agentmux_srv/backend/wcore/

dnd.rs

// Copyright 2025-2026, AgentMux Corp.
// SPDX-License-Identifier: Apache-2.0

//! Drag-and-drop operations: moving/promoting/tearing-off blocks and tabs.

use uuid::Uuid;

use crate::backend::storage::store::Store;
use crate::backend::storage::StoreError;
use crate::backend::obj::*;

use super::tab::{create_tab, delete_tab, set_active_tab};

/// Move a block from one tab to another.
/// Removes the block from `source_tab_id.blockids` and adds it to `dest_tab_id.blockids`.
/// Updates `block.parentoref` to point to the destination tab.
/// If `auto_close_source` is true, deletes the source tab when it becomes empty
/// (only if the workspace has other tabs).
pub fn move_block_to_tab(
    store: &Store,
    block_id: &str,
    source_tab_id: &str,
    dest_tab_id: &str,
    ws_id: &str,
    auto_close_source: bool,
) -> Result<(), StoreError> {
    tracing::info!(
        block_id = %block_id,
        source_tab = %source_tab_id,
        dest_tab = %dest_tab_id,
        ws_id = %ws_id,
        auto_close = %auto_close_source,
        "[dnd] move_block_to_tab"
    );
    if source_tab_id == dest_tab_id {
        tracing::debug!("[dnd] move_block_to_tab: same tab, no-op");
        return Ok(()); // no-op
    }

    // Verify block exists
    let mut block = store.must_get::<Block>(block_id)?;

    // Remove block from source tab
    let mut source_tab = store.must_get::<Tab>(source_tab_id)?;
    source_tab.blockids.retain(|id| id != block_id);
    store.update(&mut source_tab)?;

    // Add block to destination tab
    let mut dest_tab = store.must_get::<Tab>(dest_tab_id)?;
    dest_tab.blockids.push(block_id.to_string());
    store.update(&mut dest_tab)?;

    // Update block's parent reference
    block.parentoref = format!("tab:{}", dest_tab_id);
    store.update(&mut block)?;

    // Auto-close empty source tab if requested
    if auto_close_source && source_tab.blockids.is_empty() {
        let ws = store.must_get::<Workspace>(ws_id)?;
        let total_tabs = ws.tabids.len() + ws.pinnedtabids.len();
        if total_tabs > 1 {
            tracing::info!(source_tab = %source_tab_id, "[dnd] auto-closing empty source tab");
            delete_tab(store, ws_id, source_tab_id)?;
        } else {
            tracing::debug!(source_tab = %source_tab_id, "[dnd] source tab empty but is last tab — keeping");
        }
    }

    tracing::info!(block_id = %block_id, dest_tab = %dest_tab_id, "[dnd] move_block_to_tab complete");
    Ok(())
}

/// Promote a block to a new tab.
/// Removes the block from `source_tab_id`, creates a new tab in `ws_id`,
/// and adds the block to the new tab. Returns the new Tab.
/// If `auto_close_source` is true, deletes the source tab when it becomes empty.
pub fn promote_block_to_tab(
    store: &Store,
    block_id: &str,
    source_tab_id: &str,
    ws_id: &str,
    auto_close_source: bool,
) -> Result<Tab, StoreError> {
    tracing::info!(
        block_id = %block_id,
        source_tab = %source_tab_id,
        ws_id = %ws_id,
        auto_close = %auto_close_source,
        "[dnd] promote_block_to_tab"
    );
    // Verify block exists
    let mut block = store.must_get::<Block>(block_id)?;

    // Remove block from source tab
    let mut source_tab = store.must_get::<Tab>(source_tab_id)?;
    source_tab.blockids.retain(|id| id != block_id);
    store.update(&mut source_tab)?;

    // Create new tab
    let new_tab = create_tab(store, ws_id)?;

    // Add block to new tab
    let mut new_tab = store.must_get::<Tab>(&new_tab.oid)?;
    new_tab.blockids.push(block_id.to_string());
    store.update(&mut new_tab)?;

    // Update block's parent reference
    block.parentoref = format!("tab:{}", new_tab.oid);
    store.update(&mut block)?;

    // Set the new tab as active
    set_active_tab(store, ws_id, &new_tab.oid)?;

    // Auto-close empty source tab if requested
    if auto_close_source && source_tab.blockids.is_empty() {
        let ws = store.must_get::<Workspace>(ws_id)?;
        let total_tabs = ws.tabids.len() + ws.pinnedtabids.len();
        if total_tabs > 1 {
            tracing::info!(source_tab = %source_tab_id, "[dnd] auto-closing empty source tab after promote");
            delete_tab(store, ws_id, source_tab_id)?;
        }
    }

    tracing::info!(block_id = %block_id, new_tab = %new_tab.oid, "[dnd] promote_block_to_tab complete");
    Ok(new_tab)
}

