import type { User, Session } from 'better-auth/types';

/**
 * Central application state composable
 * Manages navigation context and critical app-level state
 * This is the single source of truth for "what am I viewing"
 */
export const useAppState = () => {
    // Current navigation context
    const activeAgentId = useState<string | null>('appState:activeAgentId', () => null);
    const activeTopicId = useState<string | null>('appState:activeTopicId', () => null);

    // User data
    const user = useState<User | null>('appState:user', () => null);
    const session = useState<Session | null>('appState:session', () => null);

    // Loading states
    const isInitializing = useState<boolean>('appState:isInitializing', () => true);
    const generationInProgress = useState<{ generationId: string } | null>('appState:generationInProgress', () => null);

    /**
     * Set the active agent and clear the topic
     */
    const setActiveAgent = (agentId: string | null | undefined) => {
        activeAgentId.value = agentId || null;
        // Clear topic when switching agents
        activeTopicId.value = null;
    };

    /**
     * Set the active topic
     */
    const setActiveTopic = (topicId: string | null | undefined) => {
        activeTopicId.value = topicId || null;
    };

    /**
     * Set user session data
     */
    const setUser = (userData: User | null) => {
        user.value = userData;
    };

    /**
     * Set session
     */
    const setSession = (sessionData: Session | null) => {
        session.value = sessionData;
    };

    /**
     * Mark initialization complete
     */
    const markInitialized = () => {
        isInitializing.value = false;
    };

    /**
     * Start a generation
     */
    const startGeneration = (generationId: string) => {
        generationInProgress.value = { generationId };
    };

    /**
     * End current generation
     */
    const endGeneration = () => {
        generationInProgress.value = null;
    };

    return {
        // State
        activeAgentId,
        activeTopicId,
        user,
        session,
        isInitializing,
        generationInProgress,

        // Actions
        setActiveAgent,
        setActiveTopic,
        setUser,
        setSession,
        markInitialized,
        startGeneration,
        endGeneration
    };
};