// Tiny in-app event bus for session metadata changes that need to propagate
// across hooks (e.g. AI rename arriving via WS in the session view needs to
// also refresh the sidebar's session list).

import type { Chat, ErrorReason, Project, Session } from '@/api/types';
import type { Attachment } from '@/lib/attachments';

export interface SessionRenamedEvent {
  type: 'session_renamed';
  session_id: string;
  name: string;
}

export interface ProjectCreatedEvent {
  type: 'project_created';
  project: Project;
}

export interface ProjectDeletedEvent {
  type: 'project_deleted';
  project_id: string;
}

export interface SessionCreatedEvent {
  type: 'session_created';
  session: Session;
  project_id: string;
}

export interface SessionDeletedEvent {
  type: 'session_deleted';
  session_id: string;
  project_id: string;
}

export interface SessionUpdatedEvent {
  type: 'session_updated';
  session_id: string;
  project_id: string;
  name: string;
  updated_at: string;
}

export interface SessionWorkspaceUpdatedEvent {
  type: 'session_workspace_updated';
  session_id: string;
  workspace_panes: import('@/api/types').WorkspacePane[];
}

export interface SessionLoadedEvent {
  type: 'session_loaded';
  session_id: string;
  project_id: string;
}

export interface OpenFileInBrowserEvent {
  type: 'open_file_in_browser';
  path: string; // project-relative
}

export interface AttachChatFileEvent {
  type: 'attach_chat_file';
  attachment: Omit<Attachment, 'id'>;
}

export interface OpenChatInActivePaneEvent {
  type: 'open_chat_in_active_pane';
  chat_id: string;
}

// Client-side event fired by the sidebar Settings button when a session is
// currently mounted. Session.tsx subscribes and calls
// panesHook.toggleSettingsPane() (open on first click, close on second).
// Sidebar handles the no-session case by navigating to /settings directly.
export interface OpenSettingsPaneEvent {
  type: 'open_settings_pane';
}

export interface SessionArchivedEvent {
  type: 'session_archived';
  session_id: string;
  project_id: string;
}

export interface ChatCreatedEvent {
  type: 'chat_created';
  chat: Chat;
  session_id: string;
}

export interface ChatUpdatedEvent {
  type: 'chat_updated';
  chat_id: string;
  session_id: string;
  name: string | null;
  updated_at: string;
}

export interface ChatArchivedEvent {
  type: 'chat_archived';
  chat_id: string;
  session_id: string;
}

export interface ChatUnarchivedEvent {
  type: 'chat_unarchived';
  chat: Chat;
}

export interface ChatDeletedEvent {
  type: 'chat_deleted';
  chat_id: string;
  session_id: string;
}

export interface ProjectArchivedEvent {
  type: 'project_archived';
  project_id: string;
}

export interface ProjectUnarchivedEvent {
  type: 'project_unarchived';
  project: Project;
}

export interface ProjectUpdatedEvent {
  type: 'project_updated';
  project_id: string;
  name: string;
}

// v1.8 mobile-tabs: broadcast on user channel from inference.ts so any device
// subscribed sees a chat working/idle/error. Frontend stores per-chat; panes
// derive their dot from pane.activeChatId.
// v1.8.2: optional `reason` carries a machine-readable code when status is
// 'error'. UI prefers reason for inline error rendering.
export interface ChatStatusEvent {
  type: 'chat_status';
  chat_id: string;
  status: 'streaming' | 'tool_running' | 'waiting_for_input' | 'idle' | 'error';
  at: string;
  reason?: ErrorReason;
}

export type SessionEvent =
  | SessionRenamedEvent
  | ProjectCreatedEvent
  | ProjectDeletedEvent
  | SessionCreatedEvent
  | SessionDeletedEvent
  | SessionUpdatedEvent
  | SessionWorkspaceUpdatedEvent
  | SessionLoadedEvent
  | OpenFileInBrowserEvent
  | AttachChatFileEvent
  | OpenChatInActivePaneEvent
  | OpenSettingsPaneEvent
  | SessionArchivedEvent
  | ChatCreatedEvent
  | ChatUpdatedEvent
  | ChatArchivedEvent
  | ChatUnarchivedEvent
  | ChatDeletedEvent
  | ProjectArchivedEvent
  | ProjectUnarchivedEvent
  | ProjectUpdatedEvent
  | ChatStatusEvent;
type Listener = (event: SessionEvent) => void;

const listeners = new Set<Listener>();

export const sessionEvents = {
  emit(event: SessionEvent) {
    for (const listener of listeners) {
      try {
        listener(event);
      } catch {
        // swallow — one bad listener shouldn't break others
      }
    }
  },
  subscribe(listener: Listener): () => void {
    listeners.add(listener);
    return () => {
      listeners.delete(listener);
    };
  },
};