import { Database } from "bun:sqlite";
import { mkdirSync } from "fs";
import path from "path";

let dbInstance: Database | null = null;

function migrate(database: Database) {
  database.run(`
    CREATE TABLE IF NOT EXISTS snippets (
      id INTEGER PRIMARY KEY AUTOINCREMENT,
      title TEXT,
      body TEXT NOT NULL DEFAULT '',
      sort_order INTEGER NOT NULL DEFAULT 0,
      created_at TEXT NOT NULL,
      updated_at TEXT NOT NULL
    );
  `);
  database.run(`
    CREATE TABLE IF NOT EXISTS tags (
      id INTEGER PRIMARY KEY AUTOINCREMENT,
      name TEXT NOT NULL UNIQUE COLLATE NOCASE
    );
  `);
  database.run(`
    CREATE TABLE IF NOT EXISTS snippet_tags (
      snippet_id INTEGER NOT NULL REFERENCES snippets(id) ON DELETE CASCADE,
      tag_id INTEGER NOT NULL REFERENCES tags(id) ON DELETE CASCADE,
      PRIMARY KEY (snippet_id, tag_id)
    );
  `);
  database.run(`
    CREATE TABLE IF NOT EXISTS tag_tree_nodes (
      id INTEGER PRIMARY KEY AUTOINCREMENT,
      name TEXT NOT NULL UNIQUE COLLATE NOCASE,
      parent_id INTEGER REFERENCES tag_tree_nodes(id) ON DELETE CASCADE,
      color TEXT,
      label_prefix TEXT
    );
  `);
  try {
    database.run(`ALTER TABLE tag_tree_nodes ADD COLUMN label_prefix TEXT`);
  } catch {
    /* Spalte existiert bereits */
  }
  database.run(`CREATE INDEX IF NOT EXISTS idx_tag_tree_parent ON tag_tree_nodes(parent_id);`);
  database.run(`CREATE INDEX IF NOT EXISTS idx_snippets_updated ON snippets(updated_at);`);
}

export function getDb(): Database {
  if (dbInstance) return dbInstance;
  const dir = path.join(process.cwd(), "data");
  mkdirSync(dir, { recursive: true });
  const file = path.join(dir, "notes.sqlite");
  dbInstance = new Database(file);
  dbInstance.run("PRAGMA journal_mode = WAL;");
  dbInstance.run("PRAGMA foreign_keys = ON;");
  migrate(dbInstance);
  return dbInstance;
}