import Database from 'better-sqlite3';
import { drizzle } from 'drizzle-orm/better-sqlite3';
import { app } from 'electron';
import path from 'node:path';
import * as schema from './schema';

// SQL to create all tables if they don't exist (non-destructive push strategy)
const MIGRATION_SQL = `
  CREATE TABLE IF NOT EXISTS clients (
    id TEXT PRIMARY KEY,
    parent_id TEXT,
    name TEXT NOT NULL,
    industry TEXT,
    created_at INTEGER NOT NULL
  );

  CREATE TABLE IF NOT EXISTS projects (
    id TEXT PRIMARY KEY,
    client_id TEXT,
    name TEXT NOT NULL,
    status TEXT NOT NULL DEFAULT 'active',
    ai_summary TEXT,
    created_at INTEGER NOT NULL
  );

  CREATE TABLE IF NOT EXISTS tasks (
    id TEXT PRIMARY KEY,
    project_id TEXT,
    title TEXT NOT NULL,
    description TEXT,
    status TEXT NOT NULL DEFAULT 'todo',
    priority TEXT NOT NULL DEFAULT 'medium',
    assignee TEXT,
    due_date INTEGER,
    is_ai_suggested INTEGER NOT NULL DEFAULT 0,
    is_approved INTEGER NOT NULL DEFAULT 1,
    created_at INTEGER NOT NULL
  );

  CREATE TABLE IF NOT EXISTS checkpoints (
    id TEXT PRIMARY KEY,
    project_id TEXT NOT NULL,
    title TEXT NOT NULL,
    date INTEGER NOT NULL,
    is_ai_suggested INTEGER NOT NULL DEFAULT 0,
    is_approved INTEGER NOT NULL DEFAULT 0,
    created_at INTEGER NOT NULL
  );

  CREATE TABLE IF NOT EXISTS notes (
    id TEXT PRIMARY KEY,
    project_id TEXT,
    title TEXT NOT NULL,
    content TEXT NOT NULL DEFAULT '',
    created_at INTEGER NOT NULL,
    updated_at INTEGER NOT NULL
  );

  CREATE TABLE IF NOT EXISTS task_comments (
    id TEXT PRIMARY KEY,
    task_id TEXT NOT NULL,
    author TEXT NOT NULL,
    content TEXT NOT NULL,
    created_at INTEGER NOT NULL
  );
`;

type DbInstance = ReturnType<typeof drizzle<typeof schema>>;

let dbInstance: DbInstance | null = null;

export function initDb(): DbInstance {
  const userDataPath = app.getPath('userData');
  const dbPath = path.join(userDataPath, 'adiuva.db');

  const sqlite = new Database(dbPath);

  // Enable WAL mode for better concurrent read performance
  sqlite.pragma('journal_mode = WAL');

  // Run non-destructive migrations on every start
  sqlite.exec(MIGRATION_SQL);

  // Additive column migrations (SQLite has no ADD COLUMN IF NOT EXISTS)
  try { sqlite.exec('ALTER TABLE tasks ADD COLUMN is_ai_suggested INTEGER NOT NULL DEFAULT 0'); } catch { /* already exists */ }
  try { sqlite.exec('ALTER TABLE tasks ADD COLUMN is_approved INTEGER NOT NULL DEFAULT 1'); } catch { /* already exists */ }

  dbInstance = drizzle(sqlite, { schema });
  return dbInstance;
}

export function getDb(): DbInstance {
  if (!dbInstance) {
    throw new Error('Database not initialized. Call initDb() first.');
  }
  return dbInstance;
}