import type { MessageCost } from '@@/api/chat/types';
import { getUserSettings } from 'officerdb';
import { logger } from '@@/api/chat/logger';
import { sendClaudeCode, clearClaudeCodeSession } from './send-claude-code';

const DEFAULT_MODEL = 'claude-code';

type SendAndAwaitParams = {
  userId: number;
  email: string;
  username: string;
  prompt: string;
  context: string;
  contextId: string;
  model?: string;
};

type SendAndAwaitResult = {
  text: string;
  sessionId: string;
  model: string;
  cost: MessageCost;
};

// Per-session mutex to serialize concurrent prompts
const sessionLocks = new Map<string, Promise<void>>();

// Channel model overrides — survive session eviction/recreation
const channelModelOverrides = new Map<string, string>();

function buildSessionId(context: string, userId: number, contextId: string): string {
  return `channel-${context}-${userId}-${contextId}`;
}

async function getUserDefaultModel(userId: number): Promise<string | null> {
  try {
    const settings = await getUserSettings(userId);
    const chat = settings?.chat as Record<string, unknown> | undefined;
    return (chat?.defaultModel as string) || null;
  } catch {
    return null;
  }
}

export function getSessionModel(context: string, userId: number, contextId: string): string | null {
  return channelModelOverrides.get(buildSessionId(context, userId, contextId)) ?? null;
}

export function setSessionModel(context: string, userId: number, contextId: string, model: string): void {
  const sessionId = buildSessionId(context, userId, contextId);
  channelModelOverrides.set(sessionId, model);
  // Reset the Claude session so the next prompt starts fresh under the new model.
  clearClaudeCodeSession(sessionId);
  logger.info('Channel model override stored', { sessionId, model });
}

export async function sendAndAwait(params: SendAndAwaitParams): Promise<SendAndAwaitResult> {
  const { userId, context, contextId } = params;
  const sessionId = buildSessionId(context, userId, contextId);

  // Serialize per session — if two messages arrive at once, the second waits for the first.
  const existing = sessionLocks.get(sessionId) ?? Promise.resolve();
  let releaseLock: () => void;
  const lockPromise = new Promise<void>((resolve) => {
    releaseLock = resolve;
  });
  const chained = existing.then(() => lockPromise);
  sessionLocks.set(sessionId, chained);

  await existing;

  try {
    const override = channelModelOverrides.get(sessionId);
    let model = params.model ?? override ?? (await getUserDefaultModel(userId)) ?? DEFAULT_MODEL;
    // Claude-only: coerce any legacy non-Claude model preference to the Claude default.
    if (!model.startsWith('claude-code')) model = DEFAULT_MODEL;

    return await sendClaudeCode({
      userId: params.userId,
      email: params.email,
      username: params.username,
      prompt: params.prompt,
      sessionKey: sessionId,
      model,
    });
  } finally {
    releaseLock!();
    if (sessionLocks.get(sessionId) === chained) sessionLocks.delete(sessionId);
  }
}