/**
 * MessageStore — manages token tracking and subtask mutations.
 *
 * Extracted from chatStore.ts as part of the structured refactor (Phase 3).
 *
 * Design note: The `messages[]` array stays in chatStore because
 * `sendMessage` and `initStreamListener` use Zustand's `set((s) => ...)`
 * pattern for high-frequency streaming deltas (dozens of updates per second).
 * Moving messages out would force every streaming callback through
 * `getState().updateMessage()` — adding overhead and breaking the
 * producer-writes, consumer-reads separation that Zustand excels at.
 *
 * This store owns:
 *   - Token usage counters (totalInputTokens, totalOutputTokens)
 *   - Subtask mutation helpers (addSubtask, updateSubtask)
 *
 * Messages are read from chatStore by consumers that need them.
 *
 * @see docs/superpowers/specs/2026-04-02-chatstore-refactor-design.md §3.3
 */

import { create } from 'zustand';
import type { Subtask } from '../../components/ai';

// ---------------------------------------------------------------------------
// State interface
// ---------------------------------------------------------------------------

export interface MessageState {
  totalInputTokens: number;
  totalOutputTokens: number;

  // Token tracking
  addTokenUsage: (inputTokens: number, outputTokens: number) => void;
  getTotalTokens: () => { input: number; output: number; total: number };
  resetTokenUsage: () => void;

  // Subtask mutations (delegated to chatStore internally)
  addSubtask: (messageId: string, task: Subtask) => void;
  updateSubtask: (messageId: string, taskId: string, updates: Partial<Subtask>) => void;
}

// ---------------------------------------------------------------------------
// Internal reference to chatStore for message mutations
// ---------------------------------------------------------------------------
let _chatStore: {
  getState: () => {
    addSubtask: (messageId: string, task: Subtask) => void;
    updateSubtask: (messageId: string, taskId: string, updates: Partial<Subtask>) => void;
  };
} | null = null;

/**
 * Inject chatStore reference for subtask delegation.
 * Called by chatStore during initialization to avoid circular imports.
 */
export function setMessageStoreChatStore(store: typeof _chatStore): void {
  _chatStore = store;
}

// ---------------------------------------------------------------------------
// Store
// ---------------------------------------------------------------------------

export const useMessageStore = create<MessageState>()((set, get) => ({
  totalInputTokens: 0,
  totalOutputTokens: 0,

  addTokenUsage: (inputTokens: number, outputTokens: number) =>
    set((state) => ({
      totalInputTokens: state.totalInputTokens + inputTokens,
      totalOutputTokens: state.totalOutputTokens + outputTokens,
    })),

  getTotalTokens: () => {
    const { totalInputTokens, totalOutputTokens } = get();
    return {
      input: totalInputTokens,
      output: totalOutputTokens,
      total: totalInputTokens + totalOutputTokens,
    };
  },

  resetTokenUsage: () =>
    set({ totalInputTokens: 0, totalOutputTokens: 0 }),

  addSubtask: (messageId: string, task: Subtask) => {
    if (_chatStore) {
      _chatStore.getState().addSubtask(messageId, task);
    }
  },

  updateSubtask: (messageId: string, taskId: string, updates: Partial<Subtask>) => {
    if (_chatStore) {
      _chatStore.getState().updateSubtask(messageId, taskId, updates);
    }
  },
}));