import type { Sql } from '../db.js';

export interface AgentSnapshot {
  id: string;
  session_id: string;
  chat_id: string;
  model: string;
  agent: string | null;
  mode: string | null;
  turn_number: number;
  messages: unknown[];
  tool_states: unknown[];
  created_at: string;
  updated_at: string;
}

/** Save or update the agent snapshot for a chat (UPSERT). */
export async function saveAgentSnapshot(sql: Sql, chatId: string, data: {
  session_id: string;
  model: string;
  agent?: string | null;
  mode?: string | null;
  turn_number: number;
  messages: unknown[];
  tool_states?: unknown[];
}): Promise<void> {
  await sql`
    INSERT INTO agent_snapshots (session_id, chat_id, model, agent, mode, turn_number, messages, tool_states, updated_at)
    VALUES (${data.session_id}, ${chatId}, ${data.model}, ${data.agent ?? null}, ${data.mode ?? null}, ${data.turn_number}, ${sql.json(data.messages as never)}, ${sql.json((data.tool_states ?? []) as never)}, clock_timestamp())
    ON CONFLICT (chat_id)
    DO UPDATE SET
      model = EXCLUDED.model,
      agent = EXCLUDED.agent,
      mode = EXCLUDED.mode,
      turn_number = EXCLUDED.turn_number,
      messages = EXCLUDED.messages,
      tool_states = EXCLUDED.tool_states,
      updated_at = clock_timestamp()
  `;
}

/** Load the agent snapshot for a chat. Returns null if no snapshot exists. */
export async function loadAgentSnapshot(sql: Sql, chatId: string): Promise<AgentSnapshot | null> {
  const rows = await sql<AgentSnapshot[]>`SELECT * FROM agent_snapshots WHERE chat_id = ${chatId}`;
  return rows[0] ?? null;
}

/** Delete the agent snapshot for a chat (call when session ends). */
export async function deleteAgentSnapshot(sql: Sql, chatId: string): Promise<void> {
  await sql`DELETE FROM agent_snapshots WHERE chat_id = ${chatId}`;
}