default();

        cb.on_pending("npub1recv", &msg);

        cb.on_upload_progress("p", 0, 0).ok();
        cb.on_upload_progress("p", 10, 500).ok();
        // Upload fails (server error, all retries exhausted)
        cb.on_failed("npub1recv", "p", &msg);
        cb.on_persist("npub1recv", &msg);

        let e = cb.events();
        assert_eq!(e.len(), 5);
        assert!(matches!(&e[3], CbEvent::Failed(..)));
        assert!(matches!(&e[4], CbEvent::Persist(..)));
        // No UploadComplete, no Sent
        assert!(!e.iter().any(|ev| matches!(ev, CbEvent::UploadComplete(..))));
        assert!(!e.iter().any(|ev| matches!(ev, CbEvent::Sent(..))));
    }

    #[test]
    fn file_dm_gift_wrap_fails_after_upload() {
        let cb = MockCallback::new();
        let msg = Message::default();

        // Upload succeeds but gift-wrap fails
        cb.on_pending("npub1recv", &msg);

        cb.on_upload_progress("p", 100, 10000).ok();
        cb.on_upload_complete("npub1recv", "p", "hash", "https://blossom/hash");
        // Gift-wrap retry exhausted
        cb.on_failed("npub1recv", "p", &msg);
        cb.on_persist("npub1recv", &msg);

        let e = cb.events();
        assert_eq!(e.len(), 5);
        // Upload succeeded but send failed
        assert!(matches!(&e[2], CbEvent::UploadComplete(..)));
        assert!(matches!(&e[3], CbEvent::Failed(..)));
    }

    #[test]
    fn file_dm_with_image_metadata_sequence() {
        let cb = MockCallback::new();
        let msg = Message::default();

        // Image with thumbhash + dimensions
        cb.on_pending("npub1recv", &msg);

        cb.on_upload_progress("p", 0, 0).ok();
        cb.on_upload_progress("p", 50, 50000).ok();
        cb.on_upload_progress("p", 100, 100000).ok();
        cb.on_upload_complete("npub1recv", "p", "imghash", "https://blossom/imghash.jpg");
        cb.on_sent("npub1recv", "p", &msg);
        cb.on_persist("npub1recv", &msg);

        let e = cb.events();
        assert_eq!(e.len(), 7);
        // Verify ordering: pending → progress(3x) → complete → sent → persist
        assert!(matches!(&e[0], CbEvent::Pending(..)));
        assert!(matches!(&e[4], CbEvent::UploadComplete(_, url) if url.ends_with(".jpg")));
        assert!(matches!(&e[5], CbEvent::Sent(..)));
    }

    #[test]
    fn cancel_token_config_with_upload() {
        let token = Arc::new(std::sync::atomic::AtomicBool::new(false));
        let c = SendConfig {
            cancel_token: Some(token.clone()),
            ..SendConfig::gui()
        };
        assert!(c.cancel_token.is_some());
        assert!(!token.load(std::sync::atomic::Ordering::Relaxed));

        // Simulate cancel
        token.store(true, std::sync::atomic::Ordering::Relaxed);
        assert!(c.cancel_token.as_ref().unwrap().load(std::sync::atomic::Ordering::Relaxed));
    }
}