/// Move a tab from one workspace to another.
/// Removes the tab from the source workspace's tabids/pinnedtabids and adds it
/// to the destination workspace's tabids at the specified index.
/// The tab is always added as unpinned in the destination.
/// If the tab was the active tab in the source workspace, a new active tab is chosen.
pub fn move_tab_to_workspace(
    store: &Store,
    tab_id: &str,
    source_ws_id: &str,
    dest_ws_id: &str,
    insert_index: Option<usize>,
) -> Result<(), StoreError> {
    tracing::info!(
        tab_id = %tab_id,
        source_ws = %source_ws_id,
        dest_ws = %dest_ws_id,
        insert_index = ?insert_index,
        "[dnd] move_tab_to_workspace"
    );
    if source_ws_id == dest_ws_id {
        tracing::debug!("[dnd] move_tab_to_workspace: same workspace, no-op");
        return Ok(()); // no-op
    }

    // Verify tab exists
    let _tab = store.must_get::<Tab>(tab_id)?;

    // Remove tab from source workspace
    let mut source_ws = store.must_get::<Workspace>(source_ws_id)?;
    let total_tabs = source_ws.tabids.len() + source_ws.pinnedtabids.len();
    if total_tabs <= 1 {
        tracing::warn!(tab_id = %tab_id, total_tabs = %total_tabs, "[dnd] move_tab_to_workspace blocked: last tab");
        return Err(StoreError::Other(
            "cannot move last tab out of workspace".to_string(),
        ));
    }
    source_ws.tabids.retain(|id| id != tab_id);
    source_ws.pinnedtabids.retain(|id| id != tab_id);
    if source_ws.activetabid == tab_id {
        let new_active = source_ws
            .tabids
            .first()
            .or(source_ws.pinnedtabids.first())
            .cloned()
            .unwrap_or_default();
        tracing::info!(old_active = %tab_id, new_active = %new_active, "[dnd] switching active tab in source workspace");
        source_ws.activetabid = new_active;
    }
    store.update(&mut source_ws)?;

    // Add tab to destination workspace
    let mut dest_ws = store.must_get::<Workspace>(dest_ws_id)?;
    let idx = insert_index.unwrap_or(dest_ws.tabids.len());
    let insert_at = idx.min(dest_ws.tabids.len());
    dest_ws.tabids.insert(insert_at, tab_id.to_string());
    dest_ws.activetabid = tab_id.to_string();
    store.update(&mut dest_ws)?;

    tracing::info!(tab_id = %tab_id, dest_ws = %dest_ws_id, insert_at = %insert_at, "[dnd] move_tab_to_workspace complete");
    Ok(())
}

/// Move a tab back from a tear-off workspace into a destination workspace.
/// Unlike `move_tab_to_workspace`, this skips the "last tab" guard because
/// tear-off workspaces always contain exactly one tab — and after the move
/// the source workspace has zero tabs and is deleted.
///
/// `was_pinned` controls which list in the destination receives the tab:
/// true → `pinnedtabids` (preserves pinned status across cancel-back),
/// false → `tabids`. Both paths de-dup before insert.
///
/// The whole operation runs inside a single SQLite transaction so frontend
/// readers never observe a transient state where the tab lives in two
/// workspaces' lists at once. (gemini PR #567 round-6 MEDIUM)
///
/// Used by Phase 5 cancel-back (ESC / drop-on-source) and by Phase 4 merge
/// (drop on another window's strip). Both paths produce a single-tab source
/// workspace whose only purpose is to carry the dragged tab.
pub fn restore_torn_off_tab(
    store: &Store,
    tab_id: &str,
    source_ws_id: &str,
    dest_ws_id: &str,
    insert_index: Option<usize>,
    was_pinned: bool,
) -> Result<(), StoreError> {
    tracing::info!(
        tab_id = %tab_id,
        source_ws = %source_ws_id,
        dest_ws = %dest_ws_id,
        insert_index = ?insert_index,
        was_pinned = %was_pinned,
        "[dnd] restore_torn_off_tab"
    );
    if source_ws_id == dest_ws_id {
        tracing::debug!("[dnd] restore_torn_off_tab: same workspace, no-op");
        return Ok(());
    }

    store.with_tx(|tx| {
        // Validate everything we're going to touch BEFORE mutating any of
        // it. If `dest_ws_id` is stale (e.g. user closed the original
        // window while the SC_MOVE loop was running, or sent a malformed
        // request), `must_get::<Workspace>(dest_ws_id)` fails here and
        // the transaction rolls back without ever touching the source —
        // no orphaned tab. (codex PR #567 P1 / gemini HIGH)
        let _tab = tx.must_get::<Tab>(tab_id)?;
        let mut source_ws = tx.must_get::<Workspace>(source_ws_id)?;
        let mut dest_ws = tx.must_get::<Workspace>(dest_ws_id)?;

