/**
 * SQLite 存储（任务 A3.7，依据 ADR-0007 与决策 D16）。
 *
 * - 驱动用 Node 内置 node:sqlite：零原生依赖，不需要为 Electron ABI 重编译
 * - 时间统一存整数毫秒，主键由应用侧生成（ADR-0007 两条约定）
 * - 表按 ADR-0008 的「平台库」建；审计、待确认动作、桌面授权三组等各自功能落地时再加
 */
import { mkdirSync } from 'node:fs';
import { dirname } from 'node:path';
import { DatabaseSync } from 'node:sqlite';

export type Database = DatabaseSync;

const MIGRATIONS: Array<{ version: number; sql: string }> = [
  {
    version: 1,
    sql: `
      create table if not exists projects (
        project_id text primary key,
        name text not null,
        status text not null,
        writable integer not null default 1,
        created_at integer not null
      );
      create table if not exists sessions (
        session_id text primary key,
        project_id text,
        scope text not null,
        status text not null,
        title text not null,
        owner_user_id text not null,
        owner_tenant_id text not null,
        owner_display_name text not null,
        owner_client_kind text not null,
        created_at integer not null
      );
      create index if not exists idx_sessions_project on sessions(project_id, created_at);
      create table if not exists messages (
        message_id text primary key,
        session_id text not null,
        role text not null,
        text text not null,
        ts integer not null
      );
      create index if not exists idx_messages_session on messages(session_id, ts);
      create table if not exists idempotency_keys (
        idempotency_key text primary key,
        session_id text not null,
        message_id text not null,
        run_id text not null,
        created_at integer not null
      );
    `,
  },
  {
    version: 2,
    sql: `
      create table if not exists context_checkpoints (
        session_id text primary key,
        summary text not null,
        summary_source_ids text not null,
        included_message_ids text not null,
        last_message_id text,
        pinned text not null default '[]',
        estimated_chars integer not null default 0,
        updated_at integer not null
      );
    `,
  },
];
export function openDatabase(path: string): Database {
  if (path !== ':memory:') mkdirSync(dirname(path), { recursive: true });
  const db = new DatabaseSync(path);
  try {
    db.exec('pragma journal_mode = WAL');
  } catch {
    /* 内存库不支持 WAL */
  }
  db.exec('pragma foreign_keys = ON');
  migrate(db);
  return db;
}

export function migrate(db: Database): void {
  // 先建迁移表本身，否则第一次检查版本号就会报 no such table
  db.exec('create table if not exists schema_migrations (version integer primary key, applied_at integer not null)');
  for (const migration of MIGRATIONS) {
    const applied = db.prepare('select version from schema_migrations where version = ?').get(migration.version);
    if (applied) continue;
    db.exec(migration.sql);
    db.prepare('insert into schema_migrations (version, applied_at) values (?, ?)').run(migration.version, Date.now());
  }
}