        // Compute source-side mutations in memory only (don't persist yet).
        // No last-tab guard: a tear-off workspace's only tab IS the one
        // being restored, and we'll delete the empty workspace below.
        source_ws.tabids.retain(|id| id != tab_id);
        source_ws.pinnedtabids.retain(|id| id != tab_id);
        let source_now_empty =
            source_ws.tabids.is_empty() && source_ws.pinnedtabids.is_empty();
        if source_ws.activetabid == tab_id {
            // Only assign a new active tab if one actually exists.
            // When source_now_empty, both lists are empty and we go
            // straight to delete below — no need to write an empty
            // activetabid into the persisted record. (gemini PR #567
            // round-8 MEDIUM)
            if let Some(new_active) = source_ws
                .tabids
                .first()
                .or(source_ws.pinnedtabids.first())
                .cloned()
            {
                source_ws.activetabid = new_active;
            }
        }

        // De-dup in destination before insert. A retried frontend request
        // could otherwise produce duplicate tab IDs in the workspace's
        // `tabids` array. (gemini PR #567 MEDIUM)
        dest_ws.tabids.retain(|id| id != tab_id);
        dest_ws.pinnedtabids.retain(|id| id != tab_id);

        // Choose pinnedtabids vs tabids based on the tab's original
        // status. Without this, a pinned tab torn off and cancel-backed
        // would silently come back as unpinned. (gemini PR #567 round-6
        // MEDIUM on this branch.) Pinning has since left the UI — tabbar.tsx
        // folds legacy `pinnedtabids` into `tabids` on mount — so this only
        // matters for a workspace whose pins have not been migrated yet.
        let insert_at = if was_pinned {
            let idx = insert_index.unwrap_or(dest_ws.pinnedtabids.len());
            let insert_at = idx.min(dest_ws.pinnedtabids.len());
            dest_ws.pinnedtabids.insert(insert_at, tab_id.to_string());
            insert_at
        } else {
            let idx = insert_index.unwrap_or(dest_ws.tabids.len());
            let insert_at = idx.min(dest_ws.tabids.len());
            dest_ws.tabids.insert(insert_at, tab_id.to_string());
            insert_at
        };
        dest_ws.activetabid = tab_id.to_string();

        // Inside the transaction, persistence order doesn't matter for
        // observers (they only see post-COMMIT state). Persist dest
        // first anyway to keep the function flow obvious if the txn
        // wrapper is ever removed. Skip source update entirely when
        // it's becoming empty — go straight to delete.
        tx.update(&mut dest_ws)?;
        if source_now_empty {
            tracing::info!(source_ws = %source_ws_id, "[dnd] deleting empty tear-off workspace");
            tx.delete::<Workspace>(source_ws_id)?;
        } else {
            tx.update(&mut source_ws)?;
        }

        tracing::info!(
            tab_id = %tab_id,
            dest_ws = %dest_ws_id,
            insert_at = %insert_at,
            was_pinned = %was_pinned,
            "[dnd] restore_torn_off_tab complete"
        );
        Ok(())
    })
}

/// Tear off a tab into a new workspace.
/// Removes the tab from the source workspace and creates a new workspace
/// containing just that tab. Returns the new workspace.
/// The source workspace must have more than one tab.
pub fn tear_off_tab(
    store: &Store,
    tab_id: &str,
    source_ws_id: &str,
) -> Result<Workspace, StoreError> {
    tracing::info!(tab_id = %tab_id, source_ws = %source_ws_id, "[dnd] tear_off_tab");
    // Remove tab from source workspace
    let mut source_ws = store.must_get::<Workspace>(source_ws_id)?;
    let total_tabs = source_ws.tabids.len() + source_ws.pinnedtabids.len();
    if total_tabs <= 1 {
        tracing::warn!(tab_id = %tab_id, total_tabs = %total_tabs, "[dnd] tear_off_tab blocked: last tab");
        return Err(StoreError::Other(
            "cannot tear off last tab from workspace".to_string(),
        ));
    }
    source_ws.tabids.retain(|id| id != tab_id);
    source_ws.pinnedtabids.retain(|id| id != tab_id);
    if source_ws.activetabid == tab_id {
        let new_active = source_ws
            .tabids
            .first()
            .or(source_ws.pinnedtabids.first())
            .cloned()
            .unwrap_or_default();
        tracing::info!(old_active = %tab_id, new_active = %new_active, "[dnd] switching active tab after tear-off");
        source_ws.activetabid = new_active;
    }
    store.update(&mut source_ws)?;

    // Create a new workspace with the tab
    let mut new_ws = Workspace {
        oid: Uuid::new_v4().to_string(),
        name: String::new(),
        tabids: vec![tab_id.to_string()],
        pinnedtabids: vec![],
        activetabid: tab_id.to_string(),
        meta: MetaMapType::new(),
        ..Default::default()
    };
    store.insert(&mut new_ws)?;

    tracing::info!(tab_id = %tab_id, new_ws = %new_ws.oid, "[dnd] tear_off_tab complete");
    Ok(new_ws)